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| ERRATUM Scottish Birds Vol 17.2 : The caption for the

| winning photograph in the SOC 1993 Photographic
) Competition should read Sooty Shearwater and not

_ Manx Shearwater. Apologies to Mary Macintyre for this
| error.

/

ae
670
54 S43

Brep °

SCOTTISH BIRDS

THE JOURNAL OF THE
SCOTTISH ORNITHOLOGISTS’ CLUB

Volume 1 PLctiai eS
1993-94 ue

Editor
A-M. SMOUT

Editorial Panel
D. JENKINS, J.B. NELSON AND P.J.B. SLATER

ISSN 0036 9144

Scottish Birds the official journal of the Scottish Ornithologists’ Club, publishes original
material relating to ornithology in Scotland. Papers and notes should be sent to The
Editor, Scottish Birds, 21 Regent Terrace, Edinburgh EH7 5BT.

Two issues of Scottish Birds are published each year, in June and December. Scottish
Birds is issued free to members of the Scottish Ornithologists’ Club, who also receive the
quarterly newsletter Scottish Bird News and the annual Scottish Bird Report.

The Scottish Ornithologists’ Club was formed in 1936 to encourage all aspects of
ornithology in Scotland. It has local branches which meet in Aberdeen, Ayr, the Borders,
Dumfries, Dundee, Edinburgh, Glasgow, Inverness, New Galloway, Orkney, St. Andrews,
Stiring, Stranraer and Thurso, each with its own programme of field meetings and winter
lectures. The Waterston Library at the Club’s headquarters at 21 Regent Terrace, Edin-
burgh EH7 5BT is one of the most comprehensive ornithological libraries in Scotland, and
is available for reference during office hours (Monday to Friday 0930 to 1630). A compre-
hensive stock of Scottish local bird reports is held at the headquarters and may be pur-
chased by mail order.

Published by the Scottish Ornithologists’ Club, 21 Regent Terrace Edinburgh EH7 5BT

Printed by MTM, 113-119 Glover Street, Perth PH2 OJE

SCOTTISH BIRDS
Contents of Volume 17 1993-1994

Number 1 (June 1993)

Page

Researcn Progress Reports

Research on mountain birds and their habitat.

D.B.A.Thompson and D.P. Whitfield. 1

A 20 year siudy of Kestrels in Ayrshire. G. Riddle. 9
Status of Pintail in the Orkney Islands. E.R.Meek. 14
Survey of Black Grouse leks in Perthshire. M.C.Robinson, D.Baines
and W.Mattingley. 20
Productivity of waterfowl breeding at Airthrey Loch, Stirling.
M.V.Beli. 27
Breeding numbers and breeding success of the Peregrine in
Shetland. 1961-1991. P.M.Ellis and J.D.Okill. 40
Spring passage of Pomarine Skuas off Shetland in May 1992.
H.R.Harrop, M.Mellor and D.Suddaby. 50
Short Notes

Kestrels feecing on road casualties. R.C. and A.P.Dickson. 56

Hunting times by Merlins in winter. R.C.Dickson. 56

Hunting associations between Merlins and Hen Harriers

in winter. R.C.Dickson. 58

Behaviour of Herring Gulls feeding on turnips. R.Hewson. 59
Rare Migrants

Solitary Sandpiper on Fair Isle : a third Scottish record.

Roger Riddington. 62

Kumlien’s Gull in Shetland - the fourth Scottish record.

H.Harrop and M.Mellor. 63
Obituary

Dr William Serle O.B.E. (1912-1992). R.Y.McGowan. 66
Correspondence

Further aberrant plumage in Peregrine. M.Trubridge. 68

Fulmar oiling of Peregrines. C.J.Booth. 69

Attacks by Great Skuas on an Eider and a Mute Swan.
J.Holloway. 70

The Fair Isle Baillon’s Crake and other corpses.
D. Suddaby.

ltems of Scottish interest. W.G.Harper

European joumals in the Waterston Library. M.H.Murphy.

Number 2 (December 1993)

Moult flock surveys indicate a continued decline in the Shetland
Eider population, 1984-92. M.Heubeck.

Population fluctuations and mortality of Mute Swans on an Orkney
loch system in relation to a Canadian Pondweed growth cycle.
E.R.Meek.

The Scottish Mute Swan census, 1990. A.W. & L.M.Brown.

Short Notes

Unusual behaviour of Black-necked Grebes. A.C.Ramage.

Eider Ducks eating flatfish. B.M. & E.M.Hobson.

Hen Harriers systematically testing flocks of Ring-necked
Pheasants. R.C.Dickson.

Buzzards copulating just before roosting. R.C.Dickson.

Comment and Reply
What is the scale of seabird movement across central
Scotland? C.J.Henty.
Reply to Henty. R.D.Murray.

Research Index.
Items of Scottish Interest. W.G.Harper.

European Joumals in the Waterston Library. M.Murphy.

Number 3 (June 1994)

Research Progress Reports
The density and species diversity of songbird populations
in northern upland spruce plantations. |.J.Patterson &
J.G.Ollason.
Research on Capercaillie and their habitat. R.Moss.

70
v2

74

77

85
94

104
105

105
106

108
110

ie
121

124

125
127

Prey remains at Osprey nests in Tayside and Grampian, 1987-1993
D.N.Carss & K.Brockie.
Scottish List. R.W. Forrester.

Short Notes
Mating times of Merlin. R.C.Dickson.
Merlin chick killed by adder. G.Shaw.
Site fidelity of Jack Snipe on migration? D.G.Andrew
First breeding records of the Mandarin in Argyll.
S.J.Petty & D.I.K.Anderson.
Discovery of the first British clutch of Slavonian Grebe
eggs in a museum collection. H.A.McGhie.
Rook flight-line across the Firth of Forth. H.E.M.Dott.
The diet of nestling Corn Buntings on North Uist -
insects not grains. |.R.Hartley & D.L.J.Quicke.

Correspondence
Pink and polluted Peregrines. W.R.P.Bourne.
Spring passage of Skuas in the Outer Hebrides.
D.G.Andrew.

Rare Migrants
Semi-palmated Sandpiper on Stronsay. J.Holloway.
Pallid Harrier in Shetland; second Scottish Record.
H.Harrop. ;
Cetti’s Warbler in Edinburgh: a new bird for Scotland.
|.J.Andrews.

Obituary
Dr W.J. Eggeling CBE FRSE. J.Amott.

Items of Scottish Interest. W.G.Harper.
European Joumals in the Waterston Library. M.Murphy.

Errata 17.2 Colour plates,
17.2 Page 104.

Number 4 (December 1994)

Research Progress Reports

A ten year study of Barn Owl conservation in conifer forests.

G.Shaw.

174

177

178

181

184

186

187

Changes in breeding numbers of Kittiwakes in Shetland, 1981-
1994. M.Heubeck & R.M.Mellor.

Densities of breeding Magpies and Carrion Crows in south-east
Scotland in 1992-93. H.E.M.Dott.

The breeding performance of Ravens from a sample of nesting
territories in Shetland during 1984-1993. P.M.Ellis, J.D.Okill,
G.W.Petne & D.Suddaby.

Breeding seasons and nesting success of Snow Buntings in
north-east Scotland. R.D.Smith & M.Marquiss.

Short Notes
Kestrel predation of Ring Ouzel nestling. D.Arthur.
Interaction between Red Grouse and Osprey. A.Mee.
Merlin follows prey underground. J.K.Craib.
Sparrowhawk exploiting a Sand Martin colony. J.G.Young.
A successful artificial Sand Martin banking. R.T.Smith.

Correspondence
The influence of the weather on seabird movements across
Scotland. W.R.P.Bourne.

Items of Scottish Interest. W.G.Harper.
European Joumals in the Waterston Library. M.Murphy.

Errate Vol 17.3

Supplements:
SCOTTISH BIRD REPORT 1990 No. 23. Edited by Ray Murray
(December 1992)

Editorial

Acknowledgements

Introduction

Species List

Crossbills in Scotland in 1990/91 - An Invasion Year

by David C Jardine

Notice to Contributors

The Scottish Birds Records Committee

Local Bird Report Areas, SOC Recorders and Local Bird Reports

192

205

ale
223
235
235
236

236
237

239

240

243

246

SCOTTISH BIRD REPORT 1991 No. 24. Edited by Ray Murray
(July 1993)

Editorial

Introduction

Abbreviation

Notice to Contributors

Acknowledgments

Letter: Bar-headed Geese in Sweden by veff Price

Scottish Birds Records Committee

Species List for 1991

Local Bird Report Areas, SOC Recorders and Local Bird Reports

SCOTTISH BIRD REPORT 1992 No. 25. Edited by Ray Murray
Assisted by Paul Speak & David Kelly
(July 1994)

Editorial

Introduction

Abbreviations

Notice to Contributors

Acknowledgements

Scottish Birds Records Committee

Species List for 1992

Publications affecting the Scottish List

Local Bird Report Areas, SOC Recorders and Local Bird Reports

ba |

NON

OINnNonnoast fw

=—-ONO Of FW

INDEX TO VOLUME 17
Compiled by W.G.Harper

Species mentioned in general articles and in the species lists of Scottish Bird Reports are
not indexed. The Scottish Bird Reports for 1990-92 (nos. 23-25) are treated as supple-
ments to Volume 17, but with separate pagination, and are included in the Index.

Accipiter nisus: 236

Aix galenculata: 164

Anas acuta: 14

Anas penelope: 88

ANDERSON, D.I.K. see PETTY, S.J. 164

ANDREW, D.G. Site fidelity of Jack Snipe on migration? 163
ANDREWS, I.J. Cetti’s Warbler in Edinburgh. 177

Argyll: First breeding records of Mandarin. 164

ARNOTT, J. Obituary of Dr W.J. Eggeling CBE FRSE. 178
ARTHUR, D. Kestrel predation of Ring Ouzel nestling. 235
Ayrshire: Study of Kestrels. 9

Aythya ferina: 88

Aythya fuligula: 88

BAINES, D. see ROBINSON, M.C. 20

BELL, M.V. Productivity of waterfowl breeding at Airthrey Loch, Stirling. 27
BOOTH, C.J.: Correspondence 69

BROCKIE, K. see CARSS, D.N. 132

BROWN, A.W. & BROWN, L.M. The Scottish Mute Swan census 1990. 94
BROWN, L.M. see BROWN, A.W. 94

Bunting, Corn: Diet of nestlings on North Uist. 169

Bunting, Snow: in north-east Scotland. 223

Buteo buteo: 105

Buzzard: 105

Calidris pusilla: 173

Capercaillie: researchon. 127

CARSS, D.N. & BROCKIE, K. Prey remains at Osprey nests in Tayside and Grampian,
1987-93. 132 |

Cettia cetti: 176

Charadrius morinellus: 1

Circus cyaneus: 58, 104

Circus macrourus: 174

Correspondence: ANDREW, D.G. Spring passage of Skuas in the Outer Hebrides. 172
BOOTH, C.J. Fulmar oiling of Peregrines. 69
BOURNE, W.R.P. Pink and polluted Peregrines. 171

BOURNE, W.R.P. Seabird movements across central Scotland. 239
HENTY, C.J. Seabird movements across central Scotland. 110
HOLLOWAY, J. Attacks by Great Skuas on Eider and Mute Swan. 70
MURRAY, R.D. Seabird movements across central Scotland. 110
PRICE, J. Bar-headed Geese in Sweden: SBR 1991: 5
SUDDABY, D. The Fair Isle Baillon’s Crake and other corpses. 70
TRUBRIDGE, M. Further aberrant plumage in Peregrine. 68

Corvus corax: 212

Corvus corone: 205

Corvus frugilegus: 168

CRAIB, J.K. Merlin follows prey underground. 236

Crow, Carrion: density of breeding in southeast Scotland. 205

Cygnus cygnus: 87

Cygnus olor: 69, 85, 93

DICKSON, A.P. see DICKSON, R.C. 56

DICKSON, R.C. Hunting times of Merlins in winter. 56

DICKSON, R.C. Hunting associations between Merlins and Hen Harriers in winter. 58

DICKSON, R.C. Hen Harriers systematically testing flocks of Ring-necked Pheasants.
105

DICKSON, R.C. Buzzards copulating just before roosting. 106

DICKSON, R.C. Mating times of Merlin. 160

DICKSON, R.C. & DICKSON, A.P. Kestrels feeding on roadside casualties. 56

DOTT, H.E.M. Rook flight-line across Firth of Forth. 168

DOTT, H.E.M. Densities of breeding Magpies and Carrion Crows in south-east
Scotland in 1992-93. 205

Dotterel: population ecology and conservation. 1

Duck, Mandarin: First breeding records in Argyll. 164

Edinburgh: Cetti’s Warbler. 177

Eider: eating flat fish. 105

Eider: population decline in Shetland. 77

ELLIS, P.M. & OKILL, J.D. Breeding numbers and success of the Peregrine in Shetland.
40

ELLIS, P.M., OKILL, J.D., PETRIE, G.W. & SUDDABY, G. The breeding performance of
Ravens from a sample of nesting territories in Shetland during 1984-1993. 212

Errata: SB17:3 p.176 In “Summary” Circus macrourus not macronus

Errata: 186, 246

European journals in the Waterston Library. 74, 124, 184, 243

Falco columbarius: 56, 58, 160, 161, 236

Falco peregrinus: 40, 68, 69, 171

Falco tinnunculus: 9, 56, 235

FORRESTER, R.W. (for Scottish Birds Records Committee): Scottish Bird List. 146

Fulmar: oiling of Peregrines. 69

Grampian: Prey remains at Osprey nests. 132

Grebe, Black-necked: unusual behaviour. 104

Grebe, Slavonian: First British clutch of eggs ina museum collection. 167
Grouse, Black: Perthshire. 20

Grouse, Red: interaction with Osprey. 235

Gulls, Herring: 59

HARPER, W.G. Publications of Scottish ornithological interest. 72, 121, 181,240

Harrier, Hen: 58, 105

Harrier, Pallid: 174

HARROP, H.R. Pallid Harrierin Shetland. 174

HARROP, H.R. & MELLOR, M. Kumlien’s Gull in Shetland. 63

HARROP, H.R., MELLOR, M. & SUDDABY, D. Spring passage of Pomarine Skuas off
Shetland. 50

HARTLEY, I.R. & QUICKE, D.L.J. The diet of nestling Corn Buntings on North Uisi. 169

Hebrides, Outer: Diet of nestling Corn Buntings on North Uist. 169

Hebrides, Outer: Spring passage of Skuas. 172

HENTY, C.J. Seabird movements across central Scotland. 108

HEUBECK, M. Moult flock surveys indicate a continued decline in the Shetland Eider
population... 1984-92. 77

HEUBECK, M. & MELLOR, R.M. Changes in breeding numbers of Kittiwakesin Shetland
1981-1994. 192

HEWSON, R. Behaviour of Herring Gulls feeding on turnips. 59

HOBSON, B.M. & HOBSON, E.M. Eider Ducks eating flat fish. 105

HOBSON, E.M. see HOBSON, B.M. 105

HOLLOWAY, J. Correspondence 70

HOLLOWAY, J. Semi-palmated Sandpiper in Orkney. 173

Items of Scottish interest: 72, 121, 181, 240

JARDINE, D.C. Crossbills in Scotland 1990 - an invasion year. Scottish Bird Report.1990:
65

Kestrel: Ayrshire. 9

Kestrel: feeding on road casualties. 56
Kestrel: predation of Ring Ouzel nestling. 235
Kittiwake: numbers in Shetland. 192

Lagopus lagopus: 235

Larus argentatus: 59

Larus glaucoides/hyperboreus: 63
Lymnocryptes minimus: 163

MCGHIE, H.A. Discovery of first British clutch of Slavonian Grebe eggs in a museum
collection. 167
MCGOWAN, R.Y. Obituary of Dr William Serle. 66

Magpie: density of breeding in south-east Scotland. 205

Mandarin: 164

MARQUISS, M. see SMITH, R.D. 223

Martin, Sand: 236, 237

MATTINGLEY, W. see ROBINSON, M.C. 20

MEE, A. Interaction between Red Grouse and Osprey. 235

MEEK, E.R. Population fluctuations and mortality of Mute Swans on an Orkney loch
system in relation to a Canadian Pondweed growth cycle. 85

MEEK, E.R. Status of the Pintail in the Orkney Islands. 14

MELLOR, M. see HARROP, H.R. 50, 63

MELLOR, R.M. see HEUBECK, M. 192

Merlins: 56, 58, 160, 162, 236

Miliaria calandra: 169

MOSS, R. Research on Capercaillie and their habitat. 127

MURPHY, M.H. European journals in the Waterston Library, 74, 124, 184

MURRAY, R.D. Seabird movements across central Scotland. 110

North-east Scotland: Snow Buntings. 223

Obituary: Dr W.J. EGGELING: 178

Obituary: Dr William SERLE: 66

OKILL, J.D. see ELLIS, P.M. 40, 212

OLLASON, J.G. see PATTERSON, I.J. 125
Orkney: Mute Swans and Canadian Pondweed. 85
Orkney: Semi-palmated Sandpiper on Stronsay. 173
Orkney: status of Pintail. 14

Osprey: Prey remains atnests. 132

Osprey: interaction with Red Grouse. 235

Ouzel, Ring: predation by Kestrel. 235

Owl, Bam: Conservation in conifer forests. 187

Pandion haliaetus: 132, 235

Papers and Reports of Scottish Ornithological interest: 72, 121, 181, 240

PATTERSON, I.J. & OLLASON, J.G. The density and species diversity of songbird
populations in northern upland spruce plantations. 125

Peregrine: aberrant plumage. 68, 171

Peregrine: oiling by Fulmar. 69

Peregrine: Shetland. 40

Perthshire: Black Grouse. 20

PETRIE, G.W. see ELLIS, P.M. 212

PETTY, S.J. & ANDERSON, D.I.K. First breeding records of the Mandarin in Argyll. 164
Phasianus colchicus: 104

Pheasants, Ring-necked: Harried by Hen Harriers. 105

Pica pica: 205

Pintail: in Orkney. 14

Plectrophenax nivalis: 223

Podiceps auritus: 166

Podiceps nigricollis: 103

Populations: Songbirds. 125
PRICE, J. Bar-headed Geese in Sweden: Letterin SBR 1991: 5

RAMAGE, A.C. Unusual behaviour of Black-necked Grebes. 104 (and see Errata: 186)
Ranty reports: Baillon’s Crake: 70
Cetti’s Warblerin Edinburgh: 177
Kumlien’s Gull: 63
Pallid Harrier in Shetland: 174
Semi-palmated Sandpiper on Stronsay: 173
Solitary Sandpiper: 62
Raven: Breeding performance in Shetland. 212
Research Index: fieldwork and research at Scottish universities, etc.
Aberdeen Univ 111 RSPB 113

Edinburgh Univ 111 St Andrews Univ 116
Glasgow Univ. 112 Scot. Assoc. Marine Science 116
ITE Banchory 113 Scot. Nat. Heritage 116
JNCC Seabirds Team 113 Stirling Univ 118

Research Progress Reports: 1, 9, 125, 127, 187

RIDDINGTON, R. Solitary Sandpiper on Fair Isle. 62

RIDDLE, G.S. A 20-year study of Kestreis in Ayrshire. 9

Ripana riparia: 236, 237

Rissa tridactyla; 107, 192

ROBINSON, M.C., BAINES, D. & MATTINGLEY, W. Survey of Black Grouse leks in
Perthshire. 20

Rook: Flight line across Firth of Forth. 168

Sandpiper, Solitary, on Fairlsle. 62

Scottish Birds Records Committee: Scottish Bird List. 146

SHAW, G. Merlin chick killed by adder. 162

SHAW, G. A ten year study of Barn Owl conservation in conifer forests. 187
Shetland: Eider population decline. 77

Shetland: Kittiwake numbers. 192

Shetland: Kumlien’s Gull. 63

Shetland: Pallid Harrier. 174

Shetland: Peregrine numbers. 40

Shetland: Raven’s breeding performance. 212

Shetland: Skuas, Pomarine. 50

Shetland: Solitary Sandpiper on Fairlsle. 62

Skua, Great: attacks on Eider and Mute Swan. 70

Skua, Pomarine: Shetland. 50

Skuas: Spring passage in Outer Hebrides. 172

SMITH, R.D. & MARQUISS, M. Breeding seasons and nesting success of Snow Buntings
in north-east Scotland. 223

SMITH, R.T. A successful artificial Sand Martin Banking. 237
Snipe, Jack: 163

Somateria mollissima.: 69,77, 104

South-east Scotland: Densities of breeding Magpies and Crows. 205
Sparrowhawk: 236

Stercorarius pomarinus: 50

Stercoranus spp.: 69, 107, 109, 172, 192

Stirlingshire: Waterfowl. 27

SUDDABY, D. Correspondence. 70

SUDDABY, D. see ELLIS, P.M. 212

SUDDABY, D. see HARROP, H.R. 50

Swan, Mute: Orkney. 85

Swan, Mute: Scottish Mute Swan Census 1990. 94

Tayside: Prey remains at Osprey nests. 132

Tetrao tetrix: 20

Tetrao urogallus: 127

THOMPSON, D.B.A. & WHITFIELD, D.P. Research on mountain birds and their habitat. 1
Tringa solitaria: 62

TRUBRIDGE, M. Correspondence. 68

Turdus torquatus: 235

Tyto alba: 187

Warbler, Cetti’s: 176
Waterfowl: Stirlingshire. 27
WHITFIELD, D.P. see THOMPSON, D.B.A. 1

YOUNG, J.G. Sparrowhawk exploiting a Sand Martin colony. 236

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Scottish Birds

The Journal of the Scottish Ornithologists’ Club

Editor: Anne-Marie Smout

Assisted by: Professor David Jenkins, Dr J B Nelson and Professor P J B Slater
Business Editor: The Secretary, S.O.C., 21 Regent Terrace, Edinburgh EH7 SBT
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Published by the Scottish Ornithologists’ Club 21 Regent Terrace, Edinburgh EH7 SBT.
Printed by Alexander Ritchie & Son Ltd., 163 Bonnington Road, Edinburgh EH6 5RE.

Scottish Birds (1993) 17: 1-8

Research Progress Report

D.B.A. THOMPSON AND D.P. WHITFIELD

Research on mountain birds and their habitats

This report summarises some of the progress
to date on SNH-funded research on
montane (high mountain) ecology, notably
on the population ecology and conservation
of Dotterel Charadrius morinellus.

Montane habitat in the UK

Whilst Ratcliffe (1977) provides a good
working definition of the two major upland
zones in the UK — montane (above the
former tree-line) and sub-montane (below
the tree-line down to the upper limits of
enclosed farmland) — Ratcliffe &
Thompson (1988) first described their
international significance. The montane
zone characteristically begins at 700m, but
at as low as 300-400m in north-west
Scotland. It is marked by the dwarf-shrub
heaths, notably heather Calluna vulgaris,
becoming prostrate with exposure, and by
increasing prevalence of small herbs, mosses
and lichens (Thompson & Brown 1992). The
sub-montane areas were predominantly tree-
clad until perhaps only 200-400 years ago
in some regions but the montane zone has
not held trees for at least seven thousand
years and so is much more natural. The
distinction between these two zones is
important. Whereas the complex montane
ecological inter-relationships are in many
respects natural, fragile and sensitive to
environmental change, those in the more
recently created sub-montane zone are
founded on semi-natural, arrested
successional habitats.

Thompson et a!. (1987) and Thompson
& Brown (1992) described the extent of the
montane zone as comprising just over 3%
of the GB land surface (12% of Scotland).
Thompson & Brown (1992) quantified the
habitat variability and plant community
diversity throughout montane Britain. One
of their findings was that the most extensive

montane plant community, the
Racomitrium lanuginosum — Carex
bigelowii mossy dominated heath, is the
single most extensive near-natural
community on land in the whole of UK.

The assemblage of birds

Twenty-seven bird species use the montane
zone in the UK, but only four are confined
to it (Snow Bunting Plectrophenax nivalis,
Ptarmigan Lagopus mutus, Dotterel
Charadrius morinellus and the rare Purple
Sandpiper Calidris maritima). Nineteen of
these species breed in the arctic, and only
those with arctic strongholds are restricted
in the UK to the mountains (Galbraith et al.
in press a; Ratcliffe 1990). This assemblage
is internationally distinctive not least
because the same combination of species is
not found elsewhere. Two species have their
highest recorded breeding densities in the
Scottish Highlands: Dotterel (Galbraith et
al. in press b, Thompson and Whitfield, in
press), and Ptarmigan (Watson 1965). There
have been a few breeding records of other
arctic birds in Scotland, such as Lapland
Bunting Calcarius lapponicus, Shorelark
Eremophilia alpestris and Snowy Owl
Nyctea scandiaca, but recently such records
have been scarce.

Our work on the montane birds forms
part of a wider study of montane ecology
and aims to examine the reasons underlying
differences between mountain tops in the
composition of bird communities, and
differences in their diet and habitat use.

Habitat preferences

Montane plant communities are complex,
and the variables of altitude, exposure,
wetness and snowlie contribute substantially
to habitat mosaics that vary within
mountains as well as between mountain

2 Thompson & Whitfield

SB 17 (1)

systems in the UK (eg. Ratcliffe 1977;
Thompson & Brown 1992; Brown et al. in
press), and Table 1 provides a coarse
breakdown of the principal habitats used by
breeding birds on three central Highland
areas studied in detail. Some general rules
emerge applying to the breeding birds: a)
herbivorous birds prefer dwarf-shrub
communities and montane bogs (with
variable amounts of Empetrum spp.); b)
springs, flushes, boulder fields and the
exposed Juncus trifidus heaths are least
preferred, particularly as nesting habitat, by
most birds; c) the higher-altitude
Empetrum- Vaccinium heaths are preferred
slightly over the stunted Ca/luna heaths; d)
the mossy summit heaths, Empetrum —
Vaccinium heaths, and the boggy expanses

are most preferred, and e) the springs and
flushes have high value as brood rearing
habitat for some species.

Such information is important for two
reasons. First, if particular parts of
mountains are at risk of development or
change we need to know their importance
for the birds, and the importance of their
constituent habitats and communities, for
the birds. Second, information on habitat-
nesting/feeding bird relationships for
individuals provides a springboard for a
much more detailed assessment of species
requirements. Little |comparable
quantitative information is available on
habitat use for the majority of birds
breeding in the British uplands (eg. Ratcliffe
1990; Haworth & Thompson 1990).

TABLE 1. Summary of habitat-use by the more regular breeding montane birds in the central Scottish
Highlands. The species are ranked roughly in descending order of breeding density.

Mossy Exposed Nardus
Dwarf Vaccinium- (Raco- Juncus snowbed Springs
Calluna Empetrium mitrium) trifidus — grass- Montane = and Boulder
heaths heaths heaths heaths lands bogs flushes _ fields
Ptarmigan (H) (B) B+ + (B) —_ —_ B+ =—+ B
Dotterel (I) (B) (B)+ B+ B+ - — — _
Meadow
Pipit (I) B B+ (B) — (B) + B - —
Golden
Plover (I) — (B) + B+ = — B+ — a
Dunlin (1) — — —+ _~ B+ B+ _ —
Wheatear (I) (B) B+ (B) + B+ — — —+ _
Skylark (I) (B) B+ (B) + - (B) + B _ _
Red Grouse (H) B++ B+ — _ — (B) + — —
Snow
Bunting (I) _ _ — —+ _ — —+ B
Notes (H) = mainly herbivorous; (1) = feeds mainly on invertebrates

B = main breeding habitat where available, (B) less preferred breeding habitat, — not
often used by breeding birds for nesting;
+ + = major feeding habitat, + feeding habitat. NB Many birds feed in mosaics of these

vegetation classes.

Source: Galbraith ef a/. (in press, a, c); Ratcliffe (1990); Watson (1965, 1979); Nethersole-Thompson
& Nethersole-Thompson (1986); Thompson & Brown (1992); SNH (unpublished).

1993

Population ecology and dynamics of Dotterel
We studied the Dotterel in close detail
because, unlike the other regular montane
specialists, it is listed on the EC Directive
on the Conservation of Wild Birds
(Directive 79/409/EEC). This obliges the
UK government to protect the habitat
needed to sustain UK (and therefore EC)
populations of Dotterel (and other birds
listed in the annexes of the Directive).
There were other reasons for our work,
however. The Dotterel is one of the more
widespread of the montane specialists and
may be an important indicator of the
‘health’ of mountain environments. It is also
one of only two regularly polyandrous
species in the UK (female pairs and mates
with more than one male), the other being
the Dunnock Prunellus modularis. We were
keen, therefore, to find out what affected

X SAME YEAR
o DIFFERENT YEAR

VIA N. WALES (1) ~
W. FRANCE (2
SPAIN (1)

MOROCCO (12)
ALGERIA (1)

Research Progress Reports 3

the breeding success of each sex under such
an unusual mating system. Prior to our
project there were only clues as to what
influenced breeding success, and there was
virtually no information on movements by
adults and chicks between mountain tops.
There was even less on age of breeding,
mate/site fidelity, estimated lifespan, or
causes of death and dispersal (notably rates
of immigration and emigration). We need
to understand all of these factors in order
to understand how Dotterel respond to the
vagaries of their environment, including
changes at the hand of man. Previous work
on the species had yielded some important
results but had been limited by insufficient
time to make prolonged intensive
observations as well as low numbers of
individually marked birds (Nethersole-
Thompson 1973; Nethersole-Thompson and

Yh MONGOLIA (1)

FIGURE 1. Examples of international movements by Dotterel ringed in Scotland.

4 Thompson & Whitfield

SB T7"(1)

Nethersole Thompson 1986; Watson 1988,
1989).

We established three intensive study
areas, supplemented recently by two more,
and several others which we visited less
frequently (size range = 2-8km/?). By the
early 1990s we had developed working
methods. From early May to late August we
plotted the arrival, habitat use, nesting
distributions, individual fate of nests and
broods, and movements of Dotterel (eg.
Thomas ef a/. 1989; Galbraith et a/. in press
b, c). Most nesting males were individually
colour-ringed, and the chicks were also
ringed. We then searched the mountains for
colour-ringed birds to build up a picture of
movements.

The results show that some adults
repeatedly return to the same hill to breed
in different years whilst others move large
distances between breeding attempts. As
Fig. 1 shows, some individuals breed in both
Norway and Scotland in different years as
well as in the same year. There are also
highly marked differences in productivity
between mountain areas, with some being
capable of exporting young birds to other
hills as potential breeders whilst others
appearing to act as ‘sinks’ for breeding birds
(Fig. 2). On one hill, very few chicks return
to breed whereas on others several chicks
return, sometimes nesting within 50m of
their fathers.

Males alone usually care for the eggs
and chicks, and once the first males are
incubating, the activities of the females are
uncertain. Few females seem to remain on
hills where they have laid their eggs and do
not seem to return to their wintering
grounds in Morocco earlier than the males.
Do they fly on farther north-east, to
Scandinavia, to breed with males that nest
there later? This does seem possible because
most observers in Scandinavia comment on
the relatively high numbers of females
(whilst males are on eggs or caring for
chicks). Some females, however, remain to
seek out males that have either lost their
nests, deserted or arrived late.

NUMBER FLEDGLINGS /MALE

PRODUCTIVITY -
MAIN STUDY SITES

1.20
0.80

0.40

S
°
°

1987 1988 1989 1990 1991

1987 1988 1989 1990 1991

~
—
°o

0.80

0.40

0.00 =
1987 1988 1989 1990 1991

FIGURE 2. Differences in Dotterel productivity
(fledged young: adult male ratio) between study
areas. The horizontal line gives the productivity
required to keep the population stable (calculated
across all years).

1993

Research Progress Reports 5

Breeding success in Scotland has been
affected primarily by weather and predation
and, on some hills, by trampling of nests by
sheep and red deer. At one site significant
numbers of crows and gulls were attracted
to the plateau. This site has a ski
development and it is debateable to what
extent the presence of many more people,
brought to the tops by a chairlift, attracted
birds. By taking Dotterel eggs, these
predators have reduced the production of
fledglings by almost 20%. At other sites,
20-25% of clutches have been trampled by
sheep and/or deer. It was predominantly the
later, less productive clutches that were
trampled, however, so that there has been
only some 10% reduction in the production
of fledglings through trampling. Even so,
if numbers of predators, sheep and deer
were lower, then many more young Dotterel
would be produced by the Scottish
population.

A thrée-part paper in preparation by
Whitfield et al. provides a story of
ecological differences between mountains,
years, seasons and individual birds (see also
Owens 1991). We are also reviewing
similarities and contrasts between the
Scottish, Norwegian and Finnish situations,
and also the links between the breeding birds
and their North African wintering grounds.

A major challenge is to model both the
dynamics of population change between
different mountains and the key factors
accounting for variation in productivity and
dispersal. The resulting models should help
predict future changes in status and
distribution. For example, one of the main
prey of Dotterel, the cranefly Tipula
montana, exhibits a bi-annual pattern of
emergence so that some plateaux have peaks
in the early summer-swarms of craneflies
every Other year, but nearby plateaux may
show peaks in different years. Their life-
cycle seems to be tracked by migratory
Dotterel, with flocks settling to exploit the
large pre-emergence larvae that precede the
hatch of adult craneflies every other year.
With knowledge of the cranefly life-cycle we

can predict which hills will be important
each season.

Dotterel population size in the UK

We estimate that the UK population of
Dotterel is at least 860 breeding ‘pairs’, with
the vast majority in Scotland where there
are about 1.7 pairs km? (Galbraith e¢ al. in
press b; Thompson and Whitfield, in press;
Whitfield et a/. 1991). This is considerably
higher than previous estimates (e.g. 100-150
pairs by Nethersole-Thompson &
Nethersole-Thompson 1986), but not so
different from Watson & Rae’s (1987) more
accurate assessment of at least 600 pairs.
Has the population increased? We believe
that in some areas it has, perhaps with more
birds destined for Norway stopping off to
breed in Scotland en route from North
Africa. More precipitation in Norway than
previously has resulted in greater snowlie
there (H.J.B. Birks pers. comm.), perhaps
leading to more birds breeding in Scotland.
But much more detailed research is needed
on climate change and the Scotland-
Scandinavia connection. In some areas,
more intensive survey effort has simply
resulted in more birds being seen.

The last national survey of Dotterel was
in 1987-1988 covering just over 55% of all
suitable habitat in GB. We plan to repeat
this in a later year and to look, in particular,
for colour-ringed birds. We need a much
more complete picture of movements before
the breeding season, and of the use made
by roving birds of more than one mountain
system both here and abroad.

Environmental changes and impacts

Whilst numbers of Dotterel are higher now
than recorded at anytime this century, there
is a big difference between the Scottish
Highlands and the rest of montane UK.
Way back in the mid-19th Century, records
suggest a population of at least 50 pairs in
north England and Wales (Ratcliffe 1990);
now, there are fewer than ten pairs! Work
on habitat composition suggests that the
moss-dominated heaths preferred by

6 Thompson & Whitfield

SB 17 (1)

breeding Dotterel are becoming more
grassy, especially in areas south of the
Highlands (Thompson et al. 1987;
Thompson & Baddeley 1991; Thompson &
Brown 1992).

This may be due to increasingly severe
grazing pressures from sheep, producing
habitat conditions that graduaily encourage
grasses at the expense of mosses, and to
rising acidic (notably nitrate) deposition
close to industrial centres which may also
benefit the grasses and raise soil
acidification (see also Baddeley ef al. in
press). These changes will not benefit the
food availability and nesting requirements
of Dotterel, and may explain low densities
in the south of the species’ UK range. Pre-
breeding flocks pass through north Wales,
north England and south Scotland in late
spring, but very few settle to breed there.

We are presently developing a new
method for monitoring habitat change in
montane areas. This method will contrast
climate and human-induced changes
throughout montane areas in the UK.

Conservation
The study has provided baseline
information for three montane Special
Protection Areas being proposed under the
EC Birds Directive, and a further seven
candidate sites are under consideration. A
new National Planning Guideline on Skiing
has been issued, and this has benefitted
from what we have learned about Dotterel
and their habitats. We have made numerous
representations to the Cairngorms Working
Party, which reports to the Secretary of
State for Scotland in February 1993. We are
pressing hard for reductions in grazing
pressures from sheep and deer on the
mountains where there have been serious
losses of natural habitat diversity over the
past 30 years. We also need to have a better
understanding of why predators (crows,
gulls and foxes) are more active on some
hills than on others.

At the strategic level, we need a clear
policy for these high mountain areas. This

has to be sensitive to the highly individual
nature of each mountain, but has to address
land-use and management issues lower
down the hill which impinge on the higher
tops. The Countryside Commission for
Scotland (1991) report marked an important
start in this new policy making process.

The future

We have also studied Ptarmigan, Snow
Bunting and montane invertebrate
communities. We are establishing new study
sites in the western and northern Highlands
and want to see much more research in the
montane areas of the southern uplands,
north England and north Wales. This new
work will focus more on Ptarmigan, and
build on the studies of Dotterel and Snow
Buntings. Rik Smith and Neil Metcalfe are
studying the winter behavioural ecology of
Snow Buntings and have found surprising
differences between the small stock of birds
destined to breed in the Cairngorms and the
great majority of birds that breed in more
northern countries (e.g. Smith in press).

Much more effort is being devoted to
studying pressures from grazing and to the
role of grazers, people and predators in
affecting the invertebrate biota and breeding
success of montane birds. Our work has left
us unconvinced that the mounting numbers
of hill walkers are having an adverse impact
on montane wildlife, but this needs to be .
monitored. We need to contrast past and
contemporary impacts of pollution and
climate change on plant species and
communities in order to assess what the
future holds. Some of the communities are
bound to respond rapidly to changes in
growing season, snowlie and grazing
pressures, not least because of the knife-
edge ecological niches occupied. We already
see smaller snowbeds and signs of more
wind-related erosion. How will the birds and
invertebrates react to this?

Over the next five years our success will
be marked by how accurately we can predict
responses in the montane habitat and its
wildlife to environmental change, and the

)

)

1993

Research Progress Reports 7

priority attached by government to these
special places.

Acknowledgements

We are immensely grateful to: Adam Watson,
Derek Ratcliffe and the late Desmond Nethersole-
Thompson for their inputs and guidance,
particularly during the project’s origin; Hector
Galbraith during 1986-1989; Keith Duncan, Sue
Holt, Stuart Murray, Ian Owens, Stuart Rae, Rik
Smith, Dave Pullan and Chris Thomas for
unstinting work in the most arduous of field
conditions; Dave Curtis, Michael Usher, John
Birks, Torstein Solhoy, John Atle Kalas, Ingvar
Byrkjedal, Robert Rae, Pat Thompson, Raymond
Duncan, Terry Burke, John Baddelay, Sarah
Woodin, Colin Galbraith, John Blackwood and
Derek Langslow for support and help; the mighty
band of volunteer Dotterel surveyors
(acknowledged individually in Galbraith et a/. (in
press b)); Anne-Marie Smcut for soliciting the
manuscript and David Jenkins for improving it;
and NCC/NCCS/SNH for funding.

References

Baddeley, J.A. Thompson, D.B.A. & Lee, J.A.
(in press). The effects of nitrate deposition
on the ecology of Racomitrium lanuginosum.
Environmental Pollution.

Brown, A., Horsfield, D. & Thompson, D.B.A.
(in press, a). A new _ biographical
classification of the Scottish Uplands. I.
Vegetation blocks and their spatial variation.
Journal of Ecology.

Brown, A., Horsfield, D. & Thompson, D.B.A.
(in press, b). A new _ biographical
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Countryside Commission for Scotland (1991).
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Galbraith, H., Duncan, K., Rae, S., Smith, R.,
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Galbraith, H., Murray, S., Rae, S., Whitfield,
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Owens, I.P.F. (1991). Sexual selection in the
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Ornis. Fennica, 66: 85-99.

Watson, A. & Rae, R. (1987). Dotterel numbers,
habitat and breeding success in Scotland.
Scott. Birds, 14: 191-198.

Whitfield, D.P., Duncan, K., Murray, S., Rae, S.,
Smith, R. & Thompson, D.B.A. (1991).
Monitoring the Dotterel population of Great
Britain. In ‘Britain’s Birds in 1989-90: The
conservation and monitoring review’ . (ed. by
D. Stroud & D. Glue). pp. 109-111. Nature
Conservancy Council/British Trust for
Ornithology, Peterborough.

D.B.A. Thompson and D.P. Whitfield, Uplands and Peatiands Branch,
Research and Advisory Services Directorate, Scottish Natural Heritage,

2 Anderson Place, Edinburgh EH6 5NP.

Contact: Des Thompson (Tel. 031-446 2419; Fax. 031-446 2405).

Scottish Birds (1993) 17: 9-13

Research Progress Report

A 20 year study of Kestrels in Ayrshire

In the early 1970s, enthusiasts were
becoming organised into a group to monitor
and protect the population of the Peregrine
Falcon, Falco peregrinus, in the south-west
of Scotland. The Peregrine, along with
other raptors, had declined alarmingly in the
previous two decades due to the now well
documented effects of organochlorine
pesticides. As well as taking part in the work
on the Peregrine, I decided to study that
neglected species, the Kestrel, Falco
tinnunculus, and over the past 20 years have
carried out fieldwork on it every year.

The initial aims were basic: to assess the
impact of the pesticide problem on the
Kestrel in Ayrshire, confirm its status as
common, map its distribution within the
county and document current breeding
performance. A system of annual
monitoring evolved from the early work,
sample plots of territories were targetted
annually, a ringing programme set up and
field techniques developed. The obvious
fluctuation in annual output that was found
led to an investigation into factors affecting
the breeding performance of Kestrels in the
area.

The first steps taken were to undertake
a comprehensive review of historical
literature, launch an appeal for information
and contact local naturalists to build up a
picture of the previous 20 years. The
response exceeded all expectations.
Although the data were very mixed in
quality, over 50 territories were reported and
sufficient data obtained to confirm that,
while there had been instances of adult
deaths because of chemical poisoning, there
was no evidence of clutch depletion or
brood size reductions. In fact the Kestrel
maintained a high level of production and
was confirmed as breeding in all ten
kilometre squares in the County.

G.S. RIDDLE

One of the main benefits of the trawl
was the number of productive contacts
which were made and the number of
traditional territories which were identified.
Some of the responses were bizarre,
including one from an ‘‘oologist of ill
repute’’ as he signed himself, who willingly
gave me a number of clutch sizes,
apologising profusely that the information
did not go beyond the egg stage!

Three main study areas were chosen,
each with a distinct habitat type. The
Carrick Forest, managed by the Forestry
Commission, is a good example of upland
hill pasture converted to commercial
afforestation. Responding to the increase in
vole numbers in the newly planted ground,
the Kestrel population increased from 3-4
pairs in the mid 1960s to 15 pairs by the end
of that decade, but rapidly returned to the
former numbers when the canopy closed.
Harvesting is now in progress and the re-
stocked areas are once again providing
feeding grounds for Kestrels. A nest box
scheme begun in 1992 has already attracted
nesting Kestrels and numbers should
increase in the next ten years. As the forest
cycle stabilises and landscaping improves the
quality of the habitat, open areas within the
forest will become a permanent feature and
Kestrels should be ever present.

The Waterhead area is typical upland
sheep grazing ground characterised by its
open nature and the regular spacing of
conifer shelter belts which provided the
Kestrels with nesting territories. It is a very
stable area compared to the dynamic forest
environment. A 45 kilometre section of
coastline from Ballantrae to Ayr was chosen
as the lowland study area and this was
supplemented by individual territories
inland which were of interest due to long
term occupation. Data from outside the

10 GS. Riddle

SB 77(7)

study areas were always welcomed for
comparison and since 1972 information on
440 nesting territories has accummulated.

One of the main thrusts of the work
was to monitor the same 40 sample
territories annually to achieve full
information on breeding from each one.
The following six pieces of information were
obtained: occupancy, nest site location and
time of laying the first egg, clutch size,
hatching details, brood survival and fledging
details. To obtain these required anything
from four to 15 visits per season to each
territory depending upon the outcome of the
cycle. It is imperative to get into territories
in early March in order to make sure that
pairs which fail at the pre-laying stage are
recorded. Knowing the date on which the
first egg is laid is critical from a time
management point of view as the rest of the
visits can then be planned and disturbance
minimised.

From the data collected it was obvious
that, although there was annual variation
in breeding output (see Fig. 1), no matter
which measure is used, over the 20 years the
production rate was very high. From 1979
to 1992, during which period the monitoring
had reached a very consistent level, the
figures were: 4.7 average clutch size; 73%
of eggs laid hatched; number of young
reared per successful breeding attempt
averaged 3.4, with average for all attempts
2.5; brood survival in the nest 87% with
75% of nesting attempts resulting in at least
one young reared. This fits in well with the
general pattern for middle-sized falcons in
which there is a quick turnover of
population.

Clutch sizes ranged from 3-8 in size but
the majority were 4-6. One interesting
finding is that clutch sizes have increased
over the past two decades. In the period
1971-80, the average clutch size was 4.55

KESTRELS IN AYRSHIRE

~—™\

AVERAGE YOUNG REARED AND CLUTCH SIZE

1978 1980 1982 1984
year

FIGURE 1.

6 Average number of young reared and clutch size
(30 + results per annum)

ee ae

/ fs

«~ mall nests
m-=clutch size

a
1986 1988 1990" » 1992

1993

and this had increased to 5.00 for the period
1981-1990. This trend has also been
identified by the British Trust for
Ornithology from nest record card analysis.

In general, pairs of Kestrels which
breed early lay larger clutches and fledge
more young per breeding attempt that pairs
which start their cycle later. Clutch sizes in
Ayrshire averaged 5.3 eggs for hens laying
in April as against 4.3 for May. Similarly
the number of young reared per breeding
attempt was 3.9 for early cycles compared
to 2.5 for later cycles. The advantages of
having young out of the nest early in the
summer are that they will have more time
to gain hunting experience and build up
resources before the severe winter weather
makes survival difficult. Work in Holland
by Cavé has also shown that progeny from
early breeding pairs have higher survival
rates through the first winter.

Nearly 90% of breeding failures take
place during the pre-laying or clutch stage
of the cycle in Ayrshire (failed attempts: pre-
laying 26%, clutch 63%, brood 11%).
Analysis of failed breeding attempts shows
a variety of reasons, ranging from accidents
to deliberate human interference. Accidents
and the effects of adverse weather
conditions, such as washed out sites or
desertion due to food shortages, account for
nearly a quarter of failed breeding attempts.
29% of failed attempts could definitely be
attributed to man’s activities whether
intentional, such as egg collecting, or
unintentional, such as the felling of a nesting
tree or maintenance activity in a building.
The number of nests robbed by egg
collectors or would-be falconers has
decreased in the last ten years.

Very few nests were predated (6%) but
competition for nest sites with other raptors
such as Tawny Owls Strix aluco, Barn Owls
Tyto alba, and Long-Eared Owls Asio otus
accounted for 14% of failures. Ironically,
the recovery of the Peregrine Falcon and
their re-colonisation of previously vacated
territories caused Kestrels to desert cliff sites
into which they had moved as the Peregrines

Research Progress Reports 11

declined. In some cases the adult Kestrels
were killed but in one instance the Peregrine
pair, which had their nest washed out at the
clutch stage, took over a Kestrel brood and
reared the two young.

The monitoring data are submitted to
the co-ordinator of the South Strathclyde
Raptor Study Group each year, then
collated with the rest of the raptor work by
the RSPB and published in Scottish Birds
News by the SOC. Any major change in the
breeding population of Kestrels would be
identified quickly.

Variations in clutch size and in the
number of young produced by breeding
pairs did occur as a matter of course
annually (see Fig. 1). The pattern for clutch
size was very regular, with lows in 1979-80,
1983, 1986, 1989 and 1992. However, the
number of young reared per breeding pair
was much more irregular and made
interpretation more difficult. A close
examination of possible factors ruled out
nest site availability as having great
influence. Although there was some
competition from other raptors as already
mentioned, the number of nest sites
available in each territory was high, mainly
due to the number of abandoned Carrion
Crow Corvus corone nests. Most territories
had 3-8 potential nest sites available
annually. The food supply and consistent
spells of good or bad weather were found
to be the most important factors in fledging
SUCCESS.

No monitoring of the vole population
was carried out but figures from Geoff
Shaw’s Barn Owl work within the adjacent
Galloway Forest Park was _ used.
Interestingly, the poor vole years identified
in his area coincided with the years of lowest
Kestrel clutch size. The difference was that,
whereas the Barn Owl breeding output
crashed in those years, the Kestrels merely
produced slightly fewer young per breeding
pair than normal. Kestrels are not wholly
dependent upon field voles and take a
considerable number of young passerines
(Starlings Sturnus vulgaris, Meadow Pipits

12. G.S. Riddle

SB 17 (1)

W AN
=

om

A rare instance of a cock Kestrel brooding newly hatched chicks.

Anthus pratensis, and Skylarks Alauda
arvensis) in June and July and are thus able
to switch to other food sources if their
primary prey is scarce.

Consistent spells of bad weather in
early spring can have a profound effect
upon the timing of the cycles and on
breeding success. A look at one five yar
period 1982-86 illustrates the point well.

1982 — a typical season, mixed weather
throughout.
Clutch size 4.7: hatching rate 67% and
2.4 young reared per breeding attempt.

1983 — acold and wet spring
Clutch size 4.3: hatching rate 70% and
1.9 young reared per breeding attempt.

1984 — warm and dry from beginning to end
Clutch size 5.2: hatching rate 94% and
3.8 young reared per breeding attempt.

1985 — adry early spring: all pairs started
breeding in April: followed by cold wet late
spring and early summer.
Clutch size 5.2: 93% hatching rate but
only 2.5 young reared per breeding
attempt.

1986 — acomplete disaster — cold and wet
throughout: only 58% of territories
occupied and, coincidentally, a poor vole
year.
Clutch size 4.3: hatching rate 50% and
1.3 young reared per breeding attempt.

When a poor vole year coincides with
a consistent inclement spell of weather in the
spring, as in 1986, then the breeding output
is badly affected. However, the 1987-88
production rates were well up to normal and
recovery from a bad year was swift.

The ringing programme has been a key

part of the study and has shed some light
on migration and mortality. Over 1100
young Kestrels have been ringed from the
targetted territories since 1975. A recovery
rate of 7% has shown a random dispersal
of juvenile Kestrels in the late summer in all
directions followed by a predominantly
south south-easterly migration, birds
reaching the south of England and Northern
Europe by October. One first year bird
reached Northern Spain by 22 December,
a flight of 1880 kilometres, but three
quarters of recoveries were within 400
kilometres of the natal site. Some birds
overwintered in Ireland.

First year birds were most likely to
move, only 30% being recovered in Ayrshire
compared to 50% for birds aged two years
or more. Intriguingly some of the older
birds continued to travel abroad or even
stayed there: a fourth winter hen was killed
in France, a bird in its third breeding season
died in Holland and another was killed in
its first breeding season in Norway.

Sixty percent of birds recovered had
died during their first year, by far the
majority between November-March, due
mainly to accidents or exhaustion. 18%

Research Progress Reports 13

were second year birds, 12% third year, 6%
fourth year and 4% in subsequent years.
One bird reached the commendable age of
11 years.

Trapping of adults has also shown a
rapid turnover of adults at breeding
territories. For example, six different hens
nested in one territory over a 13 year period,
six in seven years in another and eight in
eleven years in a third. There is some
evidence of movement of hens within a local
area, one bird nesting in three different
adjacent territories in a three year period.

In any work on raptors, long term
monitoring is important and the continuity
of work on the Kestrel in Ayrshire will be
maintained for as long as possible.

On a personal note, it is great therapy
having such close contact with a fine bird
like the Kestrel.

References

A comprehensive list of references relating to this

work can be found in the publications.

Riddle, G.S., 1992. Seasons with the Kestrel.
Blandford.

14 Scottish Birds (1993) 17: 14-19

SB 17 (1)

The status of the Pintail in the Orkney Islands

E.R. MEEK

A survey of all the likely breeding sites of Pintails in
Orkney in 1991 revealed a potential breeding population
of 22-26 pairs. This is believed to represent over 50% of
the British population. Habitat features characterising
breeding waters are described. Factors controlling the
species’ choice of breeding water are discussed as are
options for the conservation of these sites.

Introduction

The Pintail Anas acuta is a very scarce
breeding species in Britain and it is listed as
a Red Data Bird by Batten ef al. (1990).
Estimates of the breeding population since
the 1960s have suggested a population of
about 50 pairs with fluctuations up to 100
but in the years 1974-88 the maximum total
was only 32 pairs (Batten et a/. 1990). For
1989 the Rare Breeding Birds Panel gave a
range of 11-39 pairs (Spencer 1991).

The Pintail, like several other duck
species, is a relatively recent colonist, first
proved to breed in Scotland, in Inverness-
shire, in 1869 and in England, in Kent, in
1910. In Orkney, they probably first nested
on Sanday, in 1907 or 1908 (Noble 1908;
Hale & Aldworth 1910). By the late 1930s
Pintails were breeding more or less
consistently in Orkney, Shetland, and the
Moray, Dee and Forth basins with Loch
Leven (Kinross) being the main centre
(Berry 1939). Elsewhere in Scotland, as well
as in northern England, East Anglia and
Kent, nesting was only irregular. By the time
of the ‘Atlas’ survey of 1968-72 (Sharrock
1976), East Anglia and Kent were
accounting for about one-third of all
breeding occurrences; breeding was no
longer annual in any of the north Scottish
mainland counties, had apparently become
less regular in Orkney and had ceased in
Shetland.

More recently, however, Orkney has
become the foremost area in Britain for

breeding Pintail. In 1989, for example, 17
of the maximum total of 39 pairs in the
country were recorded from the islands
(Spencer 1991) while in 1990 14 pairs were
found (Booth ef a/. 1991).

The present study reports results from
a comprehensive survey of Orkney
conducted in 1991. It describes the habitats
associated with Pintail breeding waters and
discusses methods for their effective
conservation.

Methods

The accurate censussing of breeding ducks
is notoriously difficult, the only entirely
reliable method being rigorous nest
searching which has the major disadvantage

of increasing desertion rates. Such a method © |

would be unacceptable with a species as
scarce as the Pintail. It is, however, possible
to assess the populations of some species by
counting the numbers of males in spring at
the start of the nesting season (Bibby et al.
1992). In spring 1991 the opportunity arose,
during the course of other work, to check
all breeding waters throughout Orkney for
Pintails in the pre-laying period. This had
never been systematically done in previous
years, records being dependent on the
checking of previously known sites. All
waters, other than very acidic moorland
lochs which were considered unsuitable and
on which Pintail are not known to occur,
were checked between late March and early

1993

Status of Pintails in Orkney 15

May. The moorland lochs were checked
later in the summer. In Orkney the Pintail
is almost solely a summer visitor to its
breeding lochs so that confusion with
wintering birds was not an important factor.
It is just possible that some records may
refer to birds on passage, although in the
majority of cases the behaviour and length
of stay of the birds concerned made this
unlikely. The range of numbers given for
the population allows for the uncertainty of
some of the records.

Data on the occurrence of Pintail in
1991 and characteristics of Orkney lochs
from a survey carried out for the then
Nature Conservancy Council in 1986
(Charter & van Houten 1989) were
assembled for as many lochs as possible.
The loch characteristics considered were:
a) trophic (nutrient) status, classified into

10 types as shown in Table 3.
b) area of surface
c) altitude above mean sea level

d) conductivity measured at one or two
places
e) pH measured at one or two places.
Where two estimates of conductivity or
PH were available, the mean was used in the
analysis. For the purposes of analysis, the
only lochs considered were those which had
been surveyed for Pintail and for which all
five of the variables listed above had been
measured. This provided a total of 88 lochs
of which 12 were recorded as holding Pintail
in 1991.

Results

The 1991 survey found a total of 22-26
potential breeding pairs (Table 1). Birds
were recorded from 15 sites on seven
different islands. The _ physical
characteristics of those lochs on which
Pintail were recorded are shown in Table 2
while the occurrence of Pintail in relation
to the trophic status of all lochs for which
data were available is shown in Table 3.

TABLE 1. Potentially breeding Pintail in Orkney, Spring 1991.

Island Site
A 1

Details

First noted 27.03 (4m. + 3f.); copulation seen 20.04; peak count 4 prs

plus 1-2 males 27.04; only young seen was late brood of 2 on 12.08.
2 First noted 20.03; peak count (2m +1f.) on 28.03; display 08.05; f.+b/5

(large) 03.07.

3 Pair present 17.04 and subsequently with f. only 28.04.
4 Pair present on 04 & 08.05.

ea)

on 10.05.

SVo\y ey SN ey Gy dy Gy TS)

(Rn arr hed <7

First noted 30.03; 2 males and 2 alert females possibly with ducklings

Pair present on 29.04.

Male & 2 females 29.04, female on 30.04.

Male on 29.04 with pair plus a male 30.04.

2 males and 1 female on 30.04.

Pair on 30.04; female possibly nest searching.

Pair on 29.04 (flew to this site from unsuitable site on island B).

4 pairs present on 11.04.

A single female present on 11.05.

A pair present on two dates in April.

First noted 27.03; 2 pairs present in late April; single females in late

May/early June; single male 07.06.

16 &E.R. Meek SB 17 (1)

TABLE 2. Characteristics of Pintail breeding waters in Orkney.

Island/Site Loch Type Size Altitude Conductivity pH
(umhos)

Al 4 7 20 548* 8.05*
A2 4 19.6 12 530* 8.06*
A3 4 96.8 30 458* 8.34*
A4 No data

A5 8 0.2 <5 720 7.12
B1 Gy 1.8 <5 5590 9.03
B2 6 TS <5 14850 10.30*
B3 7A 10.9 12 510* 10.00*
B4 7A 27.8 <5 720* 9.83*
BS 7A 0.6 40 566* 8.78*
Gi 7A 6.0 <5 759 7.06
D1 No data

E1 6 4.6 <5 21600 8.65
F1 7A 17.3 <5 530 8.53
G1 7A 0.9 <5 No data

Source: Charter and van Houten, 1989. * = Mean of two readings

TABLE 3. Occurrence of Pintail in relation to trophic status of lochs.

Loch Type Number of Lochs
Without With Total
Pintail Pintail
1. Dystrophic 7 0 7
2. Oligotrophic (peat substrate) 1 0 1
3a. Oligotrophic (stone substrate) 3 0 3
3b. Oligotrophic (other) 8 0 8
4. Oligotrophic with eutrophic influence 10 3 13
5. |Mesotrophic 1 0 1
6. Brackish 5 3 8
7a. Eutrophic 37 4 41
7b. Eutrophic (species poor) 4 1 5
8. Eutrophic (enriched by livestock) 0 1 1
Totals 76 12 88

1993

Status of Pintails in Orkney 17

Ten loch types were identified during
the NCC survey but these were grouped into
six main categories for further analysis.
Type 1 lochs were dystrophic (lacking in
nutrients), Types 2 and 3 were oligotrophic
(lacking in nutrients but rich in oxygen),
Type 5 were mesotrophic (providing
moderate amounts of nutrients), Type 6
were brackish and Types 7-10 were
eutrophic (over-rich in nutrients); Type 4
lochs showed signs of both oligotrophy and
eutrophy.

The sizes of the lochs occupied by
Pintails ranged from 0.2-19.92 ha. with the
exception of one of 96.8 ha. where the
Pintails always used a particular restricted
inlet. The altitudes of the lochs ranged from
<5-40m., but only two were above 20m.
The conductivity of their waters showed a
wide range of values from 458-21600 umhos
(a measure of the speed at which electricity
passes through a unit length of water at
25°c.). However, nine were in the range
458-759 umhos, the much higher figures
being from the three waters subject to
inundation at high tides. pH values varied
from 7.06-10.30.

Lochs with Pintail were of higher pH
than lochs without Pintail but there were no
other significant differences (Table 4). To
check for the possibility that Pintail
occurrence might be affected by a
combination of two variables, logistic
regression models (Aitken et a/. 1989) were
fitted to the data, with the presence or
absence of Pintail being the dependent

variable and the effect of all pairwise
combinations of pH, conductivity, area and
altitude being tested. It was found that,
although pH had a statistically significant
effect on Pintail incidence, there was no
significant additional effect of any of the
other variables.

It is difficult to assess differences
between loch types in the incidence of
Pintail because there are many loch types
(8) compared with the number of lochs (12).
None of the 19 lochs which were dystrophic,
oligotrophic or mesotrophic held Pintails
but the loch types on which Pintails did
occur were disparate and included
oligotrophic with eutrophic influence,
brackish and eutrophic. The effect of pH
on the incidence of Pintail was found to
remain statistically significant in a logistic
regression model in which the effect of loch
type was also included (chi-squared (1) =
4.41, p <0.05). However, on the slim
evidence available it is not clear whether
Pintail incidence on Orkney lochs is more
strongly related to pH, trophic status or
possibly other unmeasured factors.

Discussion

The 1991 survey has further emphasised the
importance of Orkney for breeding Pintail
in a British context. 1991 figures for the rest
of the country are not yet to hand but it
would appear that the 22-26 pairs breeding
in the islands probably represents more than
50% of the national population.

TABLE 4. Medians and ranges of characteristics of lochs with and without Pintail. Values of U from
Mann-Whitney tests and associated P values are also given.

Variable Without Pintail With Pintail
Median Range Median Range U (12,76) P
Area (ha) 3.5 0.2-227.0 6.8 0.2-96.8 374.5 0.32
Altitude (m) 10 <5-280 <5 <5-40 346 0.16
Conductivity 527 100-22200 643 458-21600 320.5 0.10
(umhos)
pH 7.92 3.58-10.19 8.59 7.06-10.30 296 0.05

18 E.R. Meek

SB 17 (1)

TABLE 5. Conservation status of Pintail breeding lochs in Orkney.

Island/Site Conservation Status

Al RSPB Reserve; SSSI; Proposed SPA

A2 SSSI

A3 Part RSPB Reserve; part SSSI

A4 Unprotected

A5 Receiving Environmental Management Payments
B1 Unprotected

B2 Receiving Environmental Management Payments
B3 Receiving Environmental Management Payments
B4 Unprotected

B5 Unprotected

Gi Unprotected

D1 Proposed SPA but currently unprotected

E1 SSSI

F1 Unprotected

G1 Unprotected

Islands A and B have held the great
majority of Orkney’s breeding Pintail for
the last 20 years. In 1991 birds were found
on all the lochs previously recorded as
breeding sites on these two islands while
some new sites were also found. Island D
has only recently been colonised but has a
growing population at the one site. Islands
C, E, F and G have not been regularly used
in recent years and breeding was not actually
proven on them in 1991.

The preference of Orkney Pintails for
more eutrophic waters with a high pH is
notable. It has been shown that, in more
northerly latitudes, eutrophic waters
support a more abundant phytoplankton
and zoobenthos than do other water bodies
(references in Fox et a/. 1989). Further, Fox
& Bell (in press) have shown that in northern
Scottish wetlands the most important
environmental parameters in determing
species richness are pH and conductivity. In
some areas, and particularly in spring and
summer, animal food, in the form of inver-
tebrates, is known to form a major part of

the diet of the Pintail (Cramp & Simmons
1977). Such food is also known to be
important to ducklings in the pre-fledging
period. A statistical relationship could not
be found between Pintail distribution in
Orkney and conductivity but the
relationship between distribution and
trophic status and distribution and pH,
might possibly be explained in terms of the
richness of the invertebrate fauna in such
waters.

What is not explained, however, is the
absence of Pintails from numerous other
Orkney waters with apparently suitable
water characteristics. The NCC survey
identified a further 76 waters in the
eutrophic categories (together with 12
classed as brackish and 21 as eutrophic/
oligotrophic), none of which held breeding
Pintails. Other factors must also be
controlling site choice, a major one
probably being suitable surrounding
vegetation for nesting.

Batten ef al. (1990) discuss the possible
threats to the survival of the Pintail as a

1993

Status of Pintails in Orkney 19

breeding bird in Britain. They conclude that
there are few threats other than possibly
climatic factors and the species’ nomadic or
opportunistic behaviour. However, in the
Orkney context, site safeguard may play an
important role in the future. All of the sites
holding breeding Pintail in Orkney could
potentially be damaged by agricultural
drainage. Of the 15 sites listed in Table 1,
only one and part of another are RSPB
reserves and only they and two others are
Sites of Special Scientific Interest (SSSIs).
The other 11 sites have no formal protection
although four of them are, either wholly or
in part, the subject of Environmental
Management Payments under the Agricul-
tural Development Programme for Scottish
Islands. This Programme ceases to operate
in spring 1993, after which payments that
have helped to conserve these sites will no
longer be made. Attempts are being made
to ensure the continuation of such
conservation payments under some
alternative scheme, designation of the
islands as an Environmentally Sensitive
Area (ESA) being currently the best option.
Although several new Scottish ESAs were
announced in spring 1992, Orkney was not
amongst them. While further reserve
acquisition and SSSI designation is a
possibility, an Orkney ESA seems essential
for the conservation of the numerous small
wetlands on which the Pintail, together with
other wildfowl and waders, depends.

Acknowledgements

My thanks go to Tim Dodman, Ian and
Helene Sims, Craig Whyte and the staff of
North Ronaldsay Bird Observatory, all of
whom helped in the checking of sites. R.E.
Green carried out the statistical analyses and
he and A.D. Fox commented constructively
on early drafts; to them both I am most
grateful.

References

Aitken, M., Anderson, D., Francis, B. & Hinde, J.
1989. Statistical Modelling in GLIM.
Clarendon Press, Oxford.

Batten, L.A., Bibby, C.J., Clement, P., Elliot,
G.D. & Porter, R.F. (eds) 1990. Red Data
Birds in Britain. Poyser, London.

Berry, J. 1939. The status and distribution of
wild geese and wild duck in Scotland. Jnter-
national Wildfowl Inquiry, Vol.2. C.U.P.,
Cambridge.

Bibby, C.J., Burgess, N.D. & Hill, D.A. 1992.
Bird Census Techniques. Academic Press,
London.

Booth, C.J., Cuthbert, M. & Meek, E.R. 1991.
Orkney Bird Report 1990. Kirkwall.

Charter, E. & van Houten, A. 1989. Survey of
Orkney Lochs, 1986. Unpublished NCC
report.

Cramp, S. & Simmons, K.E.L. (eds.) 1973. The
birds of the western Palearctic, Vol.1.
O.U.P., Oxford.

Fox, A.D., Jarrett, N., Gitay, H. & Paynter, D.
1989. Late summer habitat selection by
breeding waterfowl in northern Scotland.
Wildfowl 40: 106-114.

Fox, A.D. & Bell, M.C. In press. Breeding bird
communities and environmental variable
correlates of Scottish peatland wetlands.
Hydrobiologia.

Hale, J.R. & Aldworth, T.P. 1910. Notes on
birds in Orkney in 1910. Brit. Birds 4:
220-221.

Noble, H. 1908. On the identification of duck
eggs. Brit. Birds 2: 21.

Sharrock, J.T.R. 1976. The Atlas of Breeding
Birds in Britain and Ireland. Poyser,
Berkhamstead.

Spencer, R. 1991. Rare breeding birds in the
United Kingdom in 1989. Brit. Birds 84:
355-356.

E.R. Meek, RSPB Orkney Officer, Smyril, Stenness, Orkney KW16 3JX

(Typescript received I March 1993.)

20 Scottish Birds (1993) 17: 20-26

SB 717'(1)

A Survey of Black Grouse leks in Perthshire

M.C. ROBINSON, D. BAINES
AND W. MATTINGLEY

This paper describes a survey of Black Grouse leks in
seven 10km grid squares in highland Perthshire in
1990-92. Counts in April and May 1992 at 79 leks
produced 697 cocks. An additional 25 cocks were found
displaying singly. Leks were generally evenly distributed
1,500m apart within the altitudinal band 230-470m ASL.
Densities of displaying cocks in Perthshire were
compared with density estimates from other British and

European studies.

Introduction

This paper presents results of a survey of
Black Grouse Tetrao tetrix leks carried out
in 1990-92 by the Perthshire Black Grouse
Study Group. The group comprised
amateur bird-watchers, including members
of the Tayside Raptor Study Group, and
staff of the RSPB, The Game Conservancy
and Forest Enterprise.

Batten et a/. (1990) list Black Grouse
as a species of special concern owing to the
recent decline and range retraction in its
European populations during the present
century, brought about largely by habitat
deterioration (reviewed in Cramp &
Simmons 1980). Locally, nonetheless, there
have been increases due to the colonisation
of recently afforested areas in parts of Wales
and Scotland (Grove et a/. 1988; Thom
1986). However, once new forests grow up
into the closed canopy post-thicket stage,
declines are to be expected, even where there
were initial benefits (Cayford 1990).

Highland Perthshire and the Angus
glens are a stronghold of the Black Grouse
in Britain (Tapper 1992), but land-use
changes have recently been far-reaching: the
area of commercial forestry in Perth and
Kinross District increased by 30% to
73,300ha between 1980 and 1990 (J.
Crawford, Tayside Region Planning Dept.,
pers. comm.). This may affect the

distribution and abundance of Black
Grouse, and it was to monitor such possible
changes that the present study was started.

The study area

This comprised seven 10km grid squares
forming a single block in highland
Perthshire mainly across the area where the
Rivers Garry, Tummel and Tay meet. To
the east, it includes the watershed between
the Rivers Tummel and Ardle (Fig. 1). This
block was chosen as we were already
recording other bird species there.

The interface between wooded valley
and open hill is particularly well represented
in most of the area. Typically the valleys and
stream sides have blocks of birch Betula
spp. wood emerging on to open moorland
between 200-300m. This pattern is not
followed however where plantations of larch
Larix spp., spruce Picea spp. or Scots Pine
Pinus sylvestris have been planted along the
valley sides. Many of these have been
established within the last ten years,
although some in the Blair Atholl and
Tummel areas are considerably older.

The heather Calluna dominant
moorland is largely traditional grouse moor
managed through rotational burning.
Blanket bog covers a comparatively small

1993

FIGURE 1. The survey area in highland Perthshire.

part of the moorland area, but small flushes
and mires are frequent. Grassland
communities form mosaics with the heather,
especially along stream sides and around
lochs. Areas of improved grassland in some
places form continuous belts or isolated

fields below the moorland edge. The extent _

of the principal habitats within the study
area were roughly estimated from 1:25,000

Ordnance Survey maps and _ personal

knowledge of the area (Table 1).

Methods

Leks are generally considered tobe
communal displays by the same group of
males on a traditional site. To qualify as a
lek in this study, two or more males had to
be seen displaying at the same place on two
or more occasions, thus discounting bouts
of display on only one day away from leks
and cocks displaying alone. Single
displaying cocks were counted separately

Black Grouse leks in Perthshire 21

Forest
Ot
Clunie

Blairgowrie ©
2 Dunkeld

and added to the total number displaying

‘communally at leks to give an overall

number of cocks within each grid square.
However, 26 sites were not found until 1992
and were then only counted once. Of these,
17 had two or more displaying birds and
were considered to be true leks.

TABLE 1. Estimate of the percentage of the study
area covered by the main habitats.

% area
Habitat covered
Unenclosed heather dominant
moorland 50%
Conifer plantation (pre-thicket) 10%
Conifer plantation (post-thicket) 15%
Birch woodland 5%
Valley bottoms, inbye fields,
towns 18%

Lochs 2%

22 M.C. Robinson et al.

In Wales, Cayford & Walker (1991)
found that peak numbers of cocks occurred
at up to 1.5 hours after dawn from mid-
April to mid-May. The remoteness of some
of the leks and the need to visit several sites
on one morning precluded the possibility of
visiting all leks during this period. However,
76% of the 208 recording visits were made
between 15 April and 15 May, 16% between
5-14 April and 8% between 16-29 May.

The first two years, 1990 and 1991,
were spent locating all leks in preparation
for a full survey in 1992. The whole of each
square, apart from some montane ground,
were searched for leks, Leks tended to be

SB 17 (1)

conspicuous, with displaying cocks heard
from up to 1km away. The location of each
lek was recorded using a six-figure grid
reference and the date and time of the visit
and the number of cocks present noted.
Hens were recorded when seen, but as they
tended to visit leks in small groups, typically
of 2-3, counts at leks gave no reliable
estimate of total hen numbers.

In 1992, observers visited 57% of the
leks once, 23% twice, 8% three times and
the remaining 12% anything up to nine
times. When more than one count was made
at a lek, the highest number of cocks seen
was used. In the case of two leks not visited

TABLE 2. Numbers and density of displaying Blackcock in 1992.

Grid

Square No. No. leks
NN76 12
NN86 7
NN96 8
NN75 11
NN85 13
NN95 9
NOO05 19
Total 79

No. single Total
cocks cocks counted
7 104
3 63
2 85
8 68
1 100
0 85
4 192
25 697

TABLE 3. Blackcock population changes at 31 leks counted between 1990-1992.

Grid

Square No. No. leks

NN76
NN86
NN96
NN75 :
NN85
NN95
NO05

Total 31

Dr nh Ow UW UW

No. of cocks counted (% change between years)

1990

285

1991 1992
68 (0) 68 (0)
29 (-19) 33 (+14)
25 (-14) 23 (-8)
45 (+2) 34 (—24)
14 (+8) 17 (+21)
12 (+33) 8 (-33)
94 (+9) 73 (-22)

287. (+1) 256 (-11)

1993

in 1992, the 1991 count was used. Variations
in numbers of cocks between years were
assessed from 31 leks counted in all three
years.

Results

In 1992, a total of 672 cocks was recorded
at 79 leks (Table 2), with numbers of cocks
at a lek ranging from 2-30 (median and
mode seven cocks). Only 13% of leks had
15 or more cocks (Fig. 2). In addition, 25
single displaying cocks, comprising 4% of
the total cock population, were found,
giving an overall total of 697 displaying
cocks. Numbers of cocks differed three-fold
within grid squares, with a maximum of 192
and a minimum of 63 cocks. Data from 31
leks counted in all three years indicated that
numbers of cocks attending leks showed

frequency

25 ee

20 |

-— |

10

Black Grouse leks in Perthsire 23

virtually no mean change between 1990 and
1991 but declined by 11% between 1991 and
1992 (Table 3). However, changes in some
of the squares between 1990 and 1991 were
larger than the overall changes between 1991
and 1992.

Displaying cocks were found within a
distinct altitudinal band, at 230-470m.
(mean 350 + 5s.e.) in 1990-92 (Fig. 3). The
area of land in each square between these
altitudes was measured from Ordnance
Survey maps. Densities ranged from 0.8-2.3
cocks per km? between different squares
giving a mean density for the study area of
1.6 cocks per km? (Table 4). The seven
squares varied considerably in the
proportion of land within this altitudinal
band, but although there was a weak
positive correlation between the area of

ee le Ee
20 25 30

lek size (max.no.of cocks)
FIGURE 2. Frequency distribution of lek size (max. no. cocks present) from 79 leks and 25 single displaying

cocks.

24 M.C. Robinson et al.

Sues SS eee

0
<200 240 280 320

SB 17 (1)

HIER SEA EGSSES eRe Pegg

360 400 440 480 >500

Altitude (m)
FIGURE 3. Altitudinal distribution of 160 Blackcock display sites including single cocks between 1990

and 1992.

ground between 230-470m and Blackcock
numbers, this correlation was not
statistically significant (r,; = 0.53). The
mean distance between leks varied two-fold
between squares from 1110-2220m. The
mean for the whole survey area was 1460m.

Discussion

The mean density of 1.6 cocks per km?
found by this study is similar to estimates
from other British studies, and is within the
range of densities found by Baines (1992)
but is slightly higher than that found by
Picozzi (unpublished) for parts of Deeside
(Table 5). Higher densities have been
reported by studies in Sweden, the Alps and
Estonia, but these studies have either used
smaller areas within which birds may be

concentrated, or only favourable habitats
have been searched.

Black Grouse favour a mosaic of
habitats that are transitional in their nature
(Cramp & Simmons 1980) or maintained by
burning or grazing. In this study, all leks
were found at 230-470m which corres-
ponded to a transitional zone between the
upper edge of the valley woodland and inbye
grasslands and much of the unenclosed
moorland. Numbers of cocks varied three-
fold between grid squares, but these
differences could not be explained solely by
variations in the amount of ground lying
within the favoured altitudinal zone.
Instead, it is possible that differences in the
availability and quality of preferred habitat
patches within this zone are more important
than the absolute amount of ground

1993

available. Such data were not collected
during this study, but will form the focus
for further analyses.

In our study, only 4% of cocks
displayed on their own. This value is low
compared to that found in Wales by Grove
et al. (1988), where 45% of 91 leks were of
single birds. Although we do not describe
such observations of single birds as leks,
there was clearly a higher proportion of
singly displaying cocks in the Welsh study.

Black Grouse leks in Perthshire 25

The difference may be due to the Welsh
population being scattered and declining
whereas there was no evidence that this was
the case in Perthshire.

The proportion of single displaying
cocks is thought to vary between years in
relation to breeding success in the previous
year (Angelstam 1983). However we found
no evidence of changes in the proportion of
single displaying cocks in this study despite
between-year differences in breeding

TABLE 4. Densities of Blackcocks and mean inter-lek distances.

Grid Area at
Square No. 230-470m (km?)
NN76 85.9
NN86 74.2
NN96 48.9
NN75 52.9
NN85 52.6
NN95 44.0
NO05 84.2
Total 442.7

1.6 + 0.2 s.e. 55

Density Inter-lek dist. (m)
(cocks/km7) n mean + se
2 9 1460 + 175

0.9 5 2220 + 365

17 5 2000 + 310

1.3 10 1110 + 90
1.9 8 1525 + 300

1.9 5 1385 + 340

23 13. 1210 + 150
1460 + 90

TABLE 5. Densities of displaying Blackcocks in spring in this and other European studies.
* densities expressed as number of cocks within the altitudinal band.

Study Area Area (km?)
Perthshire 443 (* 230-470m)
N. Britain 306 (* 250-500m)
Deeside 34

Grimso (Sweden) 90

Boda (Sweden) 32

Halsen (Sweden) 14

French Alps 8

Tessin, Switzerland Favoured

habitat only

Estonia Favoured

habitat only

Density

(Cocks/km?) Author

0.9-2.3 This study
1.2—2.3 Baines (1992)
0.8-1.2 Picozzi (unpubl)
‘Jes Angelstam (1983)
S1/ Angelstam (1983)
Ten Angelstam (1983)
1.5-3.7 Ellison et al. (1988)
4.3-6.5 Zbinden (1985)
3.9 Viht (1974)

26 M.C. Robinson et al.

success. Instead, Baines (unpublished)
recorded low breeding success in 1990 and
1991, which was correlated with reductions
in numbers of cocks attending leks in 1992.

In the next few years, counts will be
repeated and changes in Blackcock numbers
will be compared with current land use
patterns and subsequent changes. For
example, new forests under the Native
Pinewoods Grant Scheme are being planted
in the study area. These developments and
their impact on Black Grouse populations
will form a focal point for the study group
in future years. The Black Grouse has
apparently declined in relation to land-use
changes and it is hoped that, as
understanding of its habitat requirements
increases, appropriate management guide-
lines can be developed and implemented.

Acknowledgements

We thank the following group members
who searched for leks and counted the birds:
Bruce Anderson, Simon Boult, Keith
Brockie, Euan Cameron, Rob Coope,
David Delph, Fraser Ewart, Graham
Gartshore, Christine Hall, James Renny,
Duncan Stevenson and Ron Youngman.
Malcolm Wield co-ordinated counts by
Forest Enterprise rangers.

We are indebted to Jenny Crawford,
Tayside Regional Council, for providing
commercial forestry figures. Rhys Green
gave advice throughout and Nick Picozzi
made useful suggestions at the start of the
study. lan Bainbridge, David Jenkins, Rhys
Green, Peter Hudson, Dick Potts and Ron
Youngman made constructive comments on
the manuscript. We also wish to thank the
many landowners and gamekeepers who
provided information and allowed access to
their land.

SB 17 (1)

References

Angelstam, P. 1983. Population dynamics of
Tetraonids, especially the Black Grouse
Tetrao tetrix L. in boreal forests. Ph.D.
thesis, Univ. of Uppsala.

Baines, D. 1992. Black Grouse: the effects of
predator control and vegetation cover. The
Game Conservancy Review of 1991. pp.
98-100. Fordingbridge.

Batten, L.A., Bibby, C.J., Clement, P., Elliott,
G.D. & Porter, R.F. (eds.) 1990. Red data
birds in Britain. Poyser, London.

Cayford, J.T. 1990. The distribution and habitat
preferences of Black Grouse in commercial
forests in Wales: Conservation and
management implications. Proc. Int. Union
of Game Biol XIX Cong. pp. 435-447.

Cayford, J.T. & Walker, F. 1991. Counts of
male Black Grouse TJetrao tetrix in North
Wales. Bird Study 38: 80-86.

Cramp, S. & Simmons, K.E.L. 1980. The Birds
of the Western Palearctic. Vol 2. Oxford.

Ellison, L.N., Leonard, P. & Menoni, E. 1988.
Effect of shooting on a Black Grouse
population in France. In Spagnesi, M. &
Toso, S. (eds.) Acts of First National
Conference of Game Biologists 14: 117-128.

Grove, S.J., Hope-Jones, P., Malkinson, A.R.,
Thomas, D.H. & Williams, I. 1988. Black
Grouse in Wales, spring 1986. Brit. Birds 81:
2-9.

Tapper, S. 1992. Game Heritage. The Game
Conservancy, Fordingbridge.

Thom, V. 1986. Birds in Scotland. Poyser,
Calton.

Viht, E. 1974. On the abundance and composition
of the Black Grouse population of the
Estonian SSR. Suomen Riista 25: 29-35.

Zbinden, N. 1985. Notes on the distribution,
population density and lek group size of
Black Grouse Tetrao tetrix in the canton of
Tessin. Der Ornithologische Beobachter 82:
107-115.

M. Robinson, RSPB, Balrobbie Farm, Killiecrankie, Pitlochry, Perthshire.
D. Baines, The Game Conservancy, Crubenmore Lodge, Newtonmore, Inverness-shire.
W. Mattingley, Cluny House, Aberfeldy, Perthshire.

(Revised typescript received 5 March 1993.)

Scottish Birds (1993) 17: 27-39

D7,

Productivity of waterfowl breeding at Airthrey Loch, Stirling

M.V. BELL

Airthrey Loch is a small (9ha) eutrophic lowland loch in
central Scotland. The productivity of breeding waterfowl
was studied over five summers (1987-1991). The loch
supported a large population of common species for its
size with between 66-91 pairs of waterfowl breeding
annually at a density of 7.3-10.1 pairs/ha or 25-35 pairs/km
of shoreline, comprising five pairs of Little Grebe, one
pair of Mute Swan, 21-29 pairs of Mallard, 7-8 pairs of
Tufted Duck, 20-26 pairs of Coot and 9-18 pairs of
Moorhen. Productivity was variable for all species and
apparently independent of weather conditions. Predation
by mink depressed breeding output by Coot and
Moorhen in three seasons and algal blooms were
coincident with mortality of downy Tufted Duck and
Coot in two summers. The numbers of juveniles
observed suggested that the loch produced a surplus of
Little Grebe, Mute Swan, Coot and Moorhen.

Introduction

Airthrey Loch is situated in the grounds of
the former Airthrey estate on the campus
of Stirling University. The loch has a
surprisingly large breeding population of
common waterfowl which showed marked
differences in breeding success between 1987
and 1991. Most of these birds, especially
Mute Swan Cygnus olor, Mallard Anas
platyrhynchos and Coot Fulica atra, are
very tolerant of humans and sometimes
aggressive in defence of territories or young.
Even though many nests of Coot and
Moorhen Gallinula chloropus were within
two metres of the path round the loch and
extremely obvious early in the season, there
were very few losses attributed to humans.
There is some fly-fishing for trout from
boats and from the shore that sometimes led
to the loss of lines and hooks on the lochside
trees which then presented a hazard to the
birds. There was also occasional dinghy
sailing on the west bay and canoeing as far
as the marker (see Fig. 1). The area round

the island is designated as a sanctuary area,

_ though this is not always respected by

canoeists and dingy sailors.

Airthrey Loch was formed in the early
19th century by constructing an
embankment across a small burn at the west
end and diverting the flow to a new exit
stream at the south-east corner. The 9ha
loch has an unusual shape (Fig. 1) and a
correspondingly long shoreline of 2.62km;
of this the small loch is 0.28km and the
island an additional 0.18km. An access road
and embankment divides the small loch
from the main loch, these being connected
by a submerged pipe. The loch has a mean
depth of 1.5m with a maximum depth of
4.2m in the west bay. Water levels are
controlled by a sluice but can still rise by
up to 30cm after heavy rain. The loch is
eutrophic with a low water turnover,
especially in summer when dense algal
blooms occur. There is emergent vegetation,
mainly yellow iris Jris pseudacorus and

28 M.V. Bell

Inflow

Lf West pool

SBr173(1)

Marker buoy

Sanctuary area

Outflow

Small loch

FIGURE 1. Map of Airthrey Loch.

bulrush Typha latifolia, along much of the
shore east of the bridge which provided
nesting cover for Little Grebes Tachybaptus
ruficollis, Coot and Moorhen while many
over-hanging willows Salix sp. around the
entire shoreline also provided nest sites for
Coot. Mature trees with cavities in the
surrounding parkland provided some nest
sites for Mallard.

Methods

In the first four summers of this study the
loch was visited 2-4 times a week from early
April to late August with less frequent visits
before and after this period. In 1991 the loch
was visited only weekly. It was most
convenient to walk round the loch between
0615 and 0730 hrs GMT as the loch was least
disturbed at that time. However, on cold
mornings downy young were often brooded
and therefore not visible; this was

particularly a problem in late April and
May. In these circumstances the loch was
checked between 1145 and 1300 hrs also,
and very occasionally between 1615 and
1730 hrs but the birds were found to be
rather inactive and therefore not very visible
in late afternoon and evening. Visits every
few days allowed newly hatched broods to
be followed from hatching to fledging.
Nests and territories of Little Grebe,
Moorhen and Coot were marked on a map
of the site; Coot territories were a useful
reference point for broods of ducklings. No
attempt was made to find nests not visible
from the perimeter path. The island was not
visited.

Individual territory sizes were not
determined in this study. Average territory
sizes were obtained by dividing the water
area by the number of pairs of the particular
species. Each year some birds appeared not
to nest. Non-breeding pairs were identified

1993

by the following criteria: for Coot and
Moorhen, territorial pairs seen regularly (i.e.
both adults) through part or all of the
nesting season with no signs of egg-laying
or incubation of a clutch. Some pairs built
rudimentary nests. Pairs of Tufted Duck
which were regularly seen on the water (i.e.
female not incubating) throughout the
summer were taken to be non-breeders. It
is possible that some of these pairs may have
failed within a few days of starting to nest.

Results

Nesting territories of Little Grebe, Coot and
Moorhen were easily located. Almost all
Coot nests and most nests of Little Grebe
were visible from the shore. Sometimes
newly hatched chicks were the first
indication of nesting by Moorhens.
Providing losses were low, it was possible
to follow the success of individual broods
of Mallard and Tufted Duck. In 1991, with
less frequent visits, this was not possible and
there may have been total losses of broods
within the first few days which were not
noted. Laying and hatching dates were also
less accurately known.

Little Grebe

Five pairs of Little Grebe nested each year
(Table 1). Most nested east of the bridge
(Fig. 1) with single pairs in the west bay in
1988, 1989, 1990 and 1991. The maximum

Waterfowl breeding at Airthrey Loch 29

density was 1.1 pair/ha when all five pairs
were on the east part of the loch. From late
May onwards it was usually impossible to
see nests among bulrush, but later nests in
floating beds of amphibious bistort
Polygonum amphibium and yellow water
lily Nuphar lutea were very obvious and
sometimes as much as 10m from the shore.
In spite of appearing vulnerable to predators
and wind, only two out of twelve such nests
were lost; adults usually remained
incubating as the wash from canoes rocked
their nests.

Newly hatched young often remained
hidden in cover and occasionally were not
seen until about two weeks old; the number
of young hatched was therefore not known.
Post-hatching losses appeared to be low
with some young fledged from every clutch:
only 11 young were lost from 79 hatched in
32 broods. One brood of five was recorded.
Broods usually remained within the nesting
territory until dispersing about four weeks
after fledging but in 1990, a pair moved
their newly hatched brood some 200-300m
from the mid pool to the west pool from
where the young fledged. In 1987, most of
the young from the first broods left the loch

' several weeks after dispersing. The mean

size of successful broods was 2.0 (8 of 1, 16
of 2, 5 of 3, 2 of 4 and 1 of 5) over the five
summers, and the average productivity
varied from 2.0 to 4.0 young/pair.

TABLE 1. Little Grebes breeding at Airthrey Loch 1987-1991.

1987
no. of pairs 5
median hatch date 28 May

(first clutches)

broods hatched 9

single broods 2

double broods 2

triple broods 1

young fledged 20
young fledged/pair 4.0

1988 1989 1990 1991
5 5 5 5

21 May 5 Jun 2 Jul 18 Jul
6 6 5 6
4 4 3 2
1 1 1 2
0 0 0 0
11 12 10 15
Dope 2.4 2.0 3.0

a RS

30 MLV. Bell

SB 17 (1)

In 1987, there were three pairs at the
start of the summer with a fourth arriving
in the last week of June and a fifth in the
last week of July. This then became the most
successful of the five years, with two pairs
double-brooded and a third triple-brooded
(Table 1). This latter pair fledged two, two
and four young from clutches which
hatched on approximately 20 May, 13 July
and 30 August. Two other pairs also fledged
two and three young from late nests which
hatched on 20 and 29 August. In 1988, 1989
and 1990 only one pair was double-brooded,
with two pairs in 1991. In 1990 and 1991,
single pairs failed to’rear any young. 1990
was the least successful season. Although all
five pairs were present by early May they
made no attempt to nest for 4-5 weeks and
every nest was then built in amphibious
bistort and yellow water lilies well out from
the shore. Laying was also delayed until late
May or early June in 1991. In 1988, 1989
and 1990 single non-territorial adults were
present all summer.

Mute Swan

A pair of Mute Swans nested successfully
on the island each year. Eight, seven, seven,
seven and nine cygnets were hatched on 7
May, 1 June, 28 May, 27 May and 28 May
in 1987-1991 respectively and of these seven,
five, four, five and seven fledged. (In 1986,
all nine young fledged at Airthrey). In 1988

and 1990, single young were lost soon after
hatching while in 1989, all three losses
occurred at or just after fledging. In 1988,
a fledged juvenile died of ingested lead
poisoning.

Mallard

Over twenty broods of Mallard were seen
each summer but counts of drakes in April
and May underestimated the breeding
population by a large margin in every spring
except 1991 (Table 2). Numbers of Mallard
increased in June, as birds arrived from
elsewhere to moult, and large numbers were
present in late summer each year with 609
in August 1990.

Mallard nested in the lochside
vegetation and in the campus shrubberies up
to at least 400m from the water. Four nests
were found 3-4m above ground in holes in
lochside oaks, and in 1990 one such site was
occupied consecutively by different females,
both of which hatched their clutches.

Broods appeared from the second week
of April to the first week of July, with most
appearing in the last week of April and the
first two weeks of May, median hatch dates
were between 2-18 May in 1987-1990 (Table
2). Fledging success varied between 29-70%
of those ducklings first seen: 1987 was the
best season with the largest number fledged
(110) and the highest number of young
fledged/brood (5.0) (Table 2). Four

TABLE 2. Mallard breeding at Airthrey Loch 1987-1991.

1987
av. no. of drakes April-May 9
no. of broods 22
median hatch date 15 May
no. of ducklings first seen 158
ducklings fledged (6 weeks) 110
total brood failures 4
young fledged/brood seen 5.0

* five broods were probably replacements.

1988 1989 1990 1991
9 12 beatin. 21
21 23 28 34°
18 May 2 May 6 May 29 May
127 158 202° 210
41 54 79 60
7 11 7 20
2.0 2.3 33 1.8

” four broods totalling 32 ducklings left the site within a few days of hatching.

1993

aberrant pale females fledged from one
brood in 1988 and these ducks could be
identified individually over the following
three summers. In 1990, one of these ducks
was double-brooded. She abandoned three
ducklings of c.20 days old in the first week
of May and ten days later these had joined
a brood of seven ducklings of similar age
also with a pale duck; all ten ducklings
subsequently fledged. On 20 June (45 days
later), she appeared with nine newly hatched
ducklings of which five fledged. In 1987 and
to a lesser extent in 1990, broods older than
about three weeks wandered extensively
from the loch to feed (up to at least 400m)
and several ducks and young were killed on
the adjacent roads. In 1990, four broods
were thought to have left the loch shortly
after hatching, possibly for the river.

Tufted Duck

Between 7-12 pairs of Tufted Duck Aythya
fuligula were present each summer. Several
pairs remained on the water throughout the
period and did not appear to attempt to
breed. The number of broods seen varied
between 2-8 (Table 3). Four nests were
found during the study and all were in rank
grass on the banks of the loch within Im of
the water. Most broods started to break up
after four weeks though some remained
cohesive for up to six weeks.

Waterfowl breeding at Airthrey Loch 31

Fledging success was very variable in
the four years (Table 3). In 1987, the best
year, 43 ducklings out of 57 fledged from
seven broods, discounting one brood
abandoned at hatching. The duck was
found sick and all the ducklings disappeared
within two days, most being taken by
Carrion Crows Corvus corone. In 1988,
there was a synchronous failure in good
weather with six ducks appearing without
broods on 24 June; the first two broods to
hatch were very successful, fledging 16 out
of 17. In 1990, all but one brood were
abandoned between a few days and two
weeks after hatching; these broods then
fragmented making it very difficult to
follow broods and ducklings. Many
ducklings grew very slowly, taking up to two
weeks longer to fledge than usual. This also
occurred in 1991 with the first brood which
hatched in the last week of June, fledging
all nine ducklings and the subsequent seven
broods hatching from mid-July showing
brood desertion, slow growth and large
losses.

Coot

Between 20-26 pairs of Coot nested each
year with up to five additional territorial
pairs present (Table 4). The smallest average
territory size was 0.22 ha/pair for the two
pairs on the small loch in 1991, but the 11

TABLE 3. Tufted Duck breeding at Airthrey Loch 1987-1991.

1987
no. of pairs 9
no. of broods 8
median hatch date 11 Jul
ducklings first seen 64
(four weeks)
ducklings fledged 43
total failures 1
broods abandoned 1
young fledged/pair 4.8

* duck died

1988 1989 1990 1991
8-10 7-11 10-12 8-14
2 5 8 8
17 Jun 7 Jul 15 Jul 18 Jul
17 37 53 54
16 Dal 17 19
0 1 2 2
0 14 7 7
2.0 3.0 Uns SZ

32. M.V. Bell

SB 17/(1)

TABLE 4. Coot breeding at Airthrey Loch 1987-1991.

1987

territorial pairs 20
pairs laying 20
clutches laid 23
replacement clutches 3
second clutches 0
median hatch date 15 May
(first clutches)

no. of clutches hatched 22
no. from which young fledged 17
no. of young fledged 42
pairs double-brooded 0
young fledged/pair 751

pairs on the east loch in 1991 only averaged
0.26 ha/pair. The overall density varied
between 2.2 and 2.8 ha/pair in the five
summers. The average length of shoreline
available varied from 101 to 131 m/pair
with the smallest average of 78 m/pair in
the west bay in 1989. The boundaries of
Coot territories were indicated by frequent
territorial interactions. Territory size
changed during the season depending on the
stage and fortunes of neighbouring pairs,
thus pairs with young frequently took over
parts of the territories of adjacent pairs that
had failed.

First clutches became progressively
earlier during this study with egg laying
from mid-March in 1990. The median hatch
date of first clutches was very constant
between 10-15 May in the first four summers
but was almost a fortnight earlier (1 May)
in 1991 (Table 4). High spring water levels
may have prevented even earlier nesting in
each of the years. Annual productivity
varied between 0.8 and 2.3 young
fledged/nesting pair over the five summers.

Nests were rarely unattended and no
attempts were made to determine clutch size
but opportunist observations of 11 first
clutches or replacement clutches gave an
average of 6.9 eggs (4 of 5, 1 of 6, 2 of 7,

1988 1989 1990 1991
27 29 25 25
26 24 23 24
35 39 31(+) 28
7 an 8 4
2 4 0 1

14 May 11 May 10 May 1 May
29 26 18 22
24 ii 9 19
61 36 19 49
1 2 0 1
23 15 0.8 2.0

1 of 8, 2 of 9 and 1 of 10). The four largest
clutches may have contained dumped eggs
since 11 eggs were left unhatched in these
four nests. More detailed observation of
nests would have been necessary to
determine the extent of egg dumping for
both Coot and Moorhen. Newly hatched
young were often brooded and not visible
for several days post-hatching, but where
the brood size was known, 26 first broods
averaged 6.0 chicks (1 of 2, 4 of 5, 13 of
6, 7 of 7 & 1 of 8) and seven replacement
broods averaged 4.4 chicks (1 of 3, 3 of 5,
2 of 5, 1 of 6). On only one occasion were
eggs noted in the water at the edge of the
nest but it is likely that other eggs were
knocked out of the nest by the adults during
skirmishes with rival pairs of Coot or
Moorhen. Most losses occurred at the stage
of newly hatched young, with brood
reduction occurring during the first week,
probably due to starvation of the weakest
chicks following neglect by the adults. Three
instances of predation by Lesser Black-
backed Gulls Larus fuscus were seen, on
chicks about seven, nine and ten days old.
Over the five years, of the successful pairs,
21 fledged one young, 24 pairs two young,
17 pairs three young, 16 pairs four young,
4 pairs five young and | pair six young

1993

(from two broods of three). There were
seven attempts at second broods over the
four seasons and only four were successful.
In 1988, a very late attempt at a second
brood (hatching on 9 September), following
a replacement first brood, failed when the
last chick which had grown very slowly
disappeared between 29 September and 3
October. Small territories caused frequent
disputes between adults but young were
allowed to cross territorial boundaries. In
1988, young from two adjacent pairs
frequently interchanged, while another pair
lost control of a brood of five 15-day old
chicks which were adopted by a pair with
two young 11 days older. All seven fledged.

There was very little interference with
nests by humans, though in 1990 it was
thought that the failure of three adjacent
and obvious nests over the same weekend
was caused by human disturbance. In 1988,
three pairs failed on 2 May just before or
at hatching, following heavy rain and strong
easterly winds. Two of these pairs quickly
relaid in the same nests. In the summer of
1989, a mink Mustela vison was seen at the
east end of the loch on two occasions and
the agitated behaviour of some birds
indicated its presence on several other dates.
There was a marked difference in the success
of pairs at the east and west ends of the
lochs (Table 5). A mink was also present on
the same part of the loch in 1990 and 1991.

Waterfowl breeding at Airthrey Loch 33

Most of these nests failed at or shortly after
hatching and the mink was probably
attracted by the calls of the chicks. In 1989,
one pair failed four times from clutches
started before 12 April, on 28 April, 2 May
and 20 June, the last hatching but the young
disappearing within a week. In 1990,
breeding success was poor round the whole
loch though it was still poorer at the east
end. Several nests here failed early in
incubation after a dilatory start to the
season and the birds did not relay. At the
west end, five broods were abandoned
between 16 days and five weeks after
hatching, and the young eventually died
though two chicks from different broods,
abandoned at 17 days and five weeks,
eventually fledged. Other chicks were very
slow to grow, taking 2-3 weeks longer to
fledge than normal; one died after ten weeks
when it was much smaller than normal (c.
3-4 weeks retarded). In 1991, all the first
broods of Coot had fledged before the algal
bloom occurred.

Moorhen

The number of pairs of Moorhen increased
steadily over the five years (Table 6), mainly
at the west end of the loch (Table 5).
Average Moorhen territory size varied from
0.52 to 1.03ha water area/pair over the five
years with the three pairs on the small loch

in 1990 and 1991 having only 0.15 ha/pair.

TABLE 5. Breeding success of Coots and Moorhens at the east and west* ends of the loch.

Coot (nesting pairs)

West end
prs you ng prs
1987 oka P 22 8
1988 16 38 10
1989 16 39 8
1990 15 15 8
1991 13 35 11

* The west end includes the small loch.

East end

Moorhen (territorial pairs)

West end East end
young prs young prs young
20 4 172 5 18
23 8 12 4 9

9 21 5 6
13 45 5 6
14 12 47 Wy 5

34 M.V. Bell

SB 17 (1)

TABLE 6. Moorhens breeding at Airthrey Loch 1987-1991.

1987
territorial pairs 9
no. of pairs nesting 9
no. of double broods 4
no. of triple broods 0
median hatch date 12 May
(first clutches)
no. of broods hatched 17
no. from which young fledged 12
no. of young fledged (5 weeks) 30
young fledged/nesting pair 33

Length of shoreline, which may be a more
important factor for Moorhen, varied from
an average of 175-291 m/pair, with extremes
of 390 m/pair in the west bay in 1987 and
93 m/pair on the small loch in 1990 and
1991.

Over the five summers, a total of 65
pairs of Moorhens nested. There was a
minimum of 111 nesting attempts of which
at least 15 failed before hatching, and a
further 24 failed to fledge any young. Of the
65 pairs, 12 fledged no young, 8 pairs one
young, 13 pairs two young, 11 pairs three
young, 8 pairs four young, 5 pairs five
young, 3 pairs six young, 3 pairs seven
young and 2 pairs eight young.

There were very frequent disputes
between Moorhens and Coots, especially
early in the season when little cover was
available to hide Moorhens. Every Moorhen
territory overlapped with at least one Coot
territory, and on one occasion an early
Moorhen nest was taken over by Coots.
Early nests were often in the base of willows
up to a metre above the water since there
was little other cover available at this time.
A Norway spruce Picea excelsa with
branches at this height overhanging the
water was also used in three seasons. Such
sites were not accessible to Coots but could
not be used as brood nests, since chicks were
unable to climb back to them. In 1989, a

1988 1989 1990 1991
12 14 17 19
11 12 15 18
1 1 4 8
0 0 1 0

13 May 24 May 14 May 10 May
12 15 24 27,
10 10 18 22
21 27 49 52
1.9 2.3 3.3 2.9

brood of five newly hatched young from
such a nest were thought to have been killed
by Coots, whose nest was only five metres
away.

As with Coot, first hatching dates
became progressively earlier during the
study though the median hatch date of first
clutches was little changed (Table 6). The
best years were 1987, 1990 and 1991 with
about three young fledged/territorial pair.
In 1987 and 1990 four pairs were double-
brooded, and in 1991 there were eight
double-broods. All three pairs on the small
loch in 1991 were double-brooded, fledging
seven, eight and eight young; the two pairs
of Coot fledged three and five young so this
site was extremely productive that year. In
1990 there was also a triple-brooded pair
which fledged one, two & two young from
clutches hatching on about 8 April, 28 May
and 17 July. Breeding was less successful at
the east end of the loch than at the west end
in 1989, 1990 and 1991 (Table 5), especially
in the last two years. This was thought to
be because of disturbance and/or predation
from mink. Moorhen nests were vulnerable
to predation by Grey Squirrel Scuirus
carolinensis, Carrion Crow and Magpie Pica
pica, while chicks were also vulnerable to
cats which were known to have taken several
juveniles. Adults from territories adjacent
to roads were vulnerable to traffic and in

1993

1987 three of the 18 breeding adults were
killed on the roads during the summer.

In 1990, a pair incubated an infertile
clutch from at least 28 May to 14 August
(79 days), leaving two eggs on eventual
desertion. Another territory in 1990 held
three birds. After an early failure a bird was
incubating a new clutch on 11 April. On 25
April two adults were incubating side by side
(head to head) with a third in close
attendance. The following day, they were
both incubating again and the nest was
inspected to reveal at least nine eggs, one
of which was chipping. One adult was
extremely aggressive, leaving the nest only
when the observer was less than a metre
away. On the following three days, one bird
was incubating/brooding with the other two
adults in attendance. On 7 May, the nest had
been interferred with by humans and the
adults and an indeterminate number of
young were hidden in a bed of iris. The full
family of three adults and seven young was
not seen until 23 May, when three young
were clearly larger than the other four and
were estimated to be about a week older. All
seven fledged. It was thought that a second
clutch was attempted by one bird but that
this failed before hatching.

Discussion

There have been many studies of the
breeding biology of waterfowl but rather
few of these have examined breeding
productivity. Fledging success is frequently
difficult to determine because of the
wariness of waterfowl and the extensive
cover at breeding sites. The population of
waterfowl at Airthrey Loch was particularly
amenable to study because the birds were
conditioned to the presence of humans and
all parts of the loch were easily visible.
The average fledging success of Little
Grebe varied between 2.0-4.0 young/pair
over the five seasons. A Danish study found
clutches of 4-6 usual with a mean brood size
of 4.6 at hatching and 1.8 on fledging
(Ahlen 1966; cited in Cramp 1977) with two

Waterfowl breeding at Airthrey Loch 35

broods normal and possibly three
occasionally. During this study there were
15 single broods, seven double broods and
one triple brood. In 1987, the most
successful year, two pairs were double
brooded and one triple brooded, with
extreme hatching dates of 18 May and 2
September. This was the first recorded pair
of triple-brooded Little Grebe in Britain.
Another was recorded at Aylesbury sewage
works in 1988 (Glue 1990).

Over 20 broods of Mallard were seen
each summer but counts of drakes in April-
May consistently underestimated the
population of breeding females by 40-60%.
Breeding success varied between 2.0-5.0
young fledged/ 9 or 2.9-6.1 young/
successful 9 .. The annual productivity
varied from 1.9-5.5 young fledged/pair at
a gravel pit in Kent over ten summers
(Harrison 1972). Other studies reported 3.5
young/successful 2 (Iceland), 4.7 (SW
England), 5.0-7.5 (Denmark) and 7.0
(Finland) (in Cramp 1977) so the
productivity at Airthrey Loch was
comparable.

At Loch Leven, the most important site
in Britain for breeding duck, c.1150 pairs
of duck, mainly Mallard and Tufted Duck,
nested each year between 1966-1971.
Hatching success averaged 55% and 57%
respectively for these two species over the
six summers but productivity was poor with
estimates of only about one young
fledged/pair for Mallard and probably
better for Tufted Duck (Newton &
Campbell 1975), many ducklings being
taken by gulls. The breeding duck were re-
surveyed here in 1980-1984, when the
population was found to be slightly larger
at c.1200 pairs. Though relatively few
broods were again noted, the number of
ducklings per brood surviving beyond two
weeks of age was 4.3 for Mallard and 3.6
for Tufted Duck (Wright 1986).

A study of Tufted Duck in Finland
found 78% hatching success but only 11.4%
fledged with a survival of 0.5, 1.0 and 2.2
young/pair in different years (Hilden 1964).

36 M.V. Bell

At Lake Myvatn, Iceland, 1.9-3.3 full-
grown young/ © were produced over six
summers (Bengtson 1972). At Airthrey
hatching success and fledging success were
broadly similar to those found in these
studies.

An earlier study of Coot at Airthrey
Loch was carried out in 1971, when 16
territories were present (Downie 1972).
There were fewer waterside willows
available to provide nest sites in 1971 than
during this study, and recent mild winters
may also have elevated the populations of
Coot (and Moorhen). Territory size varied
between 0.14-1.06ha but measurements of
territory quality were so variable that the
results did not allow any conclusion. No
attempts were made in this study to relate
productivity of Coots or Moorhens to
territory quality. In 1971, egg laying
occurred between 20 April and 6 June, mean
clutch size was 5.6 (range 3-8), but only
40.6% of eggs hatched and only 19 young
fledged (Downie 1972). Individual territory
sizes were not determined in the present
study but some pairs were much closer than
the average values given in the results, e.g.
three pairs in the mid pool in 1988, four
pairs at the ‘elbow’ of the loch in 1988, 1989
& 1990, with three on the outer curve and
one on the apex, and three nests within 40m
at the southern end of the loch in 1991. One
of these nests probably failed because of
fighting but the middle territory supported
the only double-brooded pair in 1991. In St.
James Park, London, Coot territories
varied between 0.12-0.44ha, mean 0.36ha
(Cramp 1947). Studies in Holland have
shown that the size and quality of a Coot
territory is related to the age of the male
tenant and its neighbours, older males
having bigger and better territories (Cave et
al. 1989).

The nesting season was much more
protracted at Airthrey during this study than
in 1971, and limited observations also
suggested that the clutch size was larger.
Hatching success in 1987 and 1988 was also
much better than in the earlier study

SB 17 (1)

(Downie 1972), but fell in 1989, 1990 and
1991 because of predation by mink.
However, there were large losses of chicks
in the first two weeks post-hatching in most
broods and overall fledging success was
similar to that found by Downie (1972). In
the earlier study, several Coots used nest
boxes that attracted interference from
humans which depressed hatching success.
A study of brood reduction and brood
division in Coots in Oxfordshire found that
all chicks surviving the first week
subsequently fledged and that the earlier
hatched chicks within broods had better
survival (Horsfall 1984a,b). Brood
reduction is a means of matching the
number of young to the food supply
through the establishment of a feeding
hierarchy, leading to the starvation of the
smallest and weakest later hatching chicks.
Occasionally, chicks are killed by the
parents (Horsfall 1984b).

Violent bouts of ‘tousling’ of chicks by
the parents were noted during the present
study but it is not known whether these
resulted directly in the death of the chick.
At Airthrey, brood reduction occurred over
a longer period. In 1987 and 1988, from 48
clutches hatched where the disappearance of
chicks was accurately known, 58
disappeared in week one post-hatch, 20 in
week two, 11 in week three, four in week
four, two in week five and one in week six.
Although some of these larger chicks may
have been predated, in most cases the
circumstances (visibly slow growth, neglect
by parents) suggested starvation, poor
condition or disease. The small size of some
territories at Airthrey and thus food
shortage may have accounted for the
number of total brood failures or broods
from which only one chick fledged. In 1987
and 1988, from 48 nesting attempts which
hatched, nine failed to raise any young and
eight fledged one young. Only four out of
117 pairs of Coot were double-brooded in
1987-1991. This was surprising, since there
seemed to be sufficient time for second
broods given the early start to nesting; in

1993

1991, 17 pairs had young which were
independent by the end of June, yet only
one pair attempted a second clutch (and was
successful). A study in Somerset (Alley &
Boyd 1947) also recorded poor hatching
success but better fledging success than the
current study at Airthrey. Alley & Boyd
(1947) observed Coots killing chicks from
neighbouring pairs which wandered into
their territory. Although there were frequent
territorial disputes at Airthrey, such
aggresion was never seen directed towards
chicks. On the contrary, in one instance in
1988 young of similar age from broods of
four and five wandered between adjacent
territories at will and were possibly fed by
the other pair. In another case a pair with
two young drove off the parents of an
adjacent brood and adopted their chicks. It
is possible that in these instances of unusual
behaviour the adults were related. Lesser
Black-backed Gulls were seen cruising over
the loch frequently in late May and June and
may have been major predators of small
Coot chicks. Three successful attacks were
witnessed during this study, and three by
Downie (1972), who also observed a Lesser
Black-backed Gull attack a Coot nest.
Downie (1972) found 11 territorial
pairs of Moorhen at Airthrey in 1971.
Hatching success was only 43.5% with
humans the main cause of failure. Hatching

success was not determined in the present

study but is thought to have been better,
even though most nests were not found, but
fledging success was also low with 1.9-3.3
young fledged/pair even though most pairs
attempted two broods.

Over the five seasons, 65 pairs of
Moorhens nested and 18 of these were
double-brooded with only one triple brood.
This is in accord with the study of Wood
(1974), who found double broods unusual,
while Relton (1972) found more than a third
of her pairs double-brooded. However, a
study in Aberdeenshire under semi-artificial
conditions with an abundant food supply
and few predators found three broods to be
normal with experienced adults (Anderson

Waterfowl breeding at Airthrey Loch 37

1965). In the Avon valley, Hampshire, 1.6
and 2.6 young fledged/pair in two different
years (Wood 1974). Hatching success was
poor (13.6% and 25.8%) with only 11 out
of 53 nests hatching but fledging success was
then very good (Wood 1974). This was not
the case at Airthrey where hatching success
was much better but fledging success poor.
The high density of Moorhens encouraged
juveniles to remain on the natal territory,
and juveniles from first broods often helped
feed the chicks of second broods. A study
in Cambridgeshire found that pairs of
Moorhen with helpers reared more chicks
per nesting attempt than pairs rearing chicks
at the same tite without helpers (Gibbons
1987), but insufficient data were available
in this study to show whether this was true
at Airthrey.

Mink was believed to be the major
cause of failure of Coots and Moorhens in
1989, 1990 and 1991. Signs of mink were
seen only at the east end of the loch, where
the lacustrine vegetation was most dense,
and this coincided with the failure of most
pairs nesting in this area. Mink take a wide
range of prey items in proportion to their
availability (Akande 1972). They are
therefore particularly damaging to birds
which nest at high density such as gulls and
terns on offshore islands (Craik 1990; Lloyd
et al. 1991) and localised concentrations of
wildfowl which may be found along rivers,
streams and loch margins. Lesser Black-
backed Gulls may also have been significant
predators of young Coot which, being
unable to dive, are very vulnerable to attack
when out of cover. The other potential
predators, Carrion Crows, Magpies and
Grey Squirrels, spent most of the time
scavenging and largely ignored nests and
chicks. In June and July 1990, a bloom of
toxic algae appeared to kill many young
Tufted Duck and Coot. Adults lost interest
in and abandoned chicks, which grew very
slowly with many dying. Mallard and
Moorhen which mainly fed out of the water
had a good season. In 1991, the first brood
of Tufted Duck fledged all nine ducklings

38 =M.V. Bell

but the remaining seven broods, which
hatched three to four weeks later during a
bad algal bloom, fledged only ten out of 45
ducklings.

Despite its relatively small size,
Airthrey Loch is the most important
freshwater site in Central Region at the
present time for breeding waterfowl in terms
of density and number of pairs. The
numbers of young fledged were likely to
exceed adult mortality, certainly for Little
Grebe, Mute Swan, Coot and Moorhen.
Survival of full-grown Little Grebe, Mute
Swan, Coot and Moorhen was good, and
most young Coot and. Moorhen appeared
to remain on site through the winter, with
numbers falling only from February
onwards as territories were established.
Many Coot remained on territory
throughout the year. On only one occasion
in five winters was there snow cover and the
loch frozen at the same time, forcing most
birds to leave. The 1985/86 winter was more
severe at Airthrey than any of the
subsequent five, and the steady increase in
the population of Moorhen suggests they
were recovering from a low point. The
population of the other five species
remained stable during this period.

Breeding productivity was variable for
all species over the five seasons, but
different species were more or less successful
in different years. Success appeared to be
independent of temperature and
precipitation. A ranking of breeding success
for each species with mean temperature,
monthly precipitation and the number of
days with over 5mm rain measured at the
University weather station in each month
from April to July showed no relationship.
However, these are particularly crude
measures and a factor which integrates
precipitation and wind chill over time would
be much more meaningful since it is well
established that a combination of rain, wind
and low temperatures is particularly
damaging to small downy young. The
detailed study at Lake Myvatn found that
the weather in the week after hatching was

SB 17 (1)

the main factor determining duckling
survival (Bengtson 1972), and Harrison
(1972) also found cold, wet weather to be
very damaging to ducklings of Mallard and
Tufted Duck. At Airthrey, the birds fared
better in the poor summers of 1987 and 1990
than in the good summers of 1988 and 1989.
The reasons for this are unclear but at a
neighbouring site in south-west Perthshire,
duck bred very well in 1988 and 1989 and
badly in 1987, 1990 and 1991 (pers. obs.).
At Airthrey, the very short grass around
much of the loch may have allowed young
Mallard, Coot and Moorhen to feed without
becoming soaked and chilled during wet
weather. A relatively asynchronous and
prolonged breeding season may also have
meant that some cold wet periods in June
of 1987, 1990 and 1991 were not as
damaging as would have been the case ina
more synchronous population. Therefore,
bad weather may not have had as much
effect as expected at Airthrey. It is less clear
why success was relatively poor in the two
good summers. The loch shore is much
more disturbed by walkers and sunbathers
in good weather but this disturbance only
occurs for a few hours, mainly around mid-
day. Food shortage may have been a factor
though there was no direct evidence to
support this.

Acknowledgements

I am grateful to D.M. Bryant and A.V. &
S.F. Newton for constructive criticism of a
draft of this manuscript.

References

Akande, M. 1972. The food of feral mink
(Mustela vison) in Scotland. J. Zool.,
London 167: 475-479.

Alley, R. & Boyd, H. 1947. The hatching and
fledging success of some Coot. Brit. Birds 40:
199-203.

Anderson, A. 1965. Moorhens at Newburgh.
Scott. Birds 3: 230-233.

Ee EE

1993

Bengtson, S.-A. 1972. Reproduction and fluc-
tuations in the size of the duck population
at Lake Myvatn, Iceland. Oikos 23: 35-58.

Cave, A.J., Visser, J. & Perdeck, A.C. 1989.
Size and quality of the Coot Fulica atra
territory in relation to the age of its tennants
and neighbours. Ardea 77: 87-97.

Craik, J.C.A. 1990. The price of mink. Scottish
Bird News No. 19: 4-5.

Cramp, S. 1947. Notes on territory in the Coot.
Brit. Birds 40: 194-198.

Cramp, S. 1977. Ed. The Birds of the Western
Palearctic Vol.1. Oxford University Press.

Downie, A.J. 1972. The biology of the nidifugous
young of the Coot and the Quail. Honours
Project Thesis, University of Stirling.

Gibbons, D.W. 1987. Juvenile helping in the
Moorhen, Gallinula chloropus. Anim.
Behav. 35: 170-181.

Glue, D. 1990. Little Grebes rearing three broods
in Buckinghamshire. Brit. Birds 83: 278-279.

Harrison, J. 1972. A Gravel Pit Wildfowl Reserve.
Wildfowlers’ Association of Great Britain
and Ireland.

Waterfowl breeding at Airthrey Loch 39

Hilden, O. 1964. Ecology of duck populations
in the island group of Valassaaret, Gulf of
Bothnia. Ann. Zoologici 1: 153-279.

Horsfall, J.A. 1984a. Food supply and egg mass
variation in the European Coot. Ecology 65:
89-95.

Horsfall, J.A. 1984b. Brood reduction and brood
division in Coots. Anim. Behav. 32: 216-225.

Lloyd, C., Tasker, M.L. & Partridge, K. 1991.
The Status of Seabirds in Britain and Ireland.
T. & A.D. Poyser, London.

Newton, I. & Campbell, C.R.G. 1975. Breeding
ducks at Loch Leven, Kinross. Wildfowl 26:
83-103.

Relton, J. 1972. Breeding biology of Moorhens
on Huntingdonshire farm ponds. Brit. Birds
65: 248-256.

Wood, N.A. 1974. The breeding behaviour and
biology of the Moorhen. Brit. Birds 67:
104-115 & 137-158.

Wright, G.A. 1986. Breeding wildfowl at Loch
Leven National Nature Reserve. Scott. Birds
14: 39-43.

M.V. Bell, 48 Newton Crescent, Dunblane, Perthshire FK15 0DZ

(Revised typescript received 19 November 1992.)

40 Scottish Birds 17: 40-49

$847 (71)

Breeding numbers and breeding success of the Peregrine

in Shetland, 1961-1991

P.M. ELLIS AND J.D. OKILL

The British Trust for Ornithology (BTO) Peregrine Enquiry
in 1962 was the first attempt to survey breeding
Peregrines in Shetland (Ratcliffe 1963). Of the 19 known
traditional nesting sites visited, 11 were occupied and at
least three pairs nested. By 1991, the number of
occupied sites had fallen to five with no breeding pairs
located, making Shetland the only Scottish county
without breeding Peregrines. Available data on breeding
Peregrines in Shetland between 1961 and 1991 are
presented and compared to the situation in Orkney.
Possible reasons why Shetland’s Peregrine population

remains so small are discussed.

Historical background

The Peregrine Falco peregrinus has a long
history in Shetland, with bones found in
excavations of ninth and tenth century
Viking dwellings at Jarlshof (Venables &
Venables 1955). Dunn (1837) considered it
to be “‘pretty numerous’’ and Saxby (1874)
stated that ‘‘within the last five years the
number has increased’’. Evans and Buckley
(1899) noted about 14 occupied sites. In
1951-52, P.W. Sandeman reported ten pairs
nesting in Shetland (D.A. Ratcliffe in litt.)
and Venables & Venables (1955) stated that
Shetland ‘‘is, and apparently always has
been, one of the strongholds in Britain for
this species’’.

Methods

In national enquiries, organised by the BTO
in 1961, 1971, 1981 and 1991 and also in
1986, an attempt was made to visit all
known nesting sites at least once in April or
early May. In the intervening years, from
1978 to 1991, all known nesting sites which
had been occupied since 1974 were checked
for signs of occupation at least once in April
and May. Sites with one or more birds

present and active nests were visited
subsequently to record breeding success. All
prey items found during visits were recorded
and removed. A nesting area was considered
to be occupied if a nest was located or if one
or more Peregrines were seen in suitable
habitat. The high sea cliffs made it difficult
to locate the kills and in no cases were
definite Peregrine kills found without one
or more Peregrines also being seen. Since
1984, visits to most sites each year included
both searching from the top of the cliff and
searching from a boat. The high cliff nesting
habitat, together with the large numbers of
Fulmars Fulmarus glacialis which inhabit it,
increased the difficulty of detecting
Peregrines, particularly non-breeding birds
which, when an observer approaches, may
fly directly away from a cliff without calling
and without returning (pers. obs.).

Results

Site descriptions

All known sites and all sites occupied since
1978 were on sea cliffs 50-140m high. All
nests located since 1984 were on cliff ledges,

1993

except for one which was in the old nest of
a Raven Corvus corax and another nest
which was in the centre of the flat grassy
top of a sea stack.

Population size

Table 1 shows the results of each of the five
surveys of known Peregrine breeding sites
in Shetland. Over the years, a small number
of previously unrecorded sites have been
discovered. The rate of occupation of the
sites visited declined from 58% in 1962 to
13% in 1991, when only five single birds
occupied sites. Since 1962, when eight pairs
were located, only a small number of pairs
were recorded, with one in 1971, five in
1981, four in 1986 and naught in 1991.
Breeding attempts were only recorded in
1962, 1981 and 1986, when respectively at
least three pairs, four pairs (80% of pairs
holding territory) and three pairs (75%)
nested. Not all sites were visited each year,
and data gathered during intervening years
were incomplete, but the maximum number
of occupied sites found in any year since

Peregrines in Shetland 41

1961 was 14 in 1985, of which only half were
apparently occupied by pairs (tables 2-5). By
1991, the number of occupied sites had
fallen to only five, and all occupied by single
birds. The number of known breeding pairs
in any one year since 1961 has never
exceeded four.

Breeding success and productivity

In 30 years since 1961, the largest number
of successful nests recorded in any year was
three, and in total only about 69 young are
known to have been produced (an average
of only about 2.2 young fledging per year).
During the years when all sites were visited,
the proportion of pairs breeding successfully
varied between 25% in 1981 and 67% in
1986, with no known nesting attempts in
1991. Although up to four pairs nested in
individual years, only one or two were
successful, although overall 11 out of 15
(73%) were successful. Only in 1987 did all
known pairs nest. Usually three to five pairs
were located and about half (56%) of these
nested. We did not climb to nests until the

TABLE 1. Peregrine breeding data for the BTO National Peregrine Enquiry years and 1986, when all

known sites in Shetland were visited.

Sites checked
(%) of known sites

Sites occupied
(%) of sites checked

Sites occupied by single birds

Sites occupied by pairs

Nesting pairs

Successful pairs ©

Young fledged

Young fledged per nest

Young fledged per successful nest
Productivity (young fledged per pair)

1962 1971 1981 1986 1991

19 25 35 36 38
(68) (89) (100) (100) (100)
11 5 11 8 5
(58) (20) (31) (22) (13)
3 4 6 4 5
8 1 5 4 0
3+ 0 4 3 0
3+ 0 1 p2 0
5+ 0 3 6 0
¢ 0 0.75 2.0 0
2 0 3 3 0
2 0 0.6 1.5 0

In 1962, it was not known whether three of the pairs nested.
Data for 1962 and 1971 from D.A. Ratcliffe (in litt.).

42 Ellis & Okill SB 17'(1)

TABLE 2. Data for Peregrines breeding in Shetland in 1961-1970.

1961 1962 1963 1964 1965 1966 1967 1968 1969 1970
Sites checked 8 19 11 18 9 10 2 12 5 4

(%) of known

sites (22) (68) (31) (50) (25) (28) (6) (33) (14) (11)
Sites occupied 6 11 8 6 2 3 1 9 5 4
Sites occupied

by single birds 1 3 1 2 0 2 0 2 2 1
Sites occupied

by pairs 5 8 7 - 2 1 1 7 3 3
Nesting pairs 4+ 3+ 2+ 4 1 1 1 1 2 2
Successful

pairs 2+ 3+ 2+ 4 0 0 1 1 2 0-1
Young fledged 3+ 5+ 3+ if 0 0 2 1 4

Data from D.A. Ratcliffe (in Litt.) and Fair Isle Bird Observatory Trust (FIBOT).

TABLE 3. Data for Peregrine breeding in Shetland in 1971-1977.

1971 1972 1973 1974 1975 1976 1977
Sites checked 25 2 2 2 2 i 10

(%) of known sites (89) (2) (2) (2) (2) (19) (28)
Sites occupied 5 4 4 6 8 9 2
Sites occupied by

single birds 4 0 0 1 0 ? 2
Sites occupied by pairs 1 4 2 5 8 2 ?
Nesting pairs 0 2 0 4 2+ ? ?
Successful pairs 0 2 0 2+ 2+ 1 0
Young fledged 0 4 0 2+ 2+ 1+ 0
Young fledged per nest 0 2 0 0.25+ acl te ? 0
Young fledged per

successful nest 0 2 0 1+ 1+ ? 0
Productivity

(young fledged per pair) 0 1 0 0.4+ 0.25 + ? 0

Data from D.A. Ratcliffe (in litt.) (1971), Shetland Bird Reports 1972-1977, Shetland Bird Club, Lerwick,
and FIBOT.

1993 Peregrines in Shetland 43
TABLE 4. Data for Peregrines breeding in Shetland in 1978-1983.

1978 1979 1980 1981 1982 1983
Sites checked 21 21 19 36 28 Di,
(%) (58) (58) (53) (100) (78) (75)
Sites occupied / 6 6 tal 5 4
(%) of sites checked (33) (29) (32) (31) (18) (15)
Sites occupied by single birds 4 3 2 6 1 1
Sites occupied by pairs 3 3 4 5 4 3
Nesting pairs 2 2 4 4 0 2
Successful pairs 0 0 D 1 0 2
Young fledged 0 0 2 3 0 3
Young fledged per nest 0 0 0.5 0.75 0 125
Young fledged per successful nest 0 0 1.0 3 0 1-5
Productivity
(young fledged per pair) 0 0 0.5 0.6 0 1.0
Data from J.D. Okill and FIBOT.
TABLE 5. Data for Peregrines breeding in Shetland in 1984-1991.

1984 1985 1986 1987 1988 1989 1990 1991

Sites checked 25 30 36 27 28 31 29 38
(% of known sites) (69) (83) (100) (75) (78) (86) (81) (100)
Sites occupied 7 14 9 8 5 4 6 5
(%) of sites checked (28) (47) (25) (30) (18) (14) (21) (13)
Sites occupied by single birds 2 7 5 5 1 2 4 5
Sites occupied by pairs 5 7 4 3 4 2 2 0
Nesting pairs 3 2 3 3 yy 1 1 0
Successful pairs 2 2 2 1 Ji 1 1 0
Young fledged 4 6 6 3 4 1 3 0
Young fledged per nest 1.3 3.0 2.0 1.0 2.0 1.0 3.0 0
Young fledged per
successful nest je 3 3 3 2 1 3 0
Productivity
(young fledged per pair) 0.8 0.9 1.5 1.0 1.0 0.5 1-5 0

Data from P.M. Ellis, J.D. Okill and FIBOT.

44 Ellis & Okill

young were at lest 10 days old so there are
only three records of clutch size between
1984 and 1991. Brood size at fledging varied
from 1-3 with a mean of 2.5 from a total
of 11 fledged broods. The maximum
number of young fledged in Shetland in any
year since 1984 was six in 1986 and in 1987,
and a total of only 27 young were known
to have fledged between 1984-1991,
averaging only 3.25 young fledging in the
islands each year. Since 1984, productivity
has varied from 0-1.5 young fledged per pair
with a mean over the eight years of 0.9. Of
the four nests known to have failed since
1984, one clutch was addled, one clutch
being incubated by a female heavily
contaminated with Fulmar Fulmarus
glacialis oil disappeared (what was presumed
to be the same female was later found not
far from the nest site unable to fly), one nest
failed with small chicks and another at the
egg stage, both for unknown reasons.
Despite the incompleteness of the data, it
is clear that since 1969 few Peregrines have
nested in Shetland and very few young have
been reared.

SB 17-(1)

Organochlorine, PCB and mercury
contamination

Between 1981 and 1991, unhatched eggs
from three clutches were analysed at the
Institute of Terrestrial Ecology’s
Experimental Station at Monks Wood
(Table 6). The egg with the thinnest shell,
collected in 1986, had been incubated for
considerably longer than the normal
incubation period, and so may have lost
more calcium carbonate than eggs which
had not been incubated for so long
(Ratcliffe 1980). The sample was small, but
the levels of DDE (the main metabolic
breakdown product of DDT) and HEOD
(the main metabolic breakdown product of
aldrin and dieldrin) are unremarkabe for
British Peregrines (Newton, Bogan & Haas
1989). In contrast, the level of PCB in a
1988 egg of 1218.18 ppm in lipid (64.33 ppm
wet wt.) and the level of mercury in a 1986
egg of 4.62 ppm dry wt. are high.

Prey taken during the breeding season
Saxby (1874) mentions that the Kittiwake
Rissa tridactyla was a favourite prey on

TABLE 6. Eggshell indices, organochlorine and mercury levels in unhatched (addled) Peregrine eggs,

Shetland 1981-88.

Nest
successful=s Eggshell % shell
failed = f index thinning HEOD DDE PCB Mercury
1981 f 1.65 9 - 47 280 =
(2.9) (17.0)
f d2 16 = = = =
1986 f 1.44 21 5.38 67.74 238.44 4.62
(0.28) (3.48) (12.24)
1988 = s 1.48 19 ~ - 1218.18 2.45
(64.33)
HEOD, DDE and PCB units are parts per million (ppm) in lipid (fats), with ppm wet weight values
in brackets below. Mercury units are ppm dry weight.

% shell thinning is calculated using pre DDT mean shell index of 1.82. — indicates not analysed.

Eggshell index is calculated by dividing the dry weight of a blown eggshell by its volume.

1993

Peregrines in Shetland 45

Unst and in addition mentions 13 species of
wild birds, domestic chicken Gallus gallus
and rabbit Oryctolagus cuniculus as prey
species taken during the breeding season. In
1962, one pair appeared to be living almost
entirely on Fulmars (Ratcliffe 1963).

Table 7 gives details of the 141 prey
items recorded in Shetland during
1984-1991. By both number and weight,
about half the prey were seabirds, mainly
terns and Puffins Fratercula arctica. Waders
(mostly Redshanks Tringa totanus were also

TABLE 7. Prey recorded as taken by Peregrines during the breeding season in Shetland 1984-1991.

Species

Storm Petrel Hydrobates pelagicus
Red Grouse Lagopus lagopus
Oystercatcher Haematopus ostralegus
Ringed Plover Charadrius hiaticula
Golden Plover Pluvialis apricaria
Lapwing Vanellus vanellus

Dunlin Calidris alpina

Snipe Gallinago gallinago

Curlew Numenius arquata

Redshank Tringa totanus

Turnstone Arenaria interpres
Common Tern Sterna hirundo
Arctic Tern Sterna paradisaea
Commic Tern Sterna spp.

Black Guillemot Cepphus grylle
Puffin Fratercula arctica

Rock Dove/Feral Pigeon Columba livia
Collared Dove Streptopelia decaocto
Skylark Alauda arvensis

Meadow Pipit Anthus pratensis
Rock Pipit Anthus petrosus
Wheatear Oenanthe oenanthe
Blackbird Turdus merula

Starling Sturnus vulgaris

Chaffinch Fringilla coelebs
Common Crossbill Loxia curvirostra
Field Mouse Apodemus sylvaticus

Total number items

Total % by number % by weight

yt OF 2 0.1
] 0.7 2.6
4 2.8 8.5
2 Lede. a. 0.7
5 3-5 3.9
3 2.1 2.6
1 0.7 0.2
2 1.4 0.9
1 0.7 2.9
1 5.0 4.3
3 2.1 122
3 7a 1.5
35 24.8 17.4
8 Sail. 4.0
Nt 0.7 1.6
21 14.9 32.1
4 2.8 5.9
1 0.7 0.8
7 5.0 at
2 1.4 0.2
4 2.8 0.4
1 0.7 0.1
2 1.4 0.7
19 13.5 6.0
1 OFF 0.1
] 0.7 0.1
1 0.7 0.1
141

Commic Terns are Arctic or Common Terns which could not be specifically identified.

Bird weights from Ratcliffe (1980).

Field Mouse weight from Berry & Johnston (1980).

46 Ellis & Okill

SB 17 (1)

taken frequently, as were Starlings Starnus
vulgaris.

Contamination by Fulmar oil

Fulmars have a very effective anti-predator
defence mechanism. If they are approached
by a potential predator, both adults and
larger chicks spit oil at the intruder. In 1976,
two fledged juvenile Peregrines were found
alive but unable to fly properly and covered
in Fulmar oil. Another heavily oiled (by
Fulmars) juvenile Peregrine was found dead
in 1983. In 1987, an adult female was found
alive, but unable to fly, not far from a
recently failed nest site where the incubating
female had been seen to be coated with
Fulmar oil. In the same year a contaminated
juvenile bird was seen in flight.

Movements

At least some adult Peregrines appear to be
resident because some are seen at Shetland
breeding sites during the winter (pers. obs.).
Although only 29 nestling Peregrines have
been ringed in Shetland, a total of six have
been recovered. Five were recovered within
Shetland, two in their second calendar year
in March and April, one in its third calendar
year in June, one in its fifth calendar year
in October and one in its tenth calendar year
in February. One chick was recovered in
Orkney 190km from its natal site in its
second calendar year in January. No
Peregrines ringed outside Shetland have ever
been recovered within the islands.

Discussion

Population and breeding success

Ratcliffe (1963) stated that, ‘‘the status of
the Shetland Peregrine population was not
clear, but it may have experienced the same
slow decline since 1925 as populations in the
Western Highlands of Scotland’’. The data
presented here show that the population has
declined further since then, with only five
single birds recorded in 1991. The decline
of the Shetland Peregrine population may
not have been entirely due to contamination

by organochlorines as occurred elsewhere
(Ratcliffe 1963). By 1971, the BTO
Peregrine Enquiry showed that a marked
recovery in numbers had taken place
throughout most of Britain (Ratcliffe 1972).
The 1981 enquiry found that, although
numbers were continuing to increase in
many inland areas, Peregrines were not
recolonising many coastal districts,
particularly in the south-east of England and
north and west of Scotland (Ratcliffe 1984),
and this has been particularly the case in
Shetland, the only Scottish county in which
Peregrines did not breed in 1991 (T.D. Dick
pers. comm.).

The production of young in Shetland
has also been low since at least 1962, and
the remnant population is distant from the
expanding Peregrine population of the
Scottish mainland. There is thus little
opportunity for the Shetland population to
increase through immigration or local
production. Several factors including poor
weather, persistent pollutants, poor food
supplies and contamination with Fulmar oil
might be responsible for poor breeding
success. Possible causes include the
following:

i) Weather

Peregrine breeding success in southern
Scotland was depressed by wet, cold weather
during hatching (Mearns & Newton 1988).
Meteorological records from Lerwick
Observatory suggest that weather conditions
during the breeding seasons 1976-1991
(particularly rainfall and temperature in
April and May) were unexceptional and are
unlikely to have directly reduced breeding
success in that period.

ii) Organochlorine, PCB and mercury
contamination

Only four addled eggs from three clutches
have been analysed since 1981, but an effect
of chemical residues in depressing breeding
success cannot be ruled out, and the
chemical analysis of further eggs would be
worthwhile. Seabirds and waders, which

1993

Peregrines in Shetland 47

together constitute 68% by number and
82% by weight of the breeding season prey
found since 1984, are known to carry heavy
burdens of PCBs and mercury (Newton et
al. 1989). The pattern of breeding season
data in Shetland with a high proportion of
unoccupied territories, unpaired adults,
non-breeding pairs and nest failures but with
a few pairs rearing young, is similar to that
found in populations elsewhere in Britain
which were depressed by the effects of
organochlorine pesticides during the 1950s
and 1960s but which have now recovered
(Ratcliffe 1980). It seems likely that
Peregrines in Shetland are contaminated
with these chemicals via their breeding
season prey.

iii) Poor food supply

Although breeding season prey populations,
particularly seabirds, have fluctuated in
Shetland since 1969 (Lloyd et a/. 1991), there
is no evidence that prey availability during
the breeding season is limiting breeding
success or adult survival. At least some adult
Peregrines are probably at their Shetland
breeding sites during the winter but their
prey (and its availability) outside the
breeding season remains unknown.

iv) Contamination by Fulmar oil
Mearns (1983) showed that of four oiled
Peregrines caught at the nest in south-west
Scotland, none was retrapped in subsequent
years. In his study, one third of trapped
females were oiled in an area with relatively
few Fulmars compared with Shetland.
Fulmars first nested in Shetland in 1878, and
their numbers increased rapidly to c.236,000
pairs by 1985-87 (41% of the British and
Irish population) (Lloyd ef a/. 1991). All the
traditional Peregrine nest sites in Shetland
hold large numbers of breeding Fulmars and
at times Fulmars try to nest on ledges used
by Peregrines (pers. obs.). Contamination
by Fulmar oil has claimed a small number
of Peregrines in Shetland, but with such a
small Peregrine population this could be
critical.

Reasons for the low population level of
the Peregrine in Shetland

The Shetland Peregrine population may
have been declining since 1925, but was
probably further reduced as a result of
organochlorine contamination after 1955,
when Peregrine numbers plummeted in
most parts of Britain (Ratcliffe 1963).
Peregrines in Shetland, as in many coastal
areas, have not recovered to the same degree
as those at inland localities (Ratcliffe 1980).
The few addled eggs from Shetland which
have ben analysed are contaminated with
levels of PCBs and mercury that could be
sufficient to depress breeding success. In
addition, a small number of Peregrines have
been found debilitated by Fulmar oil
contamination. This could reduce the
survival of both fledged juveniles and adults
and in an extremely small population this
could be critical.

A comparison with the situation in
Orkney

All Orkney data are from E.R. Meek (pers.
comm.). The Orkney Islands hold
approximtely 35 known sites, a similar

‘ number to Shetland. The Peregrine

population in these islands has also had
poor breeding success since at least the
1960s. However, the population in 1991 was
larger than in Shetland with 25 occupied
sites, 16 occupied by pairs of which 6-11
nested. However, in 1991 breeding success
was poor with only 3-9 pairs rearing young.

Of a total of 327 prey items examined
in Orkney in the breeding season between
1981 and 1992, seabirds and waders made
up 40% by number and 53% by weight, as
opposed to 68% by number and 82% by
weight in Shetland. However, Rock Doves
Columba livia and Feral Pigeons were
considerably more important in Orkney
(20% by number and 26% by weight),
compared to only 3% by number and 6%
by weight in Shetland in this study. Waders
and seabirds are more heavily contaminated

48 = Ellis & Okill

with organochlorines and heavy metals than
are Rock Doves and Feral Pigeons (Newton
et al. 1989). A higher proportion of seabirds
and waders in the diet of Shetland
Peregrines could be one of the main reasons
why the Shetland Peregrine population has
declined more than that of Orkney. But
there are no data on prey taken in Orkney
outside the breeding season.

In addition, the Orkney Peregrine
population may have experienced a higher
degree of immigration than is the case in
Shetland. Some evidence for this comes
from three recoveries of Peregrines on
Mainland Orkney where the birds were
ringed as nestlings elsewhere in Scotland.

A further contributory factor could be
that Orkney has less than half the number
of Fulmars found in Shetland (82,000 pairs
in 1985-87) (Lloyd et a/. 1991), and as the
Peregrine population there has never
reached such a low level as in Shetland it
may be less affected if a few Peregrines
become oiled.

Conclusion

Probably more than one factor is involved
in preventing the recovery of the Shetland
Peregrine population. More information is
needed before the most important factors
can be determined. There are indications
that chemical contamination caused the
main decline and may be the most important
factor preventing the population from
recovering in numbers.

Acknowledgements

We would like to thank all those who
assisted with fieldwork since 1981,
particularly G.W. Allison, F.M. Beveridge,
D.R. Bird, P. Bloor, 1.D. Bullock, D.N.
Carstairs, L. Dalziel, C. Donald, C. Dore,
A. Douse, J.N. Dymond, A. Fitchett, I.
Hawkins, M. Heubeck, W. Horn, M.
Mellor, R.J. Nowicki, M.A. Peacock, M.G.

SB 17 (1)

Pennington, G.W. Petrie, M. Preece, T.
Prescott, J.S. Rowe, I. Sandison, I. Spence,
I. Stuart, D. Suddaby, B. Thomason, R.J.
Tulloch, C.E. Vawdrey, D.J. Weaver, R.M.
Wynde. R. Matthews, N.J. Riddiford and
P.V. Harvey of Fair Isle Bird Observatory.
Scottish Natural Heritage provided the boat
during the 1991 survey. D.A. Ratcliffe
provided data from 1961 to 1971, the British
Trust for Ornithology provided the ringing
data and E.R. Meek provided data on
Peregrines in Orkney and commented on the
draft. M. Marquiss assisted with prey
identification and commented on the drafts
together with R. Mearns and D.A. Ratcliffe.
Our thanks to the Institute of Terrestrial
Ecology at Monks Wood for carrying out
the analysis of addled eggs and the former
Nature Conservancy Council for funding
this work. We would also like to thank all
those who over the years gave us
information about nesting areas and those
Shetlanders who allowed us to wander so
freely over their land.

References

Dunn, R. (1837). The Ornithologist’s Guide to
the Islands of Orkney and Shetland. Dunn,
Hull.

Evans, A.H. & Buckley, T.E. (1899). A
Vertebrate Fauna of the Shetland Islands.
Douglas, Edinburgh.

Lloyd, C., Tasker, M.L. & Partridge, K., 1991.
The Status of Seabirds in Britain and Ireland.
Poyser, London.

Mearns, R., 1983. Breeding Peregrines oiled
by Fulmars. Bird Study 30: 243-244.

Mearns, R. & Newton, I., 1988. Turnover and
dispersal in a Peregrine Falco peregrinus
population. /bis 126: 347-355.

Mearns, R. & Newton, I., 1988. Factors affecting
breeding success of Peregrines in south
Scotland. J. Anim. Ecol. 57: 903-916.

Newton, I., Bogan, J.A. & Haas, M.B. 1989.
Organochlorines and mercury in the eggs of
British Peregrines Falco peregrinus. Ibis 131:
355-376.

1993

Ratcliffe, D.A. 1963. The Status of the Peregrine
in Great Britain. Bird Study 10: 56-90.
Ratcliffe, D.A. 1972. The Peregrine population
of Great Britain in 1971. Bird Study 19:
117-156.

Ratcliffe, D.A. 1980. The Peregrine Falcon.
Poyser, Calton.

Peregrines in Shetland 49

Ratcliffe, D.A. 1984. The Peregrine breeding
population of the United Kingdom in 1981.
Bird Study 31: 1-18.

Saxby, H.L. 1874. The Birds of Shetland.
Maclachlan & Stewart, Edinburgh.

Venables, L.S.V. & Venables, U.M. 1955. Birds
and Mammals of Shetland. Oliver & Boyd,
Edinburgh & London.

P.M. Ellis, Seaview, Sandwick, Shetland.
J.D. Okill, Heilinabretta, Trondra, Shetland.

(Revised typescript received 31 January 1993.)

50 Scottish Birds (1993) 17: 50-55

SB 17 (1)

Spring Passage of Pomarine Skuas off Shetland in May 1992

H.R. HARROP, M. MELLOR
AND D. SUDDABY

Between 8-17 May 1992 an unprecedented passage of
2709 Pomarine Skuas were recorded off the west coast of
mainland Shetland, 2093 of which passed Watsness on 9
May alone, representing the highest known count of this
species past one location in Western Europe. The
passage and associated weather, their behaviour,
suggested theory of arrival and their displaced
movement along the west coast of mainland Shetland

are discussed.

Introduction

During May 1992, an unprecedented
northerly passage of Pomarine Skuas
Stercorarius pomarinus was recorded from
the west coast of mainland Shetland.
Observations from Watsness and Eshaness
between 7-17 May recorded a total of at
least 2709 birds, including 2563 off
Watsness on 8 and 9 May. Watsness was
manned on five days (see Table 1) and
Eshaness on three days during the above
period when weather conditions were
thought suitable for observing passage.

Spring occurrence in Britain and Ireland

Passage of Pomarine Skuas in spring
generally occurs from late April until early
June, usually peaking during the first three
weeks of May (Davenport 1992). Skua
passage is perhaps best known to occur off
the Western Isles (e.g. Davenport 1979,
1984, 1987, 1991), but annual movements
off the western and southern coasts of
Britain and Ireland, most notably off Slyne
Head (County Galway), Carnsore Point
(County Wexford) and smaller numbers in
the English Channel at Beachy Head (East
Sussex) and Dungeness (Kent) (Davenport
1981). Since the mid-1980s, irregular spring
seawatching off Watsness and Eshaness

have recorded small numbers, the most
notable year being 1991, when 105 birds
were recorded between 14-25 May (Shetland
Bird Report 1991).

May 1992 records off Shetland

Pomarine Skuas were recorded on all days
that Watsness was visited and the results are
outlined in Table 1. Observations from
Eshaness and other localities are discussed
later (see below).

Passage and associated weather

On 7 May, weak frontal systems moving
south-eastwards across the British Isles,
introduced north-westerly force 6-7 winds
with intermittent rain showers to Shetland
(see Fig. 1). These conditions prompted a
two hour seawatch off Eshaness, during
which two Long-tailed Skuas S. longicaudus
were seen. On 8 May, the trough of low
pressure was still tracking south-eastwards
over the British Isles continuing the north-
westerly airflow over Shetland, with the
wind decreasing to force 3-4, gusting five
during more frequent showers (see Fig. 2).
Another two-hour seawatch off Eshaness
between 1100-1300 hrs BST recorded just

1993

Spring Passage of Pomarine Skuas 511

TABLE 1. Pomarine Skua passage off Watsness, 8-17 May 1992.

Date Time (BST) Wind Total
08/5 1030-1430 & NW3-4

1900-2100 470
09/5 0600-2100 NNW5-7 2093
10/5 0800-1230 NW4-5

16/5 0900-1200 W4
17/5 0815-1100 WSW3

n = number of flocks.

two Arctic Skuas S. parasiticus, whilst a
total of six hours seawatching off Watsness
produced a single flock of 44 Long-tailed
Skuas and 470 Pomarines, 359 between
1030-1230 hrs. On 9 May, a deepening low
pressure system reached south-west Ireland
and had moved across central Britain by
early evening; the northern flank of the low
gave Shetland a north-north-westerly
airstream of force 4-5, gusting 6-7 during
the frequent showers of rain, snow and hail
(see Fig. 3). A multi-observer seawatch off
Watsness from 0600-1700 and 1800-2100 hrs
recorded a total of 2093 Pomarine and three
Long-tailed Skuas. Passage started at 0645
hrs and continued throughout the day, with
the majority of flocks seen soon after
showers. There were two pronounced waves
of passage: between 0900-1100 hrs and
1445-1700 hrs, with totals of 472 and 1350
Pomarines respectively. Both waves
coincided with periods of frequent showers,
which presumably drove the birds close
inshore. On the same day, 147 Pomarines
were recorded off Eshaness between
1015-1145 hrs, exactly the same number
recorded off Watsness between the same
times suggesting that some flocks were
coasting north. Although weather
conditions in Shetland were similar on 10
May (see Fig. 4), only 58 birds were
recorded off Watsness between 0800-1230
hrs. Off Watsness on 16 May, a west-north-

Range Mean Birds/hour
(flock size) (flock size)

1-123 DA Tat 19) 78.3
1-300 37.4 (n=56) 161.0
1-20 7.3 (n=8) 1229
- not recorded 28.7
—_ — 0.73

west wind force four produced 86
Pomarines between 0900-1200 hrs with two
recorded there the following day between
0815-1100 hrs, the wind having backed to
the west-south-west and decreased to force
three.

Other west coast localities in Shetland,
namely Fair Isle, Garth’s Ness, Fora Ness
and Belmont were watched to a lesser extent
on 9 and 10-May, but failed to produce any
Pomarine or Long-tailed Skuas.

- Behaviour

The majority of flocks of Pomarine Skuas
observed flew low over the sea, and
comprised a nucleus of approximately two-
thirds bunched at the front, with the
remainder following in single file. In
advance of approaching showers all but one
flock ceased moving and rested on the sea
until conditions improved, the exception
being a flock of 72 which, on sighting a
shower, rose up from sea level and
proceeded to climb at a 70° angle until they
flew over the shower. Once the showers had
passed over the flock, a nucleus of birds
would start to climb high and circle until the
stragglers or another smaller flock following
behind had caught up with them, after
which the flock descended to sea level again
and continued in a northerly direction. This
behaviour was noted also in fine weather

8

52 H.R. Harrop et al. SB 17 (1)

TT IS

Ph et

. x
‘Der

ie

FIGURE 1. 1200 GMT 7 May 1992

Vy s "
te ©

age of Pomarine Skuas 53

Spring Pass

1993

ta

54 H.R. Harrop et al.

with occasional ‘coasting’ flocks. A likely
explanation for this behaviour is that the
nucleus of the flock were sighting their
continuing route past Watsness.

Discussion

Passage off Shetland seems to occur after
several days of strong to gale force west to
north-westerly winds, therefore displacing
those birds which are thought to follow the
continental shelf on northward spring
migration (Furness 1987). This assumption
is reinforced by the fact that skua passage
off the west coast of mainland Shetland has
been recorded only after the conditions
outlined above. These certainly applied in
May 1992, with strong to gale force west to
north-westerly winds over the Northern Isles
from 4-7 May resulting in large scale
northerly movements on 8 and 9 May.
However, it must be stressed that those
conditions found suitable for observing skua
passage off the Western Isles (Davenport
1992) have not, to date, been sufficiently
investigated off the west coast of Shetland.

Although no accurate recording of
colour phase or age was undertaken during
periods of seawatching, a conservative
estimation of dark phase birds and sub-
adult birds on 9 May, resulted in figures of
5-8% and 15-20% respectively.

Observations at other sites in 1992

Pomarine Skuas were generally noted earlier
than usual in spring 1992. In April, birds
were recorded from several western localities
from 18 April onwards, peak counts being
290 off Bowness-on-Solway (Cumbria)
between 19-30 April and 22 off Carnsore
Point (County Wexford) on 25 April (Anon.
1992a). In May, records from the Western
Isles, predominantly off Balranald and
Ardivachar Point included 1289 Pomarines
and 835 Long-taileds between 1-16 May.
Unfortunately, there was no coverage at
Balranald on 7-8 May (to correspond with
the coverage at Watsness on 8-9 May) and

SB 17 (1)

by 9 May the weather there was unsuitable
for skua passage, with light variable winds
(D. Davenport pers. comms.). Off Bowness-
on-Solway, another 303 Pomarines were
recorded between 1-15 May. Many other
records came from the west, but good
numbers were also recorded from English
Channel and North Sea coasts (Anon.
1992b; D. Davenport in litt.).

Acknowledgements

Many observers were involved during this
seawatching period, but we would like to
thank Larry Dalziel, Pete Ellis, Peter Flint,
Martin Heubeck, Mike Pennington, Ian
Sandison and the staff of Fair Isle Bird
Observatory for providing additional
information and count details. Martin
Heubeck and David Davenport commented
on and improved on earlier draft of the text,
David Davenport provided details of the
1992 passage of Skuas off the Western Isles
and Dave Wheeler provided weather charts,
reproduced from Weather Log with kind
permission of the Royal Meteorological
Society.

References

Anon. 1992a. Bird News April 1992. Birding
World 5: 125-130.

Anon. 1992b. Bird News May 1992. Birding
World 5: 165-174.

Davenport, D.L. 1979. Spring passage of Skuas

at Balranald, North Uist. Scott. Birds 10:
216-221.

Davenport, D.L. 1981. The Spring passage of
Pomarine and Long-tailed Skuas off South
and West Coasts of Britain and Ireland. Jrish
Birds 2: 73-79.

Davenport, D.L. 1984. Large passage of Skuas
off Scotland and Ireland in May 1982 and
1983. Irish Birds 2: 515-520.

Davenport, D.L. 1987. Large passage of Skuas
off Balranald, North Uist in May 1986. Scott.
Birds 14: 180-181.

Davenport, D.L. 1991. The Spring passage of
Long tailed Skuas off North Uist in 1991.
Scott. Birds 16: 85-89.

1993 Spring Passage of Pomarine Skuas 55

Davenport, David. 1992. The Spring passage of Furness, R.W. 1987. The Skuas. Poyser, Calton.
Long-tailed and Pomarine Skuas in Britain Shetland Bird Report 1991. Shetland Bird Club.
and Ireland. Birding World 5: 92-95. Lerwick.

Hugh R. Harrop. Fairview, Scatness, Virkie, Shetland ZE3 9JW.
Mick Mellor, Fairview, Quendale, Dunrossness, Shetland ZE2 9JB.
Dave Suddaby, 92 Sandveien, Lerwick, Shetland ZE1 ORU.

(Revised typescript received 3 March 1993.)

56 Scottish Birds (1993) 17: 56-61

Short Notes

Kestrels feeding on road casualties

Recently we saw Kestrels Falco tinnunculus
feeding on rabbit road casualties on a
relatively quiet moorland road in west
Galloway. On 16 December 1991, 7
February 1992, 2 April 1992 and 11
February 1993 we saw a male Kestrel feed
on rabbit carrion (twice in the early morning
and twice in the late evening) and on 22
October 1992, we disturbed in our car a
female or juvenile Kestrel feeding on the old
remains of a rabbit carcase at dusk. All five
records occurred in the same area within a
400-600m stretch of road. On 15 February
1993, we saw a male Kestrel feed on the
remains of a cock Pheasant Phasianus
colchicus on another road nearby.

Such behaviour may be unusual
because Village (1990. The Kestrel. London)
states that Kestrels are predominently

SB 17 (1)

predators of small mammals. Carrion is
probably not commonly eaten, but Cramp
& Simmons (1980. The Birds of the Western
Palearctic. Oxford. Vol.2.) state that
Kestrels may scavenge at carrion. Village’s
only record of a Kestrel eating a road
casualty was of a common toad in
Eskdalemuir while BWP gave no records.
Similarly Hope-Jones (1980. Bird scavengers
on Orkney roads. Brit. Birds 73:561-568)
makes no mention of Kestrels feeding on
road casualties but Hodson (1966. Some
notes on the habits of roadside carrion
feeders. Bird Study 13:272-273) surmised
that Kestrels were responsible for eating
dead birds that he had placed along a stretch
of road but gave no direct observation of
this behaviour.

R.C. & A.P. Dickson, Lismore, New Luce, Newton Stewart DG8 OAJ.

Hunting times by Merlins in winter

Casual or anecdotal observations of Merlins
Falco columbarius in their wintering
habitats suggest that they are either active
or inactive during much of a short winter
day. There are, however, few published
records of how Merlins spend their day and,
in particular, on the times they hunt.
Because little attention has been paid to this,
I timed and noted every individual hunting
foray, whether successful or not, by ‘brown’
and ‘blue’ Merlins from November to
February 1966-92 in west Galloway (Fig. 1).

There was a late morning peak of
activity at 1030-1200 hrs both by brown and
blue Merlins and a similar peak in the
afternoon at 1430-1600 hrs by brown and
blue Merlins respectively with a lull in
activity at midday.

Hunting forays were also plotted
between August and March (longer

daylight) and a similar pattern emerged (Fig.
2), with a further minor secondary peak of
activity by brown birds around 1830 hrs.

Peak activities in the mornings
occurred some 2-3 hours after the Merlins
had left their roosts. Unexpectedly, there
was no indication that Merlins tried quickly
to replenish energy stores lost overnight. A
need to replenish energy stores to last them
during a long winter night is, however,
suggested by the greater pattern of activity
during the late afternoon. Some Merlins
hunted until it was nearly dark but no hunts
at their roosts are included.

These finding broadly agree with
Warkentin & Oliphant (1990. Habitat use
and foraging behaviour of urban Merlin in
winter. J. Zool. Lond. 221:539-563) who
found that nine radio-tagged Merlins in
urban Saskatoon, Canada, were relatively

57

Short Notes

1993

(sayeul) sulsayy anjq, ———— —

CAN{ 10 Sajeulaj) SUIPIIW) UMOIG

‘T6-996L Yosew — ysnsny ‘Aemoyjey }saM Ul suljsap Jo sau} SunUNY *Z IANO
(y) Aep yo awn

OOvL 0001 0060 0080

“spoiiad ‘ui O¢ ul SABMIO} ZUNUNY JO JEqUINN)

76-296 Asensigay — JIQUIDAON ‘AEMO]jED JSAM UI SUIPIPW JO Sout} sununy ‘L JYNOWY
(y) Aep yo aunty
00L1 0091 OOSL 00rl OO£l 00z1 OOLL 0001 0060

ry Se 2 eo a a~ 0
aK es A 2s ON Za =

Se yee Ee

OL

07

(sayeus) suypay anyq|—————

spoiied ulus OE Ul SAB10} ZUNUNY JO JaquUINA

(CAN{ 10 Sazewiay) supe UMOIG
0€

58 Short Notes

SB 17 (1)

inactive for large parts of the day with
activity in the early morning, a midday lull
and a second activity peak in late afternoon.
Newton (1986. The Sparrowhawk. Calton)
gave a similar pattern of hunting times in

radio-tagged Sparrowhawks Acciper misus.
First-winter birds, however, were more
active than adults and had an afternoon
peak in activity which was absent in adults.

R.C. Dickson, Lismore, New Luce, Newton Stewart DG8 OAJ.

Hunting associations between Merlins and Hen Harriers in winter

Hunting associations between Merlins Falco
columbarius and Hen Harriers Circus
cyaneus have previously been described and
documented (Brit. Birds 77:72-73, 481-482,
79:430; Jbis 102:136; BWP Vol.2; Watson
1977. The Hen Harrier. Berkhamstead).
This could be a common hunting strategy,
but in west Galloway, during a study of
Merlins’ hunting activities between 1965-92,
it only occurred in 18 out of 270 hunts
(6.6%). In winter in west Galloway, Merlins
occur in the same open habitats as Hen
Harriers and other birds of prey often
hunting the same food supply in the same
areas at different times and intensity. When
the hunting areas of Merlins and Hen
Harriers overlapped, Merlins seemed
deliberately to take advantage of hunting
harriers (and vice versa) but Merlins were
usually already at a hunting place before
harriers appeared. When a harrier arrived
and hunted the same ground, the Merlin
would instantly follow and attack prey
flushed by the harrier, flying above, behind
or ahead and overtaking the hunting harrier
as prey was flushed. Both raptors then
exploited the prey in the confusion and
alarm caused. As long as the harrier was
present, the Merlin would continue to hunt
with it, but as soon as the harrier left, the
falcon continued hunting on its own or flew
away. However, I saw only one successful
capture by a Merlin in this way, a Lapwing
Vanellus vanellus; all the rest were
unsuccessful.

Nonetheless the confusion to the prey
‘s probably advantageous to both species of
raptor (see Watson 1977; Brit. Birds 79:430;

81:269-274) and has an element of
commensalism about it, since both raptors
chased the same prey. Merlins chased
Skylarks Aluada arvensis nine times,
Meadow Pipits Anthus prentensis twice,
Linnets Carduelis cannabina four times and
a Pied Wagtail Motacilla alba once, while
harriers chased the same Skylarks six times,
Meadow Pipits once, Linnets three times
and a Pied Wagtail once. Merlins hunted
with male Hen Harriers on 11 occasions and
with ‘ringtails’ on seven. Calls by Merlins
were heard once on 29 December 1991,
when a male harrier twisted after some
Skylarks, swooped up and met a female or
juvenile Merlin head-on which uttered a call;
the Merlin then chased the Skylark. During
these hunting associations, interactions
between Merlins and harriers only occurred
four times: twice when a Merlin swooped
on a harrier, once when a harrier displaced
a Merlin from a perch, and once when a
harrier chased a Merlin.

In addition, Merlins also associated
with Sparrowhawks Accipiter nisus on three
occasions. Again the Merlin was always
present before a Sparrowhawk arrived and
both chased Chaffinches Fringilla coelebs
and a Linnet flushed by Sparrowhawks
beating low across root crops and stubble.
Raines (1972. Hunting association of two
birds of prey. Cheshire Bird Report 1972:20)
has also noted similar behaviour.

As well as hunting with other raptors,
Merlins will apparently exploit prey species
flushed by others, since it has also been
reported that they have chased prey flushed
by people (Brennecke 1951. Zug Jagdweise

1993

Short Notes 59

des Merlin-Falken. Vogelwelt 72: 82-84;
Brown 1974. Lakeland Birdlife 1920-70.
Carlisle; Dekker 1988. Peregrine Falcon and
Merlin predation on small shore birds and
passerines in Alberta. Can.J.Zool. 66:

925-928); by motor vehicles and Kestrels
Falco tinnunculus (Brit. Birds 79:431) and
by a moving train (Kenyon 1942. Hunting
strategy of pigeon hawks. Auk 59:443-444),.

R.C. Dickson, Lismore, New Luce, Newton Stewart DG8 OAJ.

Behaviour of Herring Gulls feeding on turnips

In a study of damage to turnips by brown
hares Lepus europaeus, Hewson (1977)
found that gulls Larus spp. fed only on
turnips from which the hard peel had been
removed first by hares (Food selection by
brown hares (Lepus capensis) on cereal and
turnip crops. J. appl. Ecol. 14: 779-785).
However, in March 1989 Herring Gulls
Larus argentatus were feeding on turnips in
a 2.7 ha field at Eriboll, north-west
Sutherland, where there were no rabbits
Oryctolagus cuniculus or hares to break into

200

100

50

21 3)
MARCH

the turnips. By 12 March, the gulls had
damaged 3.6% of the 36,000 turnips by
pecking out a hole big enough for water to
collect in, causing rotting or frost damage,
and destroyed 6.9% leaving only an empty
shell. A month later, and before sheep were
folded on the remaining 18,000 turnips, (the
rest had been removed to feed cattle and
sheep), 7.5% had been damaged and 13.7%
destroyed by Herring Gulls. While feeding,
gulls pecked in a desultory manner at several
turnips before they found one which had

|

|

| ARRIVAL
| S

10 20 30 10
APRIL MAY
1989

FIGURE 1. The decline in the numbers of Herring Gulls feeding on turnips at Eriboll following the arrival

of sheep in April 1989.

60 Short Notes

been opened up, as if only a proportion of
the gulls were adept at breaking into turnips.

Before the sheep arrived, gulls fed in
a tight flock over about 10% of the field.
They moved away from feeding sheep,
which by opening turnips made it easier for
the gulls to feed. Gulls then fed over more

than 50% of the field in a loose flock, but -

fewer gulls continued to forage (Fig. 1).
Sub-adult Herring Gulls reacted more
strongly than adults to the presence of sheep
as juvenile Ravens Corvus corax do in an
unfamiliar situation (Heinrich, B. 1990.
Ravens in winter. London. Barrie &
Jenkins), and the proportion of sub-adults
in the flock declined (Fig. 2).

In 1990, red deer Cervus elaphus fed
widely in the same field from January
onwards; consequently many turnips were

35

30

25

% OF
sup 29
ADULTS
5
10
5
20. 331
MARCH

SB 17 (1)

made available to Herring Gulls. Sheep
arrived on 8 January and there were usually
about 80, often foraging all over the field.
Gulls started feeding in late January and
ranged widely in loose flocks. There was no
falling-off in numbers as in 1989; indeed
there were more gulls in late April than
earlier (Fig. 3).

Herring Gulls did not feed on turnips
only when bad weather restricted their
normal coastal foraging areas. There was no
significant difference in the numbers of gulls
in the turnip field in winds up to and
including force five on the Beaufort scale
and in stronger winds.

By contrast, in March 1989 there were
no Herring Gulls feeding in 23 turnip fields
in north-east Scotland, 11 of them along the
coast, although sheep were folded in five

! ARRIVAL
on SHEEP
|

1/0 ee 8 10
APRIL MAY

1989

FIGURE 2. The proportion of sub-adult Herring Gulls in the flock following the arrival of sheep.

- GULLS 200

1993 Short Notes 61

400

350

300

250

we OF

150

100

50

fOr 220). 30 10m 200s 10) 3207. 30 LOW S40 ype le)
JANUARY FEBRUARY MARCH APRIL

1990

__ FIGURE 3. Herring Gulls feeding on turnips at Eriboll in 1990, when sheep were present from January

though more widely dispersed than in 1989, and Red deer were feeding on turnips in early January,

__ making them more easily available to Herring Gulls.

fields and had been folded earlier in others, Doon Major, the variety grown also at
and in four fields turnips had been Eriboll, was the most widely damaged,
damaged, probably by rabbits. perhaps because it is a soft-skinned turnip
The extent of the damage at Eriboll was (MacFarlane Smith, pers. comm.).
unusually severe when compared with Proximity to the long shoreline of Loch
damage to turnips by brown hares, followed Eriboll may have accounted for the high
| by minor damage by birds, in north-east concentration of gulls on the study area.
Scotland where 2.8% and 6.0% of turnips The nearest other turnip crops were 21km
on two study areas had suffered minor north-west and 20km east.

damage. Of seven varieties involved there,

R. Hewson, Department of Zoology, University of Aberdeen,
Tillydrone Avenue, Aberdeen AB9 2TN.

62 Scottish Birds (1993) 17: 62-64

Rare Migrants

(It has been decided by the Editorial Committee
that full descriptions will appear in Scottish Birds
only of species which are new, or at most second
records, for Scotland.

Ed)

Solitary Sandpiper on Fair Isle: a third
Scottish record

After several days of September gales,
mostly from a westerly quarter, the
atmosphere at the Fair Isle Bird Observatory
was somewhat strained, and visitors to the
observatory a little desperate. It was
therefore with some relief that Sunday 13
September dawned bright and sunny, with
only light to moderate south south-west
winds. The wind direction was not esepcially
promising, but at least it might now be
possible to see what birds there were.
The morning census produced little of
real note, although a good fall of Meadow

Pipits Anthus pratensis (360) and a thin
scattering of common warblers were logged.
At 1215 hrs I headed up the drive towards
Field Croft in search of a first-winter Grey-
headed Wagtail Motacilla flava thunbergi,
which had been reported earlier. As I
rounded the corner of the cow byre, I
flushed a small brownish wader. The
immediate impression was of a brown Green
Sandpiper 7ringa ochropus, with a dark
rump and central tail. It did not call and
flew only a few yards before alighting.
When the bird was at rest, I was struck by
its slim, attenuated and ‘leggy’ appearance,
while the bold white eye-ring was much
more striking than the indistinct pale loral
stripe. I knew instantly that it just had to
be a Solitary Sandpiper Tringa solitaria.
Almost immediately the bird flushed again,
this time flying to a tiny pool by the main
island road. I hastened to the croft to phone
the observatory. Jane Wheeler listened to
my garbled request for the telephone with
a calm no doubt borne of several years’
experience of Fair Isle assistant wardens.

1993

There was no response from the observatory
but, seeing the minibus heading back for
lunch, I ran out to try and flag it down. It
did, however, lurch to a stop before I
reached it, and warden Paul Harvey and his
two small daughters, Holly and Bryony,
were already grilling the bird as I galloped
up. Paul’s face registered a classic mixture
of emotions: delight at the discovery of the
superb rarity and the realisation that I had
found it first.

The sandpiper flew back to the cow
byre as other birders were summoned. Here
it remained until the evening of 15
September. It was a particularly confiding
individual and provided stunning views to

Kumlien’s Gull in Shetland —- the
fourth Scottish record

On 15 January 1993, MM was conducting
a Beached Bird Survey along the pebble
beach at Scatness, Shetland, when he
noticed a ‘white-winged gull’ Larus
glaucoides/hyperboreus roosting on the
fringes of some inland freshwater pools. His
initial impression, based on head and wing
structure, was that of an Iceland Gull L.
glaucoides. However, on obtaining closer
views, he noticed grey in the outer primaries,
characteristic of the subspecies L. glaucoides
kumlieni, also known as Kumlien’s Gull. It
soon became apparent that the bird was in
an exhausted condition and it was taken into
care but, unfortunately, it died soon
afterwards. It was thoroughly examined by
HRH and MM to eliminate the possibility
of it being a Thayer’s Gull L. thayeri, or a
_ Thayer’s x Kumlien’s intergrade (which
freely interbreed, see e.g. Snell 1989).
Reference to Grant (1986) made the eventual
identification straight-forward by virtue of
the almost textbook pattern exhibited by the
outer five primaries. A detailed description

Rare Migrants 63

locals and visiting birders during its short
stay. A full description may be obtained
from the author.

The Solitary Sandpiper breeds over
most of Alaska and Canada, wintering in
Central America, South America and The
West Indies. It is a vagrant to Britain and
Ireland, the Fair Isle individual being the
29th documented record. Previous records
have all been in the period July-October,
with a marked bias to south-west counties
of Britain, particularly Scilly. This is the
third Scottish record and the first for
Shetland. Previous Scottish records are: one
shot, Lanark, before 1870; and a juvenile,
Maleclete, North Uist, 20 October 1990.

Roger Riddington, Fair Isle Bird
Observatory, Shetland ZE2 9JU

was taken and may be found in Birding
World 6: 105.

Kumlien’s Gull breeds on Baffin Island
and on the north-west sector of the Ungave

‘Peninsula in north-east Canada. It winters

along the Atlantic coasts south to Long
Island, USA (Harrison 1987; Lewington et
al. 1991), and is a vagrant to Europe.
Excluding the Faeroes, where there
were at least 38 in January 1983 (Fjeldsa &
Jensen 1985), most of the records originate
from Britain and Ireland, where a total of
11 individuals have been recorded up to the
end of 1991 (Lewington ef al. 1991; Rogers
et al. 1992). In addition, and subject to
acceptance by British Birds Rarities
Committee (BBRC), a further six
individuals were recorded in Britain during
1992 (Anon. 1992), including an adult in
Highland, bringing the Scottish total to
three. These are: Lerwick Harbour,
Shetland, adult, 4-8 February 1983
(Shetland Bird Report 1983); Banff Bay,
Grampian, adult, first seen on 17 March

64 Rare Migrants

SB 17 (1)

Kumlien’s Gull in Shetland

1985, returning sporadically during winter
months until at least February 1992 (Anon.
1992, A Murray pers. comm.); Inverness,
Highland, adult 1 January 1992 (Anon.
1992, A Murray pers. comm.).

The Scatness individual, probably a
fourth winter bird due to the tail band and
primary covert pattern will, upon
acceptance by BBRC, constitute the fourth
record for Scotland. The skin is now held
at the Royal Museum of Scotland.

Acknowledgements

We are grateful to Kevin Osborn for commenting
on and improving the manuscript and Angus
Murray for providing information on previous
Scottish records.

References

Anon. 1992. Recent Reports. Birding World 5:
3-10, 125-130, 452-455.

Fjeldsa, J. & Jensen, J-K. 1985. ‘Invasion’ af
Hvidvingede og Kumlien’s Mager pa Nolso pa
Faeroerne. Dansk Ornithologisk Forenisy’s
Tidsskrift 79: 103-106.

Grant, P.J. 1986. Gulls: a guide to identification.
Calton.

Harrison, P. 1987. Seabirds of the World: a. |

photographic guide. London.

Lewington, I., Alstrom, P. & Colston, P. 1991.
A Field Guide to the Rare Birds of Britain and
Europe. London.

Rogers, M.J. & the Rarities Committee. 1992.
Report on rare birds in Great Britain in 1991.
Brit. Birds 85: 507-554.

Shetland Bird Report 1983. Shetland Bird Club.
Lerwick.

Snell, R.R. 1989. Status of Larus Gulls at Home
Bay, Baffin Island. Colonial Waterbirds 12:
12-23.

Hugh R. Harrop, Fairview, Scatness,
Virkie, Shetland ZE3 9JW.

Mick Mellor, Fairview, Quendale,
Dunrossness, Shetland ZE2 9JB.

1993

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66 Scottish Birds (1993) 17: 66-67

SB 77 (1)

Obituary

Dr William Serle O.B.E.
(1912-1992)

William Serle died in Edinburgh on 7
October 1992 following a short period of
declining health. He was born in
Duddingston Manse, Edinburgh on 29 July
1912 and attended George Watson’s Boys’
College before studying for a degree in
medicine at Edinburgh University.

His enthusiasm for ornithology was
fired largely by his father’s own activity in
the subject. The Revered William Serle
collated extensive field notes and built up
a comprehensive (worldwide) collection of
birds’ eggs. As a boy, William Serle
accompanied his father on many excursions
from which he produced his own meticulous
notes. He travelled widely throughout the
Lothian and Border counties by bicycle and
made longer journeys to the north and to
Orkney. The first of a long series of
ornithological publications was a note on
Mergansers Mergus serrator in Scottish
Naturalist, written while he was still in his
teens.

With ready access to current bird
literature in his father’s library, William
Serle recognised the potential for increased
ornithological research in West Africa.
Following his graduation in 1936, the year
in which he was elected to the British
Ornithologists’ Union, he joined the
Colonial Medical Service and he sailed for
Lagos in 1937.

For the next 20 years William Serle
made extensive and valuable collections in
Nigeria, Sierra Leone, British Cameroon (as
then known) and parts of East Africa. This
research yielded some 60 publications from
his pen covering aspects of status,
distribution, breeding and taxonomy. A
number of these papers were classics of their
period and it must be remembered that his
ornithological work was accomplished very

much as a sideline to his professional duties
as a doctor. Not unexpectedly, in view of
his medical background, William Serle
maintained detailed and comprehensive field
notes which bore the stamp of a methodical
mind; his publications fully reflect this
clarity of thought and expression. Despite
the fashion of these years for ‘splitting’,
William Serle pushed a conservative line in
taxonomic problems, in many cases
suggesting that their resolution should be
dependent on the availability of a larger
series of specimens. Nevertheless, he is
credited with the descriptions of 18 new
avian taxa, including the Kupe Mountain
Bush-Strike Malaconotus kupeensis, a bird
with a very restricted range and always
considered rare.

During the war he was called up to
serve with the West African Field
Ambulance Corps and he saw active service
in India and Burma. He was awarded the
O.B.E. in 1946 for his outstanding army
service.

He married in 1956, and after a further

short period in Africa, he felt called to train |

for the ministry in Scotland. In 1959, he was
ordained and inducted to Drumoak in
Kincardineshire where he remained until his
retiral in 1987. Following his return to
Scotland, he continued research and
publication on personal material, much of
which had been presented to the British
Museum (Nat. Hist.). In 1977, he co-
authored Collins’ A Field Guide to the Birds
of West Africa — a work familiar to many.
A lower profile, yet significant, role was his
position as a referee for the Birds of Africa
series for which his knowledge and expertise
proved invaluable.

In 1987, Dr Serle donated his scientific
collection of West African birds’ eggs to the

1993

National Museums of Scotland, where it
joined material previously donated by him
as early as 1932. The bulk of his skin
collections are in the Natural History
Museum at Tring, though he also sent
material to major natural history museums
in Africa, Europe and North America. The
NMS has c.500 of these skins.

Obituary 67

Following his death, field notes and
other early notebooks joined his zoological
material in collections of the NMS. His
collections and published works are a lasting
reminder to a very full and varied life.
William Serle is survived by his wife Sheila,
five daughters and a son. To them all we
express our deepest sympathy.

R.Y. McGowan, Department of Natural History, Royal Museum of Scotland,

Chambers, Street, Edinburgh EH1 IJF.

68 Scottish Birds (1993) 17: 68-70

Correspondence

(The Editor welcomes correspondence on
suitable topics in Scottish Birds. It is
essential, however, that all letters are

Letters

Further aberrant plumage in Peregrine

I read with considerable interest G. Bates’s
article in Scott. Birds 16: 219 concerning
aberrant plumage in a pair of Peregrines
Falco peregrinus in north Scotland. Just a
few days earlier I had come across a
Peregrine with aberrant plumage, albeit of
an entirely different nature. On 15 June
1992 I visited a location in Central Region
where a fortnight earlier two birdwatchers
had reported a pair of Peregrines. There had
been no breeding records from this site
before but it was certainly a very promising
location. After searching around, I found
a nest and received a shock when I saw the
sitting female. She was facing me and, at
a distance of no more than 70m, the bird
showed a bright salmon-pink breast. The
rest of the bird was more normal, with a
very black head and moustachial streak, a
blue-grey back, a greyish bill with yellow at
the base, a dark iris and a yellow eye-ring.
After a while the bird took off and flew
close overhead. The underparts were heavily
barred but I could clearly see that the
salmon-pink colour extended to all areas of
the underparts that are usually white or off-
white. The tail was noticeably very short and
was tipped with the same salmon-pink
colour. The bird’s alarm call and general
flight pattern were that of a typical
Peregrine. However, when I looked at the
nest site, I received another surprise. It
contained two tiny chicks, no more than a
couple of days old, but instead of having
the usual white coloured down, both young
were bright salmon-pink all over.

SB 17 (1)

addressed to the Editor and that personal
or libellous comments should be avoided.

Eds)

Two days later I visited the site again,
this time in the company of Roger Broad.
The female Peregrine was present again, but
sadly one of the two chicks was now dead,
lying with its feet in the air in the nest
scrape. On my third and final visit on 11
July the scrape was empty and there was no
sign of any birds. On none of these
occasions did I see the male Peregrine, but
according to Patrick Stirling-Aird, who
visited the site once, this was a normal
plumaged bird. All site visits were carried
out under licence from the Scottish Natural
Heritage as part of a national monitoring
exercise.

On looking through the literature, there
is very little reference to salmon-pink

colouring in the nominate race peregrinus. -.

Derek Ratcliffe in his book The Peregrine
Falcon wrote that ‘‘the underparts are white
or cream, though the actual shade is
variable, the chest usually tending to a warm
buff or even salmon-pink or pale rufous
tint, especially in the female, whereas the
males are whiter’’. However, there is
considerable geographical variation in the
Peregrine population and BWP gives two
races that show traces of pink — F.p.
brookei (Mediterranean basin to Caucasus)
is described as ‘‘more rufous below’’, while
F.p. madens (Cape Verde Islands) has

‘underparts suffused with dull pink-buff’’. L

Both these races seem unlikely to occur in

Scotland by their own efforts as neither is |

known for its migratory movements. In

plumage characters, madens approaches the |

1993

Correspondence’ 69

Barbary Falcon P. pelegrinoides (which the
Scottish bird clearly was not), and brookei
that I have seen in Algeria were very
different from this Scottish individual. The
possibility of an escape from captivity
cannot be entirely ruled out, although this
bird did not have any jesses. Brookei and
brookei x peregrinus and other crosses are

kept in some numbers in this country.
Nevertheless, perhaps this is another case of
aberrant plumage in Scottish Peregrines.
Like the author of the previous article, I
would be very interested to see the results
of successful breeding if the bird returns to
the site next year.

Mike Trubridge, Garrison Cottage, Inversnaid, Stirling FK8 3TU.

Fulmar oiling of Peregrines

I noted with interest W.R.P. Bourne’s letter
(Scott. Birds 16: 290) suggesting that the
aberrant plumage of a pair of Peregrines
Falco peregrinus in Sutherland (Scott. Birds
16: 219) was due to oiling by Fulmars
Fulmarus glacialis.

I agree with him that Fulmar oiling is
a problem for Peregrines and this is
definitely the case in Orkney, where there
is also competition with Fulmars for nesting
ledges. Typically, oiled plumage is stained
dark brown and appears to be wet or shiny
as though the bird had just been bathing.
There is often impairment of flight, the bird
only moving a short distance before
alighting again.

The incidence of Fulmar oiling of birds
appears to have increased in Orkney in
recent years (Booth, C.J. & Reynolds, P.
1987. Fulmar oil contamination of birds in
Orkney. Orkney Bird Report 1986: 70-75).
Ravens Corvus corax, particularly newly

C.J. Booth,

Attacks by Great Skuas on an Eider and
a Mute Swan

Further to Martin Heubeck’s note on Great
Skuas Stercorarius skua attacking a flock
of moulting Eiders Somateria mollissima
(Scott. Birds 16: 284) I would like to add
two interesting sightings here on Stronsay
in 1992 concerning Great Skuas.

fledged juveniles, and Peregrines were
found to be most often affected, but
altogether 16 species were recorded with
Fulmar oil contamination. From 1971 to the
end of 1992, there have been 21 cases of
Fulmar oiled Peregrines, 11 of which were
either found dead or dying and three others
were taken into care for cleaning and then
released.

Chemical pollutants also continue to
pose a threat to Orkney Peregrines and at
two sites that I monitored in 1992 both
clutches failed to hatch, the females
continuing to sit for longer than the normal
incubation period. It would seem that, with
only a small number of pairs in Orkney
successfully rearing young and with the
combination of pollutants and Fulmar
oiling, the Peregrine population in the
county will have difficulty in making a
recovery similar to that seen in other parts
of Britain.

Ronas, 34 High Street, Kirkwall, Orkney.

i. At approximately 1100 hrs on 6 May,
Tony Hulls and I were watching a small
flock of adult Eiders (two drakes, four
ducks) swimming 50 yards off-shore at
Bomasty Bay. The birds suddenly became
agitated and we noticed a Great Skua wheel

70 Correspondence

round above the Eiders and suddenly dive
down at the flock. The Eiders dived, but the
Skua seemed to have singled out one
individual and after a chase of some 20
minutes, during which time the Eider dived
several times, the Skua eventually killed and
ate the bird. The rest of the flock had come
out of the water and watched the episode
from the rocky shore. The singled out Eider
escaped from the Skua several times but
each time the Skua followed it, as it was
swimming underwater, by a series of
flapping ‘lunges’. The Eider had been held
by the wing and nape and finally again by
the nape and seemed to be dead after about
20 minutes.

The Fair Isle Baillon’s Crake and other
corpses

Unlike a number of other recent Shetland
rarities, now in museums, the Fair Isle
Baillon’s Crake referred to by McGowan &
Kitchener (Scott. Birds 16: 289) is in a glass
case in my home in Shetland (address
below). Anyone who wishes to see it is
welcome to call. Suitable provision for
posterity has been made in my will, but until
that comes into effect I intend to keep the
specimen!

SB 17 (1)

ii. At approximately 1500 hrs on 17
September, I noticed a Great Skua flying
low over a pair of Mute Swans Cygnus olor
with two almost full-grown cygnets, which
were swimming in the sea at Whitehall
Stronsay. The Skua suddenly wheeled round
and attempted to grab one of the cynets by
the nape. The parents lunged at the Skua
and it was driven off a few yards, where it
landed on the sea. The Skua made several
further attempts to grab the same cygnet,
both from the water and from the air, but
each time the parent Swans drove it off.
After ten minutes, the Skua gave up and
flew off.

John Holloway, ‘Castle’, Stronsay, Orkney.

Incidentally, a number of other corpses
of birds found dead in Shetland in recent
years have been sent to museums in Britain,
including the following to the Royal
Museum of Scotland: Two-barred Crossbill
(2), Radde’s Warbler, Icterine Warbler,
Honey Buzzard, Kumlien’s Gull, Spoonbill,
Barn Swallow and American Redstart, the |
latter two being mummified corpses found |
onboard oil tankers arriving at Sullom Voe
from the Americans.

Dave Suddaby, 92 Sandveien, Lerwick,
Shetland ZE1I ORU.

1993 71

a

ACTA
XX CONGRESSUS INTERNATIONALIS ORNITHOLOGICI

These Acta XX Congressus Internationalis Ornithologici provide a full
and representative record of the activities of the 20th Congress held in
Christchurch, New Zealand, 2 - 9 December 1990.

Following the tradition of some recent International Ornithological
Congresses, the Acta include all symposia papers - as well as plenary
papers and business reports. In a departure from tradition, the
Organising Committee have included as a Supplement to the Acta, the
Programme and Abstracts distributed at the Congress so as to more
fully report the scientific content of the Congress.

A limited number of the complete Proceedings (five volumes) are
available for purchase by institutions or interested ornithologists who
did not attend the Congress.

Published: 1990 - 1991.
Wellington, NZ Ornithological Congress Trust Board.
31 20 pp.; black & white and colour illustrations; tables; softcover.
_ISBN 0 - 9597975 - 5 - 6 (five- -volume set)

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Facsimile: 64 - 4 - 471 3279

72 Scottish Birds (1993) 17: 72-73 SB 17 (1)

Items of Scottish Interest

Most of the following papers and reports on birds in Scotland are available in the Waterston
Library at 21 Regent Terrace for reference, and include all that have come to notice in the
period September 1992 to February 1993. The librarian would be glad to learn of anything
that has been missed, and to receive reprints or copies of papers on any aspect of ornithology
or natural history.

Bird reports marked with an asterisk are available from the SOC at the prices quoted,

but please add 50p per order for postage and packing.

Scientific papers

Belaoussoff, S. 1993. Northern Gannet and
Common Guillemot nesting on Rockall.
Brit. Birds 86: 16.

Bourne, W.R.P. 1993. Birds breeding on
Rockall. Brit. Birds 86: 16-17.

Caldow, R.W.G. & Furness, R.W. 1993. A
histochemical comparison of fibre types in
the M. pectoralis and M. supracoracoideus
of the Great Skua and the Herring Gull
with reference to kleptoparasitic capabilities.
J. Zool., Lond. 229: 91-103.

Craik, J.C.A. 1993. Mink and Common Terns
in western Scotland. Pp. 9-10 of Proc. 4th
Int. Seabird Group Conf. on ‘‘European
Seabirds’’, Glasgow, March 1992 (M.L.
Tasker ed.).

Elkins, N. 1993. Prolonged fighting between
Common Starlings. Brit. Birds 86: 21. Two
presumed young males were seen fighting
continuously for at least 30 minutes at
Cupar, Fife.

Furness, R.W. 1993. Why do Foula Great Skuas
not behave optimally? Seabird Group
Newsletter 63: 2-4.

Harris, M.P. 1992. Isle of May seabird studies
in 1992. Joint Nature Conservation
Committee Report 127: 39 pp.

Harris, M.P., Halley, D.J. & Wanless, S. 1992.
The post-fledging survival of young
Guillemots in relation to hatching date and
growth. [bis 134: 335-339. A six-year study
on the Isle of May.

Harvey, P.V., Riddington, R., Votier, S.C. &
Taylor, R. 1992. Fair Isle seabird monitoring
scheme: report to JNCC of 7th season’s
work, 1992. Joint Nature Conservation
Committee Report 129: 55 pp.

Henty, C.J. & Brackenridge, W.R. 1992. Check
List of Birds of Central Region, Scotland.
Forth Naturalist & Historian 15: 19-26.

Klomp, N.I. & Furness, R.W. 1992. The dispersal

and philopatry of Great Skuas from Foula,
Shetland. Ringing & Migration 13: 73-82.

Maguire, E.J. & Angus, R.A.G. 1991. Orni-
thological results of intensive sea-watching
in southwest Kintyre during autumn 1989.
Scot. Nat. 23-70.

Marquiss, M. & Duncan, K. 1993. Variation in
the abundance of Red-breasted Mergansers
on a Scottish river in relation to season, year,
river hydrography, salmon density and
spring culling. /bis 135: 33-41. A study on
the river North Esk in Angus, northeast
Scotland.

Mitchell, J. 1993. Shelduck at Endrick Mouth,
Loch Lomond. Glasgow Naturalist 22:
288-289.

Murray, S. 1992. A count of the Hermaness
Gannetry, Shetland, in 1991. Joint Nature
Conservation Committee Report 49: 45 pp.
A report to Scottish Natural Heritage.

Newton, I., Wyllie, I. & Rothery, P. 1993.
Annual survival of Sparrowhawks breeding
in three areas of Britain. Jbis 135: 49-60. One
of the areas was in Eskdale, south Scotland,
where the breeding population remained
fairly stable over the years 1972-90.

Owen, M., Wells, A.L. & Black, J.M. 1992.
Energy budgets of wintering Barnacle Geese:
the effects of declining food resources. Orn.
Scand. 23: 451-458. A study at Caerlaverock,
southwest Scotland.

Picozzi, N., Catt, D.C. & Moss, R. 1992.
Evaluation of Capercaillie habitat. J. Appl.
Ecol. 29: 751-762.

Prys-Jones, R.P., Corse, C.J. & Summers, R.W.
1992. The role of the Orkney Islands as a
spring staging post for Turnstones. Ringing
& Migration 13: 83-89.

Sellers, R.M. 1992. Gprmorants breeding in
Caithness. Caithness Bird Report for 1991:
64-65. Breeding cormorants have decreased
by 68% between 1969/70 and 1985/87.

1993

Items of Scottish Interest 73

Skillen, B.S. 1993. Kingfishers on the river
Kelvin. Glasgow Naturalist 22: 289-290.

Spray, C.J. & Bayes, K. 1992. The effect of neck
collars on Mute Swans. Wildfowl 43: 49-57.
A study in South Uist.

Summers, R.W., Underhill, L.G., Nicoll, M.,
Rae, R. & Piersma, T. 1992. Seasonal, size-
and age- related patterns in body-mass and
composition of Purple Sandpipers in Britain.
Ibis 134: 346-354.

Swann, R.L. 1992. Canna seabird studies 1992.
Joint Nature Conservation Committee Report
122: 9 pp. Part of a long-running series.

Wanless, S. & Harris, M.P. 1992. Activity
budgets, diet and breeding success of
Kittiwakes on the Isle of May. Bird Study
39: 145-154.

Wanless, S., Harris, M.P. & Russell, A.F. 1993.
Factors influencing food-load sizes brought
in by Shags during chick rearing. [bis 135:
19-24. A study on the Isle of May.

Watson, J. 1992. Golden Eagle breeding success
and afforestation in Argyll. Bird Study 39:
203-206.

Watson, J., Rae, S.R. & Stillman, R. 1992.
Nesting density and breeding success of
Golden Eagles in relation to food supply in
Scotland. J. Anim. Ecol. 61: 543-550.

Bird Reports

Caithness Bird Report for 1991. E.W.E.
Maughan (ed) 1992. 83 pp. * £2.50. Includes
a systematic list, a report on breeding
Cormorants, and a summary in 10-km
square format of the results of the 1988-91
atlas work.

Colonsay and Oronsay 1992 Natural History.
J. & P.M. Clarke (eds) 1993. 9 pp. An
unpublished report in a long-running series.

Fife Bird Report for 1991. D.D. Dickson (ed)
1992. 74 pp. Includes a 46 pp systematic list,
short papers on recent decisions on more
birds in Fife, Weather, The Fife Bird Atlas,
Coastal Birdwatching and four rarities
reports. * £3.30.

Forth Area Bird Report for 1991. C.J. Henty
(ed) 1992. Pp 27-53 of Forth Naturalist and
Historian vol. 15.

Grampian Ringing Group Report no. 7 for
1989-91. M. Marquiss (ed) 1992. 86 pp.
Includes a 45-page ringing record, and short
reports on Teal, Oystercatchers, Dunlins,
Meadow Pipits, Robins and Crossbills.

Highland Region (South) Bird Report for 1989
and 1990. J. Carruthers, R. Dennis, D.
Galloway & A. McNee (eds) 1992. 40 pp.

Isle of May Bird Observatory Report for 1991.
Ian Darling (ed) 1992. 48 pp. * £3.25.

Lothian Bird Report for 1991. P. Speak (ed)
1992. 125 pp. Includes a 71 pp systematic
list, and 40 pp of censuses of Mute Swans,
Geese and Herons. Also short articles on
Oystercatchers, Blue Tits, Long-tailed Skua
passage, and four rarity reports. * £4.25.

North Sea Bird Club Report for 199]. P. Doyle
(ed) 1992. 75 pp. Includes a 35 pp systematic
list, and a short article on migratory
movements of Starlings through the North
Sea.

North-East Scotland Bird Report for 1991].
A. Webb (ed) 1992. 72 pp. * £4.50. Includes
four full-page colour plates, a 50-page
systematic list, and papers on Peregrines,
Merlins, Shearwaters, and rare birds.

Orkney Ringing Group Report no. 5 for 1989-90.
C.J. Corse & E.R. Meek (eds) 1992. 54 pp.
Includes short papers on Curlew, Purple
Sandpipers, Black Guillemots and Swallows,
and a 34-page ringing record.

Perth and Kinross Bird Report for 1991. W.
Mattingley & R. Youngman (eds) 1992. 40
pp. * £2.90.

Scottish Bird Report for 1990. R. Murray (ed)
1993. 72 pp. Includes a paper by David
Jardine on the Crossbill invasion of 1990/91,
and a 60-page species list. * £4.00.

West Lothian Bird Report for 199]. West
Lothian Bird Club (comp.) 1992. 9 pp. This
is their first report and is a commendable
effort. It does not pretend to cover the whole
of West Lothian, but consists of site
descriptions and bird lists for five sites which
are watched regularly.

Multi-paper reports

RSPB Conservation Review no. 6. C.J. Cadbury
(ed) 1992. 96 pp. £7.00 post free from
RSPB, The Lodge, Sandy, Bedfordshire
SG19 2DL.

Proc. Seabird Group Conference. European
Seabirds. M.L. Tasker (ed) 1992. Held at
Glasgow University, March 1992.
(Summaries only) 26 pp.

William G. Harper

74 Scottish Birds (1993) 17: 74-75

SB 17 (1)

European journals in the
Waterston Library

The following selection of articles appeared
in European journals received in the
Waterston Library between September 1992
and March 1993, and thus follows on the
list published in Vol 16 No 4. Articles are
arranged in species order; square brackets
indicate that the article is in the original
language, other articles being in English.
The reference, abbreviated for reasons of
space, indicates merely the journal, its
number and year of publication. Journals
quoted are as follows:

Netherlands: Ardea, Limosa, Dutch Birding

France: Alauda, L’Oiseau

Switzerland: Der Ornithologische Beob-
achter

Belgium: Aves, Mergus

Germany: Seevogel, Journal fiir Orni-
thologie, Okologie der Vogel,
Corax, Die Vogelwelt,
Limicola

Austria: Egretta

Poland: Acta Ornithologica

Italy: Avocetta

Sweden: Var Fagelvarld, Ornis Svecica

Norway: Var Fuglefauna, Fauna
Norvegica

Denmark: Dansk Ornitologisk Forenings
Tidskrift

Finland: Lintumies, Ornis Fennica

Iceland: Natturufraedingurinn

General:

Flade, M. (ed) et al. Special issue on
methods of monitoring bird populations
— some articles in English, majority in
German — Vogelwelt 4-5/92.

Gatter, W. [Timing and pattern of Autumn
migration: the influence of the
greenhouse effect] _ — Jour. fiir Orn.
4/92.

Hilgerloh, G. et al. Are the Pyranees and
the Western Mediterranean barriers for
trans-Saharan migrants in Spring? —
Ardea 3/92.

Deceuninck, B. & Baguette, B. [Breeding
birds in Spruce plantations of successive
ages on the Plateau des Tailles] — Aves
4/91.

Jonkers, D.A. [Population trends of
breeding birds in the Netherlands
1969-85] — Limosa 3/92.

Beintema, A.J. [Mayfield, a necessity:
methods of calculating nesting success |
— Limosa 4/92.

Divers to Ducks:

Keller, V. [The importance of continuous
nest-building during incubation by
Great Crested Grebe | — Orn. Beob.
3/92.

Minguez, E. et al. [Status, distribution,
population size and reproductive
phenology of the European Storm
Petrel in the Basque country of Spain |
— L’Otseau 3/92.

Netherlands/Belgium Goose Working
Group. [Goose counts in _the
Netherlands and Belgium 1989/90] —
Limosa 4/92.

Nilsson, L. & Persson, H. Feeding areas
and local movement patterns of post-
breeding Greylag Geese in S Sweden —
Orn. Svec. 2/92.

Follestad, A. [Shooting pressure on Greylag
Geese] — Var Fuglefauna 3/92.

Etienne, P. et al. [Updating of status of —

Bean Geese in the Somme estuary | —
Alauda 2/92.

Devos, K. [The Tufted Duck as a breeding
bird in the Belgian coastal polders| —
Mergus 2/92.

Birds of Prey:

Pielowski, Z. [Population and breeding
success of raptors on farmland near
Czempin, W Poland] — Acta Ornith.
2/91:

Nielsen, O.K. & Bjérnsson, H. [Rare and
vagrant birds in Iceland, Report No 8:
Raptors] Ndétturufraedingurinn 3-4/92.

Bertel, B. Ageing of Marsh Harrier —
Dansk Orn. For. Tidss. 3-4/92.

a

1993

Kostrzewa, R. [On the population ecology
of the Kestrel] — Ok. der Vég. 2/91.

Tishechkin, A.K. & Ivanovsky, V.V. Status
and breeding performance of Osprey in
N Byelorussia — Orn. Fenn. 3/92.

Grouse to Cranes:

Spidso, T.K. Egg size in relation to renesting
in Capercaillie — Fauna Norveg 5/92.

Waders to Auks

Piersma, T. & van de Sant, S. Pattern
and predictability of potential wind
assistance for waders and geese
emigrating from W Africa and the
Wadden Sea to Siberia — Orn. Svec.
2/92.

Gudmundsson, G.A. & Linstr6m, A. Spring
migration of Sanderlings through S W
Iceland: where from and where to ? —
Ardea 3/92.

Trolliet, B. (Ruff wintering in the Senegal
delta] — Alauda 3/92.

Wuorinen, P. Do Arctic Skuas exploit and
follow terns during Autumn migration?
— Orn. Fenn. 4/92.

Willemyns, F. [Long-tailed Skua influx on
Belgian coast Autumn 1991] — Mergus
6/92.

Hoogendoorn, W. et al. Spring head-moult
in Mediterranean Gull in N W France
— Dutch Birding 6/92.

Schramm, A. [Mass migration of Kittiwakes
in Arctic waters in July| — Seevdgel
3/92.

Pigeons to Woodpeckers:

Olafsson, E. [Rare and vagrant birds in
Iceland. Report No. 7: Nightjars and
Swifts] — Ndtturufraedingurinn 2/92.

European Journals 75

Passerines:

Kouki, J. Habitat associations of passerines
breeding in peatland in Eastern Finland
— Orn. Fenn. 3/92.

Géroudet, P. [The Rock Pipit] — Alauda

2/92.

Sachslehner, L.M. [Breeding density of
Spotted, Collared and Red-breasted
Flycatchers in Viennese woods related
to tree die-back and selective cutting |
— Egretta 2/92.

Thingstad, P.G. Applicability of Pied Fly-
catcher’s clutch size and breeding
success as an environmental indicator —
Fauna Norveg. 5/92.

Nikander, P.J. [Identification of small
pipits — Part I] — Lintumies 4/92.

Grajetzki, B. [Diet and breeding behaviour
of female robins in hedgerow habitat in
Schleswig-Holstein] — Vogelwelt 6/92.

Hansen, R.E. [Barred Warbler breeding
records at Molen and in outer
Oslofjord] — Var Fuglefauna 1/93.

Mockel, R. [Effects of pollution damage to
forests on population dynamics of Coal
and Crested Tits in western Erzgebirge |
— Ok. der Vog. 1/92.

Mack, U. [First results of a study of the
Magpie in Ulm] — Ok. der Vog. 2/91.

Henriksen, K. [Communal roosting in
suburban Magpies] — Dansk Orn For
Tidsskr. 3-4/92.

Ellenberg, H. and Dreifke, R. | Ravens
acting as protection for other species
against Goshawk predation] — Corax
1/92.

Barthel, P.H. et al. [Mongolian Trumpeter
Finch in the Western Palearctic | =
Limicola 6/92.

Cordero, P.J. & Summers-Smith, J.D.

Hybridisation between House and Tree
Sparrow — Jour. fiir Orn. 1/93.

M.H. Murphy

76 Advice to Contributors

SB 17 (1)

Advice to Contributors

Authors should bear in mind that only a small
proportion of the Scottish Birds readership is
science-trained, and should aim to present their
material concisely, interestingly and clearly.
Unfamiliar technical terms and symbols should
be avoided wherever possible and if deemed
essential should be explained. Supporting statistics
should be kept to a minimum. All papers and
short notes are accepted on the understanding that
they have not been offered for publication
elsewhere and that they will be subject to editing.
Papers will be acknowledged on receipt and will
be reviewed by at least two members of the
editorial panel, and in some cases also by an
independent referee, before being accepted. They
will normally be published in order of acceptance
of fully revised manuscripts. The editors will be
happy to advise authors on the preparation of
papers.

Reference should be made to recent issues
of Scottish Birds for guidance on style of
presentation, use of capitals, form of references,
etc. Papers should be typed on one side of the
paper only, double-spaced and with wide margins;
two copies are required and the author should also
retain one. Headings should NOT be underlined,
nor typed entirely in capitals. Scientific names in

italics should follow the first text reference to each
species and should follow Voous’ ‘List of Recent
Holarctic Bird Species’ as given in The British
Birds’ List of Birds of the Western Palearctic
(1984).

Only single quotation marks should be used,
and numbers one to ten should be written out
whereas 11 and above should be written as
numerals. Dates should be written: ......... on
5’ August 199] seeeceee eee but on the Sth (if the
name of the month does not follow). Please note
that papers shorter than 700 words will be treated
as Short Notes where all references should be
incorporated into the text, and not listed at the
end, as in full articles.

Tables, maps and diagrams should be
designed to fit either a single column or the full
page width. Tables should be self-explanatory and
headings should be kept as simple as possible,
with footnotes used to provide extra details where
necessary. Each table should be on a separate
sheet. Maps and diagrams should be in Indian ink
and be camera ready, but drawn so as to permit
reduction to half their original size.

For details of writing Research Progress
Reports, please contact the editor in advance.

Contents, continued
Obituary
Dr William Serle O.B.E. (1912-1992). R.Y. McGowan

Correspondence
Further aberrant plumage in Peregrine. M. Trubridge
Fulmar oiling of Peregrines. C.J. Booth
Attacks by Great Skuas on an Eider and a Mute Swan. J. Holloway
The Fair Isle Baillon’s Crake and other corpses. D. Suddaby

Items of Scottish interest. W.G. Harper
European journals in Waterston Library. M.H. Murphy

Advice to Contributors.

66

Scottish Birds

|Volume 17 Part 1—_‘ June 1993
_| Contents

Research Progress Reports

Research on mountain birds and their habitat.
D.B.A. Thompson and D.P. Whitfield

A 20 year study of Kestrels in Ayrshire. G.S. Riddle
Status of the Pintail in the Orkney Islands. E.R. Meek

Survey of Black Grouse leks in Perthshire.
M.C. Robinson, D. Baines and W. Mattingley

Productivity of waterfowl breeding at Airthrey Loch, Stirling. M.V. Bell

Breeding numbers and breeding success of the Peregrine in Shetland,
1961-1991. P.M. Ellis and J.D. Okill

Spring Passage of Pomarine Skuas off Shetland in May 1992.
H.R. Harrop, M. Mellor and D. Suddaby

Short Notes
Kestrels feeding on road casualties. R.C. and A.P. Dickson
Hunting times by Merlins in winter. R.C. Dickson

Hunting associations between Merlins and Hen Harriers in winter.
R.C. Dickson

Behaviour of Herring Gulls feeding on turnips. R. Hewson

Rare Migrants

Solitary Sandpiper on Fair Isle: a third Scottish record. Roger Riddington

Kumlien’s Gull in Shetland — the fourth Scottish record.
H. Harrop and M. Mellor

Continued inside back cover |

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Scottish Birds (1993) 17: 77-84

TH.

Moult flock surveys indicate a continued decline in the
Shetland Eider population, 1984-92

M. HEUBECK

The number of Eiders in Shetland in late summer 1992 was
estimated to be c.7200 birds, based on surveys of moulting areas.
This compared with previous estimates of c.10,000 birds in 1989,
c.11,800 in 1984 and at least 16,500 in 1977. In the absence of
contrary evidence, it is assumed the Shetland Eider population is
largely sedentary. Possible reasons for a continued decline in
Fider numbers in Shetland between 1984 and 1992 are discussed
but remain unclear, although mortality from oil pollution is

unlikely to have been a significant factor.

Introduction

Surveys of flocks of moulting Eiders
Somateria mollissima began in Shetland in
the mid-1970s and counts made in 1977
were used to derive a late summer
population estimate (including juveniles) of
c.15,500 birds (Jones & Kinnear 1979), a
figure subsequently considered too low by at
least c.1000 birds (Heubeck 1987). Annual
surveys during 1980-84 led to a further
estimate of 11,500-12,000 birds in 1984,
25-30% lower than the revised 1977 figure
(Heubeck 1987). This paper presents the
results of further surveys of moult flocks
carried out annually during 1988-92.

Methods

These have been described previously
(Heubeck 1987). All known moulting areas
were surveyed at least once between
mid-August and early September from either
the land, 10-15m hard-hulled boats or a
small helicopter. Birds were either counted
singly, estimated in blocks of five or ten
depending on flock size and structure, or
counted later from photographs. Moult
flocks move locally in response to wind and
sea conditions and while the geographic
coverage of the 1988-92 surveys focussed
on where flocks had been found previously,

the length of coastline surveyed gradually
increased as boundaries of known moulting
areas were extended, to check that birds
were not being missed. Additional, largely
negative, information came from boat
journeys between known moulting areas
and, in 1990-92, from observations during
separate surveys of harbour porpoises
Phocaena phocaena. The extent of the
coastline surveyed in 1992 and the location
of moulting areas is shown in Fig. 1.

Results

Counts of Eiders in each moulting area in
1988-92 are compared with the 1977 and
1980-84 results (Table 1). All known
moulting sites should be covered in each
year’s survey as the number of birds
moulting in a given area can vary
considerably between years, while
observations of marked birds have shown
that males do not necessarily moult close to
where they winter or breed. Of 63 male
Eiders caught and wing-tagged in north-east
Yell in November 1984, three were later
seen in moult flocks : one at North Fetlar
(Area 14) in July 1985, one at Scatness
(Area 1) in August 1985 and a different bird
at Noness (Area 22) in August 1988.

78 M. Heubeck

SB 17 (2)

24
gp

Map of Shetland showing the coastline surveyed in 1992 and moulting areas identified

FIGURE 1.
in Table 1.

Coverage in 1991 and 1992 was the
most extensive to date and helped resolve
questions over how regularly some sites are
used. Papa Stour and the remote Ve
Skerries, difficult to survey by boat, may
have long been regular moulting areas (on
11 June 1890 Harvie-Brown found Eiders at
the Ve Skerries “abundant, though mostly
drakes” (Evans & Buckley 1899)) and it is
possible that flocks were overlooked there
during fixed-wing aerial surveys in 1980-82.
Surveys by helicopter in 1991 and 1992
proved extremely effective, both in terms of
coverage, accuracy of counts and quality of
photographs taken. The Fitful/St Ninian’s
Isle area has probably not been used
regularly by significant numbers of moulting
Eiders and it is now thought that the larger
flocks of birds sometimes found there in the

1980s had probably moved north from the
Sumburgh area during the moulting period
in response to adverse weather. Despite the
better coverage and knowledge of local
movements of flocks, the total number of
Eiders found in 1992 was 40% lower than in
1984, the most thorough of the 1980-84
surveys, and 56% lower than in 1977 when
at least seven moulting areas were not
covered.

In using these survey results to derive
late-summer population estimates, one must
take into account known moulting areas not
covered by the surveys (including Foula and
Fair Isle) and unsurveyed coasts holding
scattered birds (mostly females with
juveniles) which have not joined moulting
concentrations. Jones & Kinnear (1979)
cited a figure of c.300 for Foula in deriving

79

Decline_in Shetland Eiders

TABLE 1. Counts of moulting Eiders in Shetland, 1977 - 1992. Areas are as shown in Figure 1. Counts in brackets indicate incomplete
coverage of the moulting area by 1991/92 standards, those marked with an asterisk indicate coverage of the area by fixed wing aircraft
only, the method by which flocks were most likely to have been overlooked. Underlined minimum population estimates are those
derived from the most thorough surveys.

AREA

1. Sumburgh

2. Fitful/St Ninian’s

3. Burra/Trondra

4. Scalloway Islands

5. Reawick

6. Westerwick/Skeld
7. Papa Stour/Ve Skerries
8. Hillswick Ness

9. Ronas/Hevdadale
10. Sullom Voe

11. Yell Sound

12. Gloup Holm, N. Yell
13. North & east Unst
14. North Fetlar

15. South-east Yell

16. Out Skerries

17. Whalsay Skerries
18. South Nesting Skerries
19. Bressay/Noss

20. Gulberwick

21. Mail/Leebitton
22. Noness/Levenwick

SURVEY TOTAL

22. Foula, mid-July
23. Fair Isle late Aug.

KNOWN TOTAL

MININUM POPULATION EST.

ZZ,
2000

(250)

1800

794
1400

220
90

243
702
320
3336
(310)
1630
475
25))|

13821

16500+

1980
1551

594
196

1345
(45)*

946

128

108
(208)

200
823
993:
430
(433)
500
170
(246)

8916

1981
1108

(Zz
1129

943
O*

566

25

185

| Ao
30
465
(476)
670
653
1350
694
a 28
1a

8126

1018

1982

a7
(273)
QS}

1120
O*
540*

5375+

220
207
(230)
iW»
O*
O*
742
654
548
(1624)
495
201
186

9718

690

1983

WI DI
O*
294
HO}

990

927,
447*
170
136
92
i255
lis7
65
695"
80*
308*
(1021)
747
O72
221

8880

300
680

9860

10610

1984

1484
418
25

(155)

1400

650
Si
192
(5
130
75
Oy
0
965
316
475
(1415)
428
59
373

10128

565
10693

11800

1988

1468
333)3)
130

(13353)

565
(345)*
472

2ED

123

17
45*
SS
4*

8684

9534

1989

1880
21
32

(91)

545
396

1990

1856
138
115

335)
111
Vs)
(205)
224
427

43
76

Toon

1421
47
26
215

21
310
270
180
566

1992

1310
78
15
34

80 M. Heubeck

their 1977 population estimate, between
3-400 birds have been recorded in mid-July
in most recent years. along the east coast of
the island by Glasgow University staff and a
figure of 350 was used in deriving the 1984
and 1988 population estimates (Table 1).

The situation has been less clear at Fair
Isle, which lies 43km from both the southern
tip of the Shetland Mainland and North
Ronaldsay in Orkney. Counts nearest to 31
August, but not always from complete
surveys of the island, are given in Table |
although higher numbers have tended to be
recorded in autumn after the moult period. It
has been suggested that this increase may be
due to Orkney breeding birds stopping at
Fair Isle after moulting in Shetland (Jones &
Kinnear 1979) and Davis (1965) thought
some birds left the island in late autumn.
However, hardly any have been seen at any
time of year from the ferry crossing to the
Shetland Mainland (Dymond 1992) and a
lack of sightings during seawatches at the
southern tip of Shetland Mainland, Fair Isle
or North Ronaldsay gives no indication
whether Eiders move to Fair Isle from
Shetland or Orkney, but suggests that
interchange between the two island groups is
minimal. In calculating a 1977 population
figure, Jones & Kinnear (1979) estimated a
scatter of c.1000 Eiders away from known
moulting areas. In view of the overall
decline in numbers, this figure has been
reduced to c.750 in 1984 and (a probably
over-generous) c.500 in 1989-92. The
estimate of 7200 Eiders in Shetland in late
summer of 1992 was therefore 39% lower
than the 1984 population estimate and 56%
lower than that of 1977.

Discussion

In the absence of contrary evidence, it is
assumed that the Shetland Eider population is
sedentary with little or no immigration from
surrounding populations. Extensive studies at
sea during the mid-1980s found no evidence
of regular movement of Eiders between

SB 17 (2)

Shetland and Scandinavia (Tasker et al 1987)
although a few birds of unknown origin have
occasionally been seen from oil installations
between Shetland and Norway, especially in
October and November (Anderson 1990).
There has been just one recovery in Shetland
(on Fair Isle) and one in Orkney from the
many Eiders ringed in the long-term study at
the Ythan Estuary in Aberdeenshire
(Buckland et al. 1990, Mead & Clark 1990).
That Shetland Eiders are significantly
smaller than those in north-east Scotland
(Table 2) also suggests little inter-mingling
with birds from the Scottish mainland, and it
has been proposed the north isles Eiders are
best included in the Faeroese race S. m.
faeroensis rather than the nominate race S. m.
mollissima (Cramp & Simmons 1977).
There can be little doubt that the
decline in Eider numbers in moult flocks
reflects a decline in the (resident) Shetland
population. While no systematic counts have
been made, there 1s anecdotal evidence from
throughout Shetland of a decline in numbers
of nests and of females with broods. Counts
of Eiders in winter also indicated a decline
in numbers between the mid-1970s and the
mid-1980s, with a further decline by 1991]
(Suddaby 1991). Elsewhere, one Orkney
source considered there had been “no

obvious change in status” there up to 1982 ~ |

(Booth et al. 1984), although another
considered Eiders to have "decreased over a
longish period" (Meek in Berry 1985). The
recent situation is also unclear, with surveys
showing numbers of Eiders wintering in
Scapa Flow to have declined substantially
between 1977/78 and 1988/89 (Christer
1989), but to have increased in the area of
Wyre, Rousay and Gairsay Sounds over the
same period (Ribbands 1990). Nationally,
there has been no suggestion of recent
regional declines on the scale observed in
Shetland (Marchant et al. 1990), although it
is questionable whether counts of birds in
some regions would have _ been
comprehensive enough to detect anything
but gross changes in numbers.

1993

Decline in Shetland Eiders 81

TABLE 2. Measurements (mm) and weights of Eiders caught in winter at the Ythan Estuary,
Aberdeenshire and in Shetland. The Ythan birds were caught between October and March 1976/77
and 1977/78, no attempt was made to exclude repeated measurements of retrapped birds and most
measurements were taken by S.R. Baillie. The Shetland birds were cannon-netted on 23 November
1984 on the island of Linga off north-east Yell and were measured by R.W. Furness. First-year birds

were excluded from all samples.

YTHAN ESTUARY

MALES Mean S.D. n
Wing 303.8 6.9 152
Bill 55.7 2.8 15)
Head 12922 Del, 41
Tarsus 54.5 BD 151
Sternum 125-5 5.0 41
Weight 2307.2" I9W5 181
FEMALES

Wing MO 33} 9.9 129
Bill 557, Dail 129
Head 2ae5 3} 2 33
Tarsus 53) al DES, 128
Sternum 111333 3.4 32
Weight 2042.6 219.4 158

The decrease in the Shetland population
between 1977-1984 was attributed to a
combination of mortality due to oil pollution
in the winter of 1978/79 and an unexplained
(but not oil-related) heavy mortality in winter
1979/80 in north-east Shetland (Heubeck
1987), similar in many respects to the
unexplained mortality in southern Norway
the following winter (Wranes 1988).
Although oil pollution killed many Eiders in
Shetland in 1979 (Heubeck & Richardson
1980), few oiled corpses have been found on
systematic beached birds surveys since then
(Fig. 2). Of 368 corpses found between
January 1980 and December 1992, only 30
were definitely oiled (8.1%) and 10 of those
were found on just two of the 156 surveys,
April 1986 and March 1991. This incidence
of oiling was low compared to the 27%
recorded on beached bird surveys elsewhere
in the British Isles during the 1970s (Stowe
1982) and values between 45-67% recorded
by different schemes on south-eastern North
Sea coasts in the late 1970s and throughout
the 1980s (Averbeck et al. 1992) .

SHETLAND

Mean _ S.D. n t Signif.
WSN) 8 5.4 61 14.04 p<0.001
oiled 2.0 61 ee <0!001
23) 2n5 61 1015s p<0:00)
By) 1.4 61 6.93 p<0.001
{2353 Sl 61 2508 1) p<0:05
LISS" 412 61 14.06 p<0.001
284.3 7 52 6.87. p<0.001
48.1 2.4 52 8.00 p<0.001
11729 Diff 52 5.47 p<0.001
50.5 1.4 52 9.14 p<0.001
116.8 3.3 by 220i ipE0:05
IC2OO 1073 52 9.68 p<0.001

Since early 1980, the only instance of
abnormally high, unexplained mortality of
Eiders was in March-May 1986 when 21
dead birds were found (0.12/km. surveyed),
13 on beaches close to the Sullom Voe Oil
Terminal. Although apparently not oiled,
plumage samples from three of the Sullom
Voe birds were examined by gas
chromatography; two showed distinct
petroleum-based hydrocarbon residues, the
third possible petroleum residues. On 26
March 1986 there had been a suspected
discharge into the voe of contaminated
ballast water from the tanker Ariel 5, which
was treated with dispersant. Oily scum
spread across the voe and although none of
the 318 eiders counted in Sullom Voe that
day were clearly oiled, 30-40 were seen
preening and splashing and had probably
become contaminated by this scum. As well
as the three corpses whose plumage was
analysed, it is likely that the deaths of some
of the 10 others found in Sullom Voe that
spring were oil-related. A similar situation
occurred near the Flotta Oil Terminal in

82 M. Heubeck

16
144
12
10

CORPSES / 10 Km.

ne &_» @

$0 82 84

SB 17(2)

86 88 90 £92

YEAR

FIGURE 2. The number of Eider corpses found per 10km. surveyed on Shetland beached bird
surveys, 1979-1992. Solid areas = oiled corpses (n = 451, 15.5% oiled). ? indicates birds found in
Sullom Voe in 1986 which may have been slightly oiled but which were recorded as unoiled. A
period of unexplained, abnormally high mortality between December 1979 and June 1980 led to the
relatively high values for unoiled birds in those years. There was no significant trend in the number
of unoiled corpses found between 1981 and 1992 (Spearman Rank Test, rho = - 0.084, df = 10).

N.B. 1979 = March to December only.

Orkney when abnormal numbers of dead
Eiders were found several weeks after a
small spillage of crude oil from the tanker
Fanny on 11 February 1984, most having
only lightly or barely noticeably stained
plumage (Meek 1985). In this incident, 80%
of the corpses found were adult males (as
were seven of the eight found in Sullom Voe
in April 1986) although in late February
there should have been little separation of
the sexes as most adult Eiders would have
paired. Spring would appear to be a time of
relatively higher mortality for male than
female Eiders (Table 3). At this time of year
males expend greater energy than normal in
sexual display and mate-defence while
females, feeding at twice the rate of males,
accumulate fat deposits prior to egg laying

(Gorman & Milne 1971). Under such
circumstances, drakes may succumb more
easily than females to slight contamination
of their plumage.

With oil pollution apparently having
made only a minor contribution and no
unexplained mass deaths having occurred,
one can only speculate as to the cause(s) of
the decline in Eider numbers between 1984
and 1992. Many people in Shetland believe
that predation of Eider ducklings by skuas
and gulls has increased in recent years but

there is no quantitative evidence for this,

although predation of other seabirds by
Great Skuas Catharacta skua increased in
the late 1980s (Hamer et al. 1991). In
Sweden it has been shown that increased
disturbance of broods of Eider ducklings by

!

1993

Decline in Shetland Eiders 83

TABLE 3.

Monthly occurrence of unoiled Eiders (corpses/100km_ surveyed) found dead on Shetland

beached bird surveys, March 1979 to December 1992. Birds were reported as either ‘male’,
‘female’, ‘immature male’, juvenile/pullus’ or unsexed and unaged. Data from December 1979 to

June 1980, a period of high, unexplained mortality, are excluded.

Km. Male. Female
January 631.7 E90 127,
February 647.2 1.85 1.39
March 685.2 1.90 1202
April 684.0 3.95 1RO2
May 647.0 2.94 0.93
June 638.4 3.76 2.98
July 718.6 1.81 2.50
August 712.1 0.84 1.54
September 628.0 0.64 1.91
October 690.6 0.14 1.59
November 710.1 es 0.70
December 615.4 0.65 1.30
Total 143 121

Imm. Juv. °Sex Total
male ‘Age

0.47 3.64

0.15 0.46 3.86

0.44 3.36

0.58 535

0.46 4.33

0.16 0.31 20

0.97 0.83 6.12

0.56 0.28 8548)

0.32 0.48 3.34

0.43 DENY:

1.83

0.16 0.16 DD,

6 15 28 311183

boats led to increased predation rates of
ducklings by gulls (Ahlund & Gétmark
1989). The development of salmon farming
in the 1980s certainly led to increased
inshore traffic of small boats in many parts
of Shetland but again, any effect this may
have had on survival of Eider ducklings
remains conjecture.

Great Skuas in Shetland occasionally
kill adult female Eiders, either when
incubating or when flushed from the nest by
humans. Between 1969-76 it was estimated
that Great Skuas annually killed 4% of adult
female Eiders nesting on Foula, based on
annual averages of six predated corpses
found in the breeding areas and 160 nesting
females (Furness 1981). The respective
figures for 1989-92 were averages of 7.5
corpses from 117 nesting females, an
increase in the percentage taken to 6%
(R.W. Furness in litt.). Another possible
predator of nesting female Eiders are feral
ferrets Mustela vison, the population of
which has increased and spread considerably
on the Shetland Mainland in the past 2-3
years. Although they frequently attack
domestic poultry, the extent to which ferrets

predate wild birds in Shetland is unknown,
apart from one instance in 1992 of a family
group killing Puffins Fratercula arctica (C .
Donald pers. comm.). One should be
cautious about extrapolating from the Foula
example and remember that the cause(s) of
the decline in the Shetland Eider population
remain speculative. However, for long-lived
species such as Eiders which have high
annual survival rates (Coulson 1984), a
relatively small increase in adult mortality
coupled with decreased recruitment to the
breeding population could soon lead to
substantial population decline.

Acknowledgements

I am especially grateful to Bobby Tulloch
and Robbie Leask for their boatmanship, to
the Marine Services Department of Shetland
Islands Council for the use of their chartered
helicopter, to Bob Furness and Paul Harvey
for providing data from Foula and Fair Isle
respectively, and to the following people
who helped with counts during 1988-92: D.
Bird, S. Cable, G. Dunnet, N. Dymond, P.
Evans, H. Harrop, P. Harvey, R. Matthews,
M. Mellor, D. Okill and E. Stuart.

84 M. Heubeck

SB 17(2)

References

Ahlund, M. & Géttmark, F. 1989. Gull Predation
on Eider Ducklings Somateria mollissima:
Effects of Human Disturbance. Biol. Conserv.
48: 115-127.

Anderson, A. 1990. Checklist and Status of North
Sea Birds. In: Alexander, S.M.D. (ed.) Birds
and the North Sea. North Sea Bird Club 10th
Anniversary Publication, Aberdeen.

Averbeck, C., Korsch, M. & Vauk, G. 1992. Der
Einfluss von Olverschmutzungen auf
Seev6gel an den deutschen Nordseekiisten
von 1984 bis 1990. Seevdgel 13: 12-16.

Berry, R.J. 1985. The Natural History of Orkney.
Collins, London.

Booth, C.J., Cuthbert, M. & Reynolds, P. 1984.
The Birds of Orkney. The Orkney Press,
Stromness.

Buckland, S.T., Bell, M.V. & Picozzi, N. (eds.)
1990. The Birds of North-east Scotland.
North-east Scotland Bird Club, Aberdeen.

Christer, W.G. 1989. Winter concentrations of
seaducks, divers, grebes and auks in Scapa
Flow, Orkney. RSPB report, 62pp.

Coulson, J.C. 1984. The population dynamics of
the Eider Duck Somateria mollissima and
evidence of extensive non-breeding by adult
ducks. /bis 126: 525-543.

Cramp, S. & Simmons, K.E.L. (eds. ) 1977. The
Birds of the Western Palearctic. Vol. 1.
Oxford University Press.

Davis, P. 1965. A list of the birds of Fair Isle. In:
Williamson, K. Fair Jsle and its Birds. Oliver
& Boyd, Edinburgh & London.

Dymond, J.N. 1992. The Birds of Falr Isle.
Dymond.

Evans, A.H. & Buckley, T.E. 1899. A Vertebrate
Fauna of the Shetland Islands. Douglas,
Edinburgh.

Furness, R.W. 1981. The impact of predation by
Great Skuas Catharacta skua on other seabird
populations at a Shetland colony. /bis 123:
534-539.

Gorman, M.L. & Milne, H. 1971. Seasonal
changes in the adrenal steroid tissue of the
Common Eider Somateria mollissima and its

relation to organic metabolism in normal and
oil-polluted birds. /bis 113: 218-228.

Hamer, K.C., Furness, R.W. & Caldow, R.W.G.
1991. The effects of changes in food
availability on the breeding ecology of great
skuas Catharacta skua in Shetland. J. Zool.
Lond. 223: 175-188.

Heubeck, M. 1987. Changes in the status of the
Common Eider in Shetland, 1977-1984. Scott.
Birds 14: 146-152.

Heubeck, M. & Richardson, M.G. 1980. Bird
mortality following the Esso Bernicla oil
spill, Shetland, December 1978. Scott. Birds
11: 97-108.

Jones, P.H. & Kinnear, P.K. 1979. Moulting
Eiders in Orkney and Shetland. Wildfowl 30:
109-113.

Marchant, J.H., Hudson, R., Carter, S.P. &
Whittington, P. 1990. Population trends in
Brittish breeding birds. British Trust for
Ornithology, Tring.

Mead, C.J. & Clark, J.A. 1990. Report on Bird
Ringing for Britain and Ireland for 1989.
Ringing & Migration 11:137-176.

Meek, E.R. 1985. Oil-related Eider mortality in
Scapa Flow, Orkney. Scott. Birds 13:
225-228.

Ribbands, J.B. 1990. Wintering Eiders, Ducks and
Auks In the Waters of Eynhallow Sound, Wyre
Sound, Rousay Sound and Gairsay Sound,
Orkney 1989-1990. Nature Conservancy
Council report, 35pp.

Stowe, T.J. 1982. Beached bird surveys and
surveillance of cliff-breeding seabirds. Report
to the Nature Conservancy Council. RSPB,
Sandy. ;

Suddaby, D. 1991. Winter Seabird Monitoring
Project, Shetland, February/March 1991.
Unpubl. Rep. to the Nature Conservancy
Council.

Tasker, M.L., Webb, A., Hall, A.J., Pienkowski,
M.W. & Langslow, D.R. 1987. Seabirds in
the North Sea. Nature Conservancy Council,
Peterborough.

Wranes, E. 1988. Massedgd av aederfugl pa
Sgrlandet vinteren 1981/82. Var Fuglefauna
11: 71-74.

Martin Heubeck, Department of Zoology, University of Aberdeen,

Tillydrone Avenue, Aberdeen AB9 2TN.

Scottish Birds (1993) 17: 85-92

85

Population fluctuations and mortality of Mute Swans on
an Orkney loch system in relation to a Canadian

Pondweed growth cycle.

E.R.MEEK

Canadian Pondweed was first noted in the Loch of Harray in
1982. By 1987 it was the most widely distributed plant species in
the loch, being especially dense in the northern bays. From early
in 1991 there were signs that the amount of pondweed was
declining. Breeding numbers of Mute Swans on the
Harray/Stenness loch system increased from 36 nests in 1983 to
115 nests in 1990 but dropped sharply to only 13 nests in 1992.
A marked mortality of Mute Swans, involving some 250 birds,
almost all in their first year, occurred during 1991. Post mortems
revealed emaciation and heavy burdens of an internal parasite,
Polymorphus minutus. Wintering numbers of grazing wildfowl
(Mute Swan, Whooper Swan and Wigeon) increased markedly
while pondweed growth was at its height but crashed in
subsequent years. Numbers of diving ducks (Pochard and Tufted

Duck) remained unaffected.

Introduction

Mute Swans Cygnus olor have long been a
feature of the Harray and Stenness lochs, a
loch system of some !1930Qha in the southern
part of Orkney’s West Mainland (Fig.1).
The loch system shows a gradation from a
salinity close to that of sea-water in Stenness
to eutrophic freshwater in Harray, a situation
unique in Britain (Ratcliffe 1977). In the
early 1980s the lochs were known to hold
some 50% of Orkney’s population of 65
breeding pairs. Both breeding and wintering
numbers increased in the late 1980s. The
peak breeding numbers were reached in
1990 and wintering numbers in 1990/91.
Small mortality incidents had occurred in
spring in earlier years (eg. Macdonald et al.
1978) but in 1991, dead Mute Swans began
to be found around the loch shores in late
March and mortality continued throughout
the rest of that year. A marked decline in
wintering birds was apparent by 1991/92

andwwine breeding birds in 1992. Public
awareness of dead and dying swans during
1991 prompted monitoring of the mortality
and veterinary assistance was called upon in
an attempt to determine cause of death.

Canadian Pondweed Elodea
canadensis, an alien water-weed, was first
noticed in the northern part of the Loch of
Harray in 1982. By 1985 concern began to
be expressed for the future well-being of the
loch and, as a result, in 1988, Orkney Islands
Council commissioned a study of the Loch
of Harray by the Aberdeen Centre for Land
Use. Their report (Sinclair et al. 1992)
concluded that the loch was ‘mildly
enriched’ and recommended a number of
measures for reducing nutrient input.

The circumstantial evidence for a
connection between the Mute Swan
population fluctuations and the Elodea
growth cycle is strong.

86 E.R. Meek

SB.17 (2)

FIGURE 1. Location of the Lochs of Harray and Stromness, Orkney.

Methods

Counts of breeding Mute Swans were
carried out from a canoe in 1983 (Reynolds
1985) and on foot in 1990 (Corse 1991). A
full count was not possible in 1991 but an
assessment of breeding success was
undertaken. In 1992 and 1993 further full
surveys were carried out on foot followed by
further assessments of breeding success.

Wintering numbers of Mute Swans and
other wildfowl! on both lochs were available
from the National Wildfowl Counts
organised by the Wildfowl and Wetlands
Trust.

Assessment of the numbers of Mute
Swans which died during 1991 proved

difficult because of the great length of loch
shore and because some corpses were
removed by members of the public. A
complete count of corpses was carried out
on 5 July and again between 15-18 August
1991 and an incomplete one in November
199}

Post-mortems were carried out on four
Mute Swans collected in July, one in
November and two in December 1991 with
another in January 1992.

Measurements of the abundance of the
pondweed were made only in 1987 (Robson
1987) but accounts of its distribution at other
times were available from fishermen.

(993

Mute Swans in Orkney 87

Results

Mute Swan - summer numbers
The numbers of Mute Swans on the
Harray/Stenness loch system in the summers
of 1983, 1990 and 1992 are detailed in
Table 1. The 1983 figures are believed to
represent the ‘normal’ population, numbers
having changed little since a previous survey
in 1978 (Reynolds 1985). The enormous
increase to 115 pairs by 1990 resulted in a
breakdown in territoriality on part of the
Loch of Harray, the swans nesting colonially
on a series of small islands known as the
Ling Holms. Fifty-eight nests were found on
these four islands, 44 (38 with contents)
being concentrated on the largest which was
still less than Iha in area. By 1992 breeding
pairs had fallen to just 13 but the number of
territorial pairs without nests was high at 33.
However, the total population of 318
represented a 54% decrease on the 1990
figure. By 1993 breeding numbers were
beginning to show some signs of recovery
(22 pairs) but the total population had fallen
further to 275.

Breeding success has been monitored
since 199]. In that year only two broods (of

b/3 and b/6) were found. Similar searches in
1992 revealed only a single brood (of b/2)
on Stenness and none on Harray. There was
some improvement in 1993 with four broods
(b/1, b/2, b/2 and b/3) on Harray and four
(b/2, b/3, b/3 and b/5) on Stenness.

Mute Swan - winter numbers

Peak winter counts of Mute Swans on the
Harray and Stenness Lochs are shown in
Fig.2. A spectacular increase occurred on
the Loch of Harray from 1986/87 with a
peak of 1205 in 1990/91 followed by a
marked reduction in the two subsequent
winters. The Loch of Stenness showed no
comparable pattern.

Other wildfowl - wintering numbers
Other grazing wildfowl showed similar
patterns in their numbers on the Loch of
Harray. Fig.3 shows the maximum counts of
Whooper Swans Cygnus cygnus on both
Harray and Stenness. The peak count on
Harray was 1010 in December 1988 with
927 present in 1990/91.

TABLE 1. Mute Swan numbers on the Lochs of Harray And Stenness, Orkney in the summers of

1983, 1990, 1992 and 1993.

Harray
1983 Breeding pairs 14
Non-breeders
1990 __ Breeding pairs 85
Territorial pairs
(without nests) 9
Non-breeders 400
1992 Breeding pairs 6
Territorial pairs
(without nests) 24
Non-breeders 190
1993 Breeding pairs 1]
Territorial pairs
(without nests) 18
Non-breeders 148

Stenness Totals Overall
Population
DD 36
88 88 160
30 115
= 9
40 440 688
7 13
i) 33
36 226 318
ila 2)
= 18

uN
N
We)
On
No
NI
wn

88 E.R. Meek

Wigeon Anas penelope, too, show a
similar pattern (Fig.4). As with Mute Swan,
their peak was in 1990/91, with a count of
9200.

In contrast to the grazing wildfowl. the
two diving ducks, Tufted Duck Avthva
fuligula and Pochard Avythya ferina, for
which the loch system has long been
nationally important (Cranswick er al.
1992), showed no such clear pattern of
increase in the late 1980s (Figs. 5 & 6).

Mute Swan mortality

Dead and dying Mute Swans were first
reported in April 1991. Mortality reached a
peak during that summer and again in
November/December. In all, some 250 Mute
Swans are believed to have died during the
course of the incident.

All except one of the 50 or so corpses
which were critically examined were of
birds in their first summer/second winter, 1.e.
birds which had been reared in the boom
season of 1990.

Post-mortems were carried out on eight
Mute Swans found dead or dying on the
Loch of Harray during the course of the
incident (Kirkwood & Cunningham 1991,

SB I7/(2)

J.Kirkwood pers.comm., J.D.Walker pers.
comm.). The findings did not point to
bacterial or viral disease but the birds were
emaciated, anaemic and had heavy parasite
burdens. In some of the birds the intestinal
parasite was identified as Polymorphus
minutus, an Acanthocephalan worm.

The spread and subsequent decline of
Canadian Pondweed

Canadian Pondweed was first noted in the
northern part of the Harray Loch in 1982.
However. its subsequent dramatic spread
meant that by the time the loch was fully
surveved in 1987 (Robson 1987) it was the
most widely distributed plant species in the
loch, being particularly well-established in
the northern bays where it was growing in
extremely dense mono-specific stands.

In the winters of 1988/89, 1989/90 and
1990/91, the main concentrations of the
pondweed in the northern bays of the Harray
Loch were obvious from the concentrations
of Mute Swans, Whooper Swans and
Wigeon feeding there. During this period, in
contrast to previous winters, Whooper
Swans were rarely seen off the loch itself,
the weed seemingly providing all the

7 TN
ae sy EE EN y Harray
a : <4 - Stenness
800 | ut cus RL ed dM, ee

i

LLLLLLLLL LLL LSLZA.

|
|

2
{
|

|
!

ZZZZZZZZZZZZZD

LLLLLLLLLLE

No
ros
|
SZZZZZZZZD

1980/81 1982/83 _ 1984/85 ‘1986/87 «1988/89 _ =—s«1990/91_~=—s «1992/93
1981/82 1983/84 1985/86 1987/88 1989/00 1991/92

FIGURE 2. Peak winter counts of Mute Swans on Lochs of Harray and Stenness.

1993 Mute Swans in Orkney 89
ey UN
Harray
1006 == —— Se ea aN aa oe Sapo ESS ean
\ l \ ‘enness
800 [penne nee \ —-N —N [ASE eS i
\ \ A
MMs onthe ck oe \\\
aN NA
VN N A
hee \ N \ ig ae ne
VN N A
NN N A
la el lA la \ a\ a \ \ So ee
Css a N \ \
N Wiest cs NaN \ \a Se

1980,/81_ 1982/83. _ 1984/85 1986/87

1981/82 1983/84 1985/86 1987/88

1988/89 1990/91 1992/93
1989/90 1991/92

FIGURE 3. Peak winter counts of Whooper Swans on Lochs of Harray and Stenness.

nourishment required without recourse to
surrounding fields. In the early spring of
1991, however, Whoopers began leaving the
loch to feed in fields near its north-western
extremity (pers. obs.), a first indication that
perhaps the pondweed was becoming less
abundant, an indication confirmed by
fishermen later in the spring.

1980/81 1982/83 __ 1984/85 1986/87
1981/82 1983/84 1985/86 1987/88

Discussion

It would appear that the breeding and
wintering populations of Mute Swans on the
loch system closely followed the growth
cycle of the Canadian Pondweed as did the
wintering populations of the other two main
grazing wildfowl at the site, Wigeon and
Whooper Swan. The inflated number of

MAY

1988/89. 1990/41 1992/93
1989/90 1991/92

FIGURE 4. Peak winter counts of Wigeon on Lochs of Harray and Stenness.

90 E.R. Meek

|

|
|
|
|
|

© Le EAE ETE

SZZZZZZZZZZ

|

LLLLZL!

|
CZZZLLL ALA
|

S

COLLLLLLLLLLLLPLLLLSPLLSSLLLLS

SAZZZZZZZZD
WZZZZZZZZ.

]
PZZZZZZZZ
"ZIZZZZZZZD

io)

1980/81 1982/83 _ 1984/85
1981/82 1983/84 1985/86

FIGURE 5.

breeding Mute Swan pairs in 1990 and the
colonial nesting on the Ling Holms in that
season both suggest a super-abundance of
food. Colonial nesting is known also from
England (Abbotsbury), Denmark and Poland.
In the first two of these, the swan families
spread out after hatching to feed on abundant

2500

| | |
LLLLLLSSSLSLSSSOS SS SS SSS
| |

CLSLSPLLLLLELELSLLLN

| 500 oon te senna tenes sansecnan senate saunas ce smmmanrorn

|

ZZZZZZZZZZZZZZZD

S00) lina

I

CLL
STDC LLL LEE :
GOLLLLLLETE: :
LLLLL LLL

|

|

VASALLPLLL LLL LLL ELA

1980/81

1981/82 1985/84 1985.86

FIGURE 6.

|
|
|
|
|
|
|
|
|

|

VZZZLLA)

{ALLL LLL ALLL

1982/83 _ 1984/85 1986.87 _ 1988/89

fe ee ea a re

SB 17 (2)

NY

Harray

Stenness

1986/87__ 1988/89. 199041 1
1987/88 1989/90 91 et cae

Peak winter counts of Pochard on Lochs of Harray and Stenness.

inter-tidal vegetation (Kear 1972), a situation
analogous to that on the Harray Loch.
Outside the breeding season, greatly
increased Mute Swan numbers as a result of
increased availability of Elodea is known
from elsewhere in Britain (Giles 1992).
Direct observations of all three grazing

Harray

Stenness

]

| | |

ZZZZZZZZZZZZZZZZZZ

OLE

1992/93

1990/91
1987/88 1989/90 1991/92

Peak winter counts of Tufted Ducks on Lochs of Harray and Stenness.

1993

species in winter on the Harray Loch
confirmed their dependence on this
pondweed (pers.obs.) During the early 1980s
Whooper Swans fed on barley stubbles
during the autumn prior to leaving Orkney in
mid-winter. With the advent of the
pondweed, stubbles were ignored, the
Whoopers feeding on the loch throughout
the winter. Wigeon behaviour was also of
interest. Rather than leaving the loch to
graze as normal on surrounding fields, packs
of Wigeon could be watched following both
Mute and Whooper Swans. As the larger
species fed by uprooting pondweed, the
Wigeon dabbled in their wake, apparently
utilising scraps of weed discarded by the
swans.

The decline in wintering numbers of all
three grazing wildfowl and the crash in the
Mute Swan breeding population coincided
closely with observed declines in pondweed
abundance.

The large number of deaths amongst
the Mute Swan population is a more
complex issue. It was initially believed that
the birds may simply be dying of starvation.
Mute Swans in their first summer are driven
out of their natal area by the territorial male
(Cramp & Simmons 1977). It is possible that
the large numbers of young present in spring
1991 may have been prevented from feeding
effectively on what was by then a declining
food source by territorial birds.

The question remains as to why, in such a
situation, more birds did not leave the area
to feed elsewhere. Some birds obviously did;
the peak winter count in 1991/92 shows a
decline of some 650 birds compared to
1990/91 yet only some 250 corpses were
located. The ‘missing’ 400 birds were not
located during National Wildfow! Counts
elsewhere within Orkney and must therefore
have moved out of the islands presumably to
the Scottish mainland although there is no
direct evidence of this. It may be that the
250 which remained, only to subsequently
die, were never fit enough to move away,
pressure on the food resource being too great
even in the latter part of 1990.

Mute Swans in Orkney 91

It is unclear whether the poor condition of
the birds allowed the large build up of
parasites or vice verca. Mute Swans are
known to be among those waterfowl which
act as the final host in the complex life cycle
of Polymorphus minutus, the intermediate
host being freshwater shrimps of the genus
Gammarus (references in Macdonald et al.
1978, Sanford 1978). It is perhaps possible
that Gammurus was particularly numerous
in the Loch of Harray in 1991, perhaps as a
result of the decomposition of much of the
pondweed. Young Mute Swans, already in
poor condition, may have ingested large
quantities of Gammurus and thus become
heavily infested with the parasite.

Also germane to this discussion are the
factors which allowed the rapid expansion of
the Canadian Pondweed. The species is
known to thrive in nutrient-enriched
(eutrophic) waters. Fears concerning the
eutrophication of the Loch of Harray have
been expressed since the mid-1960s when
phytoplankton blooms began to be reported,
in some cases in association with fish
mortality. Eutrophication is believed to have
been caused by agricultural pollution
(fertiliser run-off, slurry and silage effluent)
and by sewage from the village of Dounby
entering the northern part of the loch.
Continuing worries over the impact of
agriculture on the loch’s condition led to a
study by the Aberdeeen Centre for Land Use
(Sinclair et al. 1992). Their report concluded
that the Loch of Harray was currently
‘mildly enriched’ but that if this enrichment
continued the potential for algal blooms
would also increase with severe
consequences for the loch’s ecology. The
abundant growth of Canadian Pondweed
was believed to have been merely due to the
plant having found itself a suitable location
but concern was expressed that if current
dieback of Elodea proves to be permanent
the nutrients previously assimilated by it
would be available to other macrophytes or
phytoplankton.

The findings of the report have been
met with some scepticism by loch users and

92 E.R. Meek

SB 17 (2)

demands have been made for further
monitoring. Continuing winter wildfowl
counts and surveys of the breeding Mute
Swan population are an essential part of
such monitoring and will continue.

Acknowledgements

Danny Cavanagh, Nicola Crockford, Russell
Cryer, Keith Fairclough, Peter Reynolds, Ian
& Helene Sims and Bill Sutherland all
helped to provide data on breeding numbers,
breeding success and mortality while Chris
Corrigan, Keith Fairclough, Martin Gray and
Peter Reynolds carried out the winter
wildfowl counts of recent years. J.K.
Kirkwood and J.D. Walker carried out the
post-mortems and kindly notified me of the
results. Early drafts were improved by
constructive comments from Jane Sears, D.
Jenkins, J.K. Kirkwood and Allan &
Lyndesay Brown while C. Perrins also made
useful suggestions. Keith Fairclough drew
the location map. My grateful thanks to
them all.

References

Corse, C.J. 1991 Mute Swan Survey 1990. Orkney
Bird Report 1990. Kirkwall.

Cramp, S.& Simmons, K.E.L. (eds.) 1977. The
Birds of the Western Palearctic Vol.1. Oxford
University Press, Oxford.

Cranswick, P.A.; Kirby, J.S. & Waters, R.J. 1992.
Wildfowl and Wader Counts 1991-92.
Wildfowl and Wetlands Trust. Gloucester.

Giles, N. 1992. Wildlife after Gravel, p.63. The
Game Conservancy.

Kear, J. 1972. Reproduction and family life. In
Scott, P. et al. The Swans, pp.79-124.
London.

Kirkwood, J.K. & Cunningham, A.A. 1991.
Mortality in Mute Swans from April to July
1991 at the Loch of Harray in Orkney.
Institute of Zoology Internal Report.

Macdonald, J.W., Lea, D. & Hamilton, G.A. 1978.
Parasitic worms causing deaths of Mute
Swans. Brit. Birds 71: 358-359

Ratcliffe, D-A. 1977. A Nature Conservation
Review. Cambridge University Press.

Reynolds, P. 1985. Mute Swan Survey 1983.
Orkney Bird Report 1984. Kirkwall

Robson, T.O. 1987. Loch of Harray, Orkney :
Survey of Aquatic Vegetation, August 1987.
Report to the Nature Conservancy Council.

Sanford, S.E. 1978. Mortality in Mute Swans in
Southern Ontario associated with infestation
with the Thorny-headed Worm, Polymorphus
boschadis Can. Vet.J. 19: 234-236.

Sinclair, A.H., Armstrong, G., Young. M., Ford,
M.A. & Raffaelli, D. 1992. The Impact of
Agriculture on Water Quality in Loch of
Harray and Feeder’ Burns. Scottish
Agricultural College (Aberdeen) &
University of Aberdeen.

E.R.Meek, RSPB, Smyril, Stenness, Orkney KW16 3JX

(Typescript received 24 July 1993.)

Scottish Birds (1993) 17: 93-102

93

The Scottish Mute Swan census 1990

A.W. AND L.M. BROWN

The 1990 Mute Swan census recorded 4856 birds in Scotland.
This represents an increase of 65% since the 1983 census and is
the highest total ever recorded. 58% of the population were
non-territorial compared with 50.5% in 1983. Populations based
on the old Scottish counties are presented, as are data on habitat
preferences and on changes since 1983. It is considered that the
increase is due to the population’s own productivity combined

wilh a series of relatively mild winters.

Introduction

The 1990 Mute Swan, Cygnus olor, census
was a repeat of the complete census which
took place in 1983 (Ogilvie 1986) and this
paper presents the results for Scotland. A
full and detailed assessment of the British
population will be published separately
(Delany & Greenwood in prep.) but the aim
of this paper is to provide an analysis of the
Scottish results and a comparison with the
1983 census (Brown & Brown 1985).

The stimulus for another British census
of the Mute Swan was the need to determine
whether or not the decline in the population,
which had apparently been halted by 1983
(Ogilvie 1986), was subsequently followed
by a population increase. The decline had
been attributed, at least in some areas of
England, to lead poisoning as a result of
birds swallowing discarded anglers’ lead
weights (Goode 1981). The sale of lead
fishing weights in England and Wales was
banned in 1987 and it was considered
opportune by the then Nature Conservancy
Council for a national census to be
undertaken in 1990 to determine whether the
apparent success of the ban in some areas, as
indicated by marked increases in the
population in 1988 and 1989 (Delany er
al.1992), was reflected at the national level.
Lead poisoning of Mute Swans in Scotland
as a result of ingested anglers’ weights was
not considered to be a problem (Brown &

Brown 1985) but in 1983 the population was
found to be 10% less than that in 1955/56
when the last full census had occurred
(Rawcliffe 1958; Brown & Brown 1985).
However, later studies in Ayrshire (Leach

1988), and especially Lothian (Brown &

Brown 1984, 1981-89), indicated that the

populations were expanding in these areas

and a national census provided the
opportunity to assess any wider
manifestation of this trend.

The objectives of the 1990 survey
therefore were to:

a) Estimate population changes since the
[933 ecensusmrand? tdescmibe 7 their
geographical pattern, particularly in
relation to the ban on the use of lead
weights by anglers.

b) estimate the current sizes of local and
national populations, and

c) Provide a baseline for future monitoring
of this species.

The census was carried out, as in 1983,
jointly by the Wildfowl and Wetlands Trust,
the British Trust for Ornithology and the
SOC.

Methods

Using the 10km square of the National Grid
as the census unit, the aim was to achieve
coverage of as many squares as possible.

94. A.W. & L.M. Brown

SB 7 (2)

The fieldwork techniques were the same as
those for the 1978 and 1983 surveys
(Ogilvie 1981 & 1986: Brown & Brown
1985) comprising separate censuses of
territorial breeding and non-territorial Mute
Swans between | April and 31 May. If pairs
did not proceed to breed. by building a nest.
then, «they, were" considered as
‘territorial-only.°

As in 1983. regional organisers. based
on the BTO regions. were circulated with a
list of 1Okm squares in their region together
with instruction sheets and recording forms
for their fieldworkers. Whilst some
flexibility in recording data was permitted
for territorial/breeding pairs. observers were
encouraged as before to try and count all
non-territorial birds in April. preferably
around the middle of the month. to reduce
problems of movement and_ thus
double-counting. Observations therefore
have been used from as near as possible to
mid-April, and all counts in early March and
after 15 May have been discounted. The
change in numbers which occurs during this
period was clearly shown in the returns for
sites with a series of counts, thus
emphasising the need for attempting
non-territorial count co-ordination as far as
was practicable.

Whilst full coverage of all 10km
Squares was the aim it was recognised that in
more remote areas and areas with no suitable
habitat this might not be possible. In such
circumstances it was agreed that observers
and regional organisers could provide
estimates for squares or part squares. To
facilitate population assessment in areas
where complete coverage was not possible
regional organisers were sent a list of the
1Okm squares in their region in random order
with instructions to cover them in that order.
This list acted also as a summary sheet for
the actual and estimated counts for each
area. This paper concentrates on the actual
observations and estimates made by the
observers and regional organisers: any
further extrapolation of the data for areas not

covered will be discussed by Delany &
Greenwood (in prep.).

Results

Coverage

A detailed assessment of coverage will be
published separately (Delany & Greenwood
in prep.) but for most areas of Scotland
coverage is considered to have been
thorough (see Appendix) and many regions
obtained complete coverage. This resulted in
little need for estimates to be made.
Problems did arise in some areas, however,
with poor coverage or none in the Outer
Hebrides (Benbecula and the Uists),
Aberdeen. Banff. Kincardine and Argyll,
while lack of observers and the nature of the
terrain may have resulted in some birds
being overlooked in Caithness, Sutherland,
Ross and Cromarty and Inverness.

As the data were collected according to
the BTO Regions and related District
Council boundaries, the data returns have
been amended to locate sites within the old
counties of Scotland to facilitate ease of
comparison with all of the earlier surveys, in
particular those for 1955/56 (Rawcliffe
1958) and 1983 (Brown & Brown 1985)
when full coverage was attempted. Surveys
in 1961 (Eltringham 1963) and 1978
(Ogilvie 1981) were sample surveys with
insufficient Scottish data to make
meaningful comparisons.

The number of breeding birds,
territorial-only birds and non-territorial birds
and the population total for each of the former
Scottish counties are presented in Table |,
together with the corresponding total figure
for each county in 1983 and the percentage
change between the censuses. Estimates for
additional territorial and non-territorial birds,
where supplied by regional organisers, are
also shown in Table |. The data for the Outer
Hebrides are based on a 1992 census
undertaken by C.J. Spray (pers. comm.) while
that for Aberdeen/Banff is an estimate
assuming a repeat of the 1983 data. This is
examined further in the discussion.

bIOS

Breeding and territorial-only birds

The totals of 1570 breeding birds and 476
territorial - only birds (Table |) represent
32.3% and 9.8% respectively of the total
population counted (Table 2). These figures
indicate a potential breeding population of
1023 pairs which represents a 40.3%
increase on the 1983 figure (729 pairs).

Table 3 shows the distribution of
breeding and territorial-only birds according
to habitat and compares percentages with
1983. Aberdeen/Banff is excluded from
these data in the absence of actual count data
but the 1992 Outer Hebrides counts have
been included.

Freshwater lochs and ponds and
sealochs, coastal and brackish water held
86% of breeding birds, in line with the 1983
figure (84.8%). Rivers held only a small
percentage (6.5%) of breeding birds,
probably reflecting the unsuitability of this
habitat in much of Scotland. In Britain in
1983 Ogilvie (1986) showed that rivers and
streams held 35.5% of the hreeding
population, comparable to the 1961 and
1978 surveys, indicating the greater
significance of this habitat in England.

The national figures mask regional
differences relating to habitat suitability and
availability. For example, no breeding pairs
occurred on rivers in Sutherland, Caithness
and Ross and Cromarty and only 3% in
Perthshire compared to 17.8% in Lothian,
25.8% in Kirkcudbright and 42% in the
Border counties. Similarly, while 76.7%,
57.5% and 39.5% of breeding birds in
Argyll, the Outer Hebrides and Ross and
Cromarty respectively nested on sealochs,
brackish or coastal waters few pairs
occupied such habitats in Eastern and
Southern Scotland. In these areas most pairs
nested on freshwater lochs and ponds e.g.
60% in Stirling/Clackmannan, 74% in Fife,
60% in Lothian, 91.2% in Ayr, 86.4% in
Dumfries and 100% in Wigtown. This is
comparable to the situation in 1983 (Brown
& Brown 1985). Use of canals was only in
Lothian (15.6%) and Dunbarton, Renfrew
and Lanark (17.6%) where the expanding

Scottish Mute Swan census 1990 95

populations are re-occupying this habitat,
while there was little use of reservoirs
throughout Scotland owing, probably, to the
generally high altitude of such sites and the
limited feeding due to fluctuating water
levels (pers. obs. in Lothian).

Non-territorial birds

The count of 2810 non-territorial birds
(Table |) represents 57.9% of the total
population (Table 2) compared with 1488
representing 50.5% in 1983. If territorial
only birds are added to this figure then
67.7% of the Mute Swan population in
Scotland did not breed (61.7% in 1983).

The distribution of non-breeding birds
(excluding territorial-only ones) according
to habitat is shown in Table 3 and can be
compared to the situation in 1983. Although
77.2% of the population is found on
freshwater lochs/ponds and sea lochs,
coastal and brackish waters, compared to
84.9% in 1983, the proportion using
freshwater lochs has increased and sea lochs
declined. Rivers and streams have increased
in importance to 20.9% (14.2% in 1983).

As with the breeding population the
overall figures mask important regional
variations related to the availability and
suitability of habitat types. Thus, the
proportion of non-territorial birds found on
brackish/sea loch habitat was 94.5% in the
Outer Hebrides, 72.3% in Ross and
Cromarty, 83.8% in Inverness, 90.2% in
Angus and 90.0% in Argyll. In contrast
freshwater lochs/ponds accounted for 78.5%
in Orkney, 97.9% in Caithness, 37% in
Lothian, 58.1% in Dunbarton, Renfrew and
Lanark and 66.7% in Kirkcudbright. Rivers
were of importance in Perth (70.3%),
Ayrshire (46.2%), the Border counties
(88.0%), Dumfries (83.5%) and Wigtown
(46.2%).

Table 4 lists all sites (20) holding flocks
of 30 birds and over. These 20 sites held
61.4% of the non-territorial population of the
Mute Swan in Scotland (excluding Aberdeen)
compared with 36.6% in six flocks of this
size in 1983 (Brown & Brown 1985).

96 A.W. & L.M. Brown SB 17 (2)

TABLE 1 Number of breeding, territorial and non-breeding Mute Swans and population totals for
each Scottish county in 1990 and total population in 1983 with % change.

1990 1983
Territorial %°
County Breeding Addit.'. Only Non Addit. Total Total Total Change
Birds Estim. Birds Breeders Estim. Counted Estim. Counted 83-90
SHETLAND 0) O O 1 O ] 1 0 —
ORKNEY 326 O 30 454 O 810 810 3238 +151
OUTER HEBRIDES 160 O 86 583 O 829 829 692 +20 |
CAITHNESS 46 6 18 94 5 158 169 20 +690 |
SUTHERLAND 8 4 O O 4 8 16 25 —63 i
ROSS & CROMARTY 76 O 30 159 2 265 267 96 +176 {
INVERNESS 22 4 24 37, 4 83 91 67 +24
NAIRN 8 O 4 0 0) ‘te 12 2 +500 |
MORAY 22 0 2 17 Dis 4] 64 oD +86 ;
ABERDEEN ' 118 O 62 144 O 324 324 324 — :
BANFF 6 0 2 4 0 12 12 12 zs
KINCARDINE? 8 0) 0) O O 8 8 (4 —33
ANGUS 46 D 4 ts O 163 165 178 8
PERTH 66 O 8 165 O 239 239 106 +125
STIRLING 32. O 6 5 O 43 43 34 +26
CLACKMANNAN 8 0 2 0 0 10 10 ae |
KINROSS 32 O 0 16 6) 48 48 16 +200
FIFE 30 0) 18 58 O 106 106 61 +74
WEST LOTHIAN 30 O 0 42 0) 72 72 9 +700
MID LOTHIAN 24 O 4 50 O 78 78 24 +225
EAST LOTHIAN 36 O 16 73 O 125 125 107 +17
AYR 72. O 8 85 O 165 165 82 +101 |
ARRAN & BUTE 0) 0) 0 8 0 8 8 10 —20
PEEBLES 4 D; 4 0 O 8 10 16 —50
SELKIRK 16 O 4 25 O 45 45 21 +114
ROXBURGH 36 2 20 139 0) 195 197, 54 +261
BERWICK 44 14 26 Di, O oF 111 49 +98
ARGYLL’ 60 46 30 80 12 170 228 142 +20
DUMBARTON 30 O 10 58 O 98 98 13 +654
RENFREW 26 O 6 9 O 4] 4] 35 +17
LANARK 46 6 18 112 O 176 182 68 +159
DUMFRIES 44 O 10 85 O Ss) 139 73 +90
KIRKCUDBRIGHT 62 0 2 141 O 25 215 197, +9
WIGTOWN 26 0 12 26 O 64 64 46 +39
TOTALS 1570 86 476 2810 50 4856 4992 2944 +65

Estimates of additional birds from regional organisers

1992 data - no coordinated survey in 1990 (see text for explanation)

1983 data - no coordinated survey in 1990 (see text for explanation)

No coordinated survey in 1990 but data obtained from coverage by Angus organiser

Poor coverage has resulted in estimate including birds recorded in 1983 in squares not covered in 1990
Based on actual counts.

OY Si Se wae

1993 Scottish Mute Swan census 1990 97

TABLE 2 Percentage of non-territorial, territorial-only and breeding Mute Swans in the total
counted population in Scotland 1983 and 1990.

NUMBER OF BIRDS

YEAR NON.-TERR. %o TERR.-ONLY %o BREEDING %
1983 1488 50.5 328 la 1128 38.3
1990 2810 Sy ee) 476 OES 1570 323

TABLE 3___ Distribution of Mute Swan in Scotland in 1990 according to habitat type and comparison
with percentage in 1983’.

HABITAT Breeding % 1983 Territorial % 1983 Non-terr. Yor 1983

Birds % Only % Birds %
Freshwater Lochs, ponds 960" TW66!479758.0 D205 VS PASS OV.8T ey SOU, i BOS
Reservoirs, Flooded pits 66 4.6 Br) 22 5.3 4.2 BP ip 0.9
River, Streams- 94 6.5 10.4 60 14.6 24.4 55a, | WO 14.2
Canals, Ditches 42 DY) ell 6 1S 0 18 0.7 0
Sea lochs, Coastal, brackish? 284 19.6 26.8 WZ Lelie 22226 O79" 4055 54.4
TOTAL 1446 412 2662

1 Data refer to actual counts and excludes Aberdeen and Banff which were not covered in the 1990 survey.
2. Includes birds counted in fields adjoining river or estuary.

TABLE 4 _ Flocks of more than 30 non-breeding Mute Swans recorded in April 1990’.

LOCATION HABITAT : NUMBER DATE-
West Loch Bee, Uists Brackish loch 412 April (1992)
Loch of Harray, Orkney Freshwater loch Bo2e April
Montrose Basin, Angus Estuary 74 5 April

R. Teviot, Near Kelso, Roxburgh River 74} 19 April
Milton Loch, Kirkcudbright Freshwater loch 7A 30 April
Easter Rhynd, Perthshire River 68 19 April

R. Tyne/Estuary, East Lothian River, estuary, fields 677 14 April
Hogganfield Loch, Glasgow, Lanark Freshwater loch 64 16 April

R. Annan, Roberthill to

Copewood, Dumfriesshire River, fields 58) 12/13 April
Loch Scarmslate, Caithness Freshwater loch 54 29 April
Loch an Strumore, Uists Brackish loch 47 April (1992)
R. Leven, Dunbarton River 45 29 April

R. Tweed, Near Kelso, Roxburgh River 45° 23 April
Loch Eye, Ross-shire Freshwater loch 43 11 April

R. Ayr, Ayr River 43 5 April

R. Dee, west of Castle Douglas,

Kirkcudbright River 42' 30 April
Linlithgow Loch, West Lothian Freshwater loch 36 7 April
Pollo, Ross-shire Estuary 36 14 April
Loch Watten, Caithness Freshwater loch 33 8 April

R. Forth, west of Stirling, Perthshire River Sil 16 April

1. Aberdeen data not available.

2. Counts nearest the recommended dates of 16/17 April have been taken where more than one count was submitted
for a site. Some sites not shown had counts above 30 birds at other dates in April.

3. Cumulative total.

98 A.W. &L.M. Brown

SB 17(2)

Discussion

It has been stated previously that the results
of the 1955/56 complete census of the Mute
Swan should be treated with caution (Brown
& Brown 1985) owing to differences in
coverage and data collection methods. The
1983 census however was the first complete
census to use standardised fieldwork
techniques and this provides a valuable
baseline on which to assess subsequent
surveys. The excellent coverage obtained in
1990 (see Appendix) provides a sound basis
on which to examine the change in numbers
and distribution which have occurred
between 1983 and 1990.

The most striking result of the 1990
census 1s the remarkable 65% increase since
1983 in the total population counted; the
figures represent also an increase of 59%
over the 1955/56 census. It would appear
therefore that the Scottish Mute Swan
population now stands at its highest
recorded level.

Some of the changes which have
occurred within counties are considerable,
even for those counties already with large
numbers of birds in 1983. The Orkney
population increased by 151% between 1983
and 1990 due apparently to excellent feeding
(the presence of Canadian Pondweed,
Elodea canadensis) at the Loch of Harray
which resulted in semi-colonial breeding
taking place. This increase has now been
dramatically reversed with the collapse of
the food supply (E. Meek and pers. comm.
1993). Thevhuge, increase in Caithness
(690%) may be the result of movement of
birds from Orkney, but this has not been
established. Certainly the results for north
Scotland represent a continuation of the
expansion of the population there identified
in 1983 (Brown & Brown 1985).

It is unfortunate that poor coverage or
none was obtained for the Outer Hebrides
and Aberdeen/Banff as these two areas held
35% of the total Scottish population in 1983.
Fortunately a complete survey of the Outer
Hebrides in 1992 by C. J. Spray has shown

changes which mirrored the population trend
recorded elsewhere and, although numbers
can fluctuate annually, it does not seem
unreasonable to include the 1992 figures in
the census results. Similarly, given the
substantial increases found elsewhere in east
Scotland, there is no reason to think that the
Aberdeen population might have dropped,
although a decline may have occurred at
some locations (P. Doyle pers. comm. and
see Appendix), so the 1983 figures are
considered the best estimate for inclusion.
Although mainland Argyll was poorly
covered compared to 1983 the birds actually
recorded still showed an increase and it
seemed most appropriate to include those
birds recorded in 1983 in squares not
covered in 1990.

The decline in numbers in Central
Scotland identified in 1983 (Brown &
Brown 1985) has now been completely
reversed with Fife up by 74%, Ayr 101%,
Lanark 159% and Lothian 96%. The Border
counties have shown a 146% increase, while
the possible re-distribution of birds between
Dumfries and Kirkcudbright in 1983 has
now been replaced by increases in both
counties, most noticeably by 90% in
Dumfries.

Ogilvie (1986) concluded from the
1983 census that the Mute Swan population
had the potential to increase but that this
varied between parts of the country and that
recovery in some areas would be dependent
upon the long-term impact of the lead
poisoning factor. Given that lead poisoning
seems not to have been a serious problem in
Scotland for the Mute Swan (Spray & Milne
1988), the increase which has occurred must
reflect improved cygnet production and
survival or immigration.

Although there has been extensive
colour ringing in Northern England, very
few English-ringed Mute Swans have been
recorded in territory in Scotland. However,
non-territorial flocks in Lothian in April
invariably include a few birds ringed in

1993.

north-east England, while Lothian ringed
cygnets have been found to be very mobile
(pers. obs.) and have been recorded at sites
ranging from Berwick to Middlesborough
(A. Bramhall and J. Coleman pers. comm.).
This implies a potential mixing of
populations between south-east Scotland and
north-east England but does not suggest any
significant immigration into Scotland, birds
moving from one area to the other probably
balancing each other out.

Comparison of the percentage of
territorial-only and breeding birds with the
non-breeding population (Table 2) has
Shown that all have increased in numbers
between 1983 and 1990. However, as a
proportion of the total population the
breeding plus territorial-only birds have
declined from 49.5% to 42.1% while the
non-territorial population has increased from
50.5% to 57.9%. Because there is virtually
no immigration into the British population
(Ogilvie 1986) this adds to the evidence that
the overall increase is due to the population’s
own productivity. It suggests also that the
breeding population may be attaining a
maximum capacity as a high population is
likely to result in fewer vacant breeding
sites; thus non-territorial birds will
encounter more difficulty in finding a
territory and therefore will remain in the
non-breeding population for longer. This
will contribute to the increase in the number
of non-territorial birds in the total
population. This is the situation which
appears to be occurring in Lothian where the
non-territorial population is now increasing
faster than the territorial/ breeding
population (Brown & Brown in prep.).

That winter weather can have a
significant effect on Mute Swan numbers
has been shown previously (Boyd & Ogilvie
1964; Ogilvie 1967). The period 1983 to
1990 did not see any winter comparable in
long term severity to that of 1962/63 and
this series of mild winters will have had a
considerahle impact upon Mute Swan
survival. In addition, as populations have

Scottish Mute Swan census 1990 99

increased, winter flocks have expanded with
many benefitting from enhanced public
feedinewerc. vat Linithcow | loch. St
Margaret’s Loch and Cramond in Edinburgh
(pers. obs.) and Hogganfield Loch in
Glasgow (B. Zonfrillo pers. comm.). This is
likely to have contributed to survival, while
other birds may have made use of winter
sown cereals (Delany et a/. 1992).

Brown & Brown (1984), when
assessing the status of the Lothian
population of the Mute Swan up to 1982,
suggested that the population was unlikely
to return to the level attained in the late
1950s and early 1960s, and Leach (1988)
came to the same conclusion for Ayrshire,
with human disturbance and interference
being considered a key factor in this.
Changes since then in Lothian (Brown &
Brown 1984-91), and the results of this
census, show this view to have been very
pessimistic. These local studies highlight the
value of and need for detailed on-going
studies of Mute Swan populations elsewhere
in Scotland supported by colour-ringing
schemes; these would help to clarify the
dynamics of local populations, their possible
interrelationships, the differences in
productivity between areas, whether one
area supported another through movement of
surplus birds and what the effect is should a
severe winter Occur.

The Scottish Mute Swan population is
now at its highest ever level with 4856 birds
counted in 1990 and 4992 estimated. The
previous peak in the British population was
considered to have occurred in) 1959
(Eltringham 1963) followed by a decline at
least in part due to a severe winter (Boyd &
Ogilvie 1964). It would seem best that a
further national census should take place in
the year 2000, supported by continuing local
studies in the interim, to determine if the
present trend has continued or if the
population has declined from a peak.

100 A.W. & L.M. Brown

SB 17 (2)

Acknowledgements

A survey of this nature relies on the efforts
of many observers and we wish to record
our thanks to them all. The following
Regional Organisers are especially thanked
for the thorough coverage obtained and for
their additional comments: G. Bates, A. T.
Bramhalls Mi: J. Cooks iG. J. Conse. Ac
Currie; No Elkins, J. E-Howie; B. Di iKerr
E. W. E. Maughan, S. F. Newton, M. A.
Ogilvie, We De Okall (CiRey nolidsscG:
Sheppard, P. Shimmings, K. Slater, R. L.
Swann, J. J. Sweeney, D. Warner, D. S.
Whitaker and R. E. Youngman. We thank
S. Delany and M. Marquiss for constructive
comments on the draft of this paper.

References

Boyd, H. & Ogilvie. M. A. 1964. Losses of Mute
Swans in England in the winter of 1962-63.
Wildfowl 15; 37-39.

Brown, A. W. & Brown, L. M. 1981-91. Annual
Mute Swan breeding census in Lothian.
Lothian Bird report. SOC.

Brown, A. W. & Brown, L. M. 1984. The status
of the Mute Swan in the Lothians. Scott.
Birds 13: 8-15.

Brown, A. W. & Brown, L. M. 1985. The Scottish
Mute Swan census 1983. Scott. Birds 13:
140-148.

Delany. S.. Greenwood, J. J. D. & Kirby, J. 1992.
National Mute Swan survey 1990. Report to
the Joint Nature Conservation Committee.

Eltringham, S. K. 1963. The British population of
the Mute Swan in 1961. Bird Study 10: 10-28.

Goode, D.A. 1981. Lead poisoning in Swans.
Report of the NCC Working Group. NCC,
London.

Leach, 1. H. 1988. Mute Swans in Ayrshire. Scott.
Birds (5: 36-39.

Meek, E. 1993. Population fluctuation and
mortality of Mute Swans on an Orkney loch
system in relation to a Canadian pondweed
growth cycle. Scott. Birds 17: 85-93

Ogilvie, M. A. 1981. The Mute Swan in Britain.
1978. Bird Study 28: 87-106.

Ogilvie, M. A. 1986. The Mute Swan Cygnus olor
in Britain 1983. Bird Study 33: 121-137.

Rawcliffe, C. P. 1958. The Scottish Mute Swan
census 1955-56. Bird Study 5: 45-55.

Spray C. J. & Milne, H. 1988. The incidence of —
lead poisoning among Whooper and Mute
Swans Cygnus cygnus and C.olor in Scotland.
Biological Conservation 44: 265-281.

Allan W. and Lyndesay M. Brown,
61, Watt’s Gardens, Cupar, Fife, KY15 4UG.

(Typescript received 29 September 1993)

ince 1992, a local Biological Records Centre "Fife
S Nature" has been established in Fife. Through special
surveys and a network of official local recorders, the centre
collects, analyses and monitors information on as many
biological groups as possible, as well as on habitats and sites
of natural history interest within the region. Information is
stored electronically and is available for purposes of
conservation, planning, research, education and general
interest.

A "Survey Pack" is available free by request from "Fife
Nature", and the centre also produces provisional atlases,
which will eventually lead to a series of fully illustrated books.
Available at present are

The Dragonflies of Fife: A Provisional Atlas £2 [incl. p.+p.)
The Butterflies of Fife: A Provisional Atlas [Dec 1993 - Price on
inquiry)

The Mammals of Fife: A Provisional Atlas [April 1994 - price
on inquiry]

Others planned are A Fife Flora, a Bumble Bee Aflas and an
Amphibian/Reptile Ailas.

The centre is also involved with the Fife Ornithological Ailas
Group, which is currently {1991-95} carrying out surveys
leading to a Fife Breeding Bird Atlas and Monthly Distribution
Ailas of Birds in Fife.

Further information is available from Anne Marie Smout, Fife

Nature, Department of Economic Develoipment and Planning,
Fife House, Glenrothes, Fife KY7 SIT.

SCOTTISH
NATURAL
HERITAGE

£

Manx Shearwater Puffinus puffinus (Argyl)

WINNING PHOTOGRAPH OF THE SOC PHOTOGRAPHIC COMPETITION 1993

Mary MaclIntyre,
Priormuir, St. Andrews, Fife

Reed Warbler Acrocephalus scirpaceus Wormiston, Fife Gerry Owens
2 Oct. 1993

er

ee

a eee

A Verditers Flycatcher Muscicapa thalassima appeared at Crail Brian Little
with Jots of unusual migrants on 3 Oct. 1993. Where did it come from?

Red-breasted Flycatcher Ficedula parva at Fife Ness D. E. Dickson

3 Oct. 1993
Colour separations by PAR GRAPHICS

THE COLOUR SECTION HAS BEEN SPONSORED BY FIFE REGIONAL COUNCIL.

4
~~

CHARTER FOR THE
ENVIRONMENT

CHARTER FOR THE ENVIRONMENT

Fife's Environmental Charter highlights the Regional Council's approach to
tackling environmental issues and sets out the basis for the Regional Council's
existing and future environmental policies. The Charter is now accompanied by
the third action programme which outlines projects the Regional Council is in
undertaking itself or in partnership with others: a Nature Conservation
Fund, a Community Planting Scheme, and a Community
Environmental Improvement Fund have been established, and a four
monthly Environmental Events Diary is produced.

Through the Charter, the Council has made a commitment to publish further
items in the Fife Heritage Series as a means of raising awareness of the rich
natural and historic environment. Titles currently available from the Dept. of
Economic Development and Planning are:

Fife's Early Archaeological Heritage - A Guide £2.50

Castles of Fife -A Heritage Guide £4.00

Topics to be published early in 1994 include:- Landforms, Townscapes, Abbeys
and Churches and a Heritage Guide to Inverkeithing.

For further information about the Fife Environmental Charter, please contact
Grace MacDonald or Andy Hills on 0592 754411 extension 6337

RUPE ARCHAEOLOGICAL SERVICE

Fife contains a wealth of archaeological sites ranging in date from prehistoric
settlements and forts dating back some 8,000 years, to industrial and military
remains of more recent times. Environmental archaeology has become a key
concern of the Regional Council as it can provide information about how the
natural environment has been altered by our ancestors. The Archaeological
Service is currently working with Scottish Natural Heritage to study and
interpret the settlement remains on the Isle of May National Nature Reserve.

The Regional Council are keen to promote the conservation of this rich heritage
and have published guides to sites which have been studied. These include:-

Balfarg - The Prehistoric Ceremonial Complex £3.00
St Monans Saltpans and the Lost Industrial Complex £1.00

The Regional Council has an Archaeological Service based in the Department
of Economic Development and Planning, and is pleased to offer advice on all
aspects of the conservation of the historic environment. To receive advice please
contact Peter Yeoman or Sarah Govan on 0592 754411 Ext. 6153.

1993

Appendix

Assessment of coverage in each county
Regional organisers were encouraged to
obtain whenever possible full coverage of all
10km squares within their area. If this was
not possible then partial coverage was
permissible with the observer and/or
organiser making an estimate of the number
of birds likely to have been overlooked. In
addition squares could be categorised as
‘probable blanks’ based on lack of habitat
and / or knowledge of the lack of swans in
the square from past experience. Birds
actually counted and the numbers estimated
for each county are shown in Table 1. No
estimates have been made apart from those
provided by the regional organisers.
Regional organisers were asked for
comment on the coverage obtained and any
trends they were aware of for the Mute
Swan population in their area. Where they
were given these comments have been noted
in the observations below for each county,
but for comparison with the 1983 survey
(Brown & Brown 1985) coverage has been
assessed as good, moderate or poor, with
additional comments where appropriate.

Shetland Good. There is no evidence of
Mute Swans. making any attempt to colonise
Shetland, the regional organiser remarking
that “you will not be surprised to hear that
the Mute Swan survey throughout Shetland
came up with nil breeding pairs”.

Orkney Good. Full coverage was obtained,
the regional organiser remarking on the
large increase in the population since 1983
in particular at the Loch of Harray and
“indeed on one isle the Mute Swans have
given up holding territory and are now
nesting in a colony”. The organiser
attributed this increase to the presence of
Canadian pondweed.

Outer Hebrides Good. Poor coverage
obtained in 1990 (other than for Lewis and
Harris) with the regional organiser able only

Scottish Mute Swan census 1990 101

to provide his own observations in the Uists
and Benbecula. However, a complete survey
including aerial counts was undertaken in
1992 by (C2 UeyS prayvon behalf of the
Wildfowl and Wetlands Trust and these data
have been used in this paper.

Caithness Moderate.

Sutherland Moderate. Regional organiser
commented that “most of the county is not
suitable.”

Ross and Cromarty Moderate. Although
full coverage was not obtained other than in
Easter Ross, the regional organiser was able
to make estimates for the western part of the
county based on recent breeding atlas data.

Inverness Moderate Full coverage was
obtained in east Inverness-shire but not west
Inverness-shire, although the regional
organiser commented on much of this area
being unsuitable for Mute Swans and
inaccessible; the estimate was however
considered to be “quite accurate” .

Nairn and Moray Good. Regional
organiser considered it “highly unlikely that
we missed any pairs” and the non-breeding
estimate was considered to be reasonably
accurate.

Aberdeen and Banff Poor. No co-ordinated
survey was undertaken and the 1983 data
have been used in the analysis (see text).
However P. Doyle (pers. comm.) did
consider that by 1991 the number of
breeding pairs were well down on past years
owing to increased disturbance at many sites
(shooting and water sports), parasites
(nematode infestation at several sites
resulting in death of swans) and lead
poisoning.

Angus and Kincardine Moderate. Regional
organiser considered coverage of Angus was

102 A.W. &L.M. Brown

Se 17 (2)

not as extensive as he had hoped. Additional
data were subsequently obtained from N. K.
Atkinson and R. Goater. A co-ordinated
survey was not undertaken in Kincardine but
data from other observers suggests that most
sites were checked.

Perth Good. Regional organiser considered
that all known breeding waters and
non-breeding areas were covered. It was
stated also that Mute Swans were “certainly
increasing again in Perthshire with breeding
at ‘new’ sites in several recent years but
productivity is rather poor.”

Stirling and Clackmannan Moderate to
Good. Most breeding pairs probably located
but some non-territorial flocks may have
been overlooked. Late organisation of this
area resulted in excellent work by D.
Matthews in obtaining satisfactory coverage.

Fife and Kinross Good. Full coverage was
obtained.

West, Mid and East Lothian Good. Full
coverage was obtained as part of a census
commenced in 1978 which has shown a
Steadily), inereasine | breeding yaaand
non-breeding population.

Ayr Good. Full coverage was obtained.
Arran and Bute Moderate.

Peebles, Selkirk, Roxburgh and Berwick
Moderate to Good.

Argyll Poor. Other than Islay, Jura and
Colonsay (which were organised separately),
the organiser for mainland Argyll considered
that the census was a disaster and he
obtained additional information from the
1990 Argyll bird report. Further data were
obtained from D. Trigg. On this basis it was
considered appropriate to use 1983 data for
those squares not covered in 1990 (see text).

Dunbarton, Renfrew and Lanark Good.
Full coverage was obtained, and the small
estimate for Lanark is considered to be
accurate.

Dumfries Good. Regional organiser
considered that coverage was very good and
that “‘all areas that were likely to hold swans
were visited”. Reference was made to the
considerable increase since 1983 but the
organiser did not know what had influenced
this increase in numbers . It was concluded
that “most of the suitable breeding areas
now have at least one pair breeding, and all
potential breeding sites may now be
occupied.”

Kirkcudbright Good. Full coverage was
obtained.

Wigtown Good. Regional organiser
considered that all squares “received
reasonable coverage” and that the number of
breeding pairs seemed “about right given the
unsuitable habitat over a lot of the area”.

Scottish Birds (1993) 17: 103-105

Short Notes

Unusual behaviour of Black-necked Grebes

I have regularly observed Black-necked
Grebes Podiceps nigricollis on a loch in
Scotland for a number of years, and in June
1993 I witnessed an unusual behaviour
between a pair, which I believe has never
been recorded and is not mentioned in
Cramp & Simmons (1977. The Birds of the
Western Palearctic. Oxford, Vol. 1) or in
del Hoyo, Elliot & Sargatal (1992.
Handbook of the Birds of the World. Lynx.
Vol. 1).

On 3 June 1993 at 1900 BST, I was
half way through a three hour observation by
the loch side when a pair of Black-necked
Grebes appeared on the east side of the loch.
The sun had just broken through after a
cloudy day and the wind was light and from
the south-east. The water surface was calm
and visibility was excellent.

The pair made for a dead alder Alnus
glutinosa which lay partly submerged in
shallow water in front of the reed bed where
some Swallows Hirundo rustica were
roosting in the higher branches and a few
Tufted Ducks Aythya fuligula were roosting
on thicker branches above the water level.
The pair of grebes found a niche near the
collapsed trunk of the alder and thereafter
followed approximately five minutes of
personal preening. The female then jumped
on to the trunk, walked unsteadily for a short

103

distance up a gently incline before lying
down on her belly and also resting her head
on the trunk. She may have been sunbathing,
as del Hoyo et al. mention that this is
common behaviour amongst grebes living in
cold parts. Alternatively she may have been
using the trunk as a breeding platform and
attempting to induce her mate to copulate.
The male was close by on the water and
began preening his mate on the trunk and
also appeared to extract oil from her oil
gland which he used on his own feathers.
This behaviour went on for eight minutes
without copulation attempts before the
female slipped back into the water to join
her mate. At this point the male chased off a
drake Pochard Aythya.ferina which was
trying to secure a roosting spot on the trunk.
After successfully evicting the Pochard, the
malJe jumped out of the water onto the trunk
and adopted the same posture as his mate
had done earlier. The female was close by
and began preening her mate for around five
minutes before he came back on to the water
to join her. The pair stayed in that area for
another ten minutes, mainly preening
themselves but also performing a brief head
shaking courtship ceremony before
disappearing into the reed bed close by.

I made these observations through a
telescope at a distance of 120 yards.

A. C. Ramage, 158 Wellesley Road, Buckhaven, Leven, Fife KY8 IHX

104 Short Notes

Fider Ducks eating flattish

On 6 March 1993, we watched a small group
of male and female Eider Duck Somateria
mollissima in the harbour at Eyemouth.
They were with several Cormorants
Phalacrocorax carbo and diving close to
moored fishing vessels. Some of the male
Eiders surfaced with flat fish, probably
flounders Platichtlhys flesus in their bills.
The fish were held head first, banged
vigorously several times on the surface of
the water and, after much head-shaking and
neck-stretching, swallowed. One male
appeared with a fish about 13cm wide,
which it attempted to swallow. The fish was
dropped several times into the water and was
then dived for by the Eider. Finally the duck
gave up all attempts to eat it. Female Eiders,
diving close to the males, did not catch any
fish during the 50 minutes we watched the

group.

SE t7 (2)

The food of Eiders has been recorded
many times at different seasons and habitats.
Mussels Mytilus edulis form the major part
of their varied diet which includes crustaceans,
echinoderms, cuttlefish, sea anemones and
fish (Cramp & Simmons 1977. The Birds of
the Western Paleartic. Oxford. Vol. 1.). The
identity of fish species is seldom recorded,
probably because their remains in Eider
stomachs are fragmentary, However, the short-
spined scorpion-fish Myoxocephalus scorpius,
the three-spined stickleback Gasterotus
aculeatus and the caplin Mallotus villosa
have been identified in their diet (Salomonsen,
F. 1950. Gronlands Fugle. Copenhagen pp
121-130; Madsen, F.J. 1954. Dan.Rev.Game
Bird Biol. 2:157-266; Bardarson, H.R.1986.
Birds of Iceland. Reykjavik ppl08-110). We
have not found any reference to flatfish
being eaten by Eiders.

B. M. Hobson and E. M. Hobson, Flat 7, Castle Terrace, Edinburgh EH1 2EL

Hen Harriers systematically testing flocks of Ring-necked Pheasants

On | January 1983 a ‘ringtail’ Hen Harrier
Circus cyaneus was hunting a large area of
rushes in west Galloway. It stooped at a
cock Pheasant Phasianus colchicus on the
ground, flushed and chased it for over 100m
but did not catch it. The harrier then returned
to the same area and systematically flushed
and chased individuals one by one from the
rest of the flock of two further males and
four females. None was killed although after
chasing one of the cocks, the harrier hovered
above it and flopped on top of it with
lowered talons but was shaken off.

On 6 October 1987 in the same area |
watched a male Hen Harrier flush three cock

Pheasants, once again systematically chasing
each in turn.

Hen Harriers frequently chase
individual Pheasants in west Galloway but
of 91 observed attacks on them, I have no
records of them killing any, nor have prey
remains been found in pellets at their
communal roosts (Scott.Birds 7:24-49;
Watson, D. 1977. The Hen Harrier. Poyser,
Berkhamstead; unpubl. data). Ash (1960.
Birds of prey numbers in a Hampshire game
preserve. Brit.Birds 53:285-300), however,
recorded them as carrion prey in winter.

R.C. Dickson, Lismore, New Luce, Newton Stewart DG& OAJ

eT

oo wee Ponce

1993

Buzzards copulating just before roosting

On 26 March 1993 I saw a female Buzzard
Buteo buteo, 49 minutes before sunset,
sitting on the top of a hawthorn bush on low
ground in west Galloway. Six minutes after
sunset, the Buzzard stretched her wings and
flew east for about 500-600 metres where
she met an approaching male Buzzard; both
Buzzards circled each other and then flew a
short distance west. The female landed on a
sloping pasture field and the male circled
just above before dropping to mount the
female, apparently copulating, slowly
flapping his wings for about 10-15 seconds.
He flew east and was mobbed by two
Carrion Crows Corvus corone; meanwhile
the female had flown to a large, solitary,
deciduous tree nearby. The male returned
and swooped up to land beside her; both
birds then roosted together in the same tree.
Although it is not unusual for Buzzards
to copulate in March, I can find no mention
in the literature of Buzzards copulating just
before roosting. BWP (Vol. 2) states that
copulation normally occurs on the nest, and

Short Notes 105

Tubbs (1974. The Buzzard. David &
Charles, Newton Abbot) noted, on the
comparatively few occasions that he
witnessed it, that it had taken place on
regularly used perches in their territories.
Kestrels Falco tinnunculus have been noted
copulating before roosting (Scott. Birds
14:215) and I have also seen Merlins Falco
columbarius copulating about an hour before
roosting in April 1975 and 1978 on their
breeding grounds in Galloway. This
behaviour might occur more often in some
birds of prey than has been recorded,
although some authors state that copulation
in some species occurs more often in the
mornings (Newton 1986. The Sparrowhawk.
Poyser, Calton; Village 1990. The Kestrel.
Poyser, London). In other Buteonine hawks,
however, Johnsgard (1990. Hawks, Eagles
and Falcons of North America. Smithsonian
Institution Press, London) mentions that
Swainson’s hawk Buteo swainsoni copulate
mainly during morning and evening.

R.C. Dickson, Lismore, New Luce, Newton Stewart DG8 OAJ

106 Scottish Birds (1993) 17: 106

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Scottish Birds (1993) 17: 107-110

Comment and Reply

107

What is the scale of seabird movement across central Scotland?

C.J.HENTY

Large numbers of Kittiwakes move westward into the inner Forth
and this has been held to indicate that considerable cross country
flights occur. It is argued here that unequivocal evidence only
exists for occasional inland movements and there is strong
negative evidence against regular flights. Observations are
reviewed that suggest a similar picture for other marine Laridae.

In an editorial comment, R.D.Murray (1992,
p38) asserted that there was a large passage
of Kittiwakes Rissa tridactyla between Forth
and Clyde with the implication that such
movements were quite frequent. This is
certainly a departure from the standard
published view in both Baxter and Rintoul
(1953) and Thom (1986), where inland
Kittiwakes are stated to be unusual and
usually storm driven. Murray is clearly
correct that this view is inadequate: he
quotes a 1990 record of 38 Kittiwakes flying
high to the east over the Erskine Bridge
whilst W.R.Brackenridge noted flocks flying
west over Carron Valley Reservoir in
October 1985 and 1987 and in December
1984. There are, however, very few such
unequivocally inland records and Murray
presumably relies on evidence of large and
regular movements into the inner Forth off
Hound Point (e.g. Lothian Bird Reports
1984-91). I wish to argue that the
interpretation of such movements is not
straightforward and there is in fact a wide
range of possible interpretations depending
on what assumptions are made on seabird
behaviour and the weighting of negative
evidence.

The problem is that west of Hound
Point there are some 100 square kilometres
of wide estuary before the Forth narrows
markedly above Kincardine Bridge; thus
there is ample space for Hound Point birds
to feed. In recent years flocks of up to 500

Kittiwakes have not been unusual in this
area and in fact large feeding flocks have
been known for a long time - around
December 1872 great numbers were in the
upper Forth feeding on enormous shoals of
Clupea sprattus (Harvie-Brown 1906). Such
birds could, conceivably, drift back
eastwards to the North Sea in a diffuse
movement some time later; a night return is
possible since Myres (1963) found that
departure from breeding colonies continued
after dark. The most convincing
observations for inland flights were made by
G.L.Sandeman (1974, 1975) in October and
November: he detected large westerly
movements off Edinburgh and followed
them to see (a) in 1974, large flocks circling
high over the Queensferry bridges and
heading west and (b) in 1973, flocks gaining
height and heading west over Skinflats. If
the latter flight direction was persistent then
the birds must have departed inland.
Although flocks of Kittiwakes in this
locality are often hesitant and not actually
seen to depart (D.M.Bryant, W.R.
Brackenridge pers. comm.) there can be
little doubt that Sandeman’s observations
support the inland observations that
Kittiwakes fly overland in flocks at least
occasionally. Several versions of Murray’s
more generous interpretation might be
distinguished: (1) overland flights occur
regularly but only involve a small
proportion of birds entering the inner Forth.

108 Comment and Reply

SB 17 (2)

(2) a significant (say >10%) of such birds
leave overland or (3) the majority of them
do so.

There are three sets of observational
evidence against regular overland flights.
First, since Sandeman’s notes there has been
intensive observation around Grangemouth
but no large and unequivocal departures
have been recorded. Second, between _1978-
1988 a group led by A.D.Wood made
frequent and thorough observations at
Carron Valley Reservoir but did not report
anything to add to the observations already
mentioned. Third, in the last 20 years I have
made many observations in autumn
specifically to look for visible migration on
the north and the south sides of the
Gargunnock Hills and have many records of
passerine and goose movement but with no
sign at all of seabirds. Admittedly,
Kittiwakes over land are often likely to be
flying high but the visible migration watches
specifically involved scanning the sky; thus
for any regular passage to be completely
overlooked it would be necessary to assume
that almost all of the birds occur at above
about 2000m. Such an assumption is
certainly conceivable but in my view would
need some independent support to carry any
conviction. I have in fact had no difficulty in
detecting large gulls, probably Larus fuscus,
with x8 binoculars against well-lit cloud at a
range of 5000m. It is worth noting that
non-systematic observation by local
observers in autumn quite regularly pick up
small numbers of Gannets Sula bassana,
usually juveniles, either flying overland or
departing inland. Radar observations made
by Evans (1968) of overland departures by
waders from the Forth might also have been
expected to detect any regular movement of
Kittiwakes but no such evidence was
obtained, although Professor Evans tells me
that high flying flocks would have been
within range of his radar. Bourne (1963),
reviewing bird migration in north-west
Europe, also mentioned Kittiwake
movements only at sea. Professor Coulson
tells me that the ringing evidence gives no

support to a theory of large scale
interchange overland between the west and
east coasts.

Occasional inland movements have
been noted for other species. In autumn,
parties of Common Terns Sterna hirundo
have twice left to S or W from Grangemouth
and a steady movement up river occurred
above Alloa on 13 September 1970. The last
was accompanied by two Little Gulls Larus
minutus and one of this species flew inland
at Skinflats on 22 August 1991. Sandwich
Terns Sterna sandvicensis have been noted
flying W over Gargunnock. However this
species illustrates the risks of interpreting
isolated observations - twice in August 1991
above Alloa large parties were seen to fly off
W gaining height, only to return with loud
calling some minutes later. The numbers of
skuas Stercorarius sp. seen around
Grangemouth are only a small percentage of
those seen passing W at Hound Point - it is
worth noting that a notable proportion also
fly E at this site, records from the Lothian
Bird Reports 1987-1991 show 27% E for
Pomarine S.pomarinus, 22% for Arctic
S.parasiticus, 8.5% for Long-tailed
S.longicaudus and 17.4% for Great Skuas
S.skua. These facts suggest that most of the
skuas eventually return to the North Sea.
However, Arctic Skuas have been seen to
leave inland from Skinflats at least once.
More surprisingly, a party of 18 arrived
from the WSW (apparently from inland) on
18 September 1976.

All these records suggest that inland
passage through Scotland occurs occasionally
in most primarily coastal Laridae but there
is no strong reason to conclude that it is
frequent. A more generous conclusion in the
case of the Kittiwake would depend on
dismissing the negative evidence detailed
above; there are certainly reasons why any
of the types of negative evidence might be
misleading, but when all are in agreement I
assert that to conclude that inland passage is
regular or on a large scale would be to go far
beyond the existing evidence. Thus I can
find no support for any of the three regular

1993

movement options mentioned earlier,
although I would agree that the option
involving a small part of inner Forth birds
should be kept in mind as a possibility. It
would be very useful if observations of
movement at Hound Point could be relayed
immediately to observers who watch in the
Grangemouth area so that specific and
simultaneous checks for inland departure
could be made.

References
Baxter, E:V. & Rintoul, L.J. 1953. The birds of
Scotland. Oliver and Boyd, Edinburgh.

Bourne, W.R.P. 1963. Bird migration in Scotland
studied by radar, Vol 2: Appendix 2, p54. MS
in Edward Grey Institute Library, Oxford.

Comment and Reply 109

Evans, P.R. 1968. Autumn movements and
orientation of waders in northeast England
and southern Scotland studied by radar. Bird
Study 15:53-64.

Harvie-Brown, J.A. 1906. A fauna of the Tay
Basin and Strathmore. Douglas, Edinburgh.

Murray, R. 1992. Scottish Bird Report 1990.
S.0.C, Edinburgh.

Myres, M.T, 1963. Observations with radar of the
feeding flights of Kittiwakes. Bird Study 10:
34-43.

Sandeman, G.L. 1974. A large movement of
Kittiwakes in the Forth. Scott. Birds 8: 77-78.

Sandeman, G.L. 1975. Another Kittiwake
movement in the Firth of Forth. Scott. Birds
8: 324-325.

Thom, V.M. (1986). Birds in Scotland. Poyser,
Calton.

C.J. Henty, University of Stirling, Stirling FK9 4LA

Reply to Henty

The fate of the seabirds that travel westwards
up the Forth at Hound Point in the autumn
has interested me ever since the scale of the
Hound Point passage first became apparent,
in relation to skua movements, in the late
1980s. In the four years between 1988-91
some 2133 skuas were counted moving
through Hound Point. Of these 1593 (75%)
travelled west while the remaining 540 were
seen moving east. Another 100 birds were
reported moving in an indeterminate manner,
usually circling round in the area immediately
east of Hound Point. Even deducting the 540
eastward travellers, as moving west and then
returning, this still leaves over 1000 skuas
passing through westwards.

Observers at Hound Point have
absolutely no doubt that these birds are
cross-country travellers from their behaviour
as they approach the main observation area.
They are reluctant to pass under the Forth
Bridges and they typically begin to tower as
they approach Hound Point. They spiral
upwards and when they reach their preferred
altitude, they move off west and south-

westwards parallel to the southern shore of
the Forth, passing directly above South
Queensferry. This behaviour is typical of
bright aftemoons when the wind is between
south-west and north. The eastwards
movements, which Henty suggests are birds
returning out of the upper Forth, only occur
in dull conditions and easterly winds
according to M. Griffin and I.J. Andrews,
two of the principal Hound Point devotees.
Their interpretation of this behaviour is that,
if the birds are unable to see their way clearly
westwards in the area where the land narrows
at the bridges, they will turn back eastwards
down the Forth, presumably to search out
another route west to the Atlantic. It is only
in clear conditions, perhaps when the
towering birds can actually see the Atlantic,
that they head westwards. It is noticeable in
this regard that most movements occur in the
afternoon when it is more likely that the birds
will see the sun shining off the ocean surface.

I personally witnessed just such a
situation in September 1992 at the summit of
Broad Law (834m) in the virtual centre of

110 Comment and Reply

southern Scotland. Whilst conducting
botanical fieldwork, our party came upon a
juvenile Arctic Skua Stercorarius
parasiticus feeding off emerging crane flies
Tipulidae. After an hour the bird flew off,
spiralled upwards for several hundred metres
before flying off westwards towards the
point where the sun was reflecting off the
Atlantic to the south of Goat Fell on Arran. I
have little doubt that this is what occurs at
Hound Point. Perhaps people who use
Edinburgh Airport and fly above the Forth
Bridges in the afternoon might confirm this.

There are remarkably few reports of
any skuas from points west of Queensferry,
and none of the flocks of skuas, which pass
Hound Point on some days. Yet it is known
that skuas routinely fly overland across
Eurasia south of their breeding range,
cross-country to the Caspian Sea and along
the flyway between the Baltic Sea and the
Gulf of Murmansk. In our case, I suspect the
skuas travel across Scotland unseen at high
levels, spreading out from the bottleneck at
the Forth Bridges, reducing the likelihood of
being spotted by observers. Certainly, the
Carron Valley and the Gargunnock Hills
seem too far north to be on the flightlines of
birds seen at Hound Point.

It seems unlikely that the Hound Point
movements are anything new. They were
overlooked despite vast numbers of
birdwatchers in the area. The spring passage
of skuas off the Western and Northern Isles
is certainly not a novel phenomenon, but this
was also overlooked until recently. What
else 1s waiting to be discovered?

The near certainty that skua movements
at Hound Point must have gone on for years
before the passage was reported tends to
reduce the impact of Henty’s negative
evidence for Kittiwake Rissa tridactyla
movements. The Hound Point observers
regularly see Kittiwake flocks, often several
hundred birds strong, towering like the skuas
and passing off westwards. Sandeman’s
evidence seems to tie in well with the

5B 17 (2)

apparent westwards passage seen more
recently at Hound Point. The fact that they
are not seen over the areas indicated in
Henty’s note may simply suggest that they
move over parts of Central Scotland which
are as yet undiscovered.

The suggestion in the 1990 Scottish
Bird Report was simply that such
movements across Scotland do occur, as
hinted at by the quoted 38 Kittiwakes
moving east high above the Erskine Bridge
in March 1990, while 1600 moved west past
Hound Point on 18 October that year. Even a
casual glance at the bird reports for Lothian
and the Clyde area in recent years shows
that these observations are not unique.
Respectable numbers of Kittiwakes
travelling westwards pass Hound Point each
October and small numbers are seen in the
Clyde area apparently moving east each
March. The movements may well be regular.

The 1991 SBR documented Long-tailed
Skuas S. longicaudus moving inland up the
Eden Estuary and the River Dee during the
large movement of September. Similarly,
numbers of Kittiwake were again seen in
Glasgow during March, some passing
eastwards. A paper on the regular passage of
Little Gulls Larus minutus across the Pennines
between the Irish Sea and the North Sea
(Messenger, D. 1993. Spring passage of Little
Gulls across Northern England. Brit. Birds
86: 397-06), records a movement that would
have been considered fantastic 20 years ago.

When preparing the species accounts
for SBR, information in local bird reports
often makes it possible to see trends or
features which are not readily apparent from
reading just one or two bird reports. My
attempts to draw together the huge amounts
of data and present these in a way that will
both interest and enlighten the reader, lead
me to hint at points which become apparent
to me, in the hope that someone will notice
and actually prove them. A letter
challenging my opinion means at least that
someone reads SBR.

R.D. Murray, 4 Bellfield Crescent, Eddleston, Peebles EH45 8RQ

Scottish Birds (1993) 17: 111-118

Wt

Research Index

The following is an index of fieldwork and
research presently undertaken with specific
Scottish interest. The index is updated every
year and researchers are either listed
alphabetically by the institute where the
research is based, or in two cases (SNH &
RSPB) by the topics and species researched.
If you are doing research in the area and are
not listed here, or know of someone who is,
please put us right by sending details to the
editor.

Aberdeen University

Coseroves et. ine importance of
conservation zones for bird populations
in upland spruce forest, concentration on
broadleaf strip, unplanted stream edges,
marshes, etc, in otherwise unbroken
conifer. Based in Kielder,
Northumberland. (PhD study).

Doyle, P. Factors associated with the
persistence of sub-colonies of the
Fulmar on Eynhallow, Orkney. (PhD
study).

Dayawansa, N.P. Distribution and feeding
ecology of waders and waterfowl on the
Ythan estuary, Grampian in relation to
algal growth on mudflats. (PhD study).

Dunnet, G.M. The Fulmar on Eynhallow in
Orkney (since 1950) concerned
primarily with population dynamics,
longevity and, recently, recruitment.

Dunnet, G.M. & Heubeck, M. Monitoring
programme (since 1978) in breeding
seabird populations in Shetland, as well
as changes in seabird and waterfowl
wintering populations in two areas: Yell
Sound and Sullom Voe and the
Bluemull/Colgrave Sounds area of
north-east Scotland.

Gorman, M.L. & Langsdale, A. Feeding
ecology of raptors (Short-eared Owl,
Hen Harrier and Kestrel) in Orkney,
particularly concerned with the effects of
changes in land use.

Patterson, I.J. & Fuchs, R.M.E. Management
of grassland to provide reserves for wild
geese; experiments with different
mowing, grazing and fertiliser regimes
at the RSPB reserve at the Loch of
Strathbeg, Grampian.

Patterson, I.J. & Laing, R. Monitoring of
wildfowl and wader numbers on the
Ythan estuary, Grampian. Twice-
monthly counts throughout the year,
with special emphasis on the Eider Duck
in the breeding season.

Edinburgh University

Carter, A. Feeding -behaviour and
micro-habitat distribution of waders on
rocky shores, especially in East Lothian
(MPhil study)

Cresswell, W. Behaviour and ecology of a
predator-prey system: Sparrowhawks
and Redshanks, concentrated on
Tyninghame, East Lothian. (PhD study).

Deag, J. Studies on communication and
social organisation in tits, with field
work mainly at Ormiston, East Lothian.
(PhD study).

Hanna, L. Barn Owl populations genetics.
(PhD study).

Lunny, C. Behaviour and ecology of
Dippers. (PhD study).

McAfferty, D. Ecological energetics of Barn
Owls. (PhD study).

Scott, G. Social behaviour and
communication in Blue Tits. (PhD
study).

Taylor, I. Long-term study (started 1978) of
Barn Owl ecology and conservation. Has
been monitoring, since 1980, changes in
Lapwing breeding density in relation to
agriculture.

Vickery, J. Behaviour and ecology of
Dippers and waders of farmland.

112 Research Index

Glasgow University

Askew, C. Survival rates and ecology of
Great Skuas on Handa: comparison of a
small and expanding population with the
large decreasing one on Foula.

Austin, G. Seabirds and their food supply.

Barber, I. Breeding performance of seabirds
on Handa in relation to industrial fishing
development. (MSc study).

Bolton, M. Energetic costs of breeding in
Storm Petrels.

Calvo, B. Effects of agricultural land use on
the breeding ecology of waders. (PhD
study).

Calvo, B. & Furness, R.W. Endosteal
lamellae in bird bones as a means of
estimating the age of dead adult birds.

Cohen, B.L., Wildon, R.H., Furness, R.W. &
Willcox, S. Molecular studies of skua
DNA to assess the evolutionary history
of skuas.

Crompton, D.W.T. & Huntingford, F.A.
Profilicollis botulus: an Eider Duck
parasite in the Clyde Estuary.

Ensor, K. Breeding season diets of Great
Skuas and gulls in relation to the
activities of the whitefish fisheries
around Scotland.

Furness, R.W. Seabird interactions with fish
stocks and fisheries, birds as monitors of
environmental change, long term
monitoring of seabird ecology on Foula,
Shetland” (since 1971). aseabird
energetics, body composition and moult.

Furness, R.W., Hamer, K.C., Klomp, N.I. &
Ratcliffe, N. Ecology of Great Skuas on
Foula, Shetland: long term studies begun
in 1960s.

Hansell, M.H. A comparative study of nest
building behaviour in birds.

Henny, V. Reproductive strategy in
Common Terns.

Horn, W. Diet selection and foraging
economics in breeding terns. (PhD
study).

Houston, D.C. Food quality and breeding
performance in Blue Tits.

SB 17 (2)

Klomp, N.I. & Furness, R.W. Recruitment
of immature Great Skuas into breeding
colonies (comparative work with
Professor E.C. Young, University of
Auckland, in southern hemisphere
skuas).

Macedo, E. Effects of fisheries on seabird
numbers: an assessment of net mortality
and fishery-induced changes in food
availability. (MSc study).

Madders, M. Hen Harrier ecology,
especially “their Wser-or, forestry
plantations (PhD study).

Metcalfe, N.B. Social behaviour and
ecology of flocking birds: reproductive
ecology of Pied Flycatchers.

Monaghan, P. Population ecology of gulls.

Monaghan, P., Burns, M. & Walton, P.
Reproductive strategies in Black
Guillemots.

Monaghan, P., Burns, M., Uttley, J.D.,
Walton, P. & Austin, G. Effect of prey
availability on reproductive and foraging
strategies in Shetland seabirds.

Monteiro, L. Heavy metal accumulation by
petrels and shearwaters. (PhD study).

Muda, F. Nest material stealing in Shags.
(PhD study).

Phillips, R. Population ecology of Arctic
Skuas in relation to climate and
variations in numbers and reproductive
success of the species they rob of fish.
(PhD study).

Ramsay, S. Nutritional factors in egg
production in tits.

Ratcliffe, N. Reproductive effort of Great
Skuas of known ages from 4-30 years
old: a test of predictions of life history
theory. (PhD study).

Selman, R. The role of female body
condition on egg production in birds.
(PhD study).

Smith, R.D. Dispersal and behaviour of
over-wintering Snow Buntings. (PhD
study).

Solomon, S.E. Comparative study of the
ultrastructure of eggshell formation in
birds.

£993

Research Index 113

Stewart, R.M. Uptake, storage and excretion
of cadmium and lead by birds and an
assessment of birds as monitors of
cadmium and lead pollution. (PhD
study).

Thomson, D.L. Energetics and ecology of
Kittiwakes. (PhD study).

Thompson, D.R. & Furness, R.W. Analysis
of stable isotope ratios of nitrogen,
carbon and other elements in feathers of
seabirds as a means of assessing their
trophic relationships in the marine
ecosystems and changes in diet of the
last 150 years.

Walsh, P.M. Feeding ecology and mercury
burdens of Gannets. (PhD study).

Williams, J. Birds as possible carriers of
Lyme disease. (PhD study).

Zonfrillo, B. Breeding ecology of seabirds
on Ailsa Craig. (PhD study).

Institute of Terrestrial Ecology, Banchory.

Bacon bo oe Palmer, S.C€.F. (Oxford).
Investigation and modelling of habitat
utilisation by Red Grouse.

Harris, M.P. & Nuttall, P. The importance of
tick-borne diseases on_ seabird
populations.

Harris, M.P., Halley, D. (St. Andrews) &
Wernham, C. (Stirling). Long-term
studies of numbers, survival, productivity
and for some species, recruitment and
body condition, of seabirds on the Isle of
May in relation to food availability and
environmental conditions.

Marquiss, M., Carss, D. & Alexander, G.
Does Goosander and Red-breasted
Merganser predation have an impact on
salmon populations.

Miosseaive, Rarnmi Ruikéeelrenholmii iT!
Population regulation in Red Grouse.
Roles of behaviour, dispersal and
predatior. in determining population size.

Moss, R., Ficozzi. N. & Catt, D.C. Studies
of habitat requirements, dispersal,
numbers and distribution of Capercaillie;
particularly the use made by Capercaillie
of commercial woodland.

Parr, R. A study of population size and
productivity of moorland waders and
Red Grouse in relation to afforestation.

Wanless, S., Harris, M.P. & Hector, J.A.L.
Reproductive and foraging energetics of
Shags with particular emphasis on the
influence of food availability and
feeding habitat.

Joint Nature Conservation Committee:
Seabirds Team, Aberdeen.

Tasker, M.L. Head of Seabird Team.

Walsh, P. Seabirds Colony Register -
collates counts of seabirds at colonies
throughout the U.K.

JNCC Seabirds at Sea Team (SAST).
Studies the distribution of seabirds in the
offshore waters around Britain
throughout the year. Staff: A. Webb
(leader), C. Stone (marine biologist), D.
Halley (ornithologist).

The Royal Society for the Protection of
Birds

The RSPB undertakes extensive research
into all aspects of birdlife: their ecology,
distribution, status and conservation. The
following projects are of particular Scottish
interest and names of the RSPB research
staff involved are given in brackets. Further
details are available from lan Bainbridge at
RSPB SHQ. In addition to this list, regular
bird monitoring is undertaken on almost all
the RSPB’s reserves in Scotland. There are
also numerous projects on many aspects of
the ecology and management of the reserves,
including ornithological, botanical,
hydrological and entomological projects,
which are too numerous to list here.

Species research
Factors affecting breeding success of
Black-throated Divers. Studies of lochs,
“fish yomvertebrates’ and a diver
productivity. (1992-95, D. Jackson, M.
Hancock, R. Summers).

114 Research Index

Individual bird calls. With University of
Nottingham. Investigation of individual
bird identification using calls; including
Black-throated Diver, Corncrake,
Bittern. (1990-93, G. Gilbert and P.
MacGregor Nottingham University, K.
Smith).

Factors affecting breeding success of
Slavonian Grebes. Studies of lochs, fish,
invertebrates and grebe productivity.
(1992-94. R. Summers, R. Mavor).

Surveying methods for Storm and Leach’s
Petrels. Development of methods for
surveying and monitoring these species,
using transects, endoscopy etc., on
Shetland and elsewhere. (1990-95, D.
Suddaby, P. Ellis, J. Sears).

Barnacle Goose feeding ecology. With
Durham University. Investigation of
reseeding, grazing and fertiliser
management on grassland use by
Barnacle Geese at Loch Gruinart.
(1992-95; J_ Welstead & P. Evans
Durham’ “University, S. Pescival
Sunderland University, I. Bainbridge, D.
Beaumont, Loch Gruinart Reserve staff).

Goose grazing management experiments.
With Aberdeen University. Studies on
the effects of grazing, mowing and
fertiliser regimes on grey goose use of
Loch of Strathbeg. (1991-95, R. Fuchs &
I.J. Patterson Aberdeen University, D.
Beaumont, I. Bainbridge, Strathbeg
Reserve staff).

Moray Firth seaduck and wader studies.
Regular surveys of Moray Firth seaduck
populations, and co-ordination of BoEE
counts, 1985 onward. (1977-95, R.
Evans, J. Stenning).

Sea Eagle population studies. With SNH and
JNCC. Monitoring and demographic
modelling of Sea Eagle populations.
(1984 ongoing, RSPB Regional staff, R.
Green).

Golden Eagle home range use. Investigation
of use of habitat by radio-tagged eagles;
relating breeding success and habitat to
prey abundance, land use and

SB 17 (2)

topography. (1991-95, M. McGrady, J.
Grant, I. Bainbridge).

Golden Eagle project, Galloway. With SNH,
Forest Enterprise and Dumfries &
Galloway RSG. Studies of the home
ranges, prey and carrion densities and
habitat use of eagles in Dumfries and
Galloway. (1992-94, C. Park, C. Rollie).

Red Kite monitoring. Joint project, with
JNCC managing English re-introduction.
Monitoring of breeding success and
dispersal of the Scottish Red Kite
population. (1989, ongoing, D.
Orr-Ewing, R. Evans).

Effect of forestry on Hen Harriers. Contract
to Glasgow University. Studies of
breeding and feeding use of forestry and
other land by harriers. (1991-94, M.
Madders & D. Houston Glasgow
University, I. Bainbridge).

Hen Harrier ecology. Studies on the
population biology and dispersal of Hen
Harriers. (1990-95, B. Etheridge, J.
Craig, R. Summers).

Merlin survey. Repeat of 1983-84 national
Merlin survey to give population size,
trends and baseline for future studies.
(1993-94, G. Rebecca, I. Bainbridge).

Relationships between raptor and grouse
populations. Joint project with ITE, GC.
SNH, JNCC. Relationships between
harriers, Peregrines and grouse
populations. (1991-972, ITE and GC
staff, I. Bainbridge).

Black Grouse and land use. Analysis of
Perthshire Black Grouse survey to
investigate relationships between grouse
density and distribution with land use.
(1993-94, R. Green).

Breeding success and habitat selection in
Capercaillie. Work on Abernethy
reserve, examining the effects of habitat,
predators and other factors on
Capercaillie productivity and survival.
(1991-95, R. Summers, R. Proctor.
Abernethy Reserve staff).

Survey and monitoring of Capercaillie
populations. Joint project with ITE, GC.

193

SNH, FC. Estimation of population size
and habitat use. (1991-94, R. Summers, I
Bainbridge).

Corncrake ecology. Studies of Corncrake
breeding biology to assist in land
management for Corncrake
conservation. (1992-95, G. Tyler, R.
Green, C. Self, E. Brindley).

Corncrake survey. Joint project with IWC.
Repeat of 1988 national survey, 1991
part survey to give population size,
trends and habitat changes. (1993, R.
Green).

Corncrake tape-luring. Experimental
tape-luring to attract Corncrakes to
suitable habitat, Loch Gruinart.
(1991-94, M. Peacock, G. Hirons).

Red-necked Phalarope ecology.
Identification of habitat and
management requirements. (1992-95, M.
O’Brien, I. Bainbridge).

Montane bird monitoring, Abernethy.
Collaborating with SNH. Development
of monitoring methods for breeding
Dotterel and Snow Buntings. (1992-95,
A. Amplett, I. Bainbridge, D. Beaumont).

Lowlands breeding waders in Scotland. Joint
project with SOC. To determine the
numbers and distribution of lowland
breeding waders in Scotland, set up a
baseline for future studies, identify key
sites for waders. (1992-94, M. O’Brien,
I. Bainbridge).

Low tide counts. Contract to BTO. Low tide
counts of distribution of waterfowl
wintering on estuaries. (1992 ongoing, J.
Evans BTO, J. Sears).

Roseate Tern. A study to monitor the
breeding range and productivity of the
east Atlantic population, identify its
wintering range, and determine threats to
the species. (1988-94, A.del Nevo).

Seabird monitoring. Monitoring of seabirds
at RSPB reserves and other sites;
particularly tern monitoring.
Contribution to joint seabird monitoring
project with JNCC and SOTEAG.
(ongoing, J. Sears).

Research Index 115

Seabird monitoring, east Caithness. Census
plot counts and productivity studies at
five colonies in east: Caithness.
(1980-93, R. Evans).

Orkney and Shetland seabird studies.
Monitoring numbers, breeding success
and body condition of Arctic Terns and
skuas in relation to food availability.
(1990 ongoing, D. Suddaby, C. Orsman,
P. Ellis, E. Meek, J. Sears).

Winter pinewoods bird survey. Crested Tit,
Crossbill and Capercaillie population
distribution and habitat studies.
(1992-95, R. Summers, A. Maclennan,
G. Rebecca).

Scottish Crossbill identification. With
Dundee Institute of Technology. Studies
on Crossbill DNA to determine species
distinction and aid future field
identification. (1992-94, R. Summers).

Habitat and legislative research.

Estuaries inventory. Development of a
database on the 57 most important
estuaries in the UK, identifying land use,
developments, bird numbers and areas
used. Includes Solway, Clyde, Forth and
Moray aircthen( 1990-955 Ke sReck;, J:
Sears).

Reedbed inventory. Development of a full
national inventory of reedbeds, with
vegetation surveys, monitoring of
reedbed condition. (1993-94, K. Smith,
M. Painter).

Upland futures. Review of the likely effects
of upland land use change on birds.
(1992-93, R. Green, N. Harding).

Review of licensed bird killing. Examination
of the level of killing of birds under
licence in the UK, how the licensing
system operates. Concentrating on
sawbills, Cormorants and geese.
(1993-94, S. Murray, P. Newbery).

nshore fisheries study. Review of inshore
(net) fisheries in Scotland and Northern
Ireland and the effects of incidental bird
kills in them. (1992-93, S. Murray, N.
Harrison).

116 Research Index

Shetland sandeels survey. Contribution to
SOAEFD survey of sandeels numbers and
distribution around Shetland, in
connection with the Braer incident.
(1993-95, SOAFD staff, J. Sears).

Beached Bird Survey. Organisation and
analysis of annual beached bird survey.
(1991 ongoing, RSPB Regional staff, I.
Sim, J. Sears).

St Andrews University

Gil, D. Field studies of Treecreeper song.
(PhD study ,31993-963) topicyito) be
decided).

Graves, J.A. & Ortega-Ruano, J. Mating and
reproductive success in Shags on the Isle
of May.

Slater, P.J.B. Field and laboratory studies on
the development and organisation of bird
vocalisations.

Scottish Association for Marine Science
(formerly Scottish Marine Biological
Association), Dunstaffnage Marine
Laboratory, PO Box 3, Oban, Argyli
PA34 4AD

Craik, J.C.A. Factors affecting breeding
success of Common Terns and Arctic
Terns in western Scotland, especially
predation by mink and otter. Effects of
such predation on smaller gull species
(Common and Black-headed) are also
receiving study.

Scottish Natural Heritage

SNH its involved in a wide range of work on
birds. Much of this is currently contracted
out to other organisations, and some is
managed on its behalf by the Joint Nature
Conservation Committee (JNCC). Names of
individual workers are not attached to the
following list, although the _ key
organisations involved are given, as is the
appropriate contact person in SNH or JNCC.
The first contact points for further
information on these projects and other

SB 17 (2)

aspects of SNH’s work on birds are Greg
Mudge (agricultural/lowland birds) and
Philip Whitfield (upland/peatland birds) at
2/5 Anderson Place, Edinburgh, EH6 5NP.
Tel 031 554 9797. Other contact persons are
also at this address, unless otherwise
specified.

International site designations: survey,
review and assessment of bird numbers
and distributions with respect to Special
Protection Areas and Ramsar sites.
JNCC. (G.P. Mudge, D.P. Whitfield, C.
Galbraith JNCC).

Services in ornithology. Including the Birds
of the Estuaries Enquiry (WEBS);
national bird ringing scheme; integrated
population monitoring; monitoring birds
of prey: monitoring of wetland birds,
special surveys; habitat management
research. JNCC/ British Trust for
Ornithology. (G.P. Mudge, C. Galbraith
JNCC).

Monitoring of rare British breeding birds.
JNCC/Rare Breeding Birds Panel. (G.P.
Mudge, D. Stroud JNCC).

Conservation of vulnerable and dispersed
species. Measures to protect birds
outside protected areas in line with UK
responsibilities under the EC Birds
directive. JNCC. (C. Galbraith JNCC).

Services in wildfowl research, including the
National Waterfowl Count scheme
(WEBS). JNCC/Wildfow! and Wetlands
Trust. (G.P.Mudge, D. Stroud JNCC).

Conservation plans for migratory waterfowl
under the Bonn Convention and Ramsar
Convention. | JNCC/International
Waterfowl and Wetland Research
Bureau. (D. Stroud JNCC).

Effect of commercial dredging on wintering
birds on the Solway. British Trust for
Ornithology. (M. Hughes, SNH
Dalbeattie).

Meteorological Office reports related to
statutory shootings bans on waterfowl
during severe winter weather.
JNCC/Meteorological Office. (D. Stroud
JNCC).

1993

Moorland bird surveys; techniques and
ecology. (D.P. Whitfield, A. Brown
English Nature).

Moorland changes and influences on birds in
the Northern Isles. (A. MacDonald,
D.B.A. Thompson).

Population ecology and conservation of
montane birds, notably Dotterel,
Ptarmigan and Snow Bunting. (D.P.
Whitfield, D.B.A. Thompson, with R.
Smith & S. Rae).

Review of bird-habitat relationship and
consequence of habitat loss. (J.B. Reid,
D.B.A. Thompson).

Atlas study of central Highland breeding
birds. (J.B. Reid).

Seabirds at sea programme, phase 4. JNCC
(A. Webb JNCC).

Seabird colony register. Maintenance of a
database of counts of seabird colonies.
JNCC/Seabird Group. (M . L. Tasker
JNCC).

Seabird monitoring programme, Annual
monitoring of breeding success at
seabird colonies. JNCC/RSPB/SOTEAG
(M.L. Tasker JNCC).

Survey of breeding seabirds of Sanda and
associated islands. (D. Hunt SNH
Kilmory).

Seabird studies, Hermaness. Contract to Dr.
T. Martin. (P. Harvey SNH Shetland).
Sule Skerry - collation of bird data. (P.

Harvey SNH Shetland).

Slavonian Grebe biology. Contribution to
RSPB study. (N. Buxton SNH
Inverness).

Grey geese - movements and habitat usage
of wintering grey geese in the Moray
Firth area. (N. Buxton SNH Inverness).

Grey geese - monitoring of numbers,
distributions and habitat usage in
Scotland. Wildfowl and Wetlands Trust.
(G.P. Mudge).

Greenland White-fronted Geese on Islay. An
investigation of flock structure, field
usage and roost occupancy. Wildfowl
and Wetlands Trust. (R. MacDonald
SNH Islay).

Research Index 117

Barnacle Geese - an investigation of the
seasonal patterns of distribution and
effectiveness of appropriate grazing and
scaring techniques. (M. Hughes SNH
Dalbeattie).

Eider survey, Sands of Forvie. Aberdeen
University. (P. Harvey SNH Shetland).

Wildfowl and wader counts on the Ythan
Estuary. Aberdeen University. (M.
Ferguson SNH Aberdeen).

Comparative feeding ecology of predatory
birds. Glasgow University. (D.B.A.
Thompson, C. Galbraith JNCC).

Re-introduction of Sea Eagles. Release of
chicks from Norway and monitoring of
the re-introduced population. Joint
project with RSPB. (G.P. Mudge).

National survey of Golden Eagles. To write
up the results of the 1992-93 survey.
Joint project with RSPB and the Scottish
Raptor Study Groups. (D.P. Whitfield).

Golden Eagle - assessment of potential prey
in Dumfries and Galloway, in
conjunction with RSPB and Forestry
Commission. (M. Hughs SNH
Dalbeattie).

Red Kite re-introduction: national and
international co-ordination. JNCC/
RSPB. (G.P. Mudge, C. Galbraith
JNCC).

Effects of predators on Red Grouse and
moorland waders in southern Scotland.
Institute of Terrestrial Ecology. (P.
Reynolds).

Past ecology of Ptarmigan in south Scotland.
(D.P. Whitfield).

Capercaillie - status and habitat needs. Joint
contract with RSPB to the Institute of
Terrestrial Ecology. (G.P. Mudge).

Peatland waders - habitat use, feeding
ecology and movements. Durham
University. (D.P. Whitfield, D.B.A.
Thompson).

The impact of afforestation on moorland
breeding birds, Glen Dye. Institute of
Terrestrial Ecology. (D. Bale SNH
Aberdeen).

Survey of breeding waders on Oronsay. (R.
MacDonald SNH Islay).

118 Research Index

Philopatry, fidelity, mating/social systems
and conservation in waders. (D.P.
Whitfield, D.B.A. Thompson).

Effect of weed mats on the distribution and
feeding ecology of waders at the Ythan
Estuary. Aberdeen University. (M.
Ferguson SNH Aberdeen).

Long term study of Greenshanks in
north-west Scotland. (D.B.A.
Thompson).

Population trends of gulls and other seabirds
on the Isle of May. Institute of
Terrestrial Ecology. (G.P. Mudge).

Co-existence of moorland passerines. A
study of the effects of heather/bracken
patchiness on the inter-relationship of
breeding Meadow Pipits, Skylarks and
Whinchats. University of York. (D.B.A.
Thompson).

A review of Chough data in parts of
south-west Scotland. (I. Langford SNH
Dalbeattie).

Ecology and conservation of Pied
Flycatchers in north-west England.
NERC/SNH Studentship. Leicester
University. (D.B.A. Thompson).

Ecology of Corn Buntings on the Outer
Isles. Leicester University. (D.B.A.
Thompson).

5B 17/2)

Stirling University

Alves, M-A. Behavioural ecology of Sand
Martins. (PhD study).

Bell, M. Wildfowl counts, Breeding wader
surveys, Raptor monitoring.

Bryan, S. Energetics of laying in birds. (PhD
study).

Bryant, D. Energy requirements of wild
birds. Populations and ecology of
estuarine birds (especially Forth).
Hirundine and Dipper breeding ecology.

Calladine, J. Breeding ecology of Larus
gulls on the Isle of May (with ITE
Banchory - PhD study).

Jalil, S.A. Effects of land use changes on
waterfowl populations. A study based on
freshwater lochs in central Scotland.
(PhD study).

Johnstone, 1. Territorial behaviour in Robins
and Dippers. (PhD study).

Hashim, R. Ecology and_ energy
requirements of Great Tits in summer
and winter. (PhD study).

Logie, J. Population ecology of Dippers in
central Scotland. (PhD study).

Wernham, C. Breeding ecology of Puffins.
(with ITE Banchory - PhD study).

|
|
|

Scottish Birds (1993) 17: 119-121

Items of Scottish Interest

Liss)

Most of the following papers and reports on birds in Scotland are available in the Waterston
Library at 21 Regent Terrace for reference, and include all that have come to notice in the period
March-September 1993. The librarian would be glad to learn of.anything that has been missed,
and to receive reprints or copies of papers on any aspect of ornithology or natural history. Bird
reports marked with an asterisk are available from the SOC at the prices quoted, but please add

50p per order for postage and packing.

Scientific papers.

Aebischer, N.J. 1993. Immediate and delayed
effects of a gale in late spring on the breeding
of the Shag. /bis 135: 225-232.

Andrew, D.G. 1993. House Martins taking over
Barn Swallow’s nest. Brit. Birds 86: 184-185.
An occurrence in East Lothian.

Ap Rheinallt, T. 1993. Notes on some
little-known Arran birds. Arran Naturalist 16:
3-10.

Aspinall, S. 1993. Avoiding double-counting in a
Gull colony. Seabird Group Newsletter. 64:
4-5.

Avery, M.I., Burges, D., Dymond, N.J., Mellor,
M. & Ellis, P.M. 1993. The status of Arctic
Terns in Orkney and Shetland in 1989.
Seabird 15: 17-23.

Bailey, R.S., Furness, R.W., Gauld, J.A. &
Kunzlik, P.A. 1991. Recent changes in the
population of the Sandeel Ammodytes
marinus at Shetland in relation to estimates of
seabird predation. /nt. Counc. Explor. Sea
Mar. Sci. Symp..193: 209-216.

Belaoussoff, S. 1993. Northern Gannet and
Common Guillemot nesting in Rockall. Brit.
Birds 86: 321.

Bibby, C.J. & Etheridge, B. 1993. Status of the
Hen Harrier in Scotland in 1988-89. Bird
Study 40: 1-11.

Bourne, W.R.P. 1993. The story of the Great Auk
Pinguinis impennis. Archives of Nat. Hist. 20:
257-278.

Brown, A.F. & Stillman, R.A. 1993. Bird-habitat
associations in the eastern Highlands of
Scotland. J. Appl. Ecol. 20: 31-42.

Cairngorms Working Party. 1992. Common sense
and sustainability- a partnership for the
Cairngorms. 180pp + 7 maps. A report to the
Secretary of State for Scotland.

Carss, D.N. 1993. Cormorants at cage fish farms
in Argyll, western Scotland. Seabird. 15:
60-67.

Craik, J.C.A. 1992. Exceptional mortality of
Auks, Terns, and Kittiwakes in western
Scotland in July 1985. Sula 6: 125-138.

Cranswick, P.A. 1992. Distribution of Pink-footed
and Greylag Geese in south-east Scotland,
especially in relation to disturbance. A report
by Wildfowl and Wetlands Trust, Slimbridge
to NCC Scotland. 1 16pp.

Cranswick, P.A., Kirby, J.S. & Waters, R.J. 1993.
Wildfowl and Wader Counts 1991-92: 109pp.

Donnelly, P.J. 1993. Yellow-browed Bunting in
Orkney. Brit. Birds 86: 411-414.

Dougall, T.W. Breeding passerine communities of
five duneland habitats in northeast Fife. Scot.
Nat. 102: 1990: 53-67. Reprint recently
received.

Dowie, M.1. 1993. Blackpoll Warbler in Shetland.
Brit. Birds 86: 206-209. An occurrence on
Fair Isle.

Forrest, G.J. 1993. Wintering Chiffchaff feeding
on peanuts. Brit. Birds 86: 186187.

Fox, A.D. & Meek, E.R. 1993. History of the
Northern Pintail breeding in Britain and
Ireland. Brit. Birds 86: 151-162. The main
Scottish sites are in Orkney and Tiree.

Furness, R.W. 1992. Implications of changes in
net mesh size, fishing effort and minimum
landing size regulations in the North Sea for
seabird populations. Joint Nature Conserv.
Comm. Report No 133: 75pp.

Galbraith, H., Murray, S., Duncan, K., Smith, R.,
Whitfield, D.P. & Thompson D.B.A. 1993.
Diet and habitat use of the Dotterel Charadrius
morinellus in Scotland. [bis 135: 148-155.

Gilburn, A.S. & Kirby, J.S. (1992). Regional
patterns of wildfowl distribution on British
wetlands. Part |. Scotland and northern
England. Joint Nature Conserv. Counc.
Report No 138: 57pp. A report from the
Wildfowl and Wetlands Trust to the JNCC,
Peterborough.

120 W.G. Harper

Greenstreet, S.P.R., Morgan, R.1:G., Barnett, S. &
Redhead, I. 1993. Variation in numbers of
Shags Phalacrocorax aristotelis and
Common Seals Phoca vitulina near the mouth
of an Atlantic salmon river at the time of the
smolt run. J. Anim. Ecol. 62: 565-576. A
study in south Kintyre.

Halley, D.J. 1993. Population changes and
territorial distribution of Common Buzzards
in the Central Highlands, Scotland. Bird
Study 40: 24-30.

Halley, D.J. & Harris, M.P. 1993. Intercolony
movement and behaviour of immature
Guillemots Uria aalge. Ibis 135: 264-270.

Hamer, K.C. & Furness, R.W. 1993. Parental
investment and brood defence by male and
female Great Skuas: the influence of food
supply, laying date, body size and body
condition. J. Zool., Lond. 230: 7-18.

Hamer, K.C., Monaghan, P., Uttley, J.D., Walton,
P. & Burns, M.D. 1993. The influence of food
supply on the breeding ecology of Kittiwakes
Rissa tridactyla in Shetland. [bis 135: 255-263.

Harris, M.P. & Calladine, J. 1993. A check on the
efficiency of finding colour-ringed Kittiwakes.
Ringing & Migration 14:113-116.

Harris, M.P. & Wanless, S. 1993. The diet of
Shags Phalacrocorax aristotelis during the
chick-rearing period assessed by three
methods. Bird Study 40: 411414.

Harrop, H. 1993. Massed Skua passage off
Shetland. Seabird Group Newsl. 64: 8-9.

Heubeck, M. 1993. After the BRAER. Seabird
Group Newsl. 65: 3.

Heubeck, M., Richardson, M.G., Lyster, ILH.J. &
McGowan R.V. 1993. Post-mortem
examination of Great Northern Divers killed
by oil pollution in Shetland in 1979. Seabird
115353259:

Jardine, D.C. 1992. Twites eating seaweed. British
Birds 85: 619. Reported from Oronsay, Inner
Hebrides.

Johnstone, I.G. 1992. Home range utilization and
roost selection by non-breeding territorial
European Robins. pp. 495-509 of Wildlife
Telemetry: Remote monitoring and tracking
of animals. J.G. Pride & S.M. Swift (eds). A
study by the Avian Ecology Group, Univ.
Stirling.

Knox, A.G. 1993. Daurian Redstart in Scotland:
captive origin and the British List. Brit. Birds
86: 359-366.

Knox, A.G. & Parkin, D. 1993. Taxonomic status
of the Red Grouse. Brit. Birds 86:92.

SB 17 (2)

McLusky, D.S., Bryant, D.M. & Elliott, M. 1992.
The impact of land-claim on macrobenthos,
fish and shorebirds on the Forth Estuary,
Eastern Scotland. Aquat. Conserv. Marine
Freshwater Ecosystems 2: 211-222.

Meek, E.R., Ribbands, J.B., Christer, W.G., Davy,
P.R. & Higginson, I. 1993. The effects of
aero-generators on moorland bird populations
in the Orkney Islands, Scotland. Bird Study
40: 140-143.

Middleton, D.A.J., Nisbet, R.M. & Kerr A.J.
1993. A mathematical model of the effect of
shooting Barnacle Geese wintering on Islay.
J. Appl. Ecol. 30: 1-12.

Mudge, G.P. & Talbot, T.R. 1993. The breeding
biology and causes of nest failure of Scottish
Black-throated Divers Gavia arctica. Ibis
135: 113-120.

Murray, R.D. 1993. The 1991 Goosander counts
in the Borders Region. Borders Bird Report
133,65-70F

Ormerod, S.J., Rundle, S.D., Lloyd, E.C. &
Douglas, A.A. 1993. The influence of riparian
management on the habitat structure and
macroinvertebrate communities of upland
streams draining plantation forests. J. Appl.
Ecol. 30: 13-24. A survey of 66 mainly
upland streams in Scotland and Wales.

Pennington, M.G. 1993. Apparent egg-dumping
by Common Gulls. Brit. Birds 86:182. An
occurrence in Orkney.

Riddiford, N. 1993. Recent changes in Fair Isle
seabird populations. Seabird 15: 60-67.

Scott, G.W. 1993. Sexing members of a Scottish
Blue Tit Parus caeruleus population in the
hand during the winter months. Ringing &
Migration 14: 124-128.

Sears, J. & Avery, M.1. 1993. Population and
productivity trends of Little Terns in Britain
1969-89. Seabird 15: 3-16.

Sim, I., Suddaby, D. & Avery, M. 1933. Body
weights of incubating Arctic Terns in Orkney
and Shetland in 1990 and 1991. Seabird 15:
24-29.

Smith, R.W.J. 1993. Forth island bird counts
1992. Edin. NHS J. for 1992: 26-27.

Stowe, T.J., Newton, A.V., Green, R.E. & Mayes,
E. 1993. The decline of the Corncrake in
Britain and Ireland in relation to habitat. J.
Appl. Ecol. 30: 53-62.

Tasker, M. (ed) 1993. Ferrets in a seabird colony.
Seabird Group Newsl. 64: 8.

Tasker, M. & Heubeck, M. 1993. Shetland oil spill:
impact on birds. Seabird Group Newsl. 64: 2.

1993

Taylor, I.R. 1993. Age and sex determination in
Barn Owls Tyto alba alba. Ringing &
Migration 14: 94-102.

Tomlinson, D. 1993. Oystercatcher chick
probably killed by rival adult. Brit. Birds 86:
223-224. An occurrence in Aberdeenshire.

Vaughan, H. 1993. Predatory behaviour of
Kittiwakes. Brit. Birds 86: 182-185. An
occurrence in East Lothian.

Vickery, J. 1992. The reproductive success of the
Dipper in relation to the acidity of streams in
southwest Scotland. Freshwater Biol. 28:
195-205.

Wialshipabavies Sims Iec& Heubeck, M.1993.
Seabird numbers and breeding success in
Britain and Ireland, 1992. UK Nature
Conservation No. 10: 87pp. Published by the
Joint Nature Conservation Committee,
Peterborough.

Wanless, S., Corfield, T., Harris, M.P., Buckland,
S.T. & Morris, J.A. 1993. Diving behaviour
of the Shag Phalacrocorax aristotelis in
relation to water depth and prey size. J. Zool.,
Lond. 231: 11-25.

Wanless, S. & Harris, M.P. 1992. At sea activity
budgets of a pursuit-diving seabird monitored
by radiotelemetry. Pp. 591-598 of Wildlife
Telemetry: Remote monitoring and tracking
of animals. A study of the Shag in Scotland.

Wanless, S., Monaghan, P., Uttley, J.D., Walton,
P. & Morris, J.A. 1922. A radiotracking study
of Kittiwakes foraging under suboptimal
conditions. Pp. 581-590 of Wildlife
Telemetry: Remote monitoring and tracking
of animals. J.G. Pride & S.M. Swift (eds).

Watson, A. 1993. Dotterels evading Peregrine
Falcon by settling near human being. Brit.
Birds 86: 131.

Walltamsravie é Slater, P-J-B.' 1993. Does
Chaffinch song vary with the habitat in which
it is sung? Ibis 135: 202-208. A study in
Scotland.

Zonfrillo, B. 1993. Low-flying aircraft and
seabirds on Ailsa Craig. Seabird Group
Newsl. 64: 7-8.

Bird Reports.

Arran Birds: Report for 1992. T. ap Rheinallt (ed)
for Isle of Arran NHS, 1993. 28pp.

Items of Scottish Interest 121

Ayrshire Bird Report for 1992. Angus Hogg (ed)
1993. 56pp. *£2.75. Includes a 40- page
systematic list and four short articles.

Borders Bird Report No 13 for 1991. R.D. Murray
(ed) 998" 223.50:

Canna Report No 15 for 1991 and 1992. R.L.
Swann (ed) 1993. 19pp. Another in the long
series of long-term ornithological studies on
Canna.

Clyde Bird Report for 1990. lain P. Gibson (ed)
LP, TSO) Ds 223-29).

Fair Isle Bird Observatory Report for 1992. Paul
Harvey & David Parkin (eds) 1993. 84pp *.
Includes a 26 page systematic list and short
articles on many aspects of life and natural
history on the island.

Fife Bird Report for 1992. D.E. Dickson (ed)
1993. *£3.50. Includes a 46 page systematic
list, reports on a Mute Swan census, and on
work on the Fife Bird Atlas. Also three rarity
reports.

Isle of May Bird Observatory Report for 1992. Tan
Darling (ed) 1993 / 56pp. *£3.00. Includes
“Memories of Isle of May characters” by
J.H.B. Munro.

Moray & Nairn Bird Report for 1992. Martin
Cook (ed) 1993. 64pp. *£2.75. Mainly a 47
page systematic list, but with short notes on
Pomarine Skuas and Mute Swans.

Orkney Bird Report for 1992. C. Booth, M.
Cuthbert & E. Meek (eds) 1993. 70pp.
*£3.00. Includes a systematic list, and short
reports on the Skua populations of Orkney, a
rarity report, a North Ronaldsay Bird
Observatory Report, and cetacean records.

Perthshire (Central/Southwest) Peregrines and
Ravens in 1992. P. Stirling-Aird 1993. 3pp.
An unpublished report in a long-running
series.

Scottish Bird Report for 199]. R.D. Murray (ed)
1993. 76pp. *£5.00

Shetland Bird Report for 1992. K. Osborn (ed)
1993. 120pp. This is an exceptional bird
report from this fascinating part of Scotland.
It has 8 pages of colour plates of rarities, 38
pages of special reports, and a 65-page
systematic list.

St. Abbs Head NNR Seabird Report for 1992. K.1.
Rideout, R.R. Elliott & W. Hepburn 1993.
18pp. An unpublished report in a
long-running series.

William G. Harper.

122 Scottish Birds (1993) 17: 122-123

European Journals in the
Waterston Library

The following selection of articles appeared
in European journals received in the
Waterston Library between April and
August 1993, thus following on the list
published in Vol. 17 No. 1. Articles are
arranged in species order; square brackets
indicate that the article is in the original
language, other articles being in English.
The reference, abbreviated for reasons of
space, indicates merely the journal, its
number and its year of publication. Journals
quoted are as follows:

Netherlands: Ardea, Limosa, Dutch Birding.

France: L’ Oiseau

Switzerland: Der Ornithologische Beobachter,
Nos Oiseaux, Ornis

Belgium: Aves, Mergus, Le Gerfaut

Germany: _Limicola, Vogelwelt, Vogelwarte,
Okologie der Vogel, Seevégel,

Corax, Ornithologischer
Anzeiger
Italy: Rivista Italiana di Ornitologia
Spain: Butlleti del Grup Catala

d’ Anellament (in Catalan)
Iceland: Bliki

Norway: Cinclus, Var Fuglefauna

Sweden: Var Fagelvarld

Finland: Suomen Riista, Linnut
(formerly Lintumies), Ornis
Fennica

General

Vaisanen, R.A. & Hildén, O. [Bird feeding
stations have led to increase in
seed-eating birds in Finland]. Linnut
3/93.

GaBmann, H. & Gliick, E. [Nest-site
selection and breeding success of
hedgerow birds]. Vogelwelt 4/93.

Divers to Ducks

Anker-Nilssen, T. & Anker-Nilssen, P.G.
Breeding of Leach’s Petrel in the Rgst
archipelago, N Norway. Cinclus 2/93.

SB (17) 2

Schneider, U. [Second pair of Gannets
attempt breeding on Heligoland].
Seevdgel 2193.

Brugiére, D. & Duval, J. [Wintering of
Cormorant in the Allier and Central
Loire valleys]. Nos Oiseaux 431/93.

Jakobsen, J. [Premature autumn migration of
wildfowl caused by shooting pressure 7].
Var Fuglefauna supplement 1/93.

Mooi, J.H. Development and management
of wintering geese in the Lower Rhine
area of N Rhine-Westphalia. Vogelwarte
1/93.

Vangeluwe, D. & Stassin, P. [Wintering of
Red-breasted Goose in the Western
Dobruja and a review of the status of the
species in winter]. Le Gerfaut 1-2/91.

Birds of Prey

Helbig, J. et al. [High density of wintering
Hen Harriers and Buzzards in area of
Dummer Lake]. Vogelwarte 3/92.
Seys, J. [Hen Harrier roost counts in winters
of 1990-1 and 1991-2]. Mergus 4/92.
Sachteleben, J. [Hunting strategy and use of
habitat by Buzzard and Kestrel: the
avoidance of competition]. Orn.
Anzeiger 1/93.

Sommani, E. [Variations in hunting
technique by Peregrines]. Riv. It. di Orn.
1-2/92.

Grouse to Cranes

Milonoff, M. er al. [Large size a risk factor
for Capercaillie chicks]. Suomen Riista
39/93.

van den Berg, A.B. et al. [Sandhill Crane at
Paesens-Moddergat Sep 91] (i.e. the
Shetland bird). Dutch Birding 1/93.

Waders to Auks

Meltofte, H. [Wader migration through
Denmark]. (special 180pp issue covering
all migratory waders in Denmark).
Dansk Orn. For. Tidsskr. 1-2/93.

993

Klemp, S. [Population trends of Lapwing in
Schleswig-Holstein]. Corax 2/93.

Pulliainen, E. & Saari, L. [Breeding biology
of Golden Plover in E. Finnish Lapland].
Orn. Fenn 1/93.

Jacob, J-P. & Fouarge, J-P. [Development of
population and habitats of Little Ringed
Plover in Wallonia and Brussels region].
Aves 3-4/92.

Schmidt, C. & Barthel, P.H. [Plumages of
Little Stint and their variations].
Limicola 3/93.

Peterson, A. [Kittiwake colonies on
Snefellsnes peninsula]. Bliki 13/93.

Mlody, B. & Becker, P.H. [The development
of body mass and mortality in Common
Tern chicks under unfavourable
environmental conditions]. Vogelwarte
219%"

Noordhuis, R. et al. [Food shortage for
Common Terns at Zeewolde in 19917].
Limosa 2/93.

Lyngs, P. Colony interchange in Baltic
Guillemots. Dansk Orn. For. Tidsskr.
3-4/93.

Pigeons to Woodpeckers

Schlapfer, A. [The immigrant from the East:
the Collared Dove]. Ornis 4/93.

Chantler, P. Identification of W Palearctic
Swift. Dutch Birding 3/93*.

Laine, T. [Hybridisation of Great Spotted
and White-backed Woodpeckers].
Linnut 2/93.

NiissonssS-G- ef al. [Lesser Spotted
Woodpecker: why it is disappearing
from Sweden?]. Var Fagelvdrld 3/93.

Furopean journals 123

Passerines

Serra, L. Ageing criteria and moult
conditions in Yellow Wagtail during
spring migration. Riv. It. di Orn. 3-4/91.

Weber, S & Hegelbach, J. [Differences in
use of habitat by breeding Grey and
White Wagtails]. Orn. Beob. 1/93.

Dubois, P.J. & Yésou, P. [Review of the
status of the British race of Pied Wagtail
in Western France]. L’Oiseau 1/93.

Paulsen, B.E. [Breeding distribution and
biology of the British race of Yellow
Wagtail in SW Norway]. Cinclus 2/93.

Jaérvinen, A. Redstart and Pied Flycatcher
nesting in same box. Orn. Fenn. 2/93.

Busche, J. [Migration of Ring Ouzel in
Schleswig-Holstein - a contribution to
loop migration theory]. Vogelwarte 1/93.

Bradshaw, C. & Dowdall, J. Identification of
Catharus thrushes. Dutch Birding 2/93.

Slagsvold, T. Sex recognition and breast-
stripe size in Great Tits: Ardea 1/93.

Kooiker, G. [Nest-sites of Magpies and
Rooks on electricity pylons]. Ok. der
Vog. 2/92.

Motis, A. Mixed breeding pairs of European
and Spotless Starling in NE Spain. But.
del Grup Catala 9/92.

Gatter, W. [Exploratory behaviour,
migration and the evolution of migratory
habits in the Common Crossbill].
Vogelwelt 2/93.

Biber, O. [Availability and use of hedges and
shrubs as nest sites by Yellowhammers
in an intensively farmed area of
Switzerland]. Orn. Beob. 2/93.

* copies of this special issue available for NLG 10
from Dutch Birding Association, Postbus 75611,
1070 AP Amsterdam.

124 ‘Seottish BirdSidg93)) 17: 124

Advice to Contributors

Authors should bear in mind that only a small
proportion of the Scottish Birds readership is
science-trained, and should aim to present their
material concisely, interestingly and clearly.
Unfamiliar technical terms and symbols should be
avoided wherever possible and if deemed
essential should be explained. Supporting
Statistics should be kept to a minimum. All papers
and Short Notes are accepted on the
understanding that they have not been offered for
publication elsewhere and that they will be
subject to editing. Papers will be acknowledged
on receipt and will be reviewed by at least two
members of the editorial panel and in some cases
also by an independent referee before being
accepted. They will normally be published in
order of acceptance of fully revised manuscripts.
The editors will be happy to advise authors on the
preparation of papers.

Reference should be made to recent issues of
Scottish Birds for guidance on style of
presentation, use of capitals, form of references,
etc. Papers should be typed on one side of the
paper only, double-spaced and with wide margins;
two copies are required and the author should also
retain one. Headings should NOT be underlined,

DB 17 (2)

nor typed entirely in capitals. Scientific names in
italics should follow the first text reference to
each species and should follow Voous’ List of
Recent Holarctic Bird Species’ as given in the The
British Birds’ List of Birds of fhe Western
Palearctic (1984). Only single quotation marks
should be used throughout, and numbers one to
ten should be written out whereas 11 and above
should be written as numerals. Dates should be
Wintte nee eeeree on S/AugistlOO ese as. but
on the 5th (if the name of the month does not
follow). Please note that papers shorter than 700
words will be treated as Short Notes where all
references should be incorporated into the text,
and not listed at the end, as in full articles.

Tables, maps and diagrams should be
designed to fit either a single column or the full
page width. Tables should be self-explanatory and
headings should be kept as simple as possible,
with footnotes used to provide extra details where
necessary. Each table should be on a separate
sheet. Maps and diagrams should be in Indian ink
and be camera ready, but drawn so as to permit
reduction to half their original size.

For details of writing Research Progress
Reports, please contact the editor in advance.

NEOTROPICAL
BIRD CLUB

Neotropical bird club launched

A club has been launched to promote the study and conservation of
the birds of the Neotropics (South America, Central America and the
Caribbean). It is currently seeking founder members to help reach
the launch budget of £2000, which is required to get the club running
and to publish the two first issues of its intended journal ‘Continga’.
Founder members will be asked to pay a minimum of £25, and will
be formally acknowledged in the first issue of ‘Continga’, planned for
January 1994. ‘Continga’ will provide a colourful and much needed
forum for exchange of information on the avifauna of this extremely
rich and diverse area, and will contain papers and features on the
birds and their conservation as well as news of recent observations
and discoveries (at present, new species are still being discovered
at the rate of more than two a year). It is hoped that in due course
the club will be able to provide direct funding and support for
practical conservation programmes.

For further details and membership forms,
please contact:

Rob Williams,

Publicity Officer,

Neotropical Bird Club,

c/o The Lodge,

Sandy,

Bedfordshire SG19 2DL

Scottish Birds

Volume 17 Part 2 December 1993

Contents

Moult flock surveys indicate a continued decline in the
Shetland Eider population, 1984-92. M. Heubeck

Population fluctuations and mortality of Mute Swans on
an Orkney loch system in relation to a Canadian Pondweed
growth cycle. E.R. Meek

The Scottish Mute Swan census 1990. A.W. & L.M. Brown

Short Notes
Unusual behaviour of Black-necked Grebes. A.C. Ramage
Eider Ducks eating flatfish. BM. & E.M. Hobson

Hen Harriers systematically testing flocks of Ring-necked
Pheasants. R.C. Dickson

Buzzards copulating just before roosting. R.C. Dickson

Comment and Reply

What is the scale of seabird movement across central Scotland?
Gol, lenby

Reply to Henty. R.D. Murray
Research Index.
Items of Scottish Interest. W.G. Harper
European Journals in the Waterston Library. M. Murphy

Advice to Contributors.

Published by the Scottish Ornithologists’ Club,
21 Regent Terrace, Edinburgh EH7 5BT. © 1992

Printed by Milne, Tannahill and Methven Ltd., Perth

.
| ma a GU)
| iW)

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Scottish Birds

The Journal of the Scottish Ornithologists’ Club

Editor: Anne-Marie Smout

Assisted by: Professor D. Jenkins, Dr J.B. Nelson and Professor P.J.B. Slater
Business Editor: The Secretary, SOC, 21 Regent Terrace, Edinburgh EH7 5BT
(tel. 031-556 6042).

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Scottish Birds (1994) 17: 125-126

Research Progress Report

125

I.J. PATTERSON & J.G. OLLASON

The density and species diversity of songbird populations in northern upland

spruce plantations

The Forestry Authority (FA) has a statutory
duty to promote a reasonable balance
between timber production and nature
conservation. The FA financed the research
described here because of its desire to
diversify upland conifer forests as wildlife
habitats, and to safeguard rare and sensitive
species.

There have been several studies of bird
populations in conifer forests in Britain, but
most were based on small samples in
restricted areas with few in the north. Most
studies have also concentrated on first
generation crops in extensive new
afforestation. There was thus a need for
study of second generation crops and of
mosaics of different aged patches of forest as
bird habitat because these were relatively
neglected. There was also a need for study
of winter bird populations, which may be
important in determining subsequent breeding
numbers and which may also have an
important influence on the abundance of
invertebrate pests of conifers.

The aim of this study was to measure the bird
density andspecies diversity in uplandspruce
forests in relation to forest habitat variables,
and to develop a computer model to predict
howthe bird populations were likely to change
under different forest management regimes.

In each of two study areas, at Cowal, Argyll
and Kielder, Northumberland, 88 study plots
were selected randomly from 24 combinations
of tree age (0-8, 9-15, 16-25 and over 25
years), plot size (1-2, 2.1-5 and over5ha) and
altitude (above or below 250m). Both pure
sitka spruce and mixedconifers were included,
as were first and second rotation crops.

Point counts, at up to five per plot, were used
to estimate bird populations, and in larger
plots additional edge points allowed the
comparison of plot centres and edges. At
each point, afive-minute settling-down period
was followed by a five-minute count period.
Birds were detected by both sight and sound,
up to a limit of 60m. Counts were made from
1990 - 1992 in winter (mid-November to mid-
March), early spring (mid-April to mid-May)
and late spring (mid-May to mid-June). Each
plot was visited once in each period. The
counting method was foundto give consistent
results both within and between days at the
same count points.

There was strong and significant variation in
bird numbers and diversity with tree age, both
being highest in older trees in winter and in 9-
25 year oldtreesinspring. Allofthe common
species (Chaffinch Fringilla coelebs, Coal Tit
Parus ater, Crossbill Loxia curvirostra,

126 Patterson & Ollason

Dunnock Prunella modularis, Goldcrest
Regulus reguius, Meadow Pipit Anthus
pratensis, Robin Erithacus rubecula, Redpoll
Acanthis flammea, Siskin Carduelis spinus,
Song Thrush Turdus philomelos, Tree Pipit
Anthus trivialis, Wren Troglodytes troglodytes
and Willow Warbler Phylloscopus trochilus)
showed significant variation in their
abundance between tree age categories, with
all except Meadow Pipit occurring at their
lowest density in the youngest trees and at
their highest densities in 9-25 year old trees.

The number of individual birds detected was
consistently higher at the edges than in the
centres of the same plots, particularly in the
first ten metres from the edge, but the type of
habitat outside the plot had little effect on this.
There was little detectable effect of plot size,
altitude, admixture of other conifer species or
planting generation on either bird numbers or
species diversity.

Spring numbers of most of those common
species, which were resident also in winter,
were significantly correlated with their winter
numbers, but the correlations were weak
(particularly in 1992) and had little predictive
value.

SB 17 (3)

The two study areas and the two years were
very similar in the way in which bird numbers
and diversity varied with forest characteristics,
suggesting that the conclusions may be of
wide relevance. Bird numbers tended to be
higher in 1991 than in 1992, due mainly to
there being more Crossbills and Siskins in
1991, when there was a very high cone crop.

A computer model has been developed to
predict how bird populations would be
expected to change as such forests are
managed to change the size and age
distributions of the plots of trees.

The study clearly identified tree age and
closeness to the forest edge as the two main
factors affecting the number and diversity of
songbirds in upland spruce plantations. This
suggests that the greatest number and
diversity of songbirds could be encouraged
by creating mosaics of small patches (i.e. with
a high ratio of edge habitat), with a mixture of
tree ages, including alarge proportion of 9-25
year old trees.

|. J. Patterson and J.G. Ollason
Zoology Department, University of

Aberdeen. . |

Scottish Birds (1994) 17: 127-131

Research Progress Report

127

R. MOSS

Research on Capercaillie and their habitat

Capercaillie Tetrao urogallus are now scarce
in Scotland. The number shot for sport in
Scotland declined roughly fourfold in the late
1970s and fell stillfurther inthe 1980s (Baines,
Goddard & Hudson 1991). Bagrecords area
fair reflection of the number of birds on the
ground where shooting is done (Moss, Weir &
Jones 1979) and so this was a reliable
indication of a widespread decline. At one
estate on Speyside, where birds were counted
each year from 1975-85, densities fell from
about 20 birds km@ in winter 1979-80 to 8 km
in 1984-85 (Moss & Weir 1987). This was
particularly worrying as the forests of Speyside
are one of the Capercaillie’s main Highland
strongholds.

Concern about falling Capercaillie numbers
has given rise to a big increase in the amount
of research onthem. This report summarises
what is being done.

Numbers and breeding success

The present distribution of Capercaillie in
Scotland is being mapped and numbers
estimated in a three-year project, due to end
in 1994. This is being conducted, financed or
supported jointly by the Institute of Terrestrial
Ecology, the Forestry Commission, the Game
Conservancy, the Royal Society for the
Protection of Birds, the Scottish Landowners
Federation, Scottish Natural Heritage andthe
Scottish Office. The project is alsocomparing

the breeding performance of Capercaillie ina
number of different forests, where factors
such as forest type and the numbers of
gamekeepers vary. The intention of this
survey !s to relate habitat and the level of
predator control to the success of hens in
rearing chicks.

Predator control is an emotive issue. Despite
anecdotal evidence suggesting that active
control of predators by gamekeepers is
associated with better breeding performance
by Capercaillie, better information is required
before conservation bodies and landowners
can reach rational conclusions on the topic.
As well as participating in the above survey,
the RSPB has begun an experimental
programme at their Abernethy reserve to
determine the importance of predation by
different predators on Capercaillie
populations, and the effects on these
populations of predator control.

Throughout the study (1991-93), breeding
has been poor sothe outlook has not improved.
| have been monitoring breeding performance
and numbers since 1975 at one estate in
Deeside, and there the last year of good
breeding was 1989.

Habitat and diet

Capercaillie are usually thought of as birds of

7128 #A.Moss

old forest where they rely largely on pine
needles for their winter diet. However, Rolstad
& Wegge (1987) concluded that old forest
seems favourable ‘simply because it offers
the necessary physical structure and key
food elements’ and not because it is old. A
comparison of the winter diets of different
populations of Capercaillie throughout their
range in the western Palaearctic with the
proportion of different native trees species in
the habitat shows that they prefer eating pine
(such as Scots or arolla pine) to fir (such as
white fir), and firto Norway spruce. However,
they subsist on fir in the absence of pine, and
spruce in the absence of fir and pine.

The inference that the structure of a forest is
more important than its age or tree species
composition has important implications.
Young forests of, for example, sitka spruce
might support Capercaillie if they are of the
right structure, if sitka spruce is an adequate
winter food, and if the forest floor supports
enough blaeberry or other ground vegetation
to provide the chicks with food and cover.
Research by ITE, fundedin part by the Forestry
Commission, the Scottish ForestryTrust,
Eagle Star and Horsens Folkeblad (a Danish
company with forestry interests in Scotland)
is looking atthe question of whether plantation
forests can be managed to support
Capercaillie. Results so far confirm that
Capercaillie do live in some sitka-dominated
forests where in winter they eat sitka spruce
as readily as Scots pine. Whether such
forests can also provide good brood habitat is
stillan open question. Management guidelines
for Capercaillie will be summarised in a
Forestry Commission Bulletin, written by
Robert Moss and Nick Picozzi, due to be
published in 1994.

The concept of forest structure has hitherto
been fairly vague and embodied in terms

SB 17 (3)

such as pre-thicket, thicket, pole stage, high-
canopy (mature) and semi-natural forest.
These terms bring an image to the mind of
somebody who has been shown examples
on the ground, but are not quantitative. To
assess the association between forest
structure and Capercaillie numbers more
rigorously, ITE developed a new measure of
forest structure (Picozzi, Catt & Moss 1992).
These authors confirmed an association
between Capercaillie numbers and oldforest,
and suggested that this is largely because the
open structure of such forests allows enough
light to reach the ground to support heather
and especially blaeberry, whichis an important
chick food. The RSPB are using this measure
of forest structure in a detailed study of habitat
preferences attheir Abernethy reserve (R.W.
Summers & R. Proctor, in progress).

Blaeberry leaves and berries are important
chickfoods, and blaeberry also supports many
ofthe arthropods upon which the chicks feed
in their first weeks. Most plantations which
support good populations of Capercaillie also
have much blaeberry. Work in Norway
(Kastdalen & Wegge 1985) indicated that in
their first month about half the food of chicks

(by volume) comprised arthropods and about —

half vegetation. The vegetation in their study
was mainly blaeberry leaves, and many ofthe
arthropods caterpillars of geometrid moths
such as the winter moth (they also eat spiders
andharvestmen). The Game Conservancy is
conducting extensive sampling of larval
abundance in relation to such factors as
longitude and the level of grazing by large
herbivores, andthe RSPB is measuring larval
abundance in relation to Capercaillie breeding
performance on the Abernethy reserve, as is
ITE at one of their intensive study areas in
Deeside.

There is, however, very little information on

1994

Research Progress Report 129

what Scottish Capercaillie chicks actually eat.
A particularly important question is whether
other foods can substitute for blaeberry and
geometrid larvae and, ifso, what. ITE andthe
Forestry Commission began to study this
topic in 1993. The answer will be relevant to
future forest management. If alternative foods,
such as low-growing willow and birch scrub,
for example, can support chicks, then
encouraging these plants might become a
valuable management procedure.

Fences

Aradio-tracking study by ITE confirmed earlier
work (Moss 1987) showing that collisions
with forest fences are an important cause of
Capercaillie mortality. Concerned about this,
the RSPB began monitoring fence lines in
Abernethy, verified that woodland grouse
frequently hit fences (Catt et a/. 1994), and
then removed most of their deer fences. This
work also suggested that fence strikes
occurred more frequently along some
stretches of fence than along others. The
characteristics of such ‘hot spots’ are currently
being investigated by continued co-operative
work between the Forestry Commission, the
Game Conservancy, ITE, RSPB and SNH.
This has confirmed that deaths of grouse and
Capercaillie from hitting fences are
widespread as well as frequentinsome places.

In one forest, such deaths continued even
after the hot spots along a deer fence were
marked with abroad band of brightly coloured
plastic. It is possible that the strike rate was
reduced by the plastic, but the data were not
sufficient to test this possibility. In principle,
steps should nowbe taken to do experimental
work on howto reduce bird strikes by re-siting
and marking fences. In practice, the scale
upon which this work would need to be done
may make a rigorous scientific study

expensive. Sensible measures meantime
include removing fences as soon as they
have served their purpose; identifying hot
spots and re-siting fences along less
dangerous lines; and, if re-siting is
impracticable, marking hot spots to make
them obvious to the birds.

Scale

Capercaillie are big birds with large home
ranges and can disperse long distances. In
Scotland (Picozzi et al. 1992), as elsewhere
(Wegge & Rolstad 1986), leks are spaced at
approximately 2 km intervals in continuous
forest, indicating that a lekking population of
cocks occupies an area of 3-4 km?. But
current radio-tracking studies by ITE with the
Forestry Commission are showing that adult
cocks may visit more than one lek and one
hen visited at least five different leks in one
spring. ITE with RSPB are studying natal
dispersal in Capercaillie by means of radio-
tracking. Samples so far are fairly small but
3 of 22 hens tagged as poults in Deeside have
moved more than 20 km before settling. One
hen tagged as a poult at Abernethy was later
recovered near Braemar, presumably having
flown over the Cairngorms.

All this means that forest management for
Capercaillie needs to be strategically planned
on a large scale, such as entire catchments,
rather than on a local forest or estate level. A
reasonable guess is that it would take a
minimum of 1000 ha of good habitat (3-4 leks)
to support a population of breeding
Capercaillie. Good habitat need not be
continuous but must provide for both adults
and chicks.

Population ecology

It may be presumed that chick production is

730 Rt. Moss

the key to Capercaillie numbers and that a
reduction in breeding success is the root
cause of the present low numbers. In turn,
one may speculate that wetter summers,
heavier predation and overgrazing of forest
vegetation by deer have contributed to this
decline. However, the evidence from two
continuing long-term|TE population studies
which started in 1975 is not obviously
consistent with these suggestions.

At an estate in Deeside, there was a big
decline in shooting bags between 1970 and
1974. Shooting ended in 1982 but counts in
summer and autumn showed no long-term
trend in density of hens between 1975 and
1993. For most of this periodchick production
generally exceeded the number needed to
replace adult mortality and the population
seemed to have been regulated by density-
dependent dispersal of youngbirds (Moss &
Oswald 1985). This meant that the more
birds there were present, the bigger the
proportion that leftthe area: so the density of
breeding hens remained at about 5.5 km2.
More recently, breeding has been poor but
adult numbers have still not declined further.

Shooting bags at an estate in Speyside also
declined in the early 1970s, and a further
decline in numbers there in the early 1980s
was associated with a decrease in the
recruitment of young birds to the population.
However, this failure of recruitment was
apparently not due to an absolute shortage
of young birds. Breeding remained good
during the decline andthe evidence suggests
that there was net dispersal of young birds
away from this Speyside population (Moss
& Weir 1987), as at the Deeside estate.

The observations are consistent with acore/
sink model in which the best ‘core’ habitats
produce an excess of young which move to

SB 17 (3)

the poorer ‘sink’ habitats where breeding is
poor and mortality high. When conditions
worsen in the sink habitats, density there may
drop and more birds may disperse out of the
core habitats into sink habitats, resulting in a
decline in both core and sink habitats.

The model is speculative but implies an
important danger. It is correct, the still wide
distribution of the Capercaillie may give a
false idea of its security as the entire Scottish
population might depend upon a relatively
small area of core habitat. It the core habitat
is destroyed or allowed to deteriorate, then
the birds in the sink habitats might go too.
Thus, a sensible conservation strategy for
Capercaillie would be to safeguard their core
habitats - pinewoods with blaeberry - while
improving the quality of sink habitats, such as
other coniferous plantations.

Acknowledgements

| thank |.P. Bainbridge, D. Baines, A. Hinde,
G.P. Mudge, S.J. Petty, N. Picozzi and R.W.
Summers for helpful comments.

References

Baines, D., Goddard, J. & Hudson, P.J. (1990).
Capercaillie in Scotland. Game Conservancy
Annual Review of 1990, pp. 153-156. The
Game Conservancy, Fordingbridge.

Catt, D.C., Dugan, D., Green, R.E., Moncrieff,
R.W., Moss, R., Picozzi, N., Summers, R.W.,
& Tyler, G.A. (1994). Collisions against fences
by woodland grouse in Scotland. Forestry,
00: 000-000.

Kastdalen, L. & Wegge, P. (1985). Animal
food in Capercaillie and Black Grouse chicks
in south east Norway - a preliminary report.
Proc. int. Symp. Grouse 3: 499-513.

Moss R. (1987). Demography of Capercaillie

1994

Tetrao urogallus in north-east Scotland J/.
Age and sex distribution. Ornis Scand. 18:
135-140.

Moss, R. & Oswald, J. (1985). Population
dynamics of Capercaillie in a North-east
Scottish glen. Ornis Scand. 16: 229-238.
Moss, R & Weir, D.N. (1987). Demography of
Capercaillie Tetrao urogallus in north-east
Scotland ///. Production and recruitment of
young. Ornis Scand. 18: 141-145.

Moss, R., Weir, D. & Jones, A.M. (1979).
Capercaillie management in Scotland. Proc.
int. Symp. Grouse 1: 140-155.

Research Progress Report igi

Picozzi, N., Catt, D.C. & Moss, R. (1992).
Evaluation of Capercaillie habitat. J. app/
Ecol., 29: 751-762.

Rolstad, J. & Wegge, P. (1987). Capercaillie
habitat: a criticalassessment ofthe role of old
forest. Proc. int. Symp. Grouse 4: 235-250.
Wegge, P. & Rolstad, J. (1986). Size and
Spacing of Capercaillie leks in relation to
social behaviour and habitat. Behav. Ecol.
Sociob. 19: 401-408.

Robert Moss, Institute of Terrestrial
Ecology (N),

Hill of Brathens, Banchory,
Kincardineshire AB31 4BY.

132 Scottish Birds (1994) 17: 132-145 SB 17 (3)

Prey remains at Osprey nests in Tayside and Grampian, 1987-
1993

D.N. Carss & K. Brockie

Prey remains were collected from twenty Osprey nests in Tayside and three
in Grampian during 1987-1993. All remains were from fishes and included
scales, pieces of skin and fins, and cranial keybones. Methods were
devised to identify these keybones to species and to determine the original
sizes of prey. Overall, 104 prey records were collected, the most numerous
being brown and rainbow trout (37%), followed by roach (21%), perch (18%),

grayling (13%), pike (11%) and flounder (1%), but proportions varied
throughout the study. The mean length of all measurable fishes (n - 113)
was 34cm and the corresponding weight 480g, but mean size varied with
species. We could find no previous record of grayling as Osprey prey
anywhere, and roach has apparently not previously been recorded as prey
of Ospreys in Scotland. The diet of Ospreys in Tayside and Grampian is
discussed in relation to other studies, the Scottish fish fauna and current

fishery practices.
Introduction

The decline and subsequent recovery of the
Osprey Pandion haliaetus population in
Scotland is well documented. The species
ceased to breed about 1916 and although
nesting attempts were recorded inthe 1950s,
breeding was not successful until 1954.
Thereafter, the population increased gradually
to 13 pairs in 1972, 25 pairs in 1981, 50 pairs
in 1986 and 76 pairs in 1992; there were 86
breeding pairs in 1993 (Osprey Study Group
pers.comm.). Despite this rapid recolonisation
there has been relatively little published on
diet in Scotland (Poole 1989). Throughout its
range the Osprey is primarily piscivorous,
taking a wide variety of fishes near the surface
depending on their relative availability (Cramp
& Simmons 1980). However, apart from an
intensive study ata single nest site in Speyside
(Green 1976) and observations of foraging

birds and their prey remains in an area of
north-east Scotland (McLeod & Duncan 1984),
little is published on the diet of the species
elsewhere in Scotland.

Most Ospreys return to the same nest and
forage in the same habitats for many
consecutive years (Postupalsky 1989). Such
nesting and foraging site fidelity could mean
that samples of prey from the same few nests
spanning several years are less representative
of the general diet of apopulationthan samples
from a larger number of nests. This paper
reports on the analysis of prey remains
collected from 23 Osprey nests in Tayside
and Grampian Regions of Scotland between
1987 and 1993.

1994 Osprey prey remains 133

nnn e ener een eee

TABLE 1. Numbers of nest samples taken each year from 23 Osprey nest sites in
Tayside and Grampian, 1987-93. Each asterisk indicates at least one visit between
May-August in any one year.

=e SS

Region and Year
site number 1987 1988 1989 1990 1991 1992 1993

Tayside
1 - t
2 t x
3 * t
A ‘ ‘ t
5 A * t f t
6 * t t s t
7 *
8 * * * *
9 * *
10 :
11 Fs
12 i
13 :
14
15 5 iy
16 ‘
We *
18 .
19 *
20
Grampian
21 * * *
22 * * * *
23
Total no.

samples 6 5 3 12 6 11 12

a Se AO SLE SSE PRON L eD DBO See TEED SD Ee POR Ne OS OS BTL i DES STE STEEL A FEI TOE TS IES BEE WANES PISO BLE SE SE
a

134 Carss & Brockie

Study area and methods
Nest material

Twenty nests in Tayside andthree in Grampian
were visited during the study period (Table 1).
These solitary nests were usually visited once
or twice, but occasionally more often, during
the breeding season (May-August) to record
nest contents and to count andring nestlings.
During these visits a handful of material was
scraped from the lining of the nest and any
uneaten food in, and under, the nest was
collected. In cases where more than one
collection was made from the sane nest in
one season, samples were combined for
analysis. Nest ‘scrapes’ were dried at room
temperature for 24-48 hours and all prey
remains extracted for examination.

SB 17 (3)

Prey identification and measurement

Prey remains were analysed in two way: (1)
the presence of all identifiable material (skin,
fins, scales and bones) was recorded and
identified using keys (Maitland 1972,
Steinmetz & Muller 1992) and a reference
collection, and (2) ‘keybones’, which could be
assigned to individual fish, were counted,
identified and measured (Fig. 1). These
included salmonid first (atlas) vertebrae and
cleithra (paired bones on either side of the
head supporting the gill arches), lower jaws
(pike Esox lucius, perch Perca fluviatilis, and
salmonids), opercularand preopercularbones
(perch and roach Autilus rutilus). These
bones were also used to determine the original
sizes of fishes using a series of regression
equations derived from intact specimens (see
Table 3). Flounder Platichthys flesus was

TABLE 2. Length:weight relationships for five fish species,
Wt = wet weight (g), L = fork length (cm).

Species Relationship

Perch Wt = 0.0135 L 3-9

Pike Wt = 0.005248 L 3-99
Roach Wt = 0.009303 L 3-1513

Brown trout

Rainbow trout

Flounder

Wt = 0.0195 L 2-822
Wt = 0.0101 L 3-05

Wt = 0.01481 L 2-925

Source

Craig (1974)

Frost & Kipling (1967)
Mills (1969)

Clelland (1979)

Carss (1993b)

Summers (1979)

1994

Osprey prey remains 135

identified from a single bone and the original
fish size estimated froma reference collection.

Intact fish were collected and measured from
the snout to the fork of the tail (fork length,
mm) and their heads were removed and
digested in a saturated solution of biological
washing powder for 4-5 days. The resulting
bones were rinsed and dried and the various

Figure 1.

keybones extracted and measured (mm) (Fig.
1). These measurements were regressed
against original fork lengths to produce a
series of conversion equations. Inthe case of
roach opercular bones, a published equation
(Mann 1973) was used. The original size of
broken bones was estimated by comparison
with reference material. Prey lengths were
convertedto weights by aseries of regression
equations (Table 2).

Keybones and the position of the measurements used to determine the

Original length of fishes. Lower jaws: pike (a), perch (b), salmonid (c); opercular
bones: perch (d), roach (e); perch preoperculum (f), salmonid cleithrum (g) and atlas

vertebra (h).

FIGURE 1

136 Carss & Brockie

SB 17 (3)

TABLE 3. Regression equations for various pike, perch, brown and rainbow trout
keybone measurements (mm) against fork length (FL, cm).

Keybone N

Pike lower jaw 31 11-53
Perch lower jaw 17 9-36
Perch preoperculum Zé 9-36
Perch operculum 17 9-36
Salmonid lower jaw 103 10-56
Salmonid atlas 100 10-56
Brown trout cleithra 60 10-56
Rainbow trout cleithra 40 10-55

Range (cm) re

Relationship

0.99 LogFL=-0.192+ 1.01 LogJ

0.99 Log FL=0.0684 + 1.01 Log J
0.97 Log FL=0.0014 + 0.955 Log P
0.98 Log FL=0.207 + 0.873 Log Op
0.97 Log FL= 0.0664 + 0.982 Log J
0.98 LogFL=0.761 + 1.08 Log At
0.98 Log FL=-0.0475 + 1.04 Log Cl

0.94 Fog FL= 0.0298 + 0.96 Log Cl

Distinguishing salmonids and estimating
the accuracy of diagnostic features

Pike, perch, roach and salmonid keybones
were very different from one another but
brown trout Salmo trutta and rainbow trout
Oncorhynchus mykiss could not be
distinguished easily. Thus a method was
devised to separate these species by closer
examination oftheir keybones. This was later
tested by one experienced and two
inexperienced observers examining a mixed
sample of brown and rainbow trout lower
jaws, cleithra and atlas vertebrae (n = 40 of
each).

Results

Distinguishing brown and rainbow trout
and estimating the accuracy of their
identification

Brown and rainbow trout atlas vertebrae,
cleithra and lower jaws could each be
distinguished using only a small number of
characteristics:

1994

(a) | The dorsal surface of the brown trout
atlas appears separated from the anterior
surface by a distinct rim. It is porous and
relatively smooth, sometimes having a pair of
small ‘bud-like’ processes emerging from it.
These processes are notconnected tothe rim
of the vertebra (Fig. 2a). The dorsal surface
of the rainbow trout atlas is often grossly
overlapped by the rim separating it from the
anterior surface. Large, smooth processes
originate from this rim and often extend
posteriorly beyond the body of the atlas.
Belowthis the dorsal surface is smooth, usually
leading to a deep depression between, and
below, the processes (Fig. 2b).

(b) The inner surface of the brown trout
cleithrum is relatively smooth (Fig. 2c) whilst
that of rainbowtrout has one, and occasionally
two, prominent antero-posterior vanes whilst
the posterior portion of bones from larger fish
also have several folds (Fig. 2d).

Osprey prey remains 137

(c) | Viewed from the inner side, brown
trout lower jaws appear relatively deep
compared to the length of the narrow surface
from which the teeth emerge. There is also
no ‘lip’ of bone on the outer edge of the teeth.
Viewed posteriorly the jaw is sharply curved,
its lower plane is almost perpendicular to the
tooth-bearing axis(Fig. 2e). Viewed fromthe
inner side, rainbow trout lower jaws appear
relatively shallow compared to the length
occupied by the teeth. The teeth emerge
from a broad surface and there is a distinct
‘lip’ of bone on their outer edge which is
clearly visible between them. Viewed
posteriorly, the jawis only slightly curved (Fig.
2f). The shape, number and exact position of
the teeth, and holes marking the position of
broken teeth, varied greatly between
individuals and no consistent patterns were
observed within, or between, species.

Figure 2. Characteristic features used to distinguish brown and rainbow trout
keybones: dorsal surfaces of the two types of brown (a) and rainbow trout (b) atlas
vertebrae; inner surfaces of brown (c) and rainbow trout (d) cleithra; lower jaws of
brown (e) and rainbow trout (f) with posterior profiles.

138 Carss & Brockie

These characters could be usedto distinguish
brown and rainbow trout in 83% (atlas), 95%
(cleithrum) and 93% (lower jaw) of cases by
an experienced observer. Corresponding
figures for two inexperienced observers were
80%, 92%, 78% and 70%, 92%, 88%,
respectively, with observers consistently
making more correct identifications based on
cleithra than the other two keybones.

Keybone regression equations

The relationships of keybone measurements
to original fish length were linear, those forthe
lower jaws and atlas vertebrae of brown and
rainbow trout (‘salmonid’) could each be
described by a single equation (Table 3).

SB 17 (3)

Species and sizes of fish from Osprey
nests

Seven fish species, roach, perch, pike,
grayling Thymallus thymallus, brown trout,
rainbow trout, and flounder were identified
from nest samples (Table 4). The three
Grampian nests yielded remains of brown
trout, rainbow trout, pike and perch. Site and
seasonal variation in prey remains were
investigated in the Tayside samples.

For Tayside, cumulative records showed that
six of the seven fish species were recorded
after nine of the 20 sites had been sampled,
the single flounder being recorded in 1993
after 17 nests had been sampled (Fig. 3).

Figure 3. The cumulative number of nest sites sampled during the study and the

number of fish species recorded.

Figure 3

fish species recorded

No.

Cumulative No.

12 3 4 5. 6 WMS 9 TO 1112 1 SaaS Ceipeipceinone.@

nests sampled

1994

Osprey prey remains 139

TABLE 4. The fish species recorded at each nest site during the study period.
Numbers refer to specific nests, as given in Table 1.

Prey 1987 1988 1989
Roach 1,.2,3,4,5 4,5 45,8
Perch 45,6 None 4,5
Pike 5 i 5
Salmonids 3,4,6 46,13 4,5,8
Grayling None None 4
Flounder None None None
No. records 12 6 10
No. sites 6 5 3

Year

1990 1991 1992 1993

13,458 1,12 16 11

9,10,11

2,9,10 2,6 2,8,14 8,15,17,18
15,21 21

6,21 18 5.8 15.21.. 15,118;20.211

1,456.8 26,12 268,11 5,6,8,11

9,10,11 22 12,14,15 15,17,18

22 16,21,22 20,2223

8,11 2,9 2,5,11,12 5,11,19,20

None None None 20

24 11 24 25

12 6 Wy 12

Overall, 104 prey records were collected; the
most numerous were salmonids (37%),
followed by roach (21%), perch (18%), grayling
(13%), pike (11%) and flounder (1%).
Proportions of salmonid, roach and ‘other
fishes’ remains were similar in 1987-89 and
1990-93, but within the ‘otherfishes’ category,
proportions of grayling increased throughout
the study (Table 5).

Most (69.8%) of the salmonids identifiedfrom
keybones (n =63) were brown trout, the
remainder (30.2%) being rainbow trout.
Proportions of rainbow trout varied annually
and in years when at least ten measurable
salmonids were recorded, proportions were
40.0% (1987, n= 10 salmonids), 71.4% (1990,
n= 14) and 7.4% (1992, n= 27).

The mean length of all measurable fishes (n
= 113) was 34cm and the corresponding
weight was 475g. However, mean sizes
varied with species (Table 6). Ignoring the
single flounder (ca. 27cm, 288g), there were
Sonllicant differences in mean fish lengths
(F4 197 = 13.92, P<0.001) with the ‘long-
Bodied: fishes, salmonids and pike, being
significantly longer (mean = 36cm, SE = 0.8)
than the ‘deep-bodied’ fishes perch androach
(mean = 26cm, SE = 1.0) (t= 6.64, df = 110,
P<0.001). Mean fish weights were also
significantly different (F 4 107=8.42, P<0.001)
with the salmonids being significantly heavier
(mean = 630g, SE = 47.3) than the other
fishes (mean = 301g, SE =27.9) (t = 5.62, df
= 110, P<0.001).

140 Carss & Brockie

Discussion
Methodology

Assessments of Osprey diet have been
obtained by several methods, for example
collecting uneaten remains from nests and
feeding perches (e.g. Hakkinen 1978),
observingforaging birds (e.g. Edwards 1988),
and recording fish delivered to the nest (eg.
Jamieson et a/. 1982, Mclean & Byrd 1991).
The latter method has the disadvantage that
itis labour intensive and may often be restricted
to asmall number of nests. Moreover, as with
observations of foraging birds, identifications
are likely to be biased in favour of distinctively
shaped or coloured fishes and, as a result,
considerable proportions of prey may be
unidentified. For example, 68% of all Bald
Eagle Haliaetus leucocephalus open-water
captures could not be identified by Mersmann
et al. (1992).

SB 17 (3)

The remains of prey taken extremely rarely
may not be found. We have for instance a
reliable field record of an Osprey carrying an
eel Anguilla anguillato a nest in Tayside but
found no remains of this species in over 45
samples. Prey remains could be lost to
scavengers such as foxes Vulpes vulpes,
Crows Corvus coroneand Magpies Pica pica.,
but this would result in bias (i.e. an incorrect
representation of the true proportions) only if
they removed an unrepresentative sample of
items. Two types of bias can occur: (1) in
species, because fishes whose scales are
relatively large and easily lost during
manipulation, or large bony species, may be
over-represented in samples and (2) in size,
because small scales and pieces of fish skin
may decompose faster than larger diagnostic
bones, particularly over time. This is
particularly relevant if samples are collected
infrequently.

TABLE 5. Top: the number of poeords of roach, salmonids and ‘other fishes’, these
were similar in 1989 and 1990-93 (X2 = = 4.39, df = 2, NS). Bottom: the number ‘of
nests where Grayling were either present or absent in each year. There was a
significant increase in grayling records throughout the study period (Snedecor &

Cochran's test for a linear trend in proportions, z = 2.54, P = 0.011).

Prey recorded 1987 1988 a 1990 1991 1992 1993
Roach 5 2 s) 8 2 Aven 1
Salmonids 3 3 3 8 3 8 8
‘Other fishes’ 4 1 4 6 4 11 12
Total no. records 12 6 10 22 9 20 21
Grayling absent 6 5 2 8 3 5 5
Grayling present 0 0 1 2 2 4 4
Total no. nests 6 5 3 10 5) 9 9

1994

Osprey prey remains 141

In the present study of prey remains, there
was thus probably some bias but the method
had the advantage that it required little effort
per nest and so several nests could be
sampled each season. Nevertheless sample
sizes were rather small: only nine out of 23
nests were visited in more than three years
and only two visited in six years. Fourteen
(more than half of the nests) were visited only
in one or two years and possibly only once.
Furthermore, as few remains (bones and
skin) were collected at each visit, it was not
possible to determine such things as the
variation in diet at particular nests or the
quality of the fish delivered. However, despite
the potential for bias it was thought data were
sufficient to determine diet and size of prey in
general terms.

General diet

Ospreys are presumed to feed on the most
abundant and available fish species in any
particular area (Poole 1989) and data from
the present study were not inconsistent with
this view. Seven fish species were recorded
but it was not possible to infer the foraging
habitat of Ospreys as all the fishes taken are
known to inhabit both running and standing
freshwaters (Maitland & Campbell 1992).
However, the species recorded were as
expected from the status and distribution of
Scottish freshwater fishes.

The Scottish freshwater fish fauna is
impoverished compared with that of
continental Europe (Maitland & Campbell
1992) and is dominated by the salmonids.
These are northern hemisphere fishes, well-
adapted to cold waters (Wheeler 1978) and
include the indigenous Atlantic salmon S.
salar and brown trout and the rainbow trout
introduced from North America. The two trout

species formed the largest proportion of
measurable remains collected (54.9%), of
which over two-thirds were brown trout. The
remains of the four largest salmonids
appeared from skin colouration and keybone
features to be those of brown trout but it was
possible that they came from the closely-
relatedsalmon. Returning adult salmon, which
may be as small as 50cm (D. Hay, SOAFD,
pers. comm.), enter freshwater throughout
the year although spawning does not take
place until the autumn. Furthermore, there
are two lochs in Tayside which are stocked
with a few hundred salmon (1.4-2.7kg) each
year for angling purposes. Ospreys have
been seen scavenging moribund salmon here
on at least one occasion (C. Langton pers.
comm.).

The cyprinid family is the largest group of
freshwater fishes in Europe (Wheeler 1978)
andincontinental Europe Osprey diet includes
atleast 11 species (Cramp & Simmons 1980).
Furthermore, species such as bream Abramis
brama, silver bream Blicca bjoerkna, and
roach often comprise the largest single dietary
component. However, cyprinids are scarce
in Scotland, particularly north of the Forth-
Clyde Canal (Mills 1969, Maitland 1972).
Apart from the minnow Phoxinus phoxinus
roach is the most widely distributed cyprinidin
Scotland and it was the only one recorded in
the present study. Cyprinids have not been
recorded previously in studies of Osprey diet
in Scotland (Green 1976, McLeod & Duncan
1984), presumably because of their relative
scarcity and patchy distribution.

Piscivorous fishes are thought to be swifter
and harder to capture than enthic-feeding or
non piscivorous limnetic fishes (Swenson
1979), and are relatively scarce in Osprey
dietary studies. For example perch and pike
have been found to comprise no more than

142 Carss & Brockie SB 17 (3)

16% and 37%, respectively, ofthe prey items _ figures for the present study were low (18%
examined in European studies (Cramp & and11%, respectively).

Simmons 1980). Similarly, corresponding

TABLE 6. Length and weight details of fishes caught by Ospreys.

Length (cm) Weight (g)
Prey N Mean SE Range Mean SE Range
Perch iG) 25 O:9iS=30 213 22.0 79-365
Pike 25 33 1.2 24-44 326 40.4 110-966
Roach 9 28 2.3 18-38 388 91.4 84-885
Brown trout 44 38 1.3, 23-60 636 59.1 136-2032
Rainbow trout 1Sean3e 1.4 29-48 614 78.1 262-1355
Salmonids, pike 87, 36 0.8 23-60 - - -
Perch, roach Pxoye CAS) 1.0 18-38 - - -
Salmonids Can: - 630 473 136-2032
Perch, roach, pike 50 - - - 301 27.9 79-996
All fishes 113 34 0:8 18-60 481 32.6 79-2032

1994

Osprey prey remains 143

We could find no previous record of grayling
in the diet of European Ospreys (Cramp &
Simmons 1980, McLeod & Duncan 1984,
Eriksson 1986). The Grayling was introduced
to Scotland in the nineteenth century and has
a limited distribution. North of the Forth-
Clyde Canal, the only Grayling populations
are currently in the River Tay system: the
rivers Tummel, Isla and Earn and at least two
Tayside lochs (Gardiner 1992). The increase
in grayling occurrences in remains couldbe a
reflection of the increase in Osprey numbers,
and their spread throughout Tayside, with
birds visiting more of the available freshwaters
and possibly foraging more on rivers than
previously. An alternative, but not mutually
exclusive, explanation is that grayling
abundance has increased in recent years.
There is known to be year to year variation in
grayling numbers leading to dominant year
classes, and catches onthe R. Tummel have
allegedly increased over the 1970s and 1980s
(R. Gardiner pers. comm.). As there have
been no further fish introductions there in
recentyears, the overall distribution of grayling
in the area is unlikely to have changed (R.
Gardiner SOAFD pers. comm.).

Size of prey

The perch and roach recorded in the present
study were smaller than the other fishes but
all the fishes taken were similar in size and
weight to those reportedforthe same species
in other studies (Cramp & Simmons 1980,
Poole 1989). The two salmonids had different
length distributions, possibly associated with
the size structure of their populations in the
wild. Brown trout exhibited a natural, multi-
modal frequency distribution which was
positively skewed towards larger (>40cm)
fish but also included smaller (<30cm)
individuals. The rainbow trout length

distribution, although positively skewed,
lacked any of these smaller fish and was
typical of stocked fish populations. Most
rainbow trout sport fisheries are maintained
by regular introductions of hatchery-reared
fish which are grown-on before release, until
large enough to be caught by anglers. Most
of these fish are about 35cm on release and
only afeware less than 30cmlong. This was
certainly the case at one fishery known to be
visited by Osprey from at least four of the
nests in the present study. The largest fish
recorded, a 60cm/2032g brown trout, was
possibly scavenged as carrion, arare, but not
unrecorded, phenomenon (Dunstan 1974).

Although piscivorous fish are relatively scarce
prey items for Ospreys, pike and perch do
dominate the diet of birds in one area of north-
east Scotland where there are few, if any,
trout (McLeod & Duncan 1984, Carss 1993a).
Here, perch (n = 173) and pike (n = 239) of
between 13-41cmand18-48cm, respectively,
have been recorded taken by Ospreys (Carss
1993a). These size ranges are strikingly
similar to those taken by Ospreys in Tayside
in the present study (18-30cm and 22-44cm,
respectively) which were obviously taken by
birds foraging in a number of different sites.

The future

As Ospreys increase in Scotland, they may
come into conflict with man. As present the
species is recorded visiting a few pond trout
farms each year but such predation can be
prevented by placing nets over small ponds
(NCC 1990). However, in 1993 there were
several reports of birds feeding regularly at
small lochs stocked with rainbow trout and in
such circumstances the birds may be
competing directly with anglers forfish (Carss
& Marquiss 1992). As a result, in one area,
the RSPB, SNH andotherconservation bodies

144 Carss & Brockie

were approached by a fisheries manager
requesting financial compensation for losses
to Ospreys (I. Francis pers. comm.). As
conflicts are extremely difficult to resolve, and
compensation payments are highly unlikely,
it seems inevitable that such complaints will
increase. Protectingthe relatively large areas
of water involved is impractical, whilst the
birds themselves receive legal protection. In
some cases, predation of stocked trout could
possibly be reduced by altering the timing of
stocking to allowing introduced fish time to
acclimatise before Ospreys arrive or by
increasing cover by providing floating islands
and encouraging bankside vegetation (R.
Dennis pers. comm.).

So far, breeding Ospreys have been carefully
guardedin Scotland andthis has discouraged
intensive research (Poole 1989) because of
the risk to a small and vulnerable population.
However the continued increase in Osprey
numbers means that the small risks involved
become increasingly acceptable, enabling
the species to be studied in greater detail.
Such studies could include further work on
diet, foraging energetics in different habitats
(e.g. natural and stocked lochs, seashores
and estuaries, andassociated river systems),
and post-fledging dispersal.

Acknowledgements

We would like to thank the appropriate
landowners for access to nest sites throughout
the study. Apart from KB, Steve Cooper,
Keith Duncan, Stuart Rae and Bradly Yule
also collected nest samples. Peter Maitland,
Alan Youngson, Willie Wilson and Peter Cubby
kindly provided us with some of the reference
fish specimens and Gavin Alexander and
Mick Marquiss acted as inexperienced

SB 17 (3)

observers whilst distinguishing salmonid
keybones. Ross Gardiner and Chris Langton
provided information on fish distribution and
abundance in Tayside. Mick Marquiss, lan
Newton and Roy Dennis commented on an
earlier draft of the manuscript.

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Carss, D.N. & Marquiss, M. 1992. Avian
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prey preference patterns of adult Ospreys.
Auk 105: 244-251.

Eriksson, M.O.G. 1986. Fish delivery,
production of young, and nest density of
Osprey (Pandion haeliatus) in southwest
Sweden. Can. J. Zool. 64: 1961-1965.
Frost, W.E. & Kipling, C. 1967. A study of
reproduction, early life, weight-length
relationship and growth of pike, Esox /ucius
L., in Windermere. J. Anim. Ecol. 36: 651-
693.

1994

Osprey prey remains 145

Gardiner, R. 1992. Scottish Grayling: history
and biology of populations. Proc. 22 Inst. Fish
Mgmt. Ann Study Course: 171-178, Institute
of Fisheries Management.

Green, R. 1976. Breeding behaviour of the
Osprey Pandion haeliatus in Scotland. Ibis
118: 475-490.

Hakkinen, |. 1978. Diet of Ospreys in Finland.
Ornis Scand. 9: 111-116.

Jamieson, |., Seymour, N.R. & Bancroft, R.P.
1982. Use of two habitats related to changes
in prey availability in a population of Ospreys
in northeastern Nova Scotia. Wilson Bulletin
94: 557-564.

Maitland, P.S. 1972. A key to the freshwater
fishes of the British Isles. Sci. Publ. Freshwat.
Biol. Ass. 27: 1-137.

Maitland, P.S. & Campbell, R.N. 1993.
Freshwater Fishes. Collins New Naturalist
Series, Harper Collins, London, pp368.
Mann, R.H.K. 1973. Observations on the
age, growth, reproduction and food of the
Roach Autilus rutilus (L.) in two rivers in
southern England. J. Fish. Biol. 6: 237-253.
Mersmann, T.J., Buehler, D.A., Fraser, J.D.
and Seegar, J.K.D. 1992. Assessing bias in
studies of Bald Eagle food habits. J. Wildl.
Mgmt. 56(1): 73-78.

Mills, D.H. 1969. The growth and population
densities of Roach in some Scottish waters.
Proc. Brit. Coarse Fish Conf. 4: 50-57.
McLean, P.K. & Byrd, M.A. 1991. The diet of
Chesapeake Bay Ospreys and their impact
on a local fishery. J. Raptor Res. 25 (4): 109-
112.

McLeod, |.C. & Duncan, K. 1984. Prey of the
Osprey (Pandion haeliatus) in north-east
Scotland. Grampian Ringing Group Heport 4:
12-20.

NCC. 1990. Fish farming and the Scottish
Freshwater Environment. NCC, Edinburgh.
Poole, A.F. 1989. Ospreys: a Natural and
Unnatural History. Cambridge University
Press, Cambridge.

Postupalsky, S. 1989. Ospreys. In Newton, I.
(ed) Lifetime reproduction in Birds. Academic
Press, London.

Steinmetz, B. & Muller, R. 1992. An Atlas of
Fish Scales and Other Bony Structures Used
For Age Determination. Samara, Cardigan.
Summers, R.W. 1979. The Ecology of the
Flounder. Unpublished PhD thesis, University
of Aberdeen.

Swenson, J.E. 1979. The relationship between
prey species and ecology and dive success in
Ospreys. Auk 96: 408-413.

Wheeler, A. 1978. Key to the Fishes of
Northern Europe. Warne, London.

D.N. Carss, Institute of Terrestrial Ecology, Hill of Brathens,
Glassel, Banchory, Kincardineshire, AB31 4BY.
K. Brockie, lolaire, Dron Farm, by Invergowrie, Dundee, DD2 5LH.

(Revised typescript received 3 March 1994)

146 Scottish Birds (1994) 17: 146-159

SB 17 (3)

Scottish List

Several attempts have been made in the past
by various people to produce alist of Scottish
Birds, but none of these lists have been
updated on aregular basis. Itbecame obvious
to many people that a need existed for a
formal Scottish List and that an organisation
(not an individual) was required to take
responsibility for such a list.

At its annual meeting held in November 1991
the Scottish Birds Records Committee (a
sub-committee of the SOCs Council) agreed
to commence work on the preparation of a
draft for such a list. Ken Shaw volunteered to
prepare an initial draft which was circulated
around all SBRC members for comment,
following which a second draft was prepared
and further amendments made. A third draft
was then circulated aroundallLocal Recorders
fortheir comments during the first few months
of 1993.

At an SOC Council meeting in July 1993, it
was agreed to adopt a fourth draft as forming
the basis of an official SOC produced Scottish
List and the Club accepted responsibility for
its continued maintenance. It was further
agreed to delegate to SBRC responsibility for
maintaining the list and publishing regular
amendments. This list which has been further
updated is now published for the first time. It
is the intention of SBRC to publish
amendments on a regular basis and from
time to time to publish revised versions of the
list.

Each species has been categorised,
depending on the criteria for its admission to
the Scottish List and the category (A, B or C)
appears before the English name. Species in
category D do not form part of the main list
and are listed separately at the end. The
categories are defined as follows:

Category A. Species which have been
recorded in an apparently wild state in Scotland
at least once since 1958.

Category B. Species which were recorded
in an apparently wild state in Scotland at least
once up to 31 December 1957, but have not
been recorded subsequently.

Category C. Species which, although
Originally introduced by man, have now
established a regular feral breeding stock
which apparently maintains itself without
necessary recourse to further introduction.

Category D. Species which would otherwise

appear in Category A or B except that :

(D1) there is a reasonable doubt
that they have ever occurred in a wild state, or

(D2) they have certainly arrived
with a combination of ship or human
assistance, including provision of food and
shelter, or

(D3) they have only everbeen found
dead, or

(D4) species that would otherwise
appear in category C except that the feral
population may or may notbe self-supporting.

1994

We have used several principles in
establishing the list:-

1. Wehaveused identical categories (A,B,C
and D) to the British Ornithologists’ Union
who are responsible for maintaining the official
list of birds recorded in Britain and Ireland.

2. We have in no instance given a bird on
our list a higher category than the BOU (e.g.
if aspecies appears in Category B on their list
it cannot appear as Category A on our list)
and have not included any species which do
not appear on the British List.

3. We have used the same systematics as
the BOU (e.g. we have not given species
status to Yellow-legged Gull as the BOU have
not yet done so).

4. We have only accepted a species in
Category A if either :-

i) It appears on the British Birds Rarities
List and the British Birds Rarities Committee
have accepted at least one Scottish Record
(they were formed in 1958 and the BOU have
therefore for that reason decided that a bird
must have occurred in Britain or Ireland since
1 January 1958 to be in Category A of their
list).

li) lt does not appear on the British Birds
Rarities List and we are satisfied that it has
occurred in a wild state in Scotland since
1958.

A few species are assigned more than one
category. With the exception of Capercaillie,
these are all either dual AandC or dual Aand
D4 to reflect the situation where records of

Scottish List 147

genuinely wild birds are supplemented by
birds from stock originally introduced by man.
In the case of Capercaillie (dual B and C) a
natural population became extinct in the 18th
century, with the present feral population
being introduced during the 19th century.

The choice of English bird names used in the
list should in no way be taken as reflecting a
particular view. The SOC do not wish at this
stage to become involved in the present
debate on English names and have decided
to continue with existing names at least for
the time being. We have therefore on the
whole stuck to conventional English bird
names.

All species appearing on the main British and
Irish List (i.e. Categories A, B and C) which
have not been admitted to the Scottish List
(Categories A, B andC), appear onthe BBRC
Listand wouldtherefore require to be accepted
by them prior to being admittedto the Scottish
List, with the exception of Egyptian Goose,
Lady Amherst’s Pheasant and Rose-ringed
Parakeet.

The Scottish List stands at 469 species (there
are now 550 species on the British and Irish
List). The 12 species which are in category D
only, do not form part of the main List.

Category A 450
Category B 13
Category C 6
469
Category D 12
481

148 A.W. Forrester

The list will require regular revision and at any
one time there is likely to be more than one
record held pending which if accepted would
affect the list. Among other decisions awaited
at present are those by the BOU which could
add Brown Flycatcher to the Scottish List and
change the category for Pallid Harrier.

The Scottish Birds Records Committee which
is responsible for maintaining the Scottish
List, now consists of Bernard Zonfrillo
(Chairman), Pete Gordon, Angus Hogg, Ken
Shaw, Eric Meek, Kevin Osborn and Ron
Forrester (Secretary).

Systematic List

Red-throated Diver
Black-throated Diver
Great Northern Diver
White-billed Diver
Pied-billed Grebe

Little Grebe

Great Crested Grebe
Red-necked Grebe
Slavonian Grebe
Black-necked Grebe
Black-browed Albatross
Fulmar

Cory’s Shearwater
Great Shearwater
Sooty Shearwater
Manx Shearwater
Mediterranean Shearwater
Little Shearwater
Wilson’s Petrel
White-faced (Frigate) Petrel
Storm Petrel

Leach’s Petrel

Gannet

>PPrPrwaorrrrrprrprrrrrrrrrrrrYr

SB 17 (3)

Ken Shaw was responsible for a large part of
the work associated with producing this list
and the Committee wish to thank all those
who commented on the early drafts. Bernie
Zonfrillo has commenced work on the
production of alist of allsub-species recorded
in Scotland, which when complete, is expected
to supplement this present list.

Ronald W. Forrester
Secretary
Scottish Birds Records Committee.

Gavia stellata

Gavia arctica

Gavia immer

Gavia adamsii
Podilymbus podiceps
Tachybaptus ruficollis
Podiceps cristatus
Podiceps grisegena
Podiceps auritus
Podiceps nigricollis
Diomedea melanophris
Fulmarus glacialis
Calonectris diomedea
Puffinus gravis ;
Puffinus griseus
Puffinus puffinus
Puffinus yelkouan
Puffinus assimilis
Oceanites oceanicus
Pelagodroma marina
Hydrobates pelagicus
Oceanodroma leucorhoa
Morus bassanus

PPPrrrrrrrrrrrrrwoarrrrworp,p

PP>
eel ek@)
mse IS

~~

>>r>yYP>

a @

-

>PrPrrrrrrrrrrodrwa>,r

Cormorant

Shag

Magnificent Frigatebird
Bittern

American Bittern
Little Bittern

Night Heron
Squacco Heron
Cattle Egret

Little Egret

Great White Egret
Grey Heron

Purple Heron

Black Stork

White Stork

Glossy Ibis
Spoonbill

Mute Swan

Bewick’s Swan
Whooper Swan
Bean Goose
Pink-footed Goose
White-fronted Goose
Lesser White-fronted Goose
Greylag Goose
Snow Goose
Canada Goose
Barnacle Goose
Brent Goose
Red-breasted Goose
Ruddy Shelduck
Shelduck

Mandarin

Wigeon

American Wigeon
Gadwall

Teal

Mallard

Black Duck

Pintail

Garganey
Blue-winged Teal
Shoveler
Red-crested Pochard

Phalacrocorax carbo

Phalacrocorax aristotelis

Fregata magnificens
Botaurus stellaris
Botaurus lentiginosus
Ixobrychus minutus
Nycticorax nycticorax
Ardeola ralloides
Bubulcus ibis
Egretta garzetta
Egretta alba

Ardea cinerea
Ardea purpurea
Ciconia nigra
Ciconia ciconia
Plegadis falcinellus
Platalea leucorodia
Cygnus olor
Cygnus columbianus
Cygnus cygnus
Anser fabalis

Anser brachyrhynchus
Anser albifrons
Anser erythropus
Anser anser

Anser caerulescens
Branta canadensis
Branta leucopsis
Branta bernicla
Branta ruficollis
Tadorna ferruginea
Tadorna tadorna
Aix galericulata
Anas penelope
Anas americana
Anas strepera

Anas crecca

Anas platyrhynchos
Anas rubripes

Anas acuta

Anas querquedula
Anas discors

Anas clypeata

Netta rufina

Scottish List 149

150

& ff

PPPPPrPPKrPPPHrP PEPPY OPPrKrYHKPrPIdIP Kr YrHrYKrYrYKrYrrYrrPrrrrrrrer
Q

R.W. Forrester

Pochard
Ring-necked Duck
Ferruginous Duck
Tufted Duck
Scaup

Eider

King Eider
Steller’s Eider
Harlequin Duck
Long-tailed Duck
Common Scoter
Surf Scoter

Velvet Scoter
Bufflehead
Barrow’s Goldeneye
Goldeneye

Smew
Red-breasted Merganser
Goosander

Ruddy Duck
Honey Buzzard
Black Kite

Red Kite
White-tailed Eagle
Marsh Harrier
Hen Harrier

Pallid Harrier
Montagu’s Harrier
Goshawk
Sparrowhawk
Buzzard
Rough-legged Buzzard
Golden Eagle
Osprey

Lesser Kestrel
Kestrel

American Kestrel
Red-footed Falcon
Merlin

Hobby

Eleonora’s Falcon
Gyr Falcon
Peregrine

Red Grouse

Aythya ferina
Aythya collaris
Aythya nyroca
Aythya fuligula
Aythya marila
Somateria mollissima
Somateria spectabilis
Polysticta stelleri
Histrionicus histrionicus
Clangula hyemalis
Melanitta nigra
Melanitta perspicillata
Melanitta fusca
Bucephala albeola
Bucephala islandica
Bucephala clangula
Mergus albellus
Mergus serrator
Mergus merganser
Oxyura jamaicensis
Pernis apivorus
Milvus migrans
Milvus milvus
Haliaeetus albicilla
Circus aeruginosus
Circus cyaneus
Circus macrourus
Circus pygargus
Accipiter gentilis
Accipiter nisus
Buteo buteo

Buteo lagopus
Aquila chrysaetos
Pandion haliaetus
Faico naumanni
Falco tinnunculus
Falco sparverius
Falco vespertinus
Falco columbarius
Falco subbuteo
Falco eleonorae
Falco rusticolus
Falco peregrinus
Lagopus lagopus

SB 17 (3)

1994 Scottish List

A Ptarmigan Lagopus mutus

A Black Grouse Tetrao tetrix

B,C Capercaillie Tetrao urogallus

C Red-legged Partridge Alectoris rufa

A,C Grey Partridge Perdix perdix
Quail Coturnix coturnix
Pheasant Phasianus colchicus
Golden Pheasant Chrysolophus pictus
Water Rail Rallus aquaticus
Spotted Crake Porzana porzana
Sora Porzana carolina
Little Crake Porzana parva
Baillon’s Crake Porzana pusilla
Corncrake Crex crex
Moorhen Gallinula chloropus
Coot Fulica atra
Crane Grus grus

>PrrrrrrrrrrrrrrrrrrrrrrrworrrrrrrrrrrnndYS

Sandhill Crane

Little Bustard

Houbara Bustard

Great Bustard
Oystercatcher
Black-winged Stilt
Avocet

Stone-curlew
Cream-coloured Courser
Collared Pratincole
Black-winged Pratincole
Little Ringed Plover
Ringed Plover

Killdeer

Kentish Plover

Greater Sand Plover
Caspian Plover

Dotterel

American Golden Plover
Pacific Golden Plover
Golden Plover

Grey Plover

Sociable Plover
Lapwing

Great Knot

Knot

Sanderling

Grus canadensis

Tetrax tetrax
Chlamydotis undulata
Otis tarda

Haematopus ostralegus
Himantopus himantopus
Recurvirostra avosetta
Burhinus oedicnemus
Cursorius cursor
Glareola pratincola
Glareola nordmanni
Charadrius dubius
Charadrius hiaticula
Charadrius vociferus
Charadrius alexandrinus
Charadrius leschenaultii
Charadrius asiaticus
Charadrius morinellus
Pluvialis dominica
Pluvialis fulva

Pluvialis apricaria
Pluvialis squatarola
Chettusia gregaria
Vanellus vanellus
Calidris tenuirostris
Calidris canutus

Calidris alba

152 A.W. Forrester

PPYrPYrPrPrPKrrYrPrrKrPYKrYrYKrPYrPrPwOrYrrrrYrryYrrrrrrrrrrrrrrr,

Semipalmated Sandpiper
Western Sandpiper
Little Stint

Temminck’s Stint
Least Sandpiper
White-rumped Sandpiper
Baird’s Sandpiper
Pectoral Sandpiper
Sharp-tailed Sandpiper
Curlew Sandpiper
Purple Sandpiper
Dunlin

Broad-billed Sandpiper
Stilt Sandpiper
Buff-breasted Sandpiper
Ruff

Jack Snipe

Snipe

Great Snipe
Long-billed Dowitcher
Woodcock

Black-tailed Godwit
Bar-tailed Godwit
Eskimo Curlew
Whimbrel

Curlew —

Upland Sandpiper
Spotted Redshank
Redshank

Marsh Sandpiper
Greenshank

Greater Yellowlegs
Lesser Yellowlegs
Solitary Sandpiper
Green Sandpiper
Wood Sandpiper
Terek Sandpiper
Common Sandpiper
Spotted Sandpiper
Turnstone

Wilson’s Phalarope
Red-necked Phalarope
Grey Phalarope
Pomarine Skua

Calidris pusilla
Calidris mauri
Calidris minuta
Calidris temminckii
Calidris minutilla
Calidris fuscicollis
Calidris bairdii
Calidris melanotos
Calidris acuminata
Calidris ferruginea
Calidris maritima
Calidris alpina
Limicola falcinellus
Micropalama himantopus
Tryngites subruficollis
Philomachus pugnax
Lymnocryptes minimus
Gallinago gallinago
Gallinago media
Limnodromus scolopaceus
Scolopax rusticola
Limosa limosa
Limosa lapponica
Numenius borealis
Numenius phaeopus
Numenius arquata
Bartramia longicauda
Tringa erythropus
Tringa totanus

Tringa stagnatilis
Tringa nebularia
Tringa melanoleuca
Tringa flavipes

Tringa solitaria

Tringa ochropus
Tringa glareola
Xenus cinereus
Actitis hypoleucos
Actitis macularia
Arenaria interpres
Phalaropus tricolor
Phalaropus lobatus
Phalaropus fulicarius
Stercorarius pomarinus

SB 17 (3)

1994

PrPrrrraoarrrrroarworrrrrprrprrrrrrrrrrrrrrrrrrrrrryp

~t

Arctic Skua
Long-tailed Skua
Great Skua
Mediterranean Gull
Laughing Gull
Franklin’s Gull

Little Gull

Sabine’s Gull
Bonaparte’s Gull
Black-headed Gull
Ring-billed Gull
Common Gull
Lesser Black-backed Gull
Herring Gull

Iceland Gull
Glaucous Gull

Great Black-backed Gull
Ross’s Gull
Kittiwake

Ivory Gull

Gull-billed Tern
Caspian Tern
Lesser Crested Tern
Sandwich Tern
Roseate Tern
Common Tern
Arctic Tern

Forster’s Tern
Bridled Tern

Sooty Tern

Little Tern
Whiskered Tern
Black Tern
White-winged Black Tern
Guillemot
Bruinnich’s Guillemot
Razorbill

Great Auk

Black Guillemot
Little Auk

Puffin

Pallas’s Sandgrouse
Rock Dove

Stock Dove

Scottish List

Stercorarius parasiticus
Stercorarius longicaudus
Stercorarius skua
Larus melanocephalus
Larus atricilla

Larus pipixcan

Larus minutus

Larus sabini

Larus philadelphia
Larus ridibundus
Larus delawarensis
Larus canus

Larus fuscus

Larus argentatus
Larus glaucoides
Larus hyperboreus
Larus marinus
Rhodostethia rosea
Rissa tridactyla
Pagophila eburnea
Gelochelidon nilotica
Sterna caspia

Sterna bengalensis
Sterna sandvicensis
Sterna dougallii
Sterna hirundo
Sterna paradisaea
Sterna forsteri

Sterna anaethetus
Sterna fuscata

Sterna albifrons
Chlidonias hybridus
Chlidonias niger
Chlidonias leucopterus
Uria aalge

Uria lomvia

Alca torda

Pinguinus impennis
Cepphus grylle

Alle alle

Fratercula arctica
Syrrhaptes paradoxus
Columba livia
Columba oenas

153

154

PPrrrrrrrrrrrrrrrrrrrrrrrrrrrrrorrwrrrworrrrry,y

Ri. W. Forrester

Wood Pigeon
Collared Dove
Turtle Dove

Rufous Turtle Dove
Great Spotted Cuckoo
Cuckoo

Black-billed Cuckoo
Yellow-billed Cuckoo
Barn Owl

Scops Owl

Eagle Owl

Snowy Owl

Hawk Owl

Little Owl

Tawny Owl
Long-eared Owl
Short-eared Owl
Tengmalm’s Owl
Nightjar

Common Nighthawk
Chimney Swift
Needle-tailed Swift
Swift

Alpine Swift

Little Swift
Kingfisher
Bee-eater

Roller

Hoopoe

Wryneck

Green Woodpecker
Great Spotted Woodpecker

Lesser Spotted Woodpecker

Calandra Lark
Bimaculated Lark
Short-toed Lark
Crested Lark
Woodlark
Skylark

Shore Lark

Sand Martin
Swallow
Red-rumped Swallow
House Martin

Columba palumbus
Streptopelia decaocto
Streptopelia turtur
Streptopelia orientalis
Clamator glandarius
Cuculus canorus
Coccyzus erythrophthalmus
Coccyzus americanus
Tyto alba

Otus scops

Bubo bubo

Nyctea scandiaca
Surnia ulula

Athene noctua

Strix aluco

Asio otus

Asio flammeus
Aegolius funereus
Caprimulgus europaeus
Chordeiles minor
Chaetura pelagica
Hirundapus caudacutus
Apus apus

Apus melba

Apus affinis

Alcedo atthis

Merops apiaster
Coracias garrulus
Upupa epops

Jynx torquilla

Picus viridis
Dendrocopos major
Dendrocopos minor
Melanocorypha calandra
Melanocorypha bimaculata
Calandrella brachydactyla
Galerida cristata

Lullula arborea

Alauda arvensis
Eremophila alpestris
Aiparia riparia

Hirundo rustica

Hirundo daurica
Delichon urbica

SB 17 (3)

1994

>PPPPrrrrrrrrrrrrrrrrrrrrrrrrrrryrrrrrrrrrrrrrpyp

Richard’s Pipit
Tawny Pipit
Olive-backed Pipit
Tree Pipit

Pechora Pipit
Meadow Pipit
Red-throated Pipit
Rock Pipit

Water Pipit
Buff-bellied Pipit
Yellow Wagtail
Citrine Wagtail
Grey Wagtail

Pied Wagtail
Waxwing

Dipper

Wren

Dunnock

Alpine Accentor
Robin

Thrush Nightingale
Nightingale
Siberian Rubythroat
Bluethroat
Red-flanked Bluetail
Black Redstart
Redstart

Whinchat
Stonechat
Isabelline Wheatear
Wheatear

Pied Wheatear
Black-eared Wheatear
Desert Wheatear
Rock Thrush

Blue Rock Thrush
White’s Thrush
Siberian Thrush
Hermit Thrush
Swainson’s Thrush
Grey-cheeked Thrush
Ring Ouzel
Blackbird
Eye-browed Thrush

Scottish List

Anthus novaeseelandiae
Anthus campestris
Anthus hodgsoni
Anthus trivialis
Anthus gustavi
Anthus pratensis
Anthus cervinus
Anthus petrosus
Anthus spinoletta
Anthus rubescens
Motacilla flava
Motacilla citreola
Motacilla cinerea
Motacilla alba
Bombyeilla garrulus
Cinclus cinclus
Troglodytes troglodytes
Prunella modularis
Prunella collaris
Erithacus rubecula
Luscinia luscinia
Luscinia megarhynchos
Luscinia calliope
Luscinia svecica
Tarsiger cyanurus
Phoenicurus ochruros
Phoenicurus phoenicurus
Saxicola rubetra
Saxicola torquata
Oenanthe isabellina
Oenanthe oenanthe
Oenanthe pleschanka
Oenanthe hispanica
Oenanthe deserti
Monticola saxatilis
Monticola solitarius
Zoothera dauma
Zoothera sibirica
Catharus guttatus
Catharus ustulatus
Catharus minimus
Turdus torquatus
Turdus merula

Turdus obscurus

155

156 AWE Oreste

PrPPrrrrrrrrrPrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrrre,r

Dusky Thrush
Black-throated Thrush
Fieldfare

Song Thrush
Redwing

Mistle Thrush
American Robin
Cetti’s Warbler
Pallas’s Grasshopper Warbler
Lanceolated Warbler
Grasshopper Warbler
River Warbler

Savi's Warbler
Aquatic Warbler
Sedge Warbler
Paddyfield Warbler
Blyth’s Reed Warbler
Marsh Warbler

Reed Warbler

Great Reed Warbler
Thick-billed Warbler
Olivaceous Warbler
Booted Warbler
Icterine Warbler
Melodious Warbler
Dartford Warbler
Subalpine Warbler
Sardinian Warbler
Ruppell’s Warbler
Orphean Warbler
Barred Warbler
Lesser Whitethroat
Whitethroat

Garden Warbler
Blackcap

Greenish Warbler
Arctic Warbler
Pallas’s Warbler
Yellow-browed Warbler
Radde’s Warbler
Dusky Warbler
Bonelli’s Warbler
Wood Warbler
Chiffchaff

Turdus naumanni
Turdus ruficollis

Turdus pilaris

Turdus philomelos
Turdus iliacus

Turdus viscivorus

Turdus migratorius
Cettia cetti

Locustella certhiola
Locustella lanceolata
Locustella naevia
Locustella fluviatilis
Locustella luscinioides
Acrocephalus paludicola
Acrocephalus schoenobaenus
Acrocephalus agricola
Acrocephalus dumetorum
Acrocephalus palustris
Acrocephalus scirpaceus
Acrocephalus arundinaceus
Acrocephalus aedon
Hippolais pallida
Hippolais caligata
Hippolais icterina
Hippolais polyglotta
Sylvia undata

Sylvia cantillans

Sylvia melanocephala
Sylvia rueppelli

Sylvia hortensis

Sylvia nisoria

Sylvia curruca

Sylvia communis

Sylvia borin

Sylvia atricapilla
Phylloscopus trochiloides
Phylloscopus borealis
Phylloscopus proregulus
Phylloscopus inornatus
Phylloscopus schwarzi
Phylloscopus fuscatus
Phylloscopus bonelli
Phylloscopus sibilatrix
Phylloscopus collybita

ince 1992, a local Biological Records Centre "Fife
S Nature" has been established in Fife. Through special
surveys and a network of official local recorders, the centre
collects, analyses and monitors information on as many
biological groups as possible, as well as on habitats and sites
of natural history interest within the region. Information is
stored electronically and is available for purposes of
conservation, planning, research, education and general
interest.

A "Survey Pack" is available free by request from "Fife
Nature", and the centre also produces provisional atlases,
which will eventually lead to a series of fully illustrated books.
Available at present are

The Dragonflies of Fife: A Provisional Atlas £2 [{incl. p.+p.}
The Butterflies of Fife: A Provisional Atlas £2.50

The Mammals of Fife: A Provisional Atlas lune 1994 - price
on inquiry)

Others planned are A Fife Flora, a Bumble Bee Atlas and an
Amphibian/Reptile Atlas.

The centre is also involved with the Fife Ornithological Atlas
Group, which is currently (1991-95) carrying out surveys
leading to a Fife Breeding Bird Atlas and Monthly Distribution
Atlas of Birds in Fife.

Further information is available from Anne Marie Smout, Fife
Nature, Department of Economic Develoipment and Planning,
Fife House, Glenrothes, Fife KY7 5U. Tel 0592 754411 ext
3793.

SCOTTISH
NATURAL
HERITAGE

Female Mandarin Aix galericulata First breeding record in Scotland |
Steve Petty |

Semi-palmated Sandpiper Calidris pusilla On Stronsay 7th June 1993
Painting by John Holloway

Ne ;
jit y
ts f

Joe Eggeling on his last visit to the Isle of May in.June 1989 Keith Brockie

Pallid Harrier Circus macrourus
15th September 1993 Shetland Dennis Coutts

Colour separations by PAR GRAPHICS

THE COLOUR SECTION HAS BEEN SPONSORED BY FIFE REGIONAL COUNCIL.

zB

ie CHARTER FOR THE ENVIRONMENT

CHARTER FOR THE

ENVIRONMENT Fife's Environmental Charter highlights the Regional Council's approach to
tackling environmental issues and sets out the basis for the Regional Council's
existing and future environmental policies. The Charter is now accompanied by
the third action programme which outlines projects the Regional Council is in
undertaking itself or in partnership with others: a Nature Conservation
Fund, a Community Planting Scheme, and a Community
Environmental Improvement Fund and a Schools Environmental
Awards Scheme have been established, and a four monthly
Environmental Events Diary is produced.

Through the Charter, the Council has made a commitment to publish further
items in the Fife Heritage Series as a means of raising awareness of the rich
natural and historic environment. Titles currently available from the Dept. of
Economic Development and Planning are:

Fife's Early Archaeological Heritage - A Guide £2.50

Castles of Fife -A Heritage Guide £4.00

Topics to be published early in 1994 include:- Landforms, Townscapes, Abbeys
and Churches and a Heritage Guide to Inverkeithing.

For further information about the Fife Environmental Charter, please contact
Grace MacDonald or Andy Hills on 0592 754411 extension 6337

FIFE ARCHAEOLOGICAL SERVICE

Fife contains a wealth of archaeological sites ranging in date from prehistoric
settlements and forts dating back some 8,000 years, to industrial and military
remains of more recent times. Environmental archaeology has become a key
concern of the Regional Council as it can provide information about how the
natural environment has been altered by our ancestors. The Archaeological
Service is currently working with Scottish Natural Heritage to study and
interpret the settlement remains on the Isle of May National Nature Reserve.

The Regional Council are keen to promote the conservation of this rich heritage
and have published guides to sites which have been studied. These include:-

Balfarg - The Prehistoric Ceremonial Complex £3.00
St Monans Saltpans and the Lost Industrial Landscape £1.00
The Capital in the Kingdom: The Archaeology of Medieval Dunfermline £3.00

The Regional Council has an Archaeological Service based in the Department
of Economic Development and Planning, and is pleased to offer advice on all
aspects of the conservation of the historic environment. To receive advice please
contact Peter Yeoman or Sarah Govan on 0592 754411 Ext. 6153.

1994

rPrrrrrrrrrrrrrrrrrrrrrrrrrrrrPrrrrrrrrrrrrrrp>

Willow Warbler
Goldcrest

Firecrest

Spotted Flycatcher
Red-breasted Flycatcher
Collared Flycatcher
Pied Flycatcher
Bearded Tit
Long-tailed Tit
Marsh Tit

Willow Tit

Crested Tit

Coal Tit

Blue Tit

Great Tit

Nuthatch
Treecreeper
Golden Oriole
Brown Shrike
Isabelline Shrike
Red-backed Shrike
Lesser Grey Shrike
Great Grey Shrike
Woodchat Shrike
Jay

Magpie

Nutcracker
Chough

Jackdaw

Rook —
Carrion/Hooded Crow
Raven

Daurian Starling
Starling
Rose-coloured Starling
House Sparrow
Tree Sparrow
Red-eyed Vireo
Chaffinch
Brambling

Serin

Greenfinch
Goldfinch

Siskin

Scottish List

Phylloscopus trochilus
Regulus regulus
Regulus ignicapillus
Muscicapa striata
Ficedula parva
Ficedula albicollis
Ficedula hypoleuca
Panurus biarmicus
Aegithalos caudatus
Parus palustris
Parus montanus
Parus cristatus
Parus ater

Parus caeruleus
Parus major

Sitta europaea
Certhia familiaris
Oriolus oriolus
Lanius cristatus
Lanius isabellinus
Lanius collurio
Lanius minor

Lanius excubitor
Lanius senator
Garrulus glandarius
Pica pica

Nucifraga caryocatactes
Pyrrhocorax pyrrhocorax
Corvus monedula
Corvus frugilegus
Corvus corone
Corvus corax
Sturnus sturninus
Sturnus vulgaris
Sturnus roseus
Passer domesticus
Passer montanus
Vireo olivaceus
Fringilla coelebs
Fringilla montifringilla
Serinus serinus
Carduelis chloris
Carduelis carduelis
Carduelis spinus

157

158

rPrPrrrrrrrrprrrrrrrrrrrrrrrrrrrwmorrrrrrrrrrrrrr

R.W. Forrester

Linnet

Twite

Redpoll

Arctic Redpoll
Two-barred Crossbill
Common Crossbill
Scottish Crossbill
Parrot Crossbill
Trumpeter Finch
Scarlet Rosefinch

Pine Grosbeak
Bullfinch

Hawtinch

Evening Grosbeak
Black-and-white Warbler
Tennessee Warbler
Yellow Warbler
Chestnut-sided Warbler
Blackburnian Warbler
Cape May Warbler
Yellow-rumped Warbler
Blackpoll Warbler
American Redstart
Ovenbird

Common Yellowthroat
Hooded Warbler
Savannah Sparrow
Song Sparrow
White-crowned Sparrow
White-throated Sparrow
Dark-eyed Junco
Lapland Longspur
Snow Bunting

Pine Bunting
Yellowhammer

Cirl Bunting

Ortolan Bunting
Cretzschmar’s Bunting
Yellow-browed Bunting
Rustic Bunting

Little Bunting
Yellow-breasted Bunting
Reed Bunting

Pallas’s Reed Bunting

SB 17 (3)

Carduelis cannabina
Carduelis flavirostris
Carduelis flammea
Carduelis hornemanni
Loxia leucoptera

Loxia curvirostra

Loxia scotica

Loxia pytyopsittacus
Bucanetes githagineus
Carpodacus erythrinus
Pinicola enucleator
Pyrrhula pyrrhula
Coccothraustes coccothraustes
Hesperiphona vespertina
Mniotilta varia
Vermivora peregrina
Dendroica petechia
Dendroica pensylvanica
Dendroica fusca
Dendroica tigrina
Dendroica coronata
Dendroica striata
Setophaga ruticilla
Seiurus aurocapillus
Geothlypis trichas
Wilsonia citrina
Ammodramus sandwichensis
Zonotrichia melodia
Zonotrichia leucophrys
Zonotrichia albicollis
Junco hyemalis
Calcarius lapponicus
Plectrophenax nivalis
Emberiza leucocephalos
Emberiza citrinella
Emberiza cirlus
Emberiza hortulana
Emberiza caesia
Emberiza chrysophrys
Emberiza rustica
Emberiza pusilla
Emberiza aureola
Emberiza schoeniclus
Emberiza pallasi

ean mc RRP Caan aa

1994

Black-headed Bunting
Corn Bunting
Rose-breasted Grosbeak
Bobolink

Brown-headed Cowbird
Northern Oriole

>rPrrr>Y

Category D

D1 White Pelican

D1 Greater Flamingo
D1 Egyptian Goose
D1 Baikal Teal

D1 Saker Falcon

D2 Northern Flicker
D1 Cedar Waxwing
D1 Chestnut Bunting
D1 Red-headed Bunting
D1 Blue Grosbeak
D1 Indigo Bunting
D1 Painted Bunting

Scottish List

Emberiza melanocephala
Miliaria calandra
Pheucticus ludovicianus
Dolichonyx oryzivorus
Molothrus ater

Icterus galbula

Pelecanus onocrotalus
Phoenicopterus ruber
Alopochen aegyptiacus
Anas formosa

Falco cherrug
Colaptes auratus
Bombycilla cedrorum
Emberiza rutila
Emberiza bruniceps
Guiraca caerulea
Passerina cyanea
Passerina ciris

Typescript received 25 January 1994

159

160 Scottish Birds (1994) 17: 160-170

Short Notes

Mating times of Merlins

There are few British data on the mating times

-of Merlins Falco columbarius. In the North
American subspecies, however, Laing (1985.
Food habits and breeding biology of Merlins
in Alaska. Raptor Research 19:42-51)
observed Merlins copulating 11 times during
16.3 hours of observations (0.67 copulations/
hour) in Alaska. Sodhi (1991. Paircopulation,
extra pair copulation and intraspecific nest
intrusions in Merlins. Condor 93:433-437)
also noted 41 copulations in 679 hours of
observations (0.06 copulations/hour) in a
rather atypical urban population in Canada.
Because so little had been published on this
subject, | timed and logged the number of
copulations seen in three breeding areas in
upland Galloway in 1973-74 and 1977-78.

In Galloway, observed matings usually
occurred on boulders or on the ground near
nest sites but not on the nest itself. No
elaborate rituals preceded matings but either
sex would initiate copulations by calling and
sometimes bowing beforehand. Males
mounted females from behind, usually
dropping down slowly from a higher perch
with wings held in a ‘V’ position, and with tail
spread andlegs lowered. Females responded
by crouching with wings held slightly down
and tail fanned. Copulations usually lasted
10-15 seconds, the males slowly flapping
their wings. The first copulations occurred
some 30 days before egg laying (the fertile
period: pre-laying and egg laying) but none
was recorded after clutches were completed
(the non-fertile period: incubation, nestling
and fledging).

SB 17 (3)

The total number of matings recorded overall
was 22 copulations during 80 hours
observations (0.28 copulations/hour) lower
than Laing’s records but similar to Sodhi’s
findings in the fertile period (Table 1). Fifteen
copulations (68%) occurred during 34 hours
observations in the mornings (0730-1200
hours), five (23%) in 39.3 hours in the
afternoon (1200-1700 hours) andtwo (9%) in
6.3 hours in the evening (1700 hours to
sunset). It would seem that copulation times
during the day do differ significantly in
Galloway, with more than expected occurring
in the morning and less in the afternoon/
evenings (X2 =5.85, 1 df, p<0.02) (Siegel, S.
1956. Nonparametric statistics for the
behavioural sciences. McGraw-Hill, New
York). Twelve copulations in 56.3 hours
observations (0.21 copulations/hour) were
recorded during the early stages of pair
formation (pre-laying 1 - 23 April) and ten
copulations in 23.3 hours (0.43 copulations/

hour) were recorded just prior to egg laying ~

(27 April - 1 May). Thus Merlins appear to
copulate at a high frequency a day or two
before the first eggs are laid and nearly twice
as much as in the pre-laying period.

Sodhi thought it was unlikely that females
traded copulations for food in Canada andthe
same conclusion seemed to be the case in
Galloway: of 22 copulations, only three
(13.6%) occurred after males brought prey to
females. However, copulations seemed to
be associated with nest selection because
ten(45.4%) occurred before and after visits to

1994 Short Notes 167

Table 1. Number of copulations per hour during non-fertile (incubation, nestling and
fledging) and fertile (pre-laying and laying) periods in the Merlin in various localities.

No. of
Copulations/hour

Locality

Denali National

Park Alaska 0.67
Saskatoon

Canada (urban) 0.06
Upland

Galloway 0.28

No. of
Copulations/hour
Non-fertile periods

0.03

No. of Source
Copulation/hour
Fertile periods
0.67 Laing 1985
0.20 Sodhi 1991
NIL 0.28 This study

eee

nests by either sex. There was no evidence
of extra-pair copulations nor was there any
interference during copulations; the only
evidence of an extra bird present was when a
strange male flew over a resident male on 1
April 1973, and when a male and female
chased a second female in another year
outwith this study. Mostcopulations occurred
before noon.

This agrees with the times ©

recorded in other falcons e.g. Kestrel Falco
tinnunculus (Village, A. 1990. The Kestrel.
Poyser, London) and the Peregrine Falcon
Falco peregrinus (Ratcliffe, D. 1980, 1993.
The Peregrine Falcon. Poyser, Calton and
London). | would like to thank Dr. Jim Reid for
kindly carrying out the statistical analysis.

R.C. Dickson, Lismore, New Luce,
Newton Stewart DG8 OAJ.

7162 Short Notes

Merlin chick killed by adder

Merlins Falco columbarius may suffer higher
rates of egg and brood predation from ground
nests than in tree nests (Little, B. & Davison,
M. 1990. Bird Study 39: 13-16). Predation
accounted for 43% of 104 nest failures in a
Grampian study (Rebecca, G.W. et al. 1992.
Scot. Birds 16: 165-183), where four species
of mammal predators were identified. On
drier moors, adders Vipera berus share the
habitat with Merlins, and are potential
predators: Macintyre (1936. Wildlife in the
Highlands. Batchworth, London) found Merlin
eggs inside an adder which he killed at a nest.
Predation by adders may be under-recorded,
since no evidence is left at the nest. This note
reports that losses to adders can continue
into the later nestling stages.

On 30 June 1993, in the Galloway Forest
Park area of south-west Scotland, '| visited a
Merlin nest immediately following a prey
delivery. Thenestcomprisedaroughly circular
platform of thin heather twigs, tramped flat, in
tallheather. An adult male adder was basking
in the centre of the platform, sheltered from
the wind while two c. 3-week old Merlin chicks
were at the edge, about 10cm fromthe adder,
which moved off when | stood at the nest,
revealing an addled egg. One of the two
chicks was freshly dead andstill warm with no
visible injury other than a small amount of

SB 17 (3)

fresh blood on its crown. It was in good
condition, weighing 152g with outer primaries
20-25mm emerged. A post mortem
examination at alater date confirmed thatthe
chick had ‘suffered acute death’, consistent
with an adder bite.

Burgess et al. (1990. RSPB Cons. Review 4:
32-35) found that small areas of bare ground,
cieared on heathland to provide nest sites for
Nightjars Caprimulgus caprimulgus, were
used as basking sites by adders. In the
Galloway Forest Park R.C. Dickson (pers.
comm.). also disturbed an adderfroma Merlin
nest (from which small young had previously
disappeared), in 1977. In the present
instance, it seems likely that the reptile was
making use of the nest platform as a sheltered
basking site in the deep heather. Intentional
predation was improbable, since the adder
was incapable of swallowing a prey item as
large as the Merlin chick, and may have
struck at it in a defensive response.

| am grateful to Neil A. Forbes, of the Clock
House Veterinary Hospital at Stroud, for post
mortem examination of the carcase, and to

G.W. Rebecca and R.C. Dickson for helpful

comments on an earlier draft.

Geoff Shaw, Forest Enterprise,
South Scotland Region,
55-57 Moffat Road, Dumfries. DG1 1NP.

1994

Short Notes 163

Site fidelity of Jack Snipe on migration?

Freshwater Haven, one mile north-east of
Gullane, is atypical East Lothian bay, backed
by a double line of sand dunes stabilised by
marram grass. The deep trough between the
two dune-lines is normally totally dry, and was
so on 7 August 1991 when | flushed a Jack
Snipe Lymnocryptes minimus there. It was
there again on almost every one of the next 11
days until 18 August.

This record on its own is mildly noteworthy for
two reasons:- the habitat was totally atypical
(though something similar was recorded
almost 100 years ago at the St. Andrews links
- Zoologist 1901: 108), and the date was
unusually early. One sees few Jack Snipe in
this country before October. Indeed a bird
seen at an undisclosed locality in Britain
between 13-23 August 1977 was included in
the annual report ‘Rare breeding birds in the
United Kingdom in 1978’ (Brit. Birds 73:19).
There was no reason to suspect breeding in
the present case, but there is a curious twist
to the story.

At the east end of the trough between the two
dune-lines there is in some years a small pool
of water which accumulates by underground
seepage from the spring, 50 yards further
inland, which gives the bay its name. There
had been such a pool in the spring of 1991
when on 11 April! flushed the first Jack Snipe

that | had ever recorded in this area. It was
from this same, now totally dry, hollow that |
first flushed the August bird, although on all
subsequent occasions | found it resting afew
yards away, higher up on the dune slopes.

These records raise interesting speculations.
At the simplest level, it is surprising that the
August bird should choose to day-roost (for
there can be no question of its feeding there)
for 12 days at precisely the same spot where
it was so regularly disturbed. More intriguing
is the possibility that (as seems highly likely in
view of the unsuitability of the habitat) the
same individual was involved in both the April
and the August records. BWP (3: 403-409)
has nothing to say about the site fidelity of
Jack Snipe either on their breeding grounds
or in their wintering quarters, although
evidence of the latter is provided by the
recoveries of ‘two ringed in Wigtown and
Shetland and recovered inthe same areas, in
November and March, one and three years
later’, quoted in Birds in Scotland : 189.
Perhaps these East Lothian records provide
the first tentative evidence that this site fidelity
may also extend to stopping places on
migration?

Dougal G. Andrew
Muirfield Gate

Gullane

East Lothian EH31 2EG

164 Short Notes

SB 17 (3)

First breeding records of the Mandarin in Argyll

The Mandarin Aix galericulataoccurs naturally
in north-east Asia and Japan (Cramp &
Simmons 1977. The Birds of the Western
Palearctic, Vol.1 Oxford). The population in
Britain originates mainly from introductions
earlier the century (Lever 1977. Naturalised
animals of the British Isles. Hutchinson). Their
present breeding range is expanding and
concentrated in south-east England (Davies
1998. Bird Study 35: 203-208). Davies (Loc.
cit.) estimated their population at just under
7000 birds. The breeding population in
Scotland is much smaller and centred on the
River Tay, but with sporadic records elsewhere
(Thom 1986. Birds in Scotland. Poyser).
Observations of birds on Loch Lomond in the
1970s were the closest to Argyll and thought
to have come from a local collection (Thom
Locscit.):

In each of the years 1991-93 one pair of
Mandarins successfully bred at Loch Eck, in
Cowal, south Argyll (Table 1). All breeding
attempts were in Tawny Owl Strix aluco
nestboxes (Petty 1987. Quarterly Journal of
Forestry 81: 103-109). They usedtwo boxes
20m apart, that were fixed to oak trees facing
out over the loch. The first breeding attempt
in 1991 occurred after the box was last
checked on 11 April. When the box was
checked for the first time in 1992, four old
unhatched eggs in a down nest were
discovered. The presence of egg fragments
and membranes indicated than an unknown
number of eggs had hatched in 1991. The
number of eggs hatching in 1992 and 1993
was ten and five respectively (Table 1).

Table 1. Details of three breeding records by the Mandarin at Loch Eck in Argyll.

Parameter 1991
Nest box number T261B
Clutch size -
Unhatched eggs 4
Hatched eggs -
Laying date * -

Egg length cm (SE) 5.26(0.03)
Egg width cm (SE) 4.00(0.01)

1992 1993
T261A T261A
14 i3
4 8
10 5

18 April -
5.23(0.04) 5.25(0.04)
3.91(0.04) 3.95(0.01)

“ date when the first egg was laid, based on an interval of one day between laying (Cramp

& Simmons 1977).

The egg measurements in 1991 were from the unhatched eggs only.

1994

The low hatching success in 1993 appears to
have been influencedby a Goosander Mergus
merganser that laid one egg in the box part-
way though the laying period of the Mandarin.
Two Mandarin eggs were foundto be cracked
after the appearance of the Goosander egg,
suggesting that the Goosander may have
beenresponsible. Goosander eggs are much
bigger than Mandarin eggs, and because of
this size difference, the Mandarin may have
been less able to incubate the clutch, resulting
inthe lowhatch-rate. The Goosander egg did
not hatch.

The female Mandarin was hand-caught in the
nest box towards the end of incubation in
1992 and 1993. She was ringed when first
caught in 1992, and the same bird was
recaptured in 1993. (Plate no. 1). There were
no other marks on the duck to indicate her
origin. Nor have we been able to locate
wildfowl collections in south and mid-Argyll
that admit to losing Mandarins, thus the origin
of this pair is unknown.

Short Notes 165

The nestboxes used for breeding had been in
place since 1988, and many other boxes
suitable for Mandarins had been available
since 1983 andchecked annually (Petty 1992.
Ecology of the Tawny Owl Strix aluco in the
spruce forests of Northumberland and Argyll.
Ph.D. Thesis, The Open University).
Therefore, we consider these breeding
attempts at Loch Eck to be a recent
phenomenon, rather than one that had been
under-recorded in the past.

However, it should be noted that Mandarins
are difficult to detect, even in an area with a
high breeding density, and particularly when
breedingin naturaltree cavities (Davies 1985.
BTO News 136:12). Away from the nest we
have only seen Mandarins three times in
three years, in an area where we undertake
much fieldwork on other species. It will be
interesting to see if these successful breeding
attempts result in the colonisation of suitable
habitat elsewhere in Argyll.

S.J. Petty and D.I.K. Anderson, Wildlife Ecology Branch,
Forestry Authority, Ardentinny, Dunoon, Argyll PA23 8TS.

166 Short Notes

SB 17 (3)

Discovery of the first British clutch of Slavonian Grebe

eggs in a museum collection

Major William Stirling of Fairburn (1859-1914)
gained a reputation for his ability to find the
nests of such secretive species as Siskin
Carduelis spinus, Scottish Crossbill Loxia
scotica, and Greenshank Tringa nebularia.
He collected the eggs of these and other
species onhis estate in Easter Ross (Highland
Region) and neighbouring districts between
1895 and 1910, both for his own collection
and to be exchanged with other collectors of
the eggs of foreign species. Sir Roderick
Stirling, William Stirling’s grandson, donated
the substantial collection and uncompleted
catalogue to Inverness Museum and Art
Gallery in 1983.

Since August 1992 | have sorted out all the
clutches and catalogued the entire collection
during the course of which work | discovered
a clutch of three heavily stained grebe eggs,
with fragments of nest material still attached,
which were notlisted in the original catalogue.
Although three eggs would form an unusually
small clutch for any grebe, incubation was
well advanced to judge from the degree of
staining of the eggs from nest vegetation, and
the clutch must have been completed. The
damaged state of one of the eggs could
indicate that the clutch had been larger but
some eggs had been broken. One of the
eggs bears the following mark in William
Stirling’s hand:
Pod. auritus
Loch Laite
Inverness
W.S
17.V.09

which implies that the eggs are those of the
Slavonian Grebe Podiceps auritus, and were
collected by William Stirling (W.S) at Loch
Laite, on 17 May 1909. The other two eggs,
one of which is cracked, bear the ‘set mark’
17.V.1909. The measurements of the eggs
(45.25 x 30.10, 45.80 x 30.20, ?x 30.70, tothe
nearest 0.05mm) agree well with those
published for Slavonian Grebe eggs (Cramp
& Simmons 1977. The Birds of the Western
Palaearctic. Oxford. Vol 1). There is no Loch
Laite in Inverness-shire, but there is a Loch
Laide (pronounced ‘Latch’) with an adjacent
settlement called Lochlait, which would appear
to be the locality from which the eggs were
collected.

The original reference regarding early
breeding attempts by Slavonian Grebe
(Ogilvie-Grant, W.R. 1910. Bull. Br. Orn. Club.
25: 75-76) state that a bird with a nest but no
eggs was shot and stuffed in 1908, after being

seen in June of the same year by aMr. H.M. > |

Warrand. The locality given was “a small
reedy sheet of water in the hills of Inverness-
shire”, a description which applies to Loch
Laide as well now as it surely would have
done in 1908 (it should be noted that this
description does not readily apply to Loch
Ruthven, which is traditionally regarded as
the Slavonian Grebe’s centre of distribution in
Scotland).

1994

Ogilvie-Grant, still quoting Warrand, writes:

“| was cheered, however, to learn the
following year(1909) that one or two pairs
had appeared at the same loch, but soon
afterwards heard that the nests had been
ruthlessly robbed by a private collector’.

Given that no other Slavonian Grebe
breeding territories were known in 1909, it
would appear that the ‘private collector’ was
William Stirling. None of the other breeding
attempts prior to 1909 had produced eggs
(Barra 1898 and Arisaig 1907 in Inverness-
shire; see Ogilvie-Grant 1910) and the
reported breeding near Gairloch (Wester
Ross, Highland Region) in the 1880s and
early 1890s supposedly referred to the Little
Grebe Tachybaptus ruficollis (Evans, A.H.
1892. Ann. Scot. Nat. Hist. 192: 171-172),
although | suggest this reidentification is
open to some doubt given that the birds were
seen by the great H.E. Dresser. Stirling’s
clutch of three eggs therefore represents the
first proven egg laying event (or at least the
second, if there were indeed two pairs in
1909) for the Slavonian Grebe in Britain.

Short Notes 167

The acknowledged 1908 date for first
breeding, cited in BWP, would appear to be
based on the presence of a single bird with a
nest which was never seen to have a mate or
to lay eggs; this date should not be accepted.

Acknowledgements

| must thank the following for their help:
Stephen Moran (Assistant Curator, Natural
Sciences) of Inverness Museum for
encouraging my work on the collection; the
librarian at the George Waterston Library for
sending me a copy of Ogilvie-Grant’s paper,
Malcolm Harvey and Roy Dennis for their
comments. Sir Roderick Stirling, who
generously donated the collection, read a
draft of this paper.

Henry A. McGhie,
Nurse’s House
West Road
Muir-of-Ord
Ross-shire V6 7TD.

768 Short Notes SB 17 (3)

Rook flight-line across Firth of Forth

In winter, Rooks Corvus frugilegus feed in
dispersed flocks by day and fly to large
communal roosts for the night, often via
intermediate points where flocks may join
others before goingto the final roost. Usually,
each roost is large, comprising birds from a
number of rookeries in the surrounding area
(Munro, 1971. Scottish winter Rook roost
survey - southern Scotland. Scoit. Birds 6:
438-443; Coombs, 1978. The Crows, a study
of the corvids of Europe. Batsford, London;
Goodwin, 1986. Crows of the world. British
Museum (Natural History), London.).

Time

Before dusk.
Near dusk.
Near dusk and
during darkness.

Date
13.10.91
10.11.91
8.12.91

TORI O2

14.11.92
W2sr2.o2
30.1.93

Late afternoon.
Near dusk.
Before dusk.
Near dusk
(4-4.30pm).

Rooks were not seencrossingthe Forth earlier
during the day on these dates or on other
days. The observations should not be taken
to indicate the numbers of Rooks which may
be involved, as birds could have passed
before or after, but they do suggest that a
regular movement was occurring.

Jackdaws Corvus monedula accompanied
the Rooks crossing the Forth in October,
November and December 1991, including
about 100 Jackdaws on 8 December 1991.
No Carrion Crows Corvus corone were seen
with these flights, although not infrequently

There appears to be a regular winter flight-
line across the Firth of Forth. In late afternoons,
| have seen Rooks arrive at the Lothian coast
from somewhere south of Dalmeny House.
Then from the shore at NT 174777 near Long
Green, usually after descending temporarily
into trees, they set out over the water keeping
astraightn.n.e. direction over Inchcolmisland
and on to the Fife mainland. This flight
crosses 7.5km of water. The following
observations were made after doing shore-
bird counts; | made no attempt to watch
Rooks over constant time periods or at
particular times of day.

numbers of Rooks

some.

some.

400 in groups, plus more
continuing while getting dark.
some.

groups of 5-15.

none.

280 in groups of 12-100.

single or pairs of Carrion Crows do cross the

Forth by day.

Rook winter roosts for all of Lothian were
surveyed and mapped by Munro (1948. Rook
roosts in the Lothians, winter 1946-47. Scott.
Nat. 60: 20-9) who showed that Rooks from
Cramond then roosted near West Calder and
Rooks from South Queensferry near Bathgate.
Neither he nor Smout (1986. The Birds of
Fife. Donald, Edinburgh) mention Rooks
crossing the Firth of Forth.

H.E.M. Dott, 70 Findhorn Place
Edinburgh EH9 2NW.

1994

Short Notes 169

The diet of nestling Corn Buntings on North Uist - insects not grain.

Watson states that the diet of nestling Corn
Buntings, Miliaria calandra, is not well known
but that he has observed adults provisioning
their young with unripe grain on numerous
occasions (Watson 1992. Scott. Birds 16:
287). The nestling diet for this species has
also been described vaguely as small beetles
(Walpole-Bond 1938. A History of Sussex
Birds Vol.1), greencaterpillars, craneflies and
an ‘unidentified whitish substance’
(MacDonald 1965. Scott. Birds 3: 235-246),
and grasshoppers, grubs and caterpillars
(Ryves & Ryves 1934. Brit. Birds 28: 2-26 &
154-164). The only real attempt to quantify
the diet of nestlings comes from work in
Germany by Schmidt and Gliemann (in
Gliemann 1972. Die Grauammer) who, intwo
separate studies, used neck collars on a total
of four broods of chicks to assess food intake.
The major food items found in their studies
were caterpillars (Lepidoptera larvae) (30.2%
of items), grasshoppers (Orthoptera) (13.6%),
Lepidoptera pupae (11.3%), beetles
(Coleoptera) (9.9%), earwigs (Dermaptera)
(8.5%) and wheat seeds (16.1%).

In the summer of 1989 we carried out a study
of nestling diet in Corn Buntings at Balranald,
North Uist. We quantified the diet using
faecal sample analyses from nestlings and
also six gizzard samples taken from chicks
which died naturally in the nest. Sixty-two
faecal samples were collected from 23 nests.
The overall proportions of food types were
similar in both the gizzard andfaecal samples,
SO we can assume that the results of faecal
sample analysis closely reflect the diet of the
nestlings.

We found thatthe diet consisted of harvestmen
(Opiliones; found in 67.7% of samples),
craneflies (Tipulidae; 61.3%), plant material
(61.3%), hovertlies (Syrphidae; 51.6%), adult
beetles (Coleoptera; 56.5%), adult moths
(Lepidoptera; 29.0%), other flies (Diptera;
25.8%), caterpillars (Lepidoptera; 25.8%),
grasshoppers (Acrididae; 24.2%), pupae
(Lepidoptera: 17.7%) and small numbers of
sawflies (Hymenoptera), earwigs
(Dermaptera), beetle larvae (Coleoptera),
spiders (Aranaea), terrestrial snails
(Gastropoda) and plant hoppers (Homoptera).
Nearly all the harvestmen (Opiliones) were
Mitopus morio (F.) and most of the hoverflies
(Syrphidae) were Helophilus sp. or Rhingia
campestris. The beetles were represented
by members of the families Scarabeidae and
Curculionidae. Much of the plant material
was pollen, mainly from grasses, and was
recorded in 29 samples (46.8%), usually in
only small amounts. Seeds of any kind were
rare and most often absent.

The results show that Corn Bunting nestlings
on North Uist are fed arange of invertebrates,
mainly harvestmen, craneflies, hoverflies and
beetles. It is perhaps surprising to find
hoverflies playing so large arole in the diet as
these tend to be fast flying and highly
manoeuvrable insects, as are grasshoppers
and plant hoppers. A possible explanation is
that hoverflies are taken early in the day
before they are warm enough to fly, and this
may also apply to the craneflies. The high
incidence of harvestmen is also of interest
because these animals are generally
considered to be distasteful due to the
secretion of noxious chemicals from their
coxal glands.

170 Short Notes

Watson found that unripe grain was more
often provided on cold days or when insects
were not abundant, and the point of this note
is to show that, under different conditions,
Corn Buntings will prefer to select invertebrate
food when provisioning their nestlings. On
North Uist the agricultural regime tends to be
non-intensive and pesticide sprays are less
commonly use than on the mainland, so
invertebrates may be more available than at
Watson’s study site. Cereal crops were

SB 17 (3)

available to forage from if the parents had
preferred to provide seeds to their nestlings.
Perhaps these observations provide a partial
explanation forthe decline of the Corn Bunting
over most of Britain. If young elsewhere are
generally being reared on suboptimal food
then we would expect to see a decline in
chick survival and recruitment in comparison
with the North Uist population, where chick
starvation is a relatively rare form of nest
failure (Hartley & Shepherd 1994 Ardea in
press).

lan R. Hartley, Department of Zoology, University of Cambridge,

Downing Street, Cambridge CB2 3EJ.

Donald L.J. Quicke, Department of Biology, Imperial College at

Silwood Park, Ascot, Berkshire SL5 7PY.

Scottish Birds (1994) 17: 171-172

Correspondence

Correspondence 17a

(The Editor welcomes correspondence on suitable topics in Scottish Birds. It is essential,
however, that all letters are addressed to the Editor and that personal or libellous

comments should be avoided. Eds)

Pink and polluted Peregrines

Since | am possibly the only person around
who has seen both the Mediterranean and
Cape Verde Peregrine Falco peregrinus
brookei and F.p. madens and their ally the
Barbary Falcon Falco pelegrinoides, may |
comment on Mike Trubridge’s report of a
potentially similar pink Peregrine and chicks
seen in Central Scotland (Scott. Birds 17: 68-
69)? While these birds are normally rufous or
cinnamon around the head and flanks, the
colour did not appear either ‘bright salmon
pink’ or concentrated on the underparts, and
in brooke/at least the chicks are not noticeably
pink either. Therefore, as in the case of the
birds potentially oiled by Fulmars Fulmarus
glacialis (Scott. Birds 16: 290, 46-48, 17: 69),
could this also be due to contamination by
some red substance, possibly sheep-marker
or paint, left in the nest or some place
frequented by Peregrines, or used in some
misguided marking experiment or practical
joke, and transferred to the chicks when they
were brooded?

While so far | have failed to detect any oiled
Peregrines along the north-east Scottish
coast, one plucking-station on a projecting
bank is regularly littered with not only the
remains of gulls and auks but also Fulmars in
varying states of decay, so that it would
appear the Peregrines must be quite capable
of catching Fulmars safely, and any pollution
with their oil may arise through squabbling
over nest-sites. It is noticeable that, while
there are a limited number of huge, old-
established, but sharply-localised Fulmar
colonies within the breeding range of the
Peregrine around Arctic North America, the
two species have only recently started to
come into wide contact during the breeding
season in Europe, so that any extensive
interaction between them must be avery new
development.

W.R.P. Bourne, Department of Zoology, Aberdeen University,

Tillydrone Avenue, Aberdeen AB9 2TN.

172 Correspondence

Spring passage of Skuas in Outer
Hebrides

R.D. Murray is not altogether correct insaying
(Scott. Birds 17:110) that the spring passage
of skuas off the Western Isles was overlooked
until recently. Harvie-Brown & Buckley (A
Vertebrate Fauna of the Outer Hebrides. 1888.
p. 151) include the following in their account
of the Pomarine Skua Stercorarius pomarinus:
‘There cannot be any doubt as to its frequent,
if not regular, summer visits to the coasts of
these islands, and the seas to the west of
Lewis, most of such birds proving to be old
birds in most perfect plumage. It frequents
the harbour of Carloway on the west of Lewis,

SB 17 (3)

and the seas over the great cod-banks
between that and the Flannan Islands, as
also still further to the westward, where we
have shot them from the deck of our yacht’.
Harvie-Brown later addedthe further comment
that ‘These birds appear to frequent the
ocean and seas of the Outer Hebrides in
some numbers every summer of late years.
The line of their migration towards the north
appears to be further west than the shores of
the Outer Hebrides’ (Annals of Scot. Nat.
Hist. 1903: 17).

Dougal G. Andrew, Muirfield Gate, Gullane, East Lothian EH31 2EG

Scottish Birds (1994) 17: 173-177

Rare Migrants

Rare Migrants 173

(It has been decided by the Editorial Committee that full descriptions will appear in Scottish

Birds only of species which are new, or at most second records, for Scotland.

Eds)

Semi-palmated Sandpiper on Stronsay; second Scottish record

Whilst filming seals during the afternoon of 7
June 1993, Mike andLynn Johnson noticed a
small party of waders flying towards them.
Fortunately the birds settled inthe ‘frame’ and
Mike continued filming the group as they fed
along the shoreline.

Three were obviously adult Dunlin Calidris
alpina but the fourth bird was considerably
smaller and, not being sure of the identification,
Mike and Lynn returned to the Stronsay Bird
Reserve where they were staying andshowed
the film to myself and Joyce Maples who was
also staying on the reserve. The bird looked
very interesting to say the least, lacking any of
the bright rufous found in summer Little Stint
Calidris minuta and we decided to have a
hasty tea and return to the site.

The bird was relocated at approx 2030hrs
and watched until 2200hrs during which time
we managed to obtain excellent views down
to 20ft for prolonged periods. It was obviously
very small with an attenuated rear-end and
knowing some of the problems of stint and
peep identification we collected as much detail
as we could before poor light forced us to
return to ‘Castle’, where my wife Sue had
been searchingall available literature to assist
with the identification.

After much searching, we came to the
conclusion that our bird was a Semi-palmated
Sandpiper Calidris pusilla and the following
day Mike Johnson obtained excellent views

of the webbing between the toes which
eliminated all others except Western
Sandpiper Calidris mauri. Western had
already been eliminated on bill shape and
length andlack of any rufous to the upperparts.
Although the bird was present up until mid-
afternoon on 8 June, it could not be located
later that day and was not seen again.

Description

Small calidris wader similar in size to Little
Stint but ‘rear-end’ more attenuated, wing-
tips level with tip of tail.

General appearance rather greyish-fawn with
no rufous in plumage. Some warm brown in
cheeks and sides of crown and tertial edges
rather brighter-edged than rest of wing
feathers. One row of scapulars very dark-
centred, contrasting with rest of upperparts
and one row of lower scapulars with distinct
anchor-shaped marks. Underparts white with
fine dark streaking to breast and breast-sides
and afew dark marks onto flanks. The mantle
was rather plain with streaks, lacking the
bright pale braces of Little Stint. There was a
large dark spot immediately before the eye.
The tertials covered all but the very tips of the
primaries.

In flight the bird showed a rather indistinct
pale wing-bar, less obvious that that of Little
Stint.

174 Rare Migrants

The legs appeared black but when seen at
very close range were in fact an extremely
dark green. (This seems to contradict the
generally held view that this species is one of
the black-legged stints, but e.g. Hollom. 1960
The Popular Handbook of Harer British Birds
states : ‘legs very dark green, appearing
black’.)

The bill was very distinct when viewed head-
on. It was very broad-based and had a
spatulate tip. Viewedfromthe side it appeared
deep-based and ended in a ‘droop-tip’.

The feeding action was quite distinct, being
generally rather plover-like, slower and more
deliberate that Little Stint.

Pallid Harrier in Shetland; second
Scottish record

On 15 September 1993 at Exnaboe, Shetland,
Dennis and John Coutts found a ‘ringtail’
Harrier Circus sp. flying over the main road at
Toab, South Mainland, Shetland. Their
attention was immediately drawn to the bird’s
relatively small size, bright rusty-orange
underparts and almost wholly dark
secondaries and inner primaries. Their initial
thought was that the bird was perhaps a
juvenile Montagu’s Harrier C. pygargus. They
followed the bird until it perched on a fence
post in nearby Exnaboe where they watched
it for 15 minutes, noting the well marked facial
pattern, consisting of a black loral line
continuing through the eye and joining a
broad patch at the ear coverts which
connected the lores, with a whitish patch
below the eye and unmarked rusty-orange
underparts. They informed me of their
discovery, and we were able to relocate the
bird, which, fromtheir description, |suspected
might be a juvenile Pallid Harrier, C.

SB 17 (3)

The call was heard on several occasions
when the birdtookto the wing. It was a rather
dry ‘drrrp’, completely different to the normal
‘chit’ of Little Stint, rather husky and flat.

The record was accepted by the BBRC and
constitutes the first occurrence of the species
in Orkney and only the second for Scotland.
The usual range of the species is North
America. It is interesting to note that Semi-
palmated Sandpipers were recorded in East
Anglia (May ‘93) and Spitzbergen (late June
‘93). Perhaps the same bird?

John Holloway,
‘Castle’, Stronsay,
Orkney.

macrourus. |notedthe unstreaked underparts
and abrief glimpse of the head pattern showed
both the broadness and the paleness of the
collar which encircled the head. As it flew
around the field, | scribbled down some notes
and mentally compared it to all the juvenile
Montagu’s | had seen when | was involved in
protection work on that species in Norfolk in
1986. The flight of this bird was slightly
heavier and less buoyant than that of a-
Montagu’s, with a fairly broad wing base that
lacked the raised hand associated with
Montagu’s, the hand itself appearing relatively
short andthe scapular and covert fringes and
tips on our bird looking tan-buff, not rufous as
on Montagu’s. We sawthe bird briefly on two
other occasions we did not, however at this
stage note dark semi-collar that borders the
pale collar, which was the most important
feature. When John Clifton arrived with a
visiting birder John Miller, the bird was flushed
again in poor light. Overnight, | read the
literature (See references) associated with
the Hen Harrier of the North American race
C.c. hudsonius and withthe rare rufous morph

1994

juvenile cyaneusandchecked andre-checked
my field notes against descriptions of harriers
| had built up over the years. The bird was
found shortly after dawn the following morning,
distantly perched side on. | noted the extent
of the dark semi-collar indicating that it was a
Pallid, but we really needed to see it in more
favourable light. Unfortunately, | had work
commitments and left the scene. Eventually
however, Mick Mellor and Nick Dymond had
superb views as it flew over the road exhibiting
all the features described, including the semi-
collar. At 1600hrs it was last seen drifting
north.

Description

General Size and Structure: aa lightly built
harner with slim tail and absolutely no bulk to
underbody. Similarin size and shape to Montagu’s
Harner, although direct comparison was only made
with a perched Hooded Crow Corvus corone comix,
with which it appeared to be about the same size,
but obviously much longer winged. The flight was
light, but not as buoyant as Montagu’s, probably
due to the shorter wings making it look more
‘compact. The usual flight consisted of gliding on
slightly raised wings but also sometimes almost
level wings.

Head: well defined facial pattem consisting of
blackish lores extending through eye to form eye-
stripe which joined a broad blackish patch on the
rear ear-covert region which also continued to
meet the lores, forming a complete ear-covert
surround. Thus surround was at it,s broadest on
the outer and lower edge. A white patch below the
eye gave a strong contrast with this surround. A
narrow creamy-white, but distinctive supercilium
extended from the creamy-white lower forehead to
the upper rear of the dark ear covert surround,
where it joined an obvious and broad whitish collar,
which bordered the lower edge of the ear-coverts
and extended beneath the lores and also extended
around the back of the head, where it formed a
slight inverted ‘V. A uniform dark brown broad
band from the nape extended around the sides of

Rare Migrants 175

the neck, forming a semi-collar, which contrasted
strongly with the pale collar.

Upperparts: mantle dark brown with thin but
distinct warm buff tips and fringesto feathers. Back
dark brown with traces of buff fringes and tips to
feathers. Obvious white rump patch, appearing as
broad as Hen Harner. Long thin tail, with at least
four thin dark tail-bars contrasting with greyish
brown bars. A broader dark brownish-black
subterminal band was bordered on the postenor
edge by creamy-white tip.

Underparts: throat, breast, belly, flanks, ventral
region and undertail coverts unmarked bnght
orange-rufous.

Upperwing: scapulars, lesser, median, greater
and primary coverts dark brown with distinct warm
buff tips, although the scapulars were both fringed
and tipped warm buff, and because of the relative
small size these feathers formed a striking
upperwing panel in flight. The greater coverts were
noticeable darker than the othercoverts, appearing
almost black. Dark brown tertials with warm buff
fringes and tips. Secondaries appeared wholly
blackish on the closed wing, but in flight exhibited
thin buff tips forming a trailing edge. Thin whitish
tips to blackish primaries. Three, sometimes four
prominent primaries were exposed on the open
wing in flight.

Underwing: underwingcovertsbright rusty orange
contrasting strongly with almost wholly black
secondaries. Silver-white primaries with dark
transverse barring across whole width except at
base where they appeared unmarked forming a
distinct place area which contrasted with dark tips
to the primary coverts. Tips to the three or four

_ ‘exposed’ primaries were blackish.

Bare parts: views attained could not allow much
bill detail to be noted although it appeared to be
small harner-type bill with yellow on upper mandible
and greyish on lower mandible contrasting with
darkertip. Legs and feetdark yellow. Eye appeared
dark.

176 Rare Migrants

Range and Status

Pallid Harrier breeds in dry temperate steppe
zones in a belt that extends from eastern
Europe across the USSR to central Asia and
winters chiefly in Africa and southern Asia. It
is a rare, but increasingly regular vagrant to
western Europe, particularly Scandinavia and
the low countries. If accepted by The British
Birds Rarities Committee, this bird will
constitute the second record for Scotland and
the fourth record for Britain and Ireland. The
three previous accepted British records are
as follows (Dymond et a/. 1989):

Shetland: Fair lsle, male, from about 24 April
to 8 May 1931 (shot).

Dorset: Studland, male, 11 April 1938.
Yorkshire: Hutton Cranswick, immature male,
shot on 2 October 1952.

Summary

A juvenile Pallid Harrier Circus macronus
was present in the Sumburgh and
Dunrossness area of Shetland from 15-16
September 1993. Upon acceptance by BBRC,
this bird will constitute the second record for
Scotland andthe fourth for Britain and Ireland.

Ceiti’s Warbler in Edinburgh: a
new bird for Scotland

On 5 October 1993 Mike Shepherd was
handed a freshly dead bird that had been
found beneath a window of the Scottish
Natural Heritage offices at 2 Anderson
Place in Leith, Edinburgh. Incredibly the
bird turned out to be a Cetti’s Warbler
Cettia cettithat had presumably flown into

SB 17 (3)

References

Dymond, J.N., Fraser, P.A. & Gantlett, S.J.M.,
1989. Aare Birds in Britain and Ireland.
Calton.

Forsman, D. Hybridising Harriers. Birding
World 6:313.

Jonsson, L. 1992 Birds of Europe. London.

Porter, R.F., Willis, |., Christenson, S. & Pors
Nielson, B. 1986. Flight Identification of
European Raptors. Calton.

Acknowledgements

Thanks are due to Dennis and John Coutts for
initially informing me of the bird’s presence,
as are thanks to Steve Gantlett and Mick
Mellorfor useful discussion on juvenile Harrier
identification.

Hugh Harrop, Fairview,
Scatness, Virkie, Shetland ZE3 9JW.

a window the night before and even more
remarkably bore a French ring. It was later
found to have been ringed as a first-year bird
at Wissant, between Cap Gris-Nez and Calais,
on 24 August 1993 (P. Rauvel & C.
Duponcheel pers. comm.).

The bird was taken to the Royal Museum of
Scotland, Edinburgh where it is now preserved
as skin number NMSZ 1993.181. Here the

1994

Hare Migrants Vs

specimen was compared with several text
books and a number of other skins in the
collection from Spain, Italy and Turkey. The
bird was clearly a small individual with all
measurements at the low end of the published
range and was less bright rufous than all
other specimens in the collection. The bill
was also finer and narrower than other
specimens.

Description

Upperparts: uniform rufous brown, becoming
darker brown on the upper tail coverts and crown
and greyer on the sides of the breast.

Underparts: under tail coverts brown and broadly
tipped off white. Vent, flanks and sides of breast
brownish grey, becoming greyer on the breast.
Centre of belly off white, greyer across the breast.
Throat white.

Head: whitish supercilium from bill to behind eye,
where it was broader and more prominent. Also
white feathering on lower eye lid. Dark line through
the eye to above the ear coverts.

Wings: darker brown than mantle, with a more
rufous panel on the closed wing. The wings were
short with a length of 56mm.

Tail: dark brown, as wings. There were 10 tail
feathers, that were slightly wom. The tail measured
57m.

Eye colour: darkest brown.

Bill: fine and rather narrow at base compared with
other skins. Dark brown above with purplish pink
base to lower mandible. Measured as 13mm from

bill tip to skull and 9mm from tip of feathering.

Tarsus: transparent flesh/pink in colour and
measured as 19.3mm.

Ankle and feet: transparent purplish pink.

Weight: 10.8g, but it may have lost about 1g
before weighing. Stomach empty, but in good
condition with good amount of subcutaneous and
deposited fat (3 on a score of 1 to 3).

Age/sex: on dissection the bird was found to be a
male and the skull was fully ossified, indicating it
was an adult.

Note that measurements and the colour of the bare
parts were noted by the taxidermist when the bird
was fresh.

For Scotland’s first Cetti’s Warbler to turn up
as a corpse beneath a window in Edinburgh
was unexpected, to say the least. It is the
longest distance travelled by a Cetti’s Warbler
ringed at the Wissant site, and also now the
furthest north record in the UK after one at
Hornsea (North Humberside) on 2-3
November 1972. The date of its arrival is
certainly typical of migrant Cetti’s Warblers
arriving in southern England from the
continent, but why it should have ended up in
Leith can only be guessed at. The site is only
1.5km from the coast and although adjacent
to the Water of Leith there is no suitable
habitat nearby. Central Edinburgh also hosted
a Hoopoe Upupa epops on 21 October anda
Firecrest Regulus ignicapilluson 28 November
- perhaps the East Lothian coast is not the
best place to look for migrants after all!

Acknowledgement

| am grateful to Mike Shepherd for allowing
me, as Local Recorder, to write up the
occurrence and Bob McGowan at the Royal
Museum of Scotland for supplying information
on the bird’s soft-part colouration and
measurements.

lan J. Andrews, 39 Clayknowes Drive,
Musselburgh, Midlothian EH21 6UW.

178 Scottish Birds (1994)17: 178-180

Obituary

Dr W.J. Eggeling CBE FRSE

Joe Eggeling, who died in February 1994,
was one of the most outstanding figures in
Scottish conservation and ornithology. Born
the son ofa GP in Fife in 1909, he progressed
to distinguished careers as a student of
forestry atthe Universities of Edinburgh and
‘Oxford and then as a practitioner of it in
Africa, joining the Colonial Forestry Service
in 1931. Both in Uganda where he became
Conservator in 1946 and in Tanganyika to
which he moved in 1950 and where he rose
to be Chief Conservator, he made an
exceptional contribution to the survey and
management of these countries’ natural
resources.

Retiring from forestry at the age of 45 in 1954
he returned to Scotland and cast about for a
new career. He recalled an incident years
before when he was wildfowling at Cameron
Reservoir in Fife and had shot a goose with
a private ringing scheme ring on its leg. He
returned the ring with a note saying ‘I shota
curious Canada-type goose with your ring
onit. Sorry.’ It was indeed acurious goose,
a ‘Barnada’: a cross between a Barnacle
gander and a Canada goose, part of the
wildfowl collection at Tayport.

Now he wrote again to the owner of the
goose, Dr John Berry, then Director in
Scotland of the Nature Conservancy: ‘You
may remember me as the man who shot
your goose. If there are any posts going in
the Nature Conservancy | hope you will
consider me.’ He was considered. He was
enthusiastically appointed to a post as a
Scientific Officer; ‘just the man for the job - it
was made for Joe’, but Civil Service

SB 17 (3)

regulations blocked the appointment. A
Scientific Officer had to be a scientist and ‘Dr
Eggeling is not ascientist but aforester’. The
late Sir Arthur Duncan, then Chairman of the
Nature Conservancy (and first Chairman of
the SOC in 1937) was determined to have
him on board and swept away the objections
by the inspired expedient of inventing a new
type of post to which a forester could be
appointed: Conservation Officer. Thus Joe
Eggeling was launched on his distinguished
conservation career in Scotland.

The Nature Conservancy in the 1950s and
60s was a much smaller organisation than its
modern counterpart but in a pioneering way it
grappled with major issues like the setting up
of the first National Nature Reserves in the
Cairngorms, in Torridon and Rhum,
designating the first Sites of Special Scientific
Interest and generally bringing a more orderly
approach to the welfare of wildlife. Joe
Eggeling relished the challenge which this
presented both in terms of directing practical
conservation work on the groundand alsothe
more humdrum and long drawn-out
bureaucratic processes which lay behind it.

In allthis he could be quite firm with everyone

concerned; he possessed the formidable
armoury of toughness combined with asense
of humour. One landowner who telephone
the Nature Conservancy with acomplaint and
who scathingly said that its staff knew nothing
of ecology comparedto his own experience of

frica found himself being addressed by Joe
Eggeling in trenchant Swahili. He succeeded
Dr Berry at Director in Scotland in 1968 until
his retirement fromthe Conservancy in 1970.
He was made CBE in 1971.

He also applied his energy to the SOC, being
elected to Council in 1955 and serving as
Vice President in the years 1963-66 and as

1994

President in 1966-69. Duringthis long service
he played a prominent part in all the Club’s
decisions including, for example, the founding
of Scottish Birds in 1958. In the late 1950s
The Scottish Naturalist, in which the Club
published material, was down to a circulation
of 250 with only 90 Club members subscribing.
It took a steady nerve to start a new journal
fromthat base. Accommodation was another
problem and Joe Eggeling served on the
committee which, thanks to the generosity of
a donor's gift of £3000, was able to oversee
the purchase of 21 Regent Terrace as the
Scottish Centre of Ornithology and Bird
Protection.

He also chaired the committee which, for
nerve, was the biggest Club undertaking of
those years: the Bird Islands Cruise of 1966.
This entailed chartering the passenger liner
Devonia andsetting up the whole organisation
for a tour for 420 foreign delegate to the
International Ornithological Congress, plus
resident members, ona journey roundthetop
of Scotlandto islands not always blessed with
fine weather.

On this occasion they were. Warm sunshine
and calm seas contributed to the outstanding
success of the trip and at the end of the first
day Joe Eggeling was able to putsome months
of anxiety behind him with abeaming grin and
the words ‘It will be all right now. Members
who were on the cruise will remember his
genial presiding presence and his excellent
commentaries from the bridge as the ship
sidled past island birds cliffs.

Of all these islands it was the May which was
closest to his heart. Familiar with its shape on
the horizon since childhood, it was a haven
for him for many years. On 25 October 1952
he wrote in the Bird Observatory log: ‘I would
like to record the extreme pleasure | have

Obituary 179

obtained from my visits to the island this
summer and autumn. | have laid up many
lovely memories to bring out of store and
linger over in Africa. That country is too large,
as even are its component parts, for one to
get to know any piece of it intimately, and that
is one of the great attractions of the May. You
can get to know every blade of grass, every
stone, and every nest’.

Never one to stay on the side-lines he soon
found himself elected as Honorary Secretary
of the Bird Observatory on his return to
Scotland. He threw himself into running it,
keeping the most meticulous records in tiny
handwriting famously at odds with his bulky
frame, and completely re-organising the
records system. In his professional role he
was instrumental in bringing about the National
Nature Reserve on the May through
negotiations with the Northern Lighthouse
Board, and also with the Bird Observatory
which was entrusted as managed of the
reserve on the Nature Conservancy’s behalf.

Not that it was all book work. A good deal of
physical effort was required to keep the
Observatory building, the Low Light, and all
the traps in good order. In the 1950s one
hazard was the lightkeepers goats which
made a habit of climbing onto the roofs of the
Heligoland traps to nibble emergingtree tops,
and crashing through the wire netting.

Often accompanied by his wife Jessie and
their children he was a frequent resident of
the Low Light, refurbishing it, repairing goat
and gale damage elsewhere, trapping and
ringing, botanising, but above all enjoying the
place with its migrant excitements and its
teeming sea-birds in summer. He took a
particular interest in the small Fulmar
population; one long-resident pair was dubbed
Joe and Jessie.

180 Obituary

But some of the work was a slog, a fact not
always appreciated by others who benefited
from it. On a lone visit in March 1958, he
wrote in the log: ‘It has been a day of toil and
my fingers are so chapped and hacked and
wire torn that | can scarcely hold the pen’.
Three days later the situation had not
improved. ‘Already | am six days overdue
and the emergency shelf now houses only
One tin of sardines, curry powder, mixed
herbs and white pepper’. It was to be yet
another six days before the weather calmed
down enough for aboatto take him off; he had
been kept going by the lightkeepers hospitality
and a plentiful supply of rabbits.

1960 saw the publication of his book The /s/e
of May in which he chronicled the whole story
of the island with its lighthouses andits wildlife
and the Bird Observatory. This was just prior
to the dramatic changes in the sea-bird
populations. Inalogentry in July 1949 he had
written: ‘The morning was spent looking for
Puffins. Two pairs were seen to enter cracks
inthe Mill Door’. By 1960 they were breeding

SB 17 (3)

‘in small numbers’ before taking off to the
present population of over 40,000. Herring
Gulls increased from about 6000 in 1960 to
30,000 ten years later, leading to the culls
carried out in the 1970s by the NCC at the
request of the Observatory committee.

Following retirement Joe Eggeling suffered a
stroke in 1973 but continued his active interest
in conservation as a Commissioner of the
Countryside Commission for Scotland and a
Vice President of the Scottish Wildlife Trust.
On his last visit to the May in 1989 he had the
pleasure of seeingthe ownership of the island
being formally handed over to the NCC,
securing its conservation for the future. He
himself had played a major part in advancing
that conservation, not only on the May but
throughout the whole of Scotland. He will be
remembered with respect for that
achievement, but he will also be remembered
with affection for his generosity of spirit, his
thoughtfulness towards others and for his
goodcompany. He was not just abig man; he
was a towering presence.

John Arnott

Scottish Birds (1994) 17: 181-183

Items of Scottish Interest

Most of the following papers and reports on
birds in Scotland are available in the Waterston
Library at 21 Regent Terrace for reference,
and include all that have come to notice inthe
period October 1993 to February 1994. The
librarian would be glad to learn of anything
that has been missed, and to receive reprints
or copies of papers on any aspect of
ornithology or natural history. Bird reports
marked with an asterisk are available from
the SOC at the prices quoted, but please add
50p per order for postage and packing.

Scientific papers.

Bones, M. 1993. The garefowl or Great Auk
Pinguinis impennis. Hebridean Nat.11: 15-
24.

Bryant, D.M. 1993. Bird communities in oak
and Norway spruce woodlands on Loch
Lomondside: a long-term study. Forth Nat. &
Hist. 16: 59-70.

Buckland, S.T. & Elston, D.A. 1993. Empirical
models for the spatial distribution of wildlife.
J. appl. Ecol. 30: 478-495. Includes case
studies of the Redstart and the Green
Woodpecker in Scotland.

Cadbury, J. 1993. Grazing and other
management of upland vegetation for birds in
the United Kingdom. ASPB Conserv. Rev. 7:
12-21.

Canham, M. 1992. Nestboxes for Kestrels.
Forestry Comm. Res. Inf. Note 215.

Craib, J. 1994. Why do Common Cuckoos ~

resemble raptors? Brit. Birds 87: 78-79. A
study in northern Scotland.

Cresswell, W. 1993. Escape response by
Redshanks Tringa totanus on attack by avian
predators. Anim. Behav. 46: 609-611.
Crockford, N.J. 1993. Action for Merlins.
ASPB Consevv. Rev. 7: 22-26.

Delany, S. 1993. Introduced and escaped

187

geese in Britain in summer 1991. Brit. Birds
86: 591-599.

Dougall, T.W. 1993. Post-juvenile moult and
dispersal in the Meadow Pipit Anthus
pratensis. Ringing and Migration 14: 137-
142. A study in southern Scotland.

Duncan, K. & Marquiss, M. 1993. The sex/
age ratio, diving behaviour and habitat use of
Goldeneye Bucephala clangula wintering in
north-east Scotland. Wildfow/l 44: 111-120.
Elliott, M.M. 1993. Greylag Goose counts in
the Uists from 1986 to 1991. Hebridean Nat.
11: 56-60.

Ellis, P. & Dawson, J. 1994. Ageing and
sexing of King Eiders. Brit. Birds 87:36-40.
Based on observations in Shetland and in
captivity.

Fairlamb, D. 1993. The year of the flood.
Perth & Kinross Bird Heporttor 1992: 42-44.
Describes the creation of an artificial wetland
at Vane Farm RSPB Reserve.

Furness, R.M. 1994. The impact of the BRAER
oil spill on Shetland’s breeding seabirds.
Seabird Group Newsletter 67: 3-6.

Gibson, J.A. 1992. The 1988 census of
Gannets on Ailsa Craig. Scot. Nat. 104: 115-
121.

Gitay, H., Fox, A.D. & Boyd, H. 1990. Analysis
of historical Pink-footed Goose ringing
recovery data. Aing 13: 103-112. A study
covering Ireland, England and Scotland (only
recently received).

Graves, J., Ortega Ruano J. & Slater, P.J.B.
1993. Sex ratio of chicks in the Shag
Phalacrocorax aristotelis determined by a
female-specific band in DNA fingerprinting.
Ibis 135: 470-472.

Green, R.E. & Stowe, T.J. 1993. The decline
of the Corncrake Crex crex in Britain and
lreland in relation to habitat change. J. appl.
Ecol. 30: 689-695.

Harrison, N. & Sears, J. 1993. Towards a
marine conservation programme.ARSPB
Conserv. Rev. 7: 35-41. Concerned with

182 W.G. Harper

seabirds, pollution and overfishing.

Hartley, |.R., Shepherd, M., Robson, T. &
Burke, T. 1993. Reproductive success of
polygynous male Corn Buntings as confirmed
by DNA fingerprinting. Behav. Ecol. 4: 310-
SHR

Hill, D., Rushton, S.P., Clark, N., Green, P. &
Prys-Jones, R. 1993. Shorebird communities
on British estuaries: factors affecting
community composition. J. appl. Ecol. 30:
220-234.

Hirst, P. 1993. RAFOS Expedition to St Kilda
28 May - 15 June 1988. Aoyal Air Force Orn.
Soc. J. 22: 1-18.

Hume, R.A. 1993. Brown Shrike Lanius
cristatus in Shetland: new to Britain and
lreland. Brit. Birds. 86: 600-604.

Johnston, R.D. 1993. The effect of direct
feeding of nestlings on weight loss in female
Great Tits Parus major. ibis 135: 311-314.A
study near Stirling.

Kenney, D. 1993. Common Buzzard taking
Common Teal in flight. Brit. Birds 86: 625.
McCracken, D.I., Foster, G.N., Bignal, E.M. &
Bignal, S. 1992. An assessment of Chough
Pyrrhocorax pyrrhocorax diet using
multivariate analysis techniques. Avocetta
16: 19-29.

Mitchell, J. 1993. The Heronry at Gartcairn
Wood, Loch Lomondside: an update. Forth
Nat. & Hist. 16: 58.

Moss, R., Watson, A., Parr, R.A., Trenholm,
|.B. & Marquiss, M. 1993. Growth rate,
condition and survival of Red Grouse chicks.
Orn. Scand. 24: 303-310.

Newton, |. 1993. Age and site fidelity in
female Sparrowhawks Accipiter nisus.
Anim.Behav. 46: 161-168.

Peach, W.J., Thompson, P.S. & Coulson,
J.C. 1994. Annual and long-term variation in
the survival rates of British Lapwings. J. Anim.
Ecol. 63: 60-70.

Percival, S.M. 1993. The effects of reseeding,
fertiliser application and disturbance on the

SB 17 (3)

use of grasslands by Barnacle Geese, and
the implications for retuge management. J.
appl. Ecol. 30: 437-443. A study on Islay.
Redfern, C. 1993. Song Thrushes feeding on
Periwinkles. Brit. Birds86:630. An occurrence
in the Outer Hebrides.

Riddiford, N. & Potts, P. 1993. Exceptional
claw-wear of Great Reed Warbler. Brit. Birds
86: 572. Found in a vagrant on Fair Isle.
Sankey, S. 1993. Our birds: a
conservationist’s view. Forth Nat. & Hist. 16:
53-57.

Watson, A., Moss, R., Parr, R., Mountford,
M.D. & Rothery, P. 1994. Kin landownership,
differential aggression between kin and non-
kin, andpopulation fluctuations in Red Grouse
Lagopus |. scoticus. J. Anim. Ecol. 63: 39-50.
Watson, J., Leitch, A.F. & Rae, S.R. 1993.
The diet of Golden Eagles Aquila chrysaetos
in Scotland. /bis 135: 387-393.

Williams, G. & Green, R. 1993. Towards an
upland habitat action plan. RSPB Conserv.
Rev. 7: 5-11.

Young, S.C. 1993. The Shetland oil disaster.
Envir. Politics 2: 333-339.

Zonfrillo, B. & Brockie, K. 1993. Daurian
Redstart in Scotland. Brit. Birds 86: 629.
Vagrant on the Isle of May.

Bird Reports

Argyll Bird Report for 1992. J.C.A. Craik (ed.)
1993. 56pp. *£3.50

Colonsay and Oronsay, Natural History of.,
for 1993. J. Clarke & P.M. Clarke (eds) 11pp.
This series is now in its 12th year under the
same editors.

Dumfries & Galloway Bird Report for 1992.
Paul Collin & Ken Bruce (eds) 1993. *£2.20
Forth Area Bird Report for 1992. C.J. Henty
(ed.) 1993. In Forth Nat. & Hist. 16: 25-52.
Covers the Districts of Falkirk, Clackmannan
and those parts of Stirling District that drain
into the River Forth.

1994

Highland Bird Report for 1997. Colin Crooke
(ed.) 1993. 31pp “£2.50

Lothian Bird Report for 1992. Paul Speak
(ed.) 1993. 122pp. *£3.95. Includes ten short
articles on special surveys, rarity reports,
atlas work and ringing, plus a 67-page
systematic list.

North Sea Bird Club Annual Report for 1992.
84pp. Includes a 43-page systematic list and
a checklist of birds seen at offshore oil
installations and vessels from 1979-92.

ltems of Scottish Interest 183

North-East Scotland Bird Heport for 1992.
Andy Webb (ed.) 1993. 76pp. *£3.50. Includes
articles on wintering waterfowl at the Loch of
Skene, on Skua movements off Peterhead,
and on Quail in north-east Scotland.

Perth & Kinross Bird Report for 1992. Wendy
Mattingley (ed.) 1993. 48pp. *£3.50. Includes
a 38-page systematic list, a short report on
ringing, and an article on the Vane Farm
RSPB reserve (see Fairlamb above).

W.G. Harper.

184 Scottish Birds (1994) 17: 184-185

European Journals in the
Waterston Library

The following selection of articles appeared
in the European journals received in the
Waterston Library between September 1993
and February 1994 inclusive, thus following
on the list published in Vol 17 No 2. Articles
are arranged in species order ; square
brackets indicate that the article is in the
Original language, other articles being in
English. The reference, abbreviated for
reasons of space, indicates merely the journal,
its number andits year of publication. Journals
quoted are as follows :

Belgium: Mergus

Netherlands: Dutch Birding, Limosa, Ardea
France: Alauda, Le Passer

Switzerland: Der Ornithologische
Beobachter

Germany: Limicola, Vogelwelt, Corax, Die
Vogelwarte, Seevogel

Poland: The Ring

Spain: Ardeola

lreland: /rish Birds

Denmark: Ornis Scandinavica (with effect
from 1994 renamed Vournal of Avian
Biology’), Dansk Ornitologisk Forenings
Tidsskrift

Norway: Var Fuglefauna, Stavanger
Museum occasional publications

Sweden: Var Fagelvarld, Ornis Svecica
Finland: Linnut, Ornis Fennica

General:

Helmich, J. [The impact of pesticides on birds;
acase study on Great Bustard]. Ardeola 2/92
(This is a special issue of Ardeola. |t contains
seminar papers on conservation in Spain

SB 17 (3)

which are too numerous to enumerate here,
but cover a wide field of subjects on this
overall theme).

Divers to Ducks:

Wink, M. etal. Genetic evidence for speciation
of Manx Shearwater and Mediterranean
Shearwater. Vogelwelt 6/93.

Ullman, M. [Field identification of Storm
Petrels]. Var Fagelvarld 7/93.

Anfinnsen, M.T. [The Great Crested Grebe at
Jzeren in the 1950’s] (includes a brief history
of Great Crested Grebe in Norway since
1774). Stavanger Museum occasional
publication 1992.

Résner, H-U. [Monitoring of Barnacle and
Brent Geese in Schleswig Holstein Wadden
Sea 1991-2]. Corax 3/93.

Clausen, P. & Fischer, K. [Identification of
age and race of Brent Geese]. Dansk Orn.
For. Tidsskr. 1/94.

Gélinaud, G. et a/, [Wintering of Shelduck in
France]. Alauda 4/92.

Schricke, V. [Mont St Michel Bay, the major
moulting area in France for Common Scoter].
Alauda 1/93.

Durinck, J. et al. Diet of Common and Velvet
Scoters wintering in the North Sea. Ornis-
Fenn. 4/93.

Birds of Prey:

Solonen, T. Spacing of raptor territories in
southern Finland. Ornis Fenn. 3/93.
Kjellén, N. [Raptor migration at Falsterbo].
Var Fagelvarld 5/93.

Wirdheim, A. [The Honey Buzzard]. Var
Fagelvarld 5/93.

Solonen, T. et al. [Where do Buzzards nest?
areview of nest sites in Finland]. Linnut 4/93.
Fernandez, C. [Selection of breeding site
cliffs by Golden Eagle]. Alauda 2/93.

1994

Fernandez, C. & Azkona, P. [Influence of
breedingsuccess on reuse of nests by Golden
Eagle]. Ardeola 1/93.

Forsman, D. [Ageing of Golden Eagle}. Linnut
6/93.

Selas, V. [How does illegal shooting of
Goshawks affect the breeding population’).
Var Fuglefauna 3/93.

Steen, O.F. [Status of Peregrine FalconinSE
Norway 1993]. Var Fuglefauna 4/93.

Grouse to Cranes:

Martin, K. & Horn, A.G. Clutch defence by
male and female Ptarmigan. Ornis Scand. 4/
93.

Waders to Auks:

Mahéo, R. [International importance of French
coasts for wintering waders]. Alauda 4/92.
De Putter, G. et a/. [Numbers and distribution
of waders on Flemish coast July 1989 - June
1990]. Mergus 1/93.

Ens, B.J. et a/. [Distribution of overwintering
waders in the Dutch Wadden Sea]. Limosa 4/
93.

Berg, A. Habitat selection by monogamous
and polygamous Lapwings on farmland - the
importance of foraging habitats and suitable
nest sites. Ardea 2/93.

Boschert, M. & Rupp, J. [Breeding biology of
Curlew at a site in the southern Upper Rhine
valley]. Vogelwelt 5/93.

Hulsmann, H. [The Redshank in Schleswig-
Holstein] Seevégel 4/93.

Leuzinger, H. & Jenni, L. [Migration of Wood
Sandpipers at Agelsee, Switzerland]. Orn.
Beob. 3/93.

Le Maréchal, P. [Development of gull (Larus
and Rissa) populations in lle-de-France 1976-
92]. Le Passer 1-2/93.

Kompanje, J.O. & Post, J.N.J. [Russian race

European Journals 185

of Common Gull in Netherlands]. Dutch
Birding 6/93.
Bartel, P. & Konigstedt, D.G.W. [Identification

of Slender-billed Gull]. Limicola 4/93.
Pigeons to Woodpeckers:

Fredriksson, R. [Identification of juvenile owls
after leaving nest]. Limicola 6/93.
Giraudoux, P. & Michelat, D. [Prey-predator-
habitat relationship of Barn Owl during
breeding season]. Alauda 2/93.

Stegen, C. [Prey composition of Barn Owl in
an area of Schleswig-Holstein]. Seevégel 3/
93.

Lind, H. Differing ecology of male andfemale
wintering Snowy Owls. Ornis Svec. 3-4/93.

Passerines:

Sjoberg, K. et a/. Differences in bird habitat
quality between plantations of Scots and
Lodgepole Pine measured in terms of Pied
Flycatcher breeding success. Ornis. Svec. 2/
93.

Mild, K. [Identification of European black-
and-white flycatchers]. Limicola 5/93.
Busse, P. Migratory behaviour of Blackcaps
wintering in Britain and Ireland : contradictory
hypotheses. The Ring 1-2/92.

Fransson, T. & Stolt, B.-O. Isthere an autumn
migration of continental Blackcaps into
Northern Europe? Vogelwarte 2/93.
Hogstad, O. & Kroglund, R.T. The throat
badge as a status signal in juvenile male
Willow Tits Jour. fur Orn. 4/93.

Berrow, S.D. eta/, 2nd International Chough
Survey in Ireland 1992. /rish Birds 1/93.
Olsen, K.M. [Field identification of Crossbill
species]. Var Fagelvarld 8/93.

M.H. Murphy

186 Scottish Birds (1994) 17: 186

Advice to Contributors

Authors should bear in mind that only a small
proportion of the Scottish Birds readership is
science-trained, and should aim to present their
material concisely, interestingly and clearly.
Unfamiliar technical terms and symbols should be
avoided wherever possible and if deemed essential
_should be explained. Supporting statistics should
be kept to a minimum. All papers and Short Notes
are accepted on the understanding that they have
not been offered for publication elsewhere and that
they will be subject to editing. Papers will be
acknowledgedon receipt and will be reviewed by at
least two members of the editonal panel and in
some cases also by an independent referee before
being accepted. They will normally be published in
order of acceptance of fully revised manuscripts.
The editors will be happy to advise authors on the
preparation of papers.

Reference should be made to recent issues of
Scottish Birds for guidance on style of presentation,
use of capitals, form of references, etc. Papers
should be typed on one side of the paper only,
double-spaced and with wide margins; two copies
are required and the author should also retain one.
Headings should NOT be underlined, nor typed

Errata

SB 17 (3)

entirely in capitals. Scientific names in italics
should follow the first text reference to each species
and should follow Voous ‘List of Recent Holarctic
Bird Species’ as given in the The British Birds’ List
of Birds of the Western Palearctic (1984). Only
single quotation marks should be used throughout
and numbers one to ten should be wniten out
whereas 11 and above should be writen as
numerals.
August 19911<ceccceee buton the 5th (ifthe name of
the month does not follow). Please note that
papers shorter than 700 words will be treated as
Short Notes where all references should be
incorporated into the text, and not listed at the end,
as in full articles.

Tables, maps and diagrams should be designed to
fit either a single column or the full page width.
Tables should be self-explanatory and headings
should be keptas simple as possible, with footnotes
used to provide extra details where necessary.
Each table should be on a separate sheet. Maps
and diagrams should be in Indian ink and be
camera ready, but drawn so as to permit reduction
to half their onginal size.

For details of writing Research Progress Reports,
please contact the editor in advance.

Scott. Birds 17(2) Colour plates. The caption to the winning photograph in the SOC 1993
Photographic competition should read ‘Sooty Shearwater Puffinus griseus and not Manx
Shearwater. The plate opposite should read ‘Verditer Flycather’, not ‘Verditers’. Apologies to

the photographers.

Scott. Birds 17: 104. Paragraph 3. line 3 should read ‘61 attacks’ not ‘91’. Apologies to the

author.

[Eds].

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Scottish Birds

Volume 17 Part 3 June 1994
Contents

Research Progress Reports
The density and species diversity of songbird populations in
northern upland spruce plantations. /.J. Patterson & J.G. Ollason
Research on Capercaillie and their habitat. R. Moss

Main articles
Prey remains at Osprey nests in Tayside and Grampian, 1987-1993.
D.N. Carss & K. Brockie
Scottish List. R.W. Forrester

Short Notes
Mating times of Merlin. R.C. Dickson
Merlin chick killed by adder. G. Shaw
Site fidelity of Jack Snipe on migration? D.G. Andrew
First breeding records of the Mandarin in Argyll. S.J. Petty &
D.1.K. Anderson
Discovery of the first British clutch of Slavonian Grebe eggs in a
museum collection. H.A. McGhie
Rook flight-line across Firth of Forth. H.E.M. Dott

The diet of nestling Corn Buntings on North Uist — insects not grains.

I.R. Hartley & D.L.J. Quicke

Correspondence
Pink and polluted Peregrines. W.R.P. Bourne
Spring passage of Skuas in the Outer Hebrides. D.G. Andrew

Rare Migrants
Semi-palmated Sandpiper on Stronsay. J. Holloway |
Pallid Harrier in Shetland; second Scottish Record. H. Harrop
Cetti’s Warbler in Edinburgh: a new bird for Scotland. /.J. Andrews

Obituary
Dr W.J. Eggeling CBE FRSE. J. Arnott
Items of Scottish Interest. W.G. Harper
European Journals in the Waterston Library. M. Murphy
Advice to Contributors
Errata

Published by the Scottish Ornithologists’ Club,
21 Regent Terrace, Edinburgh EH7 5BT. © 1992

Printed by Milne, Tannahill and Methven Ltd., Perth

Scottish Birds

The Journal of the Scottish Ornithologists’ Club

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Scottish Birds (1994) 17: 187-191

Research Progress Report

A ten year study of Barn Owl conservation in conifer 1 forests |

4
a
ete

Twenty -five years ago, when | first became
enthralled by this beautiful bird, Barn Owls
Tyto alba were a common sight hunting at
dusk over the young conifer plantations of
Galloway in south-west Scotland. The
afforestation of these upland grasslands,
mainly during the 1950s and 1960s, involved
the removal of grazing sheep, and this
encouraged a rapidincrease in the populations
of field voles Microtus agrestis in the
unchecked grass growth. Owls, and other
vole-eating birds of prey, were quick to exploit
this temporary glut of food.

Years of pastoral farming had left the Galloway
hills treeless, and trees with potential nest-
cavities simply did not exist, but the Barn
Owls found a ready supply of nesting sites in
the remote, and now abandoned, shepherds’
cottages. When | first began to study the Barn
Owls in Glentrool Forest in the early 1970s, |
located ten breeding pairs, using 12 nesting
sites, allin former dwellings. From the outset,
it was clear that the affairs of man and owl
were closely linked.

Lacking maintenance, the abandoned
cottages had a limited life; slates blew off, rain
rotted the roof timbers, and decay setin. The
Barn Owl study became a sorry tale of
diminishing numbers as nest sites were lost.
At first this hardly mattered, since the conifers
were growing up, shading out the grass and
with it the voles. Many former territories
became unviable anyway. By the mid-1980s
only four buildings remained usable as nest
sites.

LIBRARIES ~~ g. SHAW

Tee 5

Around this time the pendulum “began to
swing back to favour the owls; the earliest
plantings had become productive timber.
Clear-felling and re-stocking commenced;
large areas within the forest were opened up,
and were quickly re-colonised, first by grasses
and then by voles. Now the opportunity was
there for the owls also to re-colonise, and the
loss of the derelict buildings had become an
acute problem. The diminishing area of newly-
afforested land provided no solutions; by the
1970s there had developed a ready sale for
second homes and quiet country retreats,
and any former tied houses entered the
housing market.

With this background, in 1984 the Forestry
Commission in Newton Stewart Forest District
initiated a Barn Owl Conservation Project; the
proposition was simple - a food supply (field
voles) existed, but nest sites were lacking. If
artificial nest sites could be provided and
accepted, there was the potential to increase
the owl population many times over. A project
team of Andrew Dowell and myself, aided and
advised by lain Taylor of Edinburgh University,
and by Steve Petty from FC Research branch,
set about designing and erecting a range of
tree-mounted nestboxes throughout the
Forest District.

Several nestbox designs were employed; the
common feature was a large cavity space that
could be fixed onto a tree. At the time the
increasing interest in Barn Owl conservation,
motivated by the realisation of a serious
national decline, was at the stage of providing
static nestboxes in suitable farm. buildings.

188 G. Shaw

Our aim was to go astep further, by taking the
nest site out to where the prey was. Boxes
were erected in pairs, to avoid competition
from the earlier-nesting Tawny Owl Strix aluco.
By the spring of 1985, 33 sites were in place
and this was gradually increased to 89 by
1989, after which the number was kept
constant.

Small numbers of Barn Owis began to use the
nestboxes from the spring of 1985 onwards,
with a huge increase in 1988 from nine to 31
pairs (Fig. 1). Since then the number has
fluctuated between 26 and 37 pairs; the original
study area in Glentrool Forest (now a part of
Newton Stewart Forest District) has regularly
held 15-16 pairs in ‘new territories, in addition
to the four sites remaining in old buildings.

The first conclusion from the project was that
nestboxes do work, and that in the right piace
- where there is an abundant food supply of

SOme

30 |! ' \—

ZZ Zap TELL

1984 1986 1988 1994
1985 7 1989 1991 1993

FIGURE 1. Number of Barn Owl pairs
nesting in Newton Stewart Forest District,
1984-1994. Hatched part of column shows
nests in old buildings, rest of column
shows nestbox pairs.

SB 17 (4)

small mammals - it is feasible to create
‘designer’ owl territories, simply by providing
a suitable nest site. A Forestry Commission
Bulletin was published, describing the
methodology, and encouraging many other
Forest Districts in all six national FC Regions
to develop similar conservation schemes.
But within the original project we realised that
in monitoring an annual sample of 30+ nests,
there was an opportunity to develop a research
programme to answer some of the questions
that inevitably arose.

Where do they come from?

The spectacular increase in the nest box owl
population immediately makes one ask where
they have all come from. If established pairs
of owls had been persuaded to quit their
territories to exploit voles in the forest, then
the project might be counier-productive. We
tackled this problem in two ways; firstly, all
existing nest sites in the forest were monitored
each year. The number of owls using these
old buildings remained stable in the ten years
from 1985 (Fig. 1). Secondly, in association
with workers from the Hawk & Owl Trust, as
many owl chicks as possible were ringed at
established nest sites in a 50km felis
surrounding the forest.

From 1986 we began to trap the breeding
owls at their nestboxes, beginning with a
small number and monitoring the degree of
disturbance caused. Fortunately, no adverse
effect could be detected, and by 1988 most
female owls were routinely trapped each year.
Males were more difficult, since they spent
only a limited time at the nestbox, and the
annual sample: has always been small.
However, we were able to show that 82% of
females trapped in 1988 were first-time
breeders, and that most had been hatched in
farmland and forest nests the previous year.
The remaining, older females had bred in the

1994

nestboxes in earlier years. At ten newly-
occupied nestboxes where the male was
trapped, all were yearling birds. There was
no evidence that older birds, which may have
previously been breeding outside the forest,
had switched nest sites. Surveys conducted
in the surrounding farmland showed a stable

- occupancy throughout.

How far do they come?

The same ringing/recapture programme
showed that in 1988, 18 first-year females
had moved an average of 9.7km from their
natal site to breed ina nestbox; seven marked
males had dispersed an average of 6.1km.

_ Many subsequent handlings over the years
| have not significantly altered these figures;

the furthest movement for a female has been
22km, and half this distance fora male. Given
the spread of the chick-ringing operations, it
would have been possible to detect
movements of 50km+, if any had occurred.

Once settled, the breeding owls were
extremely site-faithful. During the period 1985-
94, only a single established male changed
nestboxes, and then merely to the nearest

_ adjacentterritory. Females were slightly more

mobile; in 70 cases where a female was

Research Progress Report 189

trapped in two successive years, 50 (71%)
were at the same site and 20 (29%) had
moved boxes. None had moved more than
three territories from their earlier breeding
site, and most were on the adjacent territory.

The sedentary nature of Barn Owls has
important implications for their conservation.
Young owls disperse over short distances,
and adults move hardly at all; once an owl
population enters a decline, or is lost, it may
be difficult to recover unless there is a source
population close by. Nestbox schemes should
work outwards from the source population,
rather than in isolation.

What do they eat?

The forest habitats provided abundant field
voles, and examination of owl pellets and
prey caches at nests showed that the owls
greatly favoured this one prey item. However
in northern temperate latitudes, grassland
voles exhibit cycles of abundance over a 3-4
year period. By sampling, using a vole sign
index, we were able to define a roughly 3-year
cycle in the Galloway forests; a year with high
vole populations was followed by a low year,
and then by a year with increasing numbers
(Table 1). Inlow vole years, the owls brought

TABLE 1. Some aspects of breeding performance by Barn Owls using nestboxes
in Newton Stewart Forest District, through two complete vole cycles 1989-94.

Columns are totals over two years.

Vole numbers LOW INCREASE HIGH
1989+1992 1990+1993 1991+1994
Occupied nestboxes 57 70
Pairs laying eggs 39 (62%) 44(77%) 68(97%)
Pairs rearing young 19(30%) 36(63%) 59(84%)
Average laying date 23 May 30 April 10 April
Young reared 103 189
Average Adult survival to
next season 54% 64% 38%"

“adult survival after high vole years based on 1988/89+1991/92

190 G. Shaw

some voles to their nests, but also shrews
and a variety of small woodland birds. These
items seemed either small and unprofitable,
or difficult to catch. In such years it was likely
that the breeding owls experienced a shortage
of suitable food, since there were no mice or
other small rodents to switch to - as there
might have been in more traditional farmland
habitats.

The low vole years did not necessarily mean
that there were fewer Barn Owls in the
nestboxes (Table 1). However, what did
happen was that in these years fewer birds
(44-77%) laid eggs, and only a small part of
the breeding population (11-35%) successfully
reared young. By contrast when vole numbers
were high, virtually all birds laid, and most
(68-85%) were successful. Inthe early stages
of the breeding attempt, from March onwards,
the female owl was very inactive, and was
always found at or in the nestbox. She
depended on her mate to bring her food, and
by conserving her energy she typicaily
achieved a rapid body weight gain of around
30%, enabling her to produce a clutch of 5-6
eggs. Inlowvole years, some females showed
only minor weight changes, and either
produced small clutches (often later
abandoned) or none at all. Those birds that
did lay took longer to reach laying condition,
resulting in a 6-week difference in average
laying dates between high and low vole years
(Table 1).

Population processes

In good food conditions the Barn Owls laid
large clutches and produced many young; a
few pairs successfully reared two broods in
high vole years. This ability to react quickly to
changing conditions meant thatthe owls could
establish a permanent population in the forest,
provided that the breeding birds could survive
the low food years and be ready to profit when
the voles increased. On average, about half

SB 17 (4)

of the females survived to the next successive |

breeding season; because we knewthatadult |

dispersal was limited, most of these that
disappeared can be assumed to have died,

though few were ever found. When vole |

numbers crashed, adult survival sometimes ©

dropped as low as 32%, and when vole »

numbers were increasing it exceeded 80%.

Barn Owls normally began to breed in their

first year of life; at the extreme a young bird |
which became independent at the beginning °

of November was found sitting on eggs the

following April. Each yeartherewasanumber /

of vacancies in the nestboxes, due to losses
of adult birds, which could be filled by first-
time breeders. However, recruitment of
yearlings was not directly related to the
opportunities available; 56 out of 78 yearlings
arriving in the population had hatched in
years when vole numbers were increasing.
Only 18 (23%) came from the high vole years,
when most chicks were produced, and a
mere four (5%) had hatched in low vole years.
This result was most likely due to young birds
being better able to survive the winter when
vole numbers were on an upward trend.

This pattern also meant that it was most

profitable for adults to produce young in those.

years when voles were increasing, since they
were more likely to contribute to future
generations of owls. Inthis light, the very poor
breeding output every third year was not such
a disaster for the owls involved; adult survival
in the low vole years (53-55%) was rather
better than after a high year (32-44%).
Survivors to the next breeding season would
gain on two counts; next year’s offspring
would have the greatest change of entering
the future breeding population, and the adult
birds themselves would have a high probability
of surviving to reproduce again. Taken in
isolation, these years of dismal breeding failure
might seem worrying, but the more complete
picture serves to emphasise the value of long
term monitoring.

ee eee eee Se See le

1994

Research Progress Report 191

Future Work

The nestbox scheme was begun as a
conservation project, and research developed
out of monitoring the project. While ihe
principle has been established, that nestboxes
can be used to increase Barn Owl numbers,
there remain some conservation objectives
that can be met from long term monitoring.
Most importantly, we have accumulated data
from 89 ‘manmade’ territories, many for a full
ten years. Fifty-eight have been used by
Barns Owls, some just once and some right
through; for the other 31 at least, our idea of
a suitable territory failed to match that of the
owls. The challenge now is to combine all the

habitat features and the breeding records for
each territory, so that in the future we can
make the best possible use of our nestbox
resources, by placing them more precisely in
the places that have most of everything that a
Barn Owl could need.

References
Methodology is outlined in:

Shaw, G & Dowell, A. 1990.
Barn Owl conservation in forests.
Forestry Commission Bulletin 90.
HMSO.

Geoff Shaw, Forest Enterprise,
South Scotland Region,
55-57 Moffat Road, Dumfries. DG1 1NP.

192 Scottish Birds (1994) 17: 192-204 SB 17 (4)

Changes in breeding numbers of Kittiwakes in Shetland, 1981-
1994.

M. HEUBECK & R.M. MELLOR

Counts of Kittiwake nests indicate that the Shetland breeding population in

1991-94 was 26% lower than in 1985-87, and 30% lower than in 1975-81. The

decline has been far from uniform. There has been only a slight, recent
decrease at Fair Isle whereas 60% fewer nests were found in 1991-94 along
the south-west and east coasts of Shetland than in 1980/81. This decline is
considered to have been due mainly to two factors. Firstly six successive
years of low breeding success in the late 1980s, caused by a scarcity of
sandeels, resulted in few new recruits to the breeding population. At the
same time, predation at Kittiwake colonies by Great Skuas increased con-
siderably and has continued at a high level at many colonies, even though
sandeel abundance has increased. Improved breeding success since 1991
may soon lead to a halt to, or a reversal of, the population decline although
this may be offset by continued predation pressure, which its also likely to

have local effects on nest site selection.

Introduction

When the Shetland Oil Terminal
Environmental Advisory Group (SOTEAG)
began monitoring seabird populations in 1978,
the Kittiwake Rissa tridactylawas selected as
one species to be studied. The original aim
was to count adults and nests in study plots
established by the former Nature Conservancy
Council (NCC) at four colonies in 1975-77,
with the assumption that changes in numbers
in these plots would reflect wider population
change.

In 1981 the NCC made the first comprehensive
census of Kittiwake colonies in Shetland,
surveying virtually the entire cliff coastline
from the sea (Richardson 1985). Also in
1981, SOTEAG made counts from land of
nests in widely scattered colonies to detect
changes since the 1969/70 ‘Operation
Seafarer counts (Cramp et al. 1974) and a
1974 survey by the Institute of Terrestrial
Ecology (Harris 1976). The SOTEAG study

found : a) although counts in SOTEAG study
plots had declined, there was no evidence of
any overall population decline between 1974-
81, b) numbers had increased at some
colonies, decreased at others, some colonies

had disappeared and some new colonies had.

formed, c) counts from land (rather than from
the sea) underestimated numbers of nests by
an average of 36% (Pritchard 1981). When
further counts were made from the sea in
1985 for the Seabird Colony Register it
became clear that inferring overall population
change by extrapolation from counts at study
plots within colonies was invalid; instead it
was decided to count total numbers of nests
froma Zodiac inflatable along entire stretches
of coastline at the appropriate time of year
(Heubeck et a/. 1986). This paper presents
the results of counts made in this way since
the 1981 survey.

1994

Methods

Counts were made from a Zodiac inflatable
boat usually crewed by three people, one
handling the boat, another counting nests
and the third counting adult Kittiwakes on the
cliffs. Exceptions were at Sumburgh Head
and Eshaness where some colonies were
counted from land one or two days after the
others had been counted from the sea. A few
colonies were counted by landing on and
climbing up rocks from which a better view of
nests was obtained. All known colonies were
visited and suitable cliff habitat was checked
during surveys for new colonies. Two factors
aided the ease of counting. Firstly, most
Kittiwake colonies in Shetland are relatively
small (only 11% in 1981 contained more than
250 nesis (Richardson 1985)) and any large
colonies were counted in sections, according
to topographical features of the cliff. Secondly,
counts tended to be made by the same
observers (using tally counters) who rapidly
gained experience, and knowledge of more
problematic colonies. Counts were normally
made during the first three weeks of June (but
some in 1981 and 1985 were in the first few
days of July) when the maximum number of
nests might be expected.

Sea conditions were critical in determining
which coasts could be surveyed each year;
counts were made in winds up to Beaufort
Force 5, as long as winds were offshore and
there was little swell. Coverage was therefore

more opportunistic than planned, although

we tried to ensure that no more than three
years elapsed between surveys of particular
coasts. Where possible, nests were
differentiated as ‘incubating’ (a well-built nest
with an adult apparently incubating or
brooding), ‘AON’ (a well-built but apparently
empty nest, whether or not attended by an
adult) and ‘trace’ (fragments of nest material
only) (Harris 1987). The ability to see trace

kKittiwakes in Shetland 193

nests varied with viewing distance and sea
conditions; here we consider well-built nests
only, i.e. ‘incubating’ and ‘AON’ combined
and referred to hereafter as AONs.
Sometimes we encountered colonies with
apparent high proportions of early breeding
failures (typically, many partially disintegrated
nests would be seen). On these occasions
itwas particularly difficult to categorise nests;
those that were essentially substantial were
counted as AONSs, but the difference between
the actual numbers of nests that had been
built and that recorded will have been greater
than normal. All adult birds ashore were
counted, those in well-defined roosts or
loafing areas being recorded separately from
those in breeding colonies, and the location
of all colonies and roosts were recorded on
1:10,000 maps. Counting error was not
quantified but was thought to have generally
been small since mostcolonies were relatively
small and surveys were usually made in
favourable sea conditions. Occasionally, a
combination of cliff topography and swell or
tidal chop made counts at particular colonies
difficult, wnen the tendency was probably to
underestimate numbers, but such errors
contributed little to the overall changes
recorded.

Kittiwake ‘colonies’ have been defined
variously as aggregations separated by more
than 50 yards (Boyd 1960) or 200 yards
(Coulson 1963) of cliff free of nests. Our
definition, of groups of nests clearly separable
on 1:10,000 maps and hence distinguishable
by different observers on subsequent visits
usually fell between these distances. We
use Coulson’s (1963) term ‘breeding station’
to refer to groups of colonies with less than a
mile of unoccupied coast between each other
or, in the case of islands, separated from the
nearest colony by less than a mile of sea.

194 Heubeck & Mellor

The large breeding stations on Fair Isle and
Noss, counted by Fair Isle Bird Observatory
and Scottish Natural Heritage staff
respectively, were subdivided into sections of
coast according to natural features rather
than discrete colonies. Also, the 1992 survey
of Foula (previously surveyed only in 1976 by
Glasgow University and in 1987 by NCC) was
the first occasion that colonies were recorded
in the manner we used elsewhere so the
history of changes at individual colonies at
these major breeding stations could not be
determined.

Results
Breeding stations

In addition to Fair Isle and Noss, 57 breeding
stations were recorded between 1981 and
1994 (Fig. 1; Table 1). Over Shetland as a
whole, the most recent counts of AONs were
c.26% lower than in 1985-87 and c.30% lower
than in 1975-81 (Table 1). Breeding had
ceased by 1991-94 at seven small stations
and only one new one was established, at
Siggar Ness, where roosting adults but no
nests were recorded in 1981. At stations
surveyed in 1980/81 (i.e. all except Fair Isle
and Foula), the number of AONs had
decreased by 51% by 1991-94 while the
number of adults decreased by 53% (Table

4):

The total counts of AONs at breeding stations
on Foula suggested lesser changes,
decreases of 22% between 1975 and 1987,
and only 1% between 1987 and 1992.
However, these counts may be less
comparable than at other breeding stations
as some colonies were counted from land in
1976, while the 1992 survey was conducted
in perfect sea conditions with absolutely no
wind or swell. Less favourable conditions in

SB 17 (4)

1987 and 1976 limited access to some
colonies (R.W. Furness & M.G. Richardson
pers. comm.).

At Fair Isle, the numbers of AON’s increased
until at least 1988 but fell by 6% between
1988 and 1992, although some colonies were
overlooked in 1988 and the actual decrease
was probably c.10% (Harvey et al. 1992).

Breeding areas

To examine regional and temporal trends in
breeding numbers more critically, we used
arbitrary geographical areas within which all
breeding stations were counted in the same
years (Fig. 1; Table 2).

Area A: AtSumburgh Head and Horse Island
the number of AONs declined during the
1980s to a peak rate of -13% p.a. between
1989 and 1991, lessening slightly to -10%
p.a. between 1991 and 1993; the number of
AONSs in 1994 was similar to 1993 and 56%
lower than in 1981.

Area B: I|n the south-west Mainland there
was little difference in the totals of AONs in
1981 and 1987, after which numbers fell with
the highest rate of decrease (-14% p.a.) again
between 1989 and 1991, a further decrease
causing the 1993 total to be 46% less than in
1981.

Area C: Inthe west Mainland the number of
AONs fell between 1981 and 1986 but rose
again by 1988, after which there was a steep
decline with numbers in 1993 being 70%
lower than in 1981. —

Area D: At Papa Stour and Muckle Roe there
was little change in totals of AONs until gradual
decreases between 1989, 1992 and 1993,
the last count being 18% less than in 1981.
Area E: At Eshaness, after a slight decrease
in the early 1980s, numbers of AONs
increased by 7% p.a. between 1985 and
1989, but thereafter fell substantially with the
1994 total being 32% lower than in 1981.
Area F : Many abandoned, disintegrated
nests were noted on the 1985 survey of north-
west Mainland and early breeding failures

1994 Kittiwakes in Shetland 195

FIGURE 1. The location of Kittiwake breeding stations in Sheltand, 1981-94, and the
areas within which all stations were counted in individual years.

196 Heubeck & Meller SB 17 (4)

TABLE 1. The number of apparently occupied nests (AONs) at Kittiwake breeding
stations in Shetland in 1981, 1985-87, and the most recent count (1991-94). Where
counts were made in more than one year in 1985-87 both are given, consecutively, and
the later count was used to calculate the total. In 1985-87 no count was made at Gruna
Stack (No. 24) and those at Braga Ness (No. 15), Watsness (No. 16) and Tingon (No. 23)
were made from the land. No counts were made at Fair Isle or Foula in 1981, those given
were from 1975 and 1976, respectively. Indicated are the number of colonies known to
have existed between 19871 and 1991-94, the number at which numbers of AONs
increased or decreased between 1981 and 1991-94, the number of new colonies that
formed, the number that disappeared and the number presumed missed by the 1981
survey. *= some colonies formed since 1981 had disappeared by 1991-94.

1981 1985-7 1991-4 Missed
Breeding Station AONs AONs AONsCols. Inc. Dec.New Dis. 1981

1. Sumburgh Head 2641 2451 1366 25 4. 164 2Onneee 1
2. Horse Island 594 516/327 62 7 0 log, Oe 0
3. Siggar Ness 0 1 102s 0 0.3.4 40 420
4. Fitful Head 500 258 177 6 0 AON al 1
5. St Ninian’s Isle AT OSI 77 140 3 2 T 307-0 0
6. Ness of Ireland 203 151 126 3 0 Afar 1 0
7. South Havra 29 9 0 1 0 Ore Omeed 0
8. Kettla Ness 280 O15 48 2 0 25"\ (08 0 0
9. West Burra 615 897 304 8 2 5 Oral 0
10. Reawick — 2/2 197 41 4 0 SOMO 0
11. Skelda Ness 186 64 58 5 1 2420s 22, 120
12. Westerwick 454 284 1 SSmeuO 0 Broa 4 0
13. Burga Stacks 58 3 Vine al 0 gape 0 cal). 40)
14. Vaila 255 291 102 14 1 5 on Oh eee
15. Braga Ness 12 27 AS ig) tl 1 Or: OF Orr s.0
16. Wats Ness 11 0 1 1 0 1 OO; *0 6)
17. Papa Stour 1059 1087 894 17 3 WN) Ome oee O.
18. South Muckle Roe 96 99/69 33. 4 0 2 60m Ziel
19. Swabie Stack 56 46/83 60 1 1 O° Or aOR war 0
20. Dore Holm 375 328 197 2 0 21 NOME AO 0
21. Skerry of Eshanessi266 1271 756,25 1 4 0 On 0
22. Mainland Eshaness837 31 718 5 2 Ayes) OM Rare 0
23. Tingon cliffs 35 722 3/4 0 0. itileer Sano
24. Gruna Stack 50 - 81 8} 2 Oar aO 0
25. Uyea 731 365 450 9 2 5) Orme 0
26. Fethaland 14 0 0 1 0 0. OF Fd 0

:

1994
27.Ramna Stacks 1350
28. Trumba 2
29. Varnadil 56
30. Gloup Holm 78
. Blue Mull 158
32. Lang Holm 32
— 33. South Holms 121
34. Hermaness 3872
35. Saxavord 141
. Virdik 84
37. Burgar 217
_ 38. Mooa Stack 53
39. Clett Stack 30
40. Strandburgh Ness 273
. South-east Fetlar 32
_ 42. Lambhoga 37
_ 48. Birrier 82
| 44. Burravoe 392
45. Grunay 261
46. North Benelip 23
47. Clett Head 25
48. Noss (1980) (11050)
49. Millburn Geo 19
50. Hole of Bugars 19
51. Mousa 148
_ 52. Noness 1627
58. Troswick Ness 716
54. Boddam 256
| Total AONs 31380
Total Adults 47292
| 55. Hodden Geo, Foula
_ 56. South-east Foula
. 57. The Noup, Foula
58. North-west Foula
Foula Total (5570)
Total AONs 36950

994/1047598 14

1/11 TOMO

10 LOZ

7 81 3

114 87 = 4

2 Cal

305 71 3

3497 2280 51

186/432 447 13

72 Zoe sl

211 IWS. 2

92 Cia

26/50 Orr ol

129/51 49 3

0/3 AS)

66/67 11 2

11/43 62) ware

169/168 109 9

148 12) Gai6
24 ZO Tle:

8 33m "2

9348 4301

27 Oral

0 Oa acl

14 Orang 2

1489 614 8

520 LSWheas

2r7 Zoo mmo

2/518 15406 295

22104

I 2

%O 16

520) 72

3688 31

4350 4306 41

31868 19739 335

kittiwakes in Shetland

—s

NO

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Shetland Total AONs 53950 50940 £37898

198 Heubeck & Mellor

undoubtedly contributed to the low total count.
Accepting this, the directions of changes
recorded were similar to Eshaness although
slower, the 1994 total being 48% less than in
1981.

Area G: There was little change in AON
totals in Unst and north Yell until a decrease
between 1987 and 1991, when 32% fewer
were recorded than in 1981. Unfortunately,
sea conditions in 1994 prevented counts in
the Area.

Area H: The number of AONs on Fetlar and
Yell more than halved between 1981 and
1985, with lesser decreases until a further
substantial decline between 1989 and 1991.
Numbers increased between 1991 and 1993
(mainly at the Yell colonies), when the total of
AONs was 69% lower than in 1981.

Area! : The number of AONSs fell throughout
1981-92 at colonies on Whalsay and Out
Skerries, with the greatest rate of decrease (-
20% p.a.) between 1986 and 1989. Ason Yell
there was a slight increase in 1993, when
numbers were 78% lower than in 1981.
Area J: One small colony on Bressay
disappeared by 1988, the other by 1993.
Numbers of AONs on Ness fell increasingly
rapidly throughout, the 1994 count being 61%
lower than in 1980.

Area K: After a slight decrease in the early
1980s counts of AONs in south-east Mainland
indicated periods of relative stability
punctuated by steep declines between 1988-
90 (-21% p.a.) and 1992-93 (-30%). As in
Area A the 1994 count was similar to 1993 but
62% lower than in 1981.

Breeding colonies

Breeding had ceased by 1991-94 at 91
colonies known to have existed since 1981
(30% of the total) while only 19 new ones
were known to have formed, six of which had
disappeared by 1991-94. Itwas commonplace

SB 17 (4)

for changes in the number of AONs at nearby
colonies to occur both in different directions
and at highly variable rates. An example was
at Noness, where counts of nests were also
made from black and white and colour slide
photographs taken from the sea in 1977 (Fig.
2; Table 3). There was some reduction in
numbers at most colonies between 1977 and
1981 but by 1988 there had been substantial
decreases at colonies 3 and 4, but large
increases at colonies 5 and 6. By 1993,
colonies 3 and 4 had disappeared completely
and breeding was almost entirely confined to
the four southern colonies, which in 1977 held
only 53% of all AONs at the breeding station.

Some recorded changes in breeding
distribution strongly suggested that
established, breeding adults were moving
from one colony to another. On the headland
of Hermaness, the number of AONSs in the
central colonies between Saito and The Neap
fell from 1,275 in 1981 to 694 in 1987 (-45%)
and 223 by 1991 (68%). At other colonies on
the headland to the north and south the
respective decreases were only 2% and 23%,
while there was a Substantial (150%) increase
at the South Holms immediately south of

Hermaness between 1981 and 1987 (Table. —

1), and to the east at Saxavord where one
colony (around a large cave entrance)
increased from just two AONs in 1981 to 112
in 1985, 337 in 1987 and 361 by 1991. At
Papa Stour, where there was little change in
AON totals for the breeding station between
1981 and 1989, the numbers at colonies in
relatively open situations on the cliffs of Papa
Stour itself fell progressively from 27% of the
total for the breeding station in 1981 to 17% in
1989 and just 8% in 1993, with corresponding
increases in the proportion of the total of
AONs occurring on the offshore stack of
Fogla and Lyra Skerries, where colonies were
mostly inlarge cave entrances. This tendency

35)

Kittiwakes in Shetland

1994

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200 Heubeck & Mellor

for a greater proportion of AONs at breeding
stations to be concentrated in colonies in
caves or other sheltered situations was noted
elsewhere, e.g. at Boddam where of the six
colonies, three in the entrances of deep caves
held 41% of the total (256) in 1981 but 70% in
1994 (n=239). A possible explanation for this
is given below.

Discussion

Accepting uncertainties over currentnumbers
in Unst and former numbers on Fair Isle and
Foula, the breeding population of Kittiwakes
in Shetland has declined by at least 30%
since 1975-81. The greatest decrease
occurred since the Seabird Colony Register
counts of 1985-87 (Lloyd etal. 1991). This is
the largest regional decline known to have
occurred recently in Britain and Ireland; the
only other significant regional decrease has
been atcolonies in south-east |lreland although
substantial local declines have occurred, e.g.
on the Isles of Scilly (Walsh etal. 1994). Even
in Orkney, whose nearest Kittiwake colonies

SB 17 (4)

are only 100km from Mainland Shetland, there
has been no evidence of arecent, widespread
decline in numbers although there was a 40%
decrease between 1969/70 and 1985-87
(Lloyd et al. 1991), which mainly occurred
between 1980 and 1984 and halted in 1985
(Benn et a/. 1987). Itis also notable that the
decline on Fair Isle, mid-way between the two
island groups, has been much less and more
recent than elsewhere in Shetland. Within
Shetland, the greatest proportional decrease
occurred at colonies along the south-west
and east coasts (Areas A-C and H-kK), where
the most recent total count of nests (8,364)
was 53% lower than in 1985-87 (17,856) and
60% lower than in 1981 (21,147).

Oil pollution around Shetland is unlikely to
have contributed much to this decrease since
beached bird survey data indicate no
significant recent increase in the proportion of
birds found that were oiled, which anyway
was low compared to other areas of the North
Sea (Heubeck in press a).

TABLE 3. Numbers of Kittiwake AONSs at colonies at Noness, 1977 - 1994. Made
from a Zodiac inflatable except those in 1977 which were made from photographs
taken from the sea. The 1985 count was not plotted accurately enough for colony

comparisons.

Dates : 25/6/77, 15/6/81, 20/6/85, 12/6/88, 15/6/90, 8/6/91, 13/6/92, 6/6/93, 2/6/94.

Colony

1977 1981 1985 1988
1 34 22 30
2 83 49 26
3 323 300 aif
4 390 407 105
5 508 488 661
6 176 145 269
V/. 106 110 136
8 148 106 163
Total 1/768 1627 1489 1417

1990 1991 1992 1993 1994
16 18 mS 9 5
) 0) ) ) 0
9 i 2 ) 0)
15 25 14 0) 0
A464 A75 444 309 358
116 146 139 82 88
93 91 99 66 66
89 100 102 76 97
806 862 819 544 614

1994

Instead, there are two more likely explanations
for the population decline. Firstly, reduced
abundance of lesser sandeels Ammodytes
marinus around Shetland caused Kittiwakes
to suffer progressively reduced breeding
success from around 1985 onwards,
culminating in 1990 when most colonies
experienced virtually complete breeding
failure (Walsh et a/. 1992). Although some
colonies in other parts of the British Isles also
experienced moderate to poor breeding
success during this period, in no other region
was there such a loss of potential recruits to
the breeding population as in Shetland and it
is notable that high breeding success was
maintained in Orkney inthe late 1980s (Walsh
et al. 1992). Within Shetland, moderate
breeding success was maintained during the
late 1980s at north-western colonies where
proportional decreases in breeding numbers
were less. Whether the stress of breeding in
such adverse conditions affected adult survival
rates is unclear, but brooding adults were
Significantly lighter in 1990 than in 1991
(Hamer etal. 1993), when there was amarked
and broadly sustained improvement in
breeding success after an increase in the
abundance of sandeels spawned that year
(Wright & Bailey 1993; Heubeck et al. in
press).

Kittiwakes first breed when three, but most
not until four or five years old (Wooler &
Coulson 1977). The greatest effects of
reduced recruitment to the breeding

population might therefore have been —

expected at colonies between 1989 and 1994,
which indeed corresponds to the years when
the greatest proportional reductions in
numbers of nests were recorded in most
areas. Assuming no unusually low survival
rates of immatures or increased dispersal to
or from Shetland of potential recruits, it might
also be expected that the benefits of improved

Kittiwakes in Shetland 201

breeding success in 1991-94 (Heubeck et al.
in press) will be reflected in nest counts from
1995 onwards. Large roosts of Kittiwakes,
including many first-year birds, were noted
around colonies in 1993 and 1994 and possibly
most of these birds were not yet of breeding
age.

The second factor likely to have contributed
to population decline has been increased
predation pressure. The main predators at
Kittiwake colonies in Shetland are Great Skuas
Stercorarius skua, Ravens Corvus corax and
Hooded Crows Corvus corone (Great Black-
backed Gulls Larus marinusand Herring Gulls
Larus argentatus also sometimes take eggs
orsmall chicks). Corvids predate eggs and in
Our experience their attentions are rather
transitory and highly localised (Heubeck &
Mellor 1994), with sometimes a large
proportion of eggs being taken for a few years
at a particular colony and then the predation
ceasing, presumably as specialist individual
birds die. This behaviour has long been
recorded (Saxby 1876) and we have no
evidence of a recent increase in corvid
predation of Kittiwake eggs.

FIGURE 2. The location of Kittiwake
colonies at the Noness breeding station
(Table Ill).

202 Heubeck & Mellor

SB 17 (4)

Great Skuas predate eggs, nestlings, recently
fledged and adult Kittiwakes, characteristically
swooping into colonies and dragging birds
from nests or catching them in mid-air, then
falling to the sea where they are drowned and
eaten. Predation by skuas has been known
to occur for many years at some Shetland
Kittiwakes colonies, e.g. Noss (Perry 1948)
and Hermaness (Lockie 1952), and as the
population of Great Skuas increased this
century there was debate as to whether or not
predation was reducing breeding numbers of
Kittiwakes. Some authors believed it was
(e.g. Venables & Venables 1955) but offered
only anecdotal evidence, while Andersson
(1976) believed that predation of nestlings
may have reduced breeding success but was
unlikely to cause decreases in breeding
numbers (Andersson estimated that there
were 600 pairs of Kittiwakes in his Hermaness
study colony in 1972; the respective 1981,
1987 and 1991 counts were 370, 174 and
Six).

Furness (1981) reviewed the diet of Great
Skuas of Foula in the mid-1970s and warned
that any restrictions on the quantity of whitefish
discarded from fishing boats or reductions in
sandeel abundance close to their colonies
could resultin Great Skuas turning to predation
as a main feeding technique, in which case
“all Shetland seabirds would suffer’ with the
greatest influence on populations of, among
other species, Kittiwakes. This proved
prophetic, when sandeels became less
available to seabirds during the 1980s. In
1983 there was a sudden, sustained increase
in the proportion of birdmeat in the diet of non-
breeding skuas on Foula, the occurrence of
bird remains in regurgitated pellets during
1983-89 being on average five times greater
than in 1973-82 (Hamer et al. 1991); the
incidence of bird remains in pellets
regurgitated by skua chicks increased
markedly in 1988, when it was four times the

average values for 1983-87 and nine times

those for 1974-82. Pellet analyses indicated
that Great Skuas fed predominantly on
seabirds on Fair Isle in 1989, principally
Kittiwakes (Harvey etal. 1989). These findings
accord with widespread but largely
unquantified observations of an increase in
skua predation at Shetland Kittiwake colonies
around 1988 which, despite a markedincrease
in sandeel abundance from 1991 onwards
(Wright & Bailey 1993), seems to have become
progressively more widespread rather than
abating (Heubeck et al. in prep.). Increased
predation of adult birds, in particular, could
result in a rapid decline in breeding
populations.

Since Great Skuas characteristically circle
around a colony before swooping in to attack
a nest, and prefer to attack nests higher on
the cliff, cliff topography is likely to determine
which colonies and nests are predated and
which are in too sheltered situations or are too
low for skuas to manoeuvre effectively. Of
1,020 nests on Papa Stour colonies checked
from a Zodiac on 14 July 1988, chicks were
seen in only 94, virtually all of which were
situated in recesses, under overhangs or in

the backs of caves; none was seeninnests _

on ‘open’ cliff faces. At Kettlaness breeding
success was monitored between 1987 and
1993 at a colony that, it transpired, suffered
intense predation by skuas (only three chicks
survived to fledging size during 1988-93). As
the number of nests decreased (from 261 in
1987 to 42 in 1993) the upper parts of the
colony were the first to be abandoned and
typically, the chicks that survived longest
were those in the lowest nests and under rock
overhangs.

If the current levels of predation by Great
Skuas are maintained, then the proportion of
the Shetland Kittiwake population nesting in
cave entrances or other highly sheltered

1994

situations will probably increase, in which
case censusing from the sea is essential as
such colonies are usually difficult to view from
land.

Acknowledgements

The 1985-94 surveys were carried out under
contract to the Shetland Oil Terminal
Environment Advisory Group, with the
assistance of staff of the former Nature
Conservancy Council and Scottish Natural
Heritage, who provided the Zodiacs used and
also data from Noss. Fairlsle Bird Observatory
provided date from that island, gathered under
contract to the Joint Nature Conservation
Committee. P. Kinnear and M. Richardson
made available the 1977 photographs of
Noness and field maps of the 1981 survey,
respectively. We are indebted to those who
assisted on surveys : D. Bird, E. Danchin, C.
Dore, A. Douse, V. Egan, P. Ellis, P. Evans,
B. Fox, H. Harrop, P. Harvey, M. Leopold, J.
Morton, D. Okill, K. Osborn, A. Prior, P.
Reynolds, M. Richardson, |. Robertson, R.
Schofield, E. Stuart, D. Suddaby, J. Swale, R.
Wynde. Earlier drafts of the manuscript were
improved by comments from G. Dunnet, P.
Harvey, J. B. Nelson and M. Richardson.

References

Andersson,M.1976.Predation and
kleptoparasitism by skuas in a Shetland
seabird colony. /bis 118: 208-217.
Benn, S., Tasker, M.L. & Reid, A. 1987.
Changes in numbers of cliff-nesting
seabirds in Orkney, 1976-1985. Seabird
NOP Si-57..

Boyd, J.M. 1960. The distribution and
numbers of Kittiwakes and Guillemots at
St Kilda. Brit. Birds 53: 252-264.

Coulson, J.C. 1963. The status of the
Kittiwake in the British Isles. Bird
Study 10: 147-179.

Kittiwakes in Shetland 203

Cramp, S., Bourne, W.R.P. & Saunders, D.
1974. The seabirds of Britain andlreland.
Collins, London.

Furness, R.W. 1981. The impact of
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skua on other seabird populations at a
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Hamer, K.C., Furness, R.W. & Caldow
R.W.G. 1991. The effects of food
availability on the breeding ecology of
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Hamer, K.C., Monaghan, P., Uttley, J.D.,
Walton, P. & Burns, M.D. 1993. The
influence of food supply on the
breeding ecology of Kittiwakes Rissa
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Harris, M.P. 1976.The seabirds ofShetland
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Harris, M.P. 1987. A Low-input Method of
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1-10.

Harvey, P.V., Silcocks, A.F. & Howlett, P.
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Harvey, P.V., Riddington, R., Votier, S.C. &
Taylor, R. 1992. Fair Isle seabird
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Heubeck, M. & Mellor, R.M. 1994.
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Heubeck, M., Harvey, P.V., Mellor, R.M. &
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breeding parameters of the Kittiwake

204 Heubeck & Mellor

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Seabird.

Heubeck, M., Richardson, M.G. & Dore,
C.P. 1986. Monitoring numbers of
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Lockie, J.D. 1952. The food of Great
Skuas on Hermaness, Unst, Shetland.
Scott. Nat. 64: 158-162.

Lloyd, C., Tasker, M.L., & Partridge, K.
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and Ireland. T. & A.D. Poyser, London.

Perry, R. 1948. Shetland Sanctuary.
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Pritchard, D.E. 1981. Monitoring for
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Shetland. Unpublished M.Sc. thesis,
University College London.

Richardson, M.G. 1985. The status and
distribution of the Kittiwake in Shetland
in 1981. Bird Study 32: 11-18.

Saxby, H.L. 1876. The birds of Shetland
with observations on their habits,
migration and occasional appearance.
Maclachlan & Stewart, Edinburgh.

Venables, L.S.V. & Venables, U.M. 1955.
Birds and mammals of Shetland. Oliver
& Boyd, Edinburgh.

SB 17 (4)

Walsh, P.M., Sim, |. & Heubeck, M. 1992.
Seabird numbers and breeding success
in Britain and Ireland, 1991. Joint
Nature Conservation Committee,
Peterborough (UK Nature
Conservation, No. 6).

Walsh, P.M., Brindley, E & Heubeck, M.
1994. Seabird numbers and breeding
success in Britain and Ireland, 1994.
Joint Nature Conservation Committee,
Peterborough (UK Nature
Conservation, No. ).

Wooler, R.D. & Coulson, J.C. 1977.
Factors affecting the age of first
breeding of the Kittiwake Rissa
tridactyla. Ibis 119: 339-349.

Wright, P.J. & Bailey, M.C. 1993. Biology
of Sandeels in the Vicinity of Seabird
Colonies at Shetland. SOAFD
Fisheries Research Report No. 15/93.

lM. Heubeck, Department of Zoology,
University of Aberdeen, Tillydrone
Avenue

Aberdeen AB9 2TN.

R.M. Mellor, Fairview, Quendale,
Shetland ZE2 9JB.

(Revised Typescript received 10 September 1994)

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Ne ee, ee Oe

Scottish Birds (1994) 17: 205-211

205

Densities of breeding Magpies and Carrion Crows in south-east

Scotland in 1992-93.

H.E.M. DOTT

Densities of breeding pairs of Magpies and Carrion Crows, based on nests
found in 2km X 2km squares, are reported for different habitats in Lothian
and Borders Regions in south-east Scotland. Differences in density are
discussed in relation to habitat and other factors.

Introduction

The distribution and numbers of Magpies
Pica pica and Carrion Crows Corvus corone
in Britain have undergone changes in the
past, andrecently both species have increased
nationally. The increases have not been the
same in different parts of Britain or in all
habitats (Thom 1986, Marchant et al. 1990,
Birkhead 1991).

The populations of both Magpies and Carrion
Crows have two components: a breeding
component comprising pairs of birds holding
nesting territories, and a non-breeding
component of mainly younger birds which
usually form loose groups or flocks and do not
hold defined territories (Goodwin 1986,
Birkhead 1991). Most population studies
have been based on numbers of breeding
pairs (e.g. Parslow 1973, Sharrock 1976,
Tatner 1982a, Marchant et al. 1990, Gibbons
et al. 1993). In Scotland there are few
published records of population densities,
particularly forthe Magpie. This article reports
on the densities of breeding pairs in selected
parts of south-east Scotland obtained by an
easily repeatable method which will provide a
basis for future comparisons.

Methods

Densities were recorded in sample areas of a
constant size in 1992 and 1993. The whole of
each sample area was surveyed, during
February - June. These sample areas were
2km x 2km squares (tetrads) taken from
Ordnance Survey maps, in a variety of
geographical locations and habitats in south-
east Scotland. ‘Habitats’ sampled in this
study are broad ones such as suburban or
farmland, rather than components of these
such as garden, park, tree line or field.
Individual Magpie or Crow territories could
span more than one of these components.
Tetrads were considered to be a better size
than 1km x 1km squares for sampling these
broad habitats, as smaller units would be
more strongly biased towards particular
features such as woodland strip or field within
farmland, or housing scheme or school ground

~ within cities.

Within each tetrad, a search was made for all
nests of Magpies and Carrion Crows.
Searching was done in late winter and spring,
as nests are easier to locate before trees are
in leaf, and checks were made after this time.
Care was taken to distinguish nests from a
previous year, and to distinguish those of

206 H.E.M.Dott

Magpies, Carrion Crows, Rooks Corvus
frugilegus, raptors, squirrels Sciurus spp. or
other species. Two nests built in the same or
neighbouring trees were taken to represent
one breeding pair, as pairs are known to build
close to old nests or to new, abandoned nests
(Picozzi 1975, Hewson & Leitch 1982,
Birkhead 1991). Differences in habitat affected
the ease of discovering nests, that requiring
most time-effort being suburban habitat for
Magpies with numerous garden boundaries
and thick evergreen trees. The method was
kept constant and was done by the same
observer in each tetrad, so that the results
should be comparable with each other.

Observations outside the tetrads were also
made very widely throughout Lothian and
Borders Regions in connection with fieldwork
for the breeding bird atlas for this area (in
prep.), SO giving an impression of how similar
or otherwise sampled tetrads were to
surrounding areas.

Results and Discussion

Magpie

Table 1 shows the numbers of Magpie nests
found in each tetrad, and the densities of

breeding pairs. The densities ranged from
1.5 to 2.25 per km2:

SB 17 (4)

City and suburban Magpies tended to nest
near the tops of medium sized deciduous
trees with thick twig-growth such as hawthorn,
silver birch and whitebeam, and evergreen
spruce. Wider observations suggested that
the Edinburgh and Dalkeith tetrad results
were typical of much of the north, west and
south of the city and suburbs. The Riccarton
tetrad was mainly rural, with University campus
(which resembles suburban habitat) filling a
quarter of the tetrad. The tetrad near Broxburn
was typical of much of West Lothian, with
undulating hills and hollows, small farms with
stock on pasture, some grain crops, shelter
belts, and numerous hedges of hawthorn
both trimmed and well-grown. Magpie nests
were mainly in lines or patches of hawthorn,
with some in taller trees near farm buildings.

In town and country, Magpies showed a
distinct preference for nesting in hawthorn.
This occurred evenin places where hawthorns
were very scarce anda range of other suitable
tree species was present. Other trees used
for nesting were beech, alder, larch, pine,
yew, holly and once (at Cramond in 1993) in
the top of a monkey puzzle tree; this may be
one of the few records of any British wildlife

using this introduced species of tree, though ©

J.B.Reid (in litt.) has recorded Rooks nesting
in a monkey puzzle tree in Fife.

Table 1 Annual densities of breeding Magpies in south-east Scotland, 1992-93

Tetrad: Location Habitat Number Density of Higher density within
map ref. to of Nests breeding pairs tetrad of nests per

centre point per km2 km2 (see text)
NT 230690 Edinburgh urban 6 1.50 16.00

NT 330670 Dalkeith suburban 9 2.25 5

NT 170690 Riccarton rural and 8 2.00 ;

suburban
NT 070740 nr Broxburn rural if WE AS 4.00

1994

The results indicate a higher density in
suburban habitat of about 2.25 pairs per km2,
and lower in city and rural habitats of 1.5 to
1.75 pairs per km2. Interestingly, in the
Edinburgh city tetrad some clumping of nests
occurred; four of the nests were within one
quarter km2 - a density of 16 nests per km2 for
this group. Part of this tetrad comprised
playgrounds and playing fields, but there was
much garden and tree-line habitat apparently
suitable for Magpie nests but lacking them,
and so the clumping could not obviously be
explained by habitat variation. A possible
explanation was that Magpies may have been
avoiding nesting near places with Crows’
nests; Crows are known to interfere with
Magpie breeding success (Baeyens 1981,
Tatner 1982b). In the rural tetrad near
Broxburn, five of the Magpie nests were
spaced at about 4.0 per km 2, but this did
seem to be related to habitat; hawthorn hedges
and scrub with small trees were more
abundant in this part of the tetrad than in the
remainder.

Over Britain as a whole, sample plots in 1972
gave mean densities of 2.3 pairs per km2 for
farmland, and 2.8 for woodland (Sharrock
1976), but these have risen since to over five
pairs per km? for farmland, and over ten for
both woodland and suburban habitat (Gooch
etal. 1991). InManchester, Magpies occurred
at six to seven pairs per km2 in the city, but
less than this in the surrounding farmland
(Tatner 1982a). In Manchester central city
parks, Groom (1993) recorded up to 49 pairs
per km2, but suggested that this should be
‘compared cautiously’ with other studies due
to his small sample areas. In Sheffield city
densities were about 1.3 pairs per km2 in
1946, 4.1 in 1976 (Roberts 1977) anduptoa
maximum of 32 recently, but much lower just
Outside the city (Birkhead 1991). One
published density for Scotland is 0.22 pairs

Magpies & Crows in SE Scotland 207

per km? for farmland with few hedges in
Aberdeenshire (Love & Summers 1973). The
wide variation in published densities may
result from different size of study areas as
well as genuine differences in Magpie
densities.

As at Manchester and Sheffield, this study
shows Magpie densities in south-east
Scotland to be higher in suburban areas than
in surrounding rural habitat. These south-
east Scotland densities are much lower than
the recent ones for English cities, but much
higher than rural Aberdeenshire in the 1970s.
The New Atlas (Gibbons et a/. 1993) shows
that from the 1970s to the 1990s the main
Magpie breeding distribution has changed
very little, but that the abundance within this
range has continued to increase, and that
England, Wales and Ireland have widespread
high abundance compared to Scotland. In
West Lothian, Magpie density may be lower
than it potentially could be due to Carrion
Crows, because some Crows there nest in
lines of well-grown hawthorn which would
otherwise be favoured Magpie habitat.

Throughout Borders Region, East Lothian
District, and Midlothian District except for
Edinburgh satellite towns, Magpies are still
too scarce as a breeding species for density
sampling to be meaningful, although records
show their range to be increasing in recent
years (Borders Bird Reports, Lothian Bird
Reports, 1979-1992). Interestingly, Magpies
in Borders and perhaps in eastern East Lothian
tend to nest in patches of dense conifer
plantation, thus differing from those in West
Lothian and west of there (pers. obs.).
Magpies were present generally through
south-east Scotland until the 1840s, and
keepering is accepted to be the main reason
for their disappearance (Thom 1986). There
is no record that Magpies were ever absent

208 H.E.M. Dott

from West Lothian, and round the western
parts of Edinburgh they were judged to be
more plentiful than in other parts of Scotland
in the 1930s (Rintoul & Baxter 1935). In the
1950s they were still very scarce in central
and eastern Edinburgh (Edinburgh Bird
Bulletins 1950-1958) where they are now
widespread. However, there has been no
quantitative assessment until now.

The sampling of whole tetrad squares over
rural, urban, or other broad habitats should
provide a useful method for future comparison.
This could be more meaningful for this species
than sampling smaller component habitats
for example woodland strips, where a
‘woodland density’ obtained might be based
on nests of pairs whose territories were largely
in the surrounding habitat.

Magpies have been increasing steadily in
Britain as a whole over several decades, and
faster in suburban than in rural areas (Parslow
1973, Marchant et a/. 1990, Birkhead 1991).
This increase has included the colonisation of
new coniferous plantations and cities (Watson
1948, Prestt 1965, Sharrock 1976). There
are signs that the national population may
now be stabilising (Stroud & Glue 1991), but
locally, asin East Lothian and Borders Region,
the spread is continuing.

Carrion Crow

Table 2 shows the numbers of Carrion Crow
nests found in each tetrad and the densities of
breeding pairs. The highest densities were
some ten times greater than the lowest.

In Edinburgh city and its suburbs, Crows
nested very conspicuously, mainly choosing
sites high in tall deciduous trees such as
sycamore, beech, elm, poplar and lime. In
farmland preferred nest sites were in high,

SB 17 (4)

mature trees, growing singly or in spaced-out
lines and, in contrast to Magpies, usually not
close to houses. Lower trees were also used,
and in West Lothian Crows nested in lines of
tall hawthorns (often former railway routes)
where, as suggested earlier, they may have
been excluding Magpies. No Crow nests
were seen on man-made structures, perhaps
suggesting that Crows are not under pressure
from lack of nest sites in south-east Scotland
(see Marchant et al. 1990).

The Edinburgh and Dalkeith tetrads showed
densities of 2.5 and 1.75 pairs per km2 , and
wider observations suggested that these
would be typical of most of Edinburgh and its
satellite towns. Such high densities are of
interest as urban habitat is one which Carrion
Crows have only colonised relatively recently
(Prest 1965, Parslow 1973, Sharrock 1976).
The other high figure of 2.5 pairs per km2 was
for rural West Lothian where, as described for
the Magpie, the farmland is mixed stock and
arable with many well-grown hawthorn
hedges, scrub, tree-lines and shelter strips. A
much lower density averaging 0.21 pairs per
km2 was found for six contiguous tetrads in
East Lothian around Elphinstone. This area
has a flatter landscape of larger farm fields
mainly of grain, fewer hedges usually trimmed
very low, and fewer shelter belts, but some
boundary lines of tall, spaced trees where
most of the Crow nests were situated. In an
area overlapping these tetrads, da Parto
(1985) obtained a rather higher density of one
pair per km2 for farmland, but his study area
probably included more varied habitat.

The hill and moor tetrads south-east of
Teviothead were mainly devoid of trees (apart
from coniferous plantations), except for a few
growing at isolated and mainly derelict
farmhouses where Crow nests occurred.
Elsewhere in Borders Region single small

i

:

tee

1994

Magpies & Crows in SE Scotland 209

Table 2 Annual densities of breeding Carrion Crows in south-east Scotland, 1992-93

Tetrad: Location Habitat Number Density of | Higher density
within
map ref. to of nests breeding pairs tetrad of nests
per
centre point per km2 km2 (see text)
NT 230690 Edinburgh urban 10 2.50 -
NT 330670 Dalkeith suburan 1. 1.75 :
NT 170690 Riccarton rural and suburban 5 e245) -
NT 070740 nr Broxburn rural 10 2.50 -
NT 370690 nr Elphinstone mainly rural 1
NT 390690 nr Elphinstone rural 2
NT 410690 nr Elphinstone rural and suburban 0 0.21 -
NT 390710 nr Elphinstone mainly rural 0
NT 410710 nr Elphinstone mainly rural 1
NT 430710 nr Elphinstone rural 1
NT 710690 eastern Lammermuir low hills and 4/6* TOWN 250: 44.0
Hills valleys
NT 430050 s.e..of Teviothead hill, moor & coniferous 1 0.25 =
plantation
NT 450050 s.e. of Teviothead hill, moor & coniferous 1 0.25 -
plantation

NT 450030 s.e. of Teviothead hill and moor 2 0.50 -

“Four nests were found, but a small part (0.04%) of the tetrad was not surveyed and was likely to

have hald 1-2 additional nests.

stunted rowan, birch or willow trees in remote
gullies were used for nesting. Certain narrow
valleys in treeless hills hold long, narrow
thickets of trees such as birch, willow and

alder. This was the case inthe tetrad surveyed ~

in the eastern Lammermuir Hills, where the
four Crow nests found gave a density of 44
nesis per km2 if calculated for the wood alone.
However, these Crows would use the area of
the surrounding hills so that the tetrad density
of 4-6 pairs per km? gives a more realistic picture.

Dense or extensive woodland is one habitat
in which Carrion Crows do not normally nest

(Goodwin 1986), though they have spread
into some ‘sparsely wooded country’ (Parslow
1973), and more recently into some upland
conifer plantations (Marchant etal. 1990). In
south-east Scotland, Crows still do not
normally nest in woods larger than narrow
shelter strips, nor in coniferous plantations,
although on 24 April 1993 a Carrion Crow
nest was found in a spruce tree in a 1.5 X
1.5km plantation of 3m tall spruces and pines
on a valley slope south-east of Teviothead,
0.25km in from the forest edge.

Published Crow densities do not compare

210 H.E.M. Dott

easily with the present data due to differing
study areas and methods. For Britain
generally, mean densities for 1972 are stated
as 3.2 and 4.7 pairs per km? for farmland and
woodland respectively (Sharrock 1976).
However, the ‘woodland’ figure must include
mainly pairs whose nests were on the edges
of woods but whose territories were mainly in
surrounding habitats. In East Lothian, da
Prato (1985) recorded one pair per km? for
farmland, and 19 per km2 for woodland and
scrub but these were based on stands of only
27 and 10ha respectively, where again the
Crows would use adjacent habitats. In
Kincardineshire, Picozzi (1975) recorded
Crows at 2.3 - 3.0 pairs per km? on farmland
and woods not including adjacent moorland
which the Crows used. Hewson & Leitch
(1982) in Argyll found 26 pairs per km2 ina
coastal strip of wooded habitat which excluded
the adjacent moor occupied by the Crows,
and Rebecca (1985) found six pairs in 25ha
(=24 per km) of trees surrounded by farmland
in Aberdeenshire. Petty (1985) recorded
0.17 and 0.67 pairs per km2 in two areas of
moor with newly planted conifers in Argyll.
Most of the above published densities are not
comparable with the tetrad densities here, as
they concern nests in confined patches of
habitat where the Crows would be largely
occupying the surrounding areas as in the
right-hand column of Table 2. The tetrad
method should be good for sampling general
habitats such as urban, mixed farmland, hill-
sheep land, or others.

The present results suggest that in south-
east Scotland, the highest Carrion Crow
densities are found in urban habitats and in
West Lothian mixed farmland, and lowest
densities are found in arable land and in hill
country of East Lothian and Borders Region.
To what extent these different densities are
due to habitat alone, or to a combination of
habitat and human interference, is not known.

SB 17 (4)

Persecution of Crows has lessened greatly
since the two World Wars and has enabled a
national increase in Crows which is still
continuing (Prestt 1965, Parslow 1973,
Marchant et al. 1990, Stroud & Glue 1991).
However, shooting and trapping still occur
widely on keepered estates and on hill-sheep
land, which in south-east Scotland occurs
mainly in East Lothian District, Midlothian
District, and Borders Region.

Acknowledgements

| thank Dr. Stan da Parto and Mark Holling for
help with improvements and production of
this article.

References

Baeyens, G. 1981. Magpie breeding success
and Carrion Crow interference. Ardea
69: 125-139.

Birkhead, T.R. 1991. The Magpies. Poyser,
London.

Borders Bird Reports. 1979-92. SOC.

Edinburgh Bird Bulletins. 1950-58. SOC.

Gibbons, D.W., Reid, J.B. & Chapman, R.A.
1993. The new atlas of breeding birds in
Britain and Ireland: 1988-1991. Poyser,
London.

Gooch, S., Baillie, S.R. & Birkhead, T.R.
1991. The impact of Magpies Pica pica
on songbird populations. Retrospective
investigation of trends in population
density and breeding success. J. Appl.
Ecol. 28: 1068-1086.

Goodwin, D. 1986. Crows ofthe world. 2nd
ed. BM(NH), London

Groom, D.W. 1993. Magpie Pica pica
predation on Blackbird Turdus merula
nests in urban areas. Bird Study 40: 55-
62.

Hewson, R. & Leitch, A.F. 1982. The
spacing and density of Hooded Crow

|
|
|
|
|

1994

nests in Argyll (Strathclyde). Bird Study
29: 235-238.

Lothian Bird Reports. 1979-92. SOC.

Love, J.A.& Summers, R.W. 1973. Breeding
biology of Magpies in Aberdeenshire.
Scott. Birds 7: 399-403.

Marchant, J.H., Hudson, R., Carter, S.P. &
Whittington, P. 1990. Population trends
in British breeding birds. BTO, Tring.

Parslow, J.L.F. 1973. Breeding birds of
Britain and Ireland. Poyser,
Berkhampsted.

Petty, S.J. 1985. Counts of some breeding
birds in two recently afforested areas of
Kintyre. Scott. Birds 13: 258-262.

Picozzi, N. 1975. A study of the Carrion /
Hooded Crow in north-east Scotland.
Brit. Birds 68: 409-419.

da Prato, S.R.D. 1985. The breeding birds
of agricultural land in south-east
Scotland. Scott. Birds 13: 203-216.

Prestt, |. 1965. An enquiry into the recent
breeding status of some of the smaller
birds of prey and crows in Britain. Bird
Study 12: 196-221.

Rebecca, G. 1985. High density breeding
and ground nesting of Carrion Crows.

Magpies & Crows in SE Scotland 211

Scott. Birds 13: 188.

Rintoul, L.J. & Baxter, E.V. 1935. A vertebrate
fauna of the Forth. Oliver and Boyd,
Edinburgh.

Roberts, P. 1977. Magpies in Sheffield. The

Magpie 1: 4-6.

Sharrock, J.T.R. 1976. Theatlas of breeding
birds in Britain and Ireland. BTO,. Tring.

Stroud, D.A. & Glue, D. (eds.) 1991. Britain’s
birds in 1989-90: a conservation and
monitoring review. BTO/NCC, Thetford.

Tatner, P. 1982a. The density of breeding
Magpies Pica pica L. in an urban
environment. The Naturalist 107; 47-58.

Tatner, P. 1982b. Factors influencing the
distribution of Magpies Pica pica in an
urban environment. Bird Study 29; 227-
234.

Thom, V.M. 1986. Birds in Scotland. Poyser,
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Harry E.M. Dott, 70 Findhorn Place,
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(Revised typescript received 18 June 1994)

212 Scottish Birds (1994) 17:212-234

The breeding performance of Ravens from a sample of nesting
territories in Shetland during 1984-1993

P.M. ELLIS, J.D. OKILL, G.W. PETRIE & D. SUDDABY.

This paper summarises the breeding performance of some Raven territories
in Shetland during 1984-93. There were no significant annual differences.
Shetland Ravens showed broadly similar breeding performance to that
found during previous studies from various areas of Britain, Europe, North
and Central America. However breeding success (the percentage of nesting
pairs which fledged at least one young) in Shetland was lower than that
found in all but three of 18 other studies cited.

Introduction

After a retreat since mediaeval times from
much of lowland Britain, particularly during
the era of intensive game preservation, the
population of the Raven Corvus corax had not
declined seriously in many areas until the
1960s (Ratcliffe 1962). However, since then
ithas declined in south, south-west and central
Scotland, mainly as a result of changes in
land use (Marquiss et a/. 1978, Mearns 1983,
Mitchell 1981), in Speyside possibly due to
human persecution andin particular the illegal
use of poisoned baits (Weir 1978) and the
English Pennines, also probably due to illegal
poisoning (D.A. Ratcliffe pers. comm.). Its
status is of sufficient concern for it to have
been included in alist of candidate species for
inclusion in ‘Red data birds in Britain’ (Batten
et al. 1990). However over much of the
western Highlands and Islands, Shetland and
Orkney the Raven remains widespread (Thom
1986, Booth 1979, Ewins et a/. 1986).

In Shetland, Ewins et al. (1986) carried outa
survey of breeding Ravens during 1982-83.
He investigated diet by examining pellets and
also gathered some data on breeding
performance from a sample of c. 60 nesting
attempts.
breeding performance gathered at 43 Raven
territories from widely disiributed localities
throughout Shetland which were visited
annually and involved 311 nesting attempts
during 1984-1993.

Study area

Shetlandis an archipelago of over 100 islands
lying at the northern end of the North Sea at
latitude 60° north. It has a cool maritime
climate influenced by the relatively warm
waters of the North Atlantic Drift. The rugged
1,450km long coastline has many high
seacliffs, with no point in the islands more
than 5km from the sea (Flinn 1974). Much of

This paper presents data on .

1994

the land area of 1,468kmaz2 is rough grazing,
carrying about 380,000 sheep (Anon. 1993).

This study was carried out during the course
of other ornithological work, particularly the
annual monitoring of Peregrine Falcons Falco
peregrinus and Merlins Falco columbarius.
The monitored Raven sites were not chosen
randomly, but were chosen to be relatively
near to the routes to the monitored falcon
breeding sites (so that this work fitted in easily
with higher priority raptor monitoring), or were
on the islands of Fetlar and Yell where RSPB
nature reserve wardens were resident during
the summer. Nevertheless, the sample of 43
territories included in this study represents
21% of the known Raven territories in Shetland
and there was a deliberate attempt to include
sites from a wide area; 11 (26%) were on the
island of Fetlar, two (5%) on the island of Yell,
six (14%) in the north Mainland, 12 (28%) in
the central Mainland, four (9%) in the west
Mainland and eight (18%) in the south
Mainland.

Methods

Each year, the monitored territories were
visited at least once and all suitable nesting
habitat within about one kilometre of any past
nesting site was searched. During 1984-
1986 suitable territories were still being
located, but during 1987-1993 the same 43
territories were visited each year. Any sites
occupied on the first visit were visited a second
time and any active nests were visited
subsequently to ring or record any young and
to check if young had fledged. Twenty-three
(c. 50%) of the nest sites were relatively
accessible, but were usually climbed to only
in order to ring young when they reached an
estimated ten days of age. A territory was
recorded as occupied if it contained at least
one displaying individual, birds showing alarm,

Ravens nesting in Shetland 213

a pair regularly seen in suitable breeding
habitat, or a nest which had been built up and
lined that season or containing eggs or young.
A breeding attempt was recorded if a nest
with eggs or young was located or an empty
nest that had been built up and lined.

Nest sites

In 34 (79%) of the nesting territories monitored
during this study, nests were usually located
onseacliffs, although in five of these territories
at least one alternative site was not on a
seacliff. In the other nine territories (21%)
nests were always in inland locations up to
1.7km from the coast. Inland sites varied
from the bank of streams (one nest being only
3m above the stream bed), active or disused
quarries, roadside cuttings to, in one case, a
tree.

Results

Table 1 gives the breeding data for the
monitored Raven territories. During 1984-93
there was a Significant difference between
the percentage of nests which were occupied
each year (X2 = 16.972, df =9, p<0.05). This
was because during 1984-86 a small number
of occupied, but previously unknown nesting
territories, were located and these were
subsequently included in the monitoring
programme. This resulted in a bias in the
percentage of occupied sites during the first
three years of the study. Consequently, unless
otherwise stated, further discussion refers

only to data gathered during 1987-1993.

Annual breeding performance

The average proportion of sites occupied
each year was 79.7%, (range 67%-93%) and
there was no significant difference between
years (X2= 10.28, df=6, p>0.05,n=43). The
average proportion of territorial pairs which

214 P.M. Ellis et al.

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1994 Ravens nesting in Shetland 215

nested was 92.1%, (range 87%-94%) and
there was no significant difference between
years (X2 = 2.595, df = 2,p>0.05). (The
degrees of freedom were reduced because
the expected frequency per cell was below
the permitted minimum of five, therefore
several years were aggregated together;
1987-88, 1989-91 and 1992-93). There was
no significant difference in mean brood size
between years (Kruskal-Wallis analysis of
variance = 5.319, df =6, p>0.05, mean brood
size 3.07, range 1-6, sd = 1.30), nor was there
any significant difference over the entire ten
years of the study (Kruskal-Wallis analysis of
variance = 10.485, df = 9, p>0.05, mean
brood size 3.18, sd = 1.33). There was no
significant difference in productivity between
years (Kruskal-Wallis analysis of variance =
5.555, df = 6, p>0.05, mean productivity 1.62
young fledged per pair, sd = 1.80) and there
was also no significant difference in the
proportion of successfully nesting pairs
between years (X2 = 4.045, df = 6, p>0.05).
The mean proportion of successful pairs
(nesting pairs which fledged at least one
young) was 57.9%, (range 47%-69%).

Clutch size

Table 2 shows the frequency distribution of
clutches and mean clutch size for a sample of
43 complete clutches recorded during 1984-
1933. The mean clutch size was 4.63, sd =
1.35, range 1-7.

Number of known nesting territories
and nesting density

Ewins (1986) documented 196 Raven
territories in Shetland. Between 1984 and
1993 an additional ten territories were located,
nine of which were in inland locations. This
brings the number of known Raven territories
in Shetland to 206, giving a density of 14.0
territories/1 00kmae, but with amean occupation
rate during 1987-93 of 80% this would produce
a density of 11.2 occupied territories/100kmz2
and with a mean of 73% of territories holding
nesting pairs during 1987-93 give a density of
10.2 nesting pairs/100kmz.

Table 2. Clutch size data for a sample of clutches from Ravens nesting in Shetland

during 1984-1993, all years combined.

Clutch size 1 2g HA

Number of clutches
of each size recorded

Se

Total Mean S.d.
clutches size

4.63 1.35

216"—-P: MEEllis.eual: SB 17 (4)

Human persecution and nesting
failures

Definite proof of persecution was recorded on
several occasions atfive of the 43 sites (12%),
and was suspected at severai others. All but
one of the persecuted territories were inland
sites. One nest was shot into, one was
dislodged with a length of pipe, one was
pushed off a small cliff and two had rocks
dropped into them. Of the 127 nest failures
recorded during 1984-93 only six (4.7%)
definitely occurred after young had hatched,
and three of these were due to human
persecution. The reason for most nest failures
was unknown.

Discussion

Although the sample of Raven territories
involved in this study was not chosen
randomly, they were from a wide geographical
area of Shetland and from both seacliff and
inland sites, so were likely to give areasonably
representative indication of the breeding
performance of Ravens in Shetland between
1984 and 1993. It appears that, although
Shetland Ravens show annual variations in
breeding performance, these are relatively
small and in this study were not significant.

Comparisons with other areas

Table 3 shows breeding data from this study
compared to those found in several other
areas of Britain, Europe, North and Central
America. Nineteen of these studies showed
a range of mean clutch sizes of 4.2-6.0,
average 4.9, 27 studies showed a range of
mean brood sizes of 2.5-4.0, average 3.1, 19
studies gave a range of mean breeding
success Of 47.4-89%, average 71% and eight
studies gave a range of mean percentage of
pairs nesting of 64-95%, average 87%.

Although the mean clutch size, mean brood
size and mean percentage of pairs nesting
found in this study was similar to those found
elsewhere, breeding success was towards
the lower end of the range. Lower nesting
success than the present study (58%) or that
of Ewins et al. (1986) (52%) was reported
from only two areas: 57% in Orkney during
1983-85 (Booth 1985) and 47.4% in Utah
during 1967-70 (Smith & Murphy 1973). Dorn
(1972) found a mean nesting success of 58%
(equal to the present study) in Wyoming in
1971.

Possible reasons for the low breeding
success of Ravens in Shetland

The use of illegal poisoned baits has never
been recorded in Shetland by the RSPB and
during 1984-93 no cases of egg collecting
involving Ravens was known to the RSPB
(PME pers. obs.). The Raven is one of the
few species in Shetland which is persecuted
by man (pers. obs.). Although definite proof
of persecution was recorded at only a few
sites, itis possible that the actual amount was
substantially higher.
unlikely that this is the main reason for such
a high number of nest failures.

Breeding performance may be related to the
food supply in spring and early summer (Ewins
etal. 1986). Ewins etal. (1986) described the
diet of Shetland Ravens obtained from the
examination of 540 pellets. Since there is
much sheep carrion, and rabbits and birds
apparently available as prey (pers obs.), food
shortage would seem to be an unlikely reason
for poor breeding success.

Ravens in Shetland nest at relatively high
densities: only seven of the 38 studies cited
by Skarphedinsson etal. (1990) and Nogales

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220 P.M. Ellis et al.

(1994) found higher densities (table 3). The
mean nesting density from the 38 studies
cited was 9.4 nesting pairs/100km2, range
0.35-72.6. The differences between the
densities found in this study and those found
by Ewins et al. (1986) may in part be due to
that authors use of a lower figure for the area
of Shetland and a different method of
calculating the proportion of territories
occupied by nesting pairs. In addition flocks
of failed breeders or non-breeding Ravens
occur in Shetland. During 1975-1992 in most
years, the largest flocks of Ravens reported
were published in the annual Shetland Bird
Report (Shetland Bird Club 1975-92). Innine
of the 18 years, the largest flocks were
recorded during the breeding season. The
mean size of these large flocks of failed
breeders or non-breeding Ravens was 60,
range 19-80. As such a high population
density recorded in Shetland, it is possible
that density dependent effects on breeding
are operating (D.A.Ratcliffe pers. comm.).
The reasons for the poor breeding success of
Ravens in Shetland are worthy of further
investigation.

Population trend

The non-random selection of the sample of
sites used in this study precludes any
conclusions on population trends. However,
casual observations suggest that no major
changes have occurred since 1982-83,
although a repeat survey would be required to
confirm this.

Acknowledgements

We would like to thank all those who assisted
with fieldwork since 1984, particularly A.
Aitken, G.W.Allison, G.W.Anderson,
F.M.Beveridge, D.R.Bird, |.D.Bulloch,
J.N.Dymond, P.J.Ewins, 1|.Hawkins,

SB 17 (4)

M.Heubeck, W.Horn, R.Lidstone-Scoitt,
R.Matthews, R.J.Nowicki, M.A.Peacock,
M.Preece, T.Prescott, J.S.Rowe, S.Smith,
C.E.Vawdrey, M.|l.Walker, D.J.Weaver,
R.M.Wynde, D.A. Ratcliffe and M. Marquiss
commented on earlier drafts. We would also
like to thank all those who over the years gave
us information about nesting territories,
particularly P.J.Ewins, and those Shetlanders
who allowed us to wander so freely over their
land.

References

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SB 17 (4)

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(Revised typescript received 7 July 1994)

Scottish Birds (1994) 17: 223-234

223

Breeding seasons and nesting success of Snow Buntings in

north-east Scotland

R.D.SMITH & M. MARQUISS

The timing and success of breeding Snow Buntings was monitored over a six year
period and two montane areas in north-east Scotland. Successful first broods were
initiated slightly earlier on the more eastern massif in two of four summers, perhaps
as a result of its more continental climate. Successful second broods were found
more frequently on the eastern massif, but clutch and brood sizes and nest failure
rates were similar. On the western massif, early summer snowfalls appeared to limit
the early production of first brood fledglings, and this, in turn, was associated with a
reduction in the frequency of successful second broods. Little difference in
productivity was noted between summers, except in 1992 when clutch and brood
sizes were low. This poor breeding success occurred in a snow-free summer, and
followed a particularly mild winter in which losses of breeding adults were unusually

high.

Introduction

The Snow Bunting Plectrophenax nivalis is
one of Britain’s rarest breeding birds, existing
here onthe southern margin of its circumpolar
Arctic distribution. Itis confined to the Scottish
Highlands where it breeds in the high corries
and boulder fields. Numbers have increased
in the past 20 years, and the estimated total
of 50-100 Scottish territories in some recent
summers (Watson & Smith 1991, Smith 1993)
far exceeds the single figure estimates
previous to this (Nethersole-Thompson 1966).

Although Nethersole-Thompson’s (1966)
Snow Bunting monograph provided many
novel observations on the behaviour and
distribution of the Scottish population, low
numbers of birds at that time (mainly 1930s -

1950s) restricted the collection of data on
breeding biology. Also, the behaviour and
breeding ecology of Scottish Snow Buntings
may have changed in association with, or as
a result of, the population increase.

In this paper we describe aspects of the
timing and success of breeding in north-east
Scottish Snow Buntings during 1987-1993.
Higher population levels have also allowed
us to look for variation in the timing and
success of breeding between summers.
Finally we have been able to compare
breeding biology onthe main Scottish breeding
area with that of a small number of pairs ona
lower nearby massif.

224 R.M. Smith & M. Marquiss

Methods

The main study area (A) was the central and
western parts of the Cairngorms (57°N, 4°W),
approximately 32km2_ of granitic mountain
plateaux and corries between 1000 and
1300m in altitude, divided by adeep mountain
pass, the Lairig Ghru. Observations began in
1987, but were confined to a census of pairs
east of the Lairig Ghru and the monitoring of
four nests found by chance. In 1988 we
censused the whole area, and attempted to
locate all successful breeding attempts east
of the Lairig Ghru. Also, six nests were found
west of the Lairig Ghru. From 1989 to 1993
we monitored nests and broods throughout
the whole study area. Snow Buntings were
rarely reported in the 5km band surrounding
area A in the breeding season, suggesting
that the area chosen held a discrete Snow
Bunting population. Nests were also found
on a second, smaller area (B) in the south-
eastern Grampian mountains (approximately
30km from area A) from 1990 to 1993. In this
area Snow Buntings nested mainly in large
granitic corries between 900 and 1100m in
altitude. Area A held 26-40 pairs of Snow
Buntings during 1989 to 1993 and a totai of
256 active nests or fledged broods were
located. On area B there were 2-5 pairs and
23 nests/broods were found.

Most breeding sites were visited on four or
more occasions. Breeding pairs were usually
identified within two visits although some
could be more elusive. Inthe first years of our
study it was possible to differentiate between
pairs on the basis of plumage differences, at
least in males. Later, this became less
necessary because up to 80% ofthe breeding
birds were individually marked with coloured
leg rings.

Before 1992, attempts to find nests were

SB 17 (4)

biased towards times when nestlings were
expected to be present. This was possible
because nesting behaviour was fairly
synchronised at the start of the breeding
season, or on other occasions after heavy
snowfalls had caused widespread nest failure
(see Results). Second breeding attempts
were begun soon after (and sometimes
probably before) the first brood fledged,
allowing us to predict the best time to search
for second broods. In 1992 and 19983 effort
was spread more evenly, so more nests were
found during incubation or soon after hatching.

Two hundred and twenty-nine active nests
and an additional 50 fledged broods were
found during 1987-1993. Thirty-three percent
of nests were initially found with eggs, 19%
with small young (oldest chick less than five
days old), 33% with medium-sized young (5-
9 days old), and 14% with large young (10
days or older). We tested for differences in
breeding parameters (e.g. clutch or brood
size) between these four nest stages where
appropriate, to allow for the possibility that
eggs or young were removed from (or left)
some nests. First egg dates were back-
calculated from estimated chick (youngest)
or fledgling ages assuming that one egg was

laid each day, that incubation lasted for 12 ©

days, the nestling period for 14 days, and that
young became independent at two weeks
after fledging (Nethersole-Thompson 1966,
pers. obs.). Two failed clutches of three eggs
were omitted from calculations of clutch-size
because they may have been deserted before
the clutch was complete.

Criteria used for estimating nestling ages
were similar to Maher (1964): size relative to
the egg in the first three days after hatching,
length of growing primary sheath in days four
to seven (when the feather emerged from the
sheath), and wing-length/emerged primary

1994 Snow Buntings in NE Scotland 225

length until fledging. At 16 days old the
fledglings were still relatively immobile with
very short tails. Chicks of this age often
crouched when approached, flights were
hesitant, and they retreated under boulders if
possible. By 20 days they made short flights
in pursuit of their parents, attempted to feed
themselves, and often took flight when
approached. Over the nest week pursuit of
parents became well-developed and families
could range over large areas in a short space
of time. By the end of the second week after
fledging, the wings and tail were of similar
length to those of adults (primaries full-grown
when about 35 days old - unpubl. data), the
chicks spent most of their time feeding
themselves (although often in the company of
a parent), and the frequency and success of
begging behaviour was reduced.

The contents of nests were last counted on
the day the nestlings were ringed so as to
reduce the likelihood of chicks departing
prematurely. The young could be ringed
when only four days old, although 6-8 day old
young were ideal and most were done at this
stage. The number of young alive in the nest
when they were ringed is referred to as the
brood size at ringing. Subsequently, it was
not possible to count the number of chicks
accurately without handling them. However,
as most nests were revisited after the young
had fledged, we could also calculate the
fledging brood size by subtracting the number
of dead chicks in the nest from the brood size

at ringing. This measure will inevitably be an |

overestimate because, on a few occasions,
nestlings known to have died were not found
and must have been removed from nests by
the parents or by predators.

Of the 229 nests found, 31 definitely failed
(contents deserted or disappeared long before
fledging could have occurred) while 161 almost

certainly fledged chicks. Evidence for
successful fledging was considered sufficient
if the nestlings were known to be alive in the
nest at 12 days old or older (at this stage they
could evade a predator by scrambling out of
the nest and hiding in cracks within the nest
cavity), or if they were seen after fledging.
This was aided from 1989 onwards by colour-
ring coded broods, or individuals (in 1992 and
1993). A further 37 nests were treated as
failures because most of the young, especially
the oldest, were found dead in the nest ona
follow-up visit after the expected fledging
date or because the young appeared
emaciated on the final visit. The main reason
for the unproven outcome of the remaining 31
nests was too few follow-up visits. They were
hence treated as successful because of the
advanced age and obvious health of the
chicks on the final visit, and the low nest
failure rate (see Results).

First and second broods were separated by
date (first egg date before or after 1 July
respectively) or whether the pair were known
to have already successfully produced a
fledged brood. Second attempts invariably
involved the construction of anew nest, usually
within 10-500m of the first. On only one
occasion, when a snowfall forced a female to
abandon a full first-brood clutch, was a nest
re-used within the same summer: the second
attempt was started several days later (still,
by definition, a first brood) and the new clutch,
which later produced fledged young, was laid
directly on top of the first.

Results
Laying dates

First egg dates for individual clutches ranged
from 21 May to 23 July, apart from one
exceptionally early nest on area B (newly
fledged young on 6 June, estimated first egg

226 R.D. Smith & M. Marquiss SB 17 (4)

date 9 May). Peaks of egg-laying occurred in
late May/early June and in late June/early
July (Fig. 1). The average first egg date of
successful first broods was 29 May on area B,
but 6 days later on area A. This varied
between summers, however: successful first
brood nests on area B fledged 12-18 days
ahead of those on area A in 1990 and 1991.
but fledging dates were similar in both areas
in 1992 and 1993.

On area A alone there was considerable
annual variation in first egg dates of first
broods (one way ANOVA Fes 461=4.62,
P<0.001). This was associated with the
occurrence and extent of snowfalls during
May and early June (Fig. 2) which apparently
delayed egg-laying in one year and led to

FIGURE 1
Z 50 May | June | July
=
ua mae
Vy) Z
Q 30 AY l
g Ay He Ae
gq 20 AAiaiaie Z
Chey aul AAG
AIAIAIIAInclclale

10 20 30 40 50 60 70 80

First egg date

failure of initial nesting attempts in others. In
1988 and 1992, the second half of May and
June was mild with little fresh snow. These
laying season were synchronised and largely
successful with a low proportion of late first
clutches. In 1993 there was no snow during
the laying season, but a heavy and prolonged
period of snow just prior to it (13-17 May).
Although some birds initiated breeding
attempts on expected dates (before the end
of May, as in 1988 and 1992), half of the pairs
did not lay until after this, perhaps as a result
of energy deficiencies incurred during the
snow storm. 1989, 1990 and 1991 all had two
peaks in the distribution of first egg dates of
first broods, and in each case a snowfall
occurred between early andlate first nests. In
both former years, nests with early first egg
dates were successfui but the nests
themselves were mostly found during the
nestling stage. The behaviour of other pairs
seen prior to these snowfall (females carrying
nest materials, or males resuming singing
with no signs of their mates) suggested that
other females also initiated early first nests,
but were forced to abandon them during the
snow. Hence they were never detected. The
later mean first egg date of successful first
broods in these three years therefore probably
represents the second nesting effort of the
summer for many pairs, rather than simply a
weather-induced delay to the first efforts. In
1991 this was confirmed to some extent: only
two out of seven nests located prior to
snowfalls on 2-5 June survived. Three of the
five females which failed laid the first egg of
their next nesting attempts during 9-12 June,
the peak of the second wave of nesting
attempts in that summer.

1994 Snow Buntings in NE Scotland 227

IGURE 2 | May | June | | May | June |
Et So ¥ 10 ¥ ¥
BD : % 1988 - 5 S 1989
QO
arti 4 y
‘ L y
° 2 Z 2 WG
c 0 AANA 0 Z
0 10 20 30 40 50 60 0 10 20 30 40 50 60
§ 145 ¥ ¥ 14 ¥
8 12 3 ~ 1990 12 = 2 1991
a)
F p
o J
l
; 7
©
7,
0 10 20 30 40 50 60 0 10 20 30 40 50 60
£1075 ¥ 10
QD 4
1992
8 | g
a 6 7 6
o y
PS 4 y 4
ce -2 y 2
oO 0
Zz

0 10 20 30 40 50 60 0 10 20 30 40 50 60

First egg date First egg date

228 R.D. Smith & M. Marquiss

Number of broods

Snow Buntings on area B successfully reared
more broods (1.69 per pair) than did those on
area A (1.20 per pair; log-linear meer taking
into account annual variation, X@ 9=9.36,
P<0.01). On area A, an average of 60% of
pairs reared one brood each summer, 30%
reared two broods and 10% apnarently failed
completely (n=174). Pairs were more likely to
rear two broods successfully if their first
successful brood was initiated early in the
nesting season (mean 29 May, n=52). Pairs
which attempted but failed to rear a second
brood initiated their first successful clutches
on 2 June (n=18) on average, whilst those in
which no second brood was detected were
later still (mean 8 June, n=78; ANOVA taking
into account annual variation in first egg dates
of successful first broods: Fo 439=35.0,
P<0.001). Similarly, amongst females which
successfully reared first broods, the proportion
which went on to successfully rear a second
was higher in years when successful first
broods were initiated early in the season
(R,=-0.83, n=6, P<0.05; Fig. 3).

FIGURE 3
50

45
40
35
30
25

20

4% rearing second brood

28 30 32 34 36 38 40

Mean first egg date

SB 17 (4)

The inter-nest interval of a pair, defined as the
number of days between laying the last egg of
their first successful brood and laying the first
egg in a second brood, averaged 30 days
(s.d.=6 days, n=81 pairs), although it peaked
at 26-29 days, perhaps indicating that long
intervals were due to a failure of an
intermediate nesting attempt. We noted nest-
building by several females which still had
young in the nest, enabling a small overlap of
broods.

Clutch size, brood size and partial nest
losses

The mean number of eggs in 71 nests
observed during incubation was 4.83
(s.d.=0.96). The total contents (number of
eggs or young) of 44 nests first counted when
the oldest chick was no more than four days
old was slightly, but not significantly, higher
(5.05+0.89eggs+young; ANOVA,
F4 99=0.99, n.s.). This indicates that losses
of contents during incubation and early brood
rearing were negligible. The overall mean of
4.91+0.93 eggs or young in these 115 nests
is therefore the best estimate of clutch size
(Fig. 4).

FIGURE 4
100

80
60
40

20

Number of nests

1“ °2 “St PaaS

Gy 7

Estimated clutch size

1994 Snow Buntings in NE Scotland 229

TABLE 1. Annual variation in Snow Bunting breeding parameters. Broods fledged
per female includes data from Area A only, otherwise data from Areas A and B are
combined. Clutch size is calculated from nests containing eggs or small young.
Brood size at ringing age excludes nests failing before this. The percentage of
nests losing small young, may include cases where unhatched eggs were removed
by the parents. Daily nest failure rate in 1991 excludes the five nests lost ina
snowstorm at the beginning of the breeding season.

Parameter 1988 1989 1990 1991 1992 1993 Mean
Broods fledged per female 1 AD al 268 1224 1202) 4 1206) 51239 1.20
(no. of females) G2) (20). (SAK (4) e(26)n-(8'1) (174)
Clutch size 5:2ilyo623 4:7 5:27% 4-47, 5:00 4.91
(no. of nests) GA) (Sig Ca a G5) °F G2)e (29) (115)
% nests with unhatched eggs 65 a4 24 25 B2 A445 39
(no. of nests) (20)e.(25)" (38)5-4(40)-..(33) (47) (207)
% nests losing small young 30 14 2M, 33 36) 26 30
(no. of nests) dO) GS)" =O) 26) (27) (94)
First brood size at ringing 3:92..3.69. 4.38 4.57 3.68 4.33 4.20
(no. of broods) G2), sG3)e .(24)., (28). 5 (19) i(27) (125)
Second brood size at ringing 3.40 3.60 3.27 3.67 2.57 3.26 S20
(no. of broods) (5)y 1G1O)t CS)igtd2) ge(t4)i5-(19) (77)
Daily nest failure rate (%) 253) iy Wie le ee) yeleOnertl 1 LEY A

(no. of days at risk) (215) (218) (324) (185) (510) (454) (1936)

230 = R.D. Smith & M. Marquiss

The total contents of nests with medium-
sized young was significantly lower
(mean=4.67+1.17, n=76; ANOVA taking into
account annual variation, Fo 153=9-24,
P<0.05), while the total contents of nests with
large young were smaller still (3.94+1.27,
n=32). This was probably due to removal of
some addled or infertile eggs, death and
removal of some young, increased mobility
of young within the nest cavity (scrambling
into inaccessible cracks between rocks to
avoid being caught, an anti-predator strategy),
or early fledging of some brood members
(which can occur from 12 days old; Maher
1964).

There was no difference in mean estimated
clutch size of firstand second broods (ANOVA
with nest stage and year: Rae 474=2.70, n.s.),
or between Areas A andB (ANOVA with nest
stage and year: Fy 157-0. 05,n.s.). However,
there was variation in clutch sizes between
summers (Table 1; ANOVA with nest stage
and brood category, i.e. first or second brood,
effect of year: Fs 474=3-10, P<0.02). This
was mainly a result of low clutch sizes in 1992
(mean=4.47) compared to the other five
summers during 1988-1993 (mean=5.08).

In 39% of nests which hatched, one or more
eggs were infertile or addled, amounting to
13% of alleggs. On average 1.6 eggs failed
to hatch in nests with incomplete hatching.
There was no significant difference in hatching
rate between areas. Between year, the
proportion of nests with unhatched eggs
varied substantially, from 24% in 1990 to
65% in 1988 (Table 1).

In 1992 and 1993, innests with partial hatching
success, eggs which failed to hatch were
broken to record their stage of development.
Twenty nests had eggs with no signs of

SB 17(4)

embryonic development, five had limited signs
of development, one embryo was half
developed and three were well-developed.
Most eggs failing to hatch were therefore
infertile or ‘died’ during the egg-laying or early
incubation periods.

Further losses occurred between incubation
and the day when the chicks were ringed.
The majority of this appeared to be due to
deaths of chicks rather than loss of viable
eggs or removal of addled eggs. In some
cases dead chicks were left in the nest, but
probably most were removed by the parents
(inferred in some nests by higher counts of
chicks close to hatching than present when
the chicks were ringed). Partial predation
was suspected on only one occasion, when
the nest was virtually destroyed. Losses prior
to ringing occurred in 30% of 94 nests found
with eggs or small young, and were
independent of site, year or nest stage.

The mean brood size at ringing was 3.85
young (s.d.=1.34, n=202). There was no
difference between study areas (ANOVA
correcting for brood category: F, ,198=0.23,

s.) but, as with clutch size, brood-size was
smaller in 1992 (Table 1; ANOVA correcting
for brood category: Fs. 186=2-43, P<0.05). °
The most obvious difference, however, was
that first broods were larger than second
broods by an average of almost one chick per
nest (Fig. 5). Dead chicks were found in the
nest or nest-cavity on 20% of post-fledging
visits to nests where fledging was known or
assumed. However, mortality of young post-
ringing was probably under-estimated due to
removal of bodies by the parents.

Total nest failure
As well as partial losses of nest contents,

complete nest failures occurred as a result of
the accumulation of partial losses or

1994

FIGURE 5

NO
(2)

Percentage of nests
°

Oo

Number of young

instantaneously through nest desertion or
predation. We quantified the rate of nest
mortality (percentage of nests failing per day)
using the Mayfield method (Mayfield 1961,
Johnson 1979).

Snow Buntings in NE Scotland 231

Nest mortality rates, although ranging from
1.1% of nests per day for nests with small
young to 2.1% nests/day for nests with eggs,
did not differ significantly between stages of
the nesting cycle (maximum ratio of difference
in mortality rates to their standard errors,
z=1.21, n.s.). From the daily mortality rate
averaged across all stages (1.8% nests/day),
we can calculate that typical nests (5 eggs
hatching asynchronously over a one-day
period) would have a success rate of 60%, i.e.
at least one chick fledged in 60% of nesting
attempts (95% confidence interval 50-71%).
Nest mortality rate was similar between sites
(z=1.17,n.s.), and did not vary between years
except in 1991 when five nests were lost in an
early season snowstorm (Table 2).

Reasons for nest failure are listed in Table 2.
Most failures were due to starvation of young
(as evidenced by thin or emaciated condition
on the penultimate visit, gradual
disappearance of the youngest brood
members, or all chicks dead in the nest at a
variety of ages) and perhaps reflected a poorer
food supply toward the end of the season.
Several cases where the nest was deserted

TABLE 2. Causes of failure of first and second brood Snow Bunting nests.

No. occurring in:

~ Cause of failure First Brood Second Brood
Weather (desertions in snow) 5 0
Desertion (eggs) 3 2)
Desertion (young) 1 3
Starvation of young 1 12
Predation 0 1
Unknown 1 2

232 FR.D. Smith & M. Marquiss

or the cause of nest mortality was unknown
may also have been due to seasonal food
shortage.

Five nests were deserted because of a heavy
snowfall. These all occurred in 1991, but the
double peak of first egg dates of first broods
(Fig. 2) in 1989 and 1990 suggested that
snowfalls caused widespread desertion of
undiscovered clutches in these summers also.
This factor is therefore probably
underestimated in Table 2, because few nests
were found at the egg-laying/incubation
stages. Three periods of snow occurred
during the brood-rearing periods: on 29 June
1989, 18 June 1991 and 9 July 1993. No fall
deposited more than 5cm of snow and all had
largely gone within a day. There was little
evidence of nest failure during these periods.

Predation was unequivocal on only one
occasion; the remains of the female and her
young were found dead in the nest hole and
were most likely the victims of a stoat or
weasel. The contents of two other nests
disappeared completely, possibly predated,
but removal of starving young by the parents
was equally plausible. The other nest which
failed in unknown circumstances may have
been a result of death or predation of the
female. The male continued to visit the partially
incubated clutch in her absence.

Survival of adults

Just over half of individually colour-ringed
breeding adults returned to the study area to
breed the following year. The return rate was
similar on areas A and B (means for 1990 to
1993: 50% & 58% respectively, n=136 &12;
X24 =0.06, n.s.), and also’during four of the
five years (range 59-64%, n=15-49) but was
lower from 1991 to 1992 (37%, n=57; loglinear
X2,=9.23, P=0.056).

SB 17 (4) |

Discussion
Variation between sites

Area A in the Cairngorms is almost certainly
the most extensive and most consistently
used area of suitable Snow Bunting habitat in
Britain. We might therefore have expected
that breeding success would be higher there
than on area B where 4-5 pairs in 1992 and
1993 represents an all-time high, and which
may be devoid of birds in some summers
(only single pairs were seen on any eastern
Grampians hills during 1970-87, Watson &
Smith 1991).

However, egg-laying dates of successful first
broods were on average almost six days
earlier on area B than on area A. First egg
dates of first nesting attempts (rather than
first successful attempts) may have been
similar on both areas because it is believed
that many pairs on area A failed at an early
stage in 1990 and 1991 due to snowfalls (Fig.
2). These setbacks may account for the lower
frequency of double-brooding on areaA. The
risk of nest failure as a result of early season
snowfalls may be lower on area B because,
within Britain, montane areas further to the

south and east have a warmer and drier

summer climate (Thompson & Brown 1992).
The differences in altitude between the two
sites may be less important: no overall
relationship was found between first egg dates
of successful first brood nests and altitude
within area A (Smith & Marquiss, unpubl.
data).

Some of the difference in the number of
broods reared between areas may, however,
have been artificial because broods were
more likely to have been missed on the larger
site, and follow-up visits to nests on area B,
especially to second brood nests, were less

1994

frequent. In conclusion, however, there is
certainly no evidence to suggest that area B
was any /ess productive than areaA. Because
return rates of adults and settlement rates of
their offspring are similar between the two
sites (Smith & Marquiss in prep.), previous
low counts of breeding birds on area B may
result from periodic extinctions associated
with a small population size, although the lack
of thorough searching in previous years could
not be entirely excluded.

Annual variation

Spring and early summer snowfalls appeared
to delay the early fledging of first brood young,
hence reducing the chances of rearing two
broods successfully. However, snowfalls did
not cause all extant nests to fail. The ability of
some females to continue incubation in such
conditions may have been due to fortuitous
nest-site choice rather than depletion of energy
reserves during snow, because the duration
of 100% snow cover was short. Also the
ensuing snow thaw may have provided rich
feeding conditions: Snow Buntings were often
seen feeding along the edges of melting snow
patches, perhaps on invertebrates flushed to
the surface. Three of the five females known
to lose clutches in 19971 laid the first eggs of
replacement clutches within ten days of losing
their initial attempts, despite the snow
persisting for the first two of these days.
Witness also the peak of presumed
replacement clutches only 5-10 days after
snowfalls (Fig. 2).

Our data on the causes of nest failure in
second broods suggest that the end of the
breeding season is set by food shortage: 12-
14 out of 23 failures could directly be attributed
to starvation of the young, while a further
eight pairs may have deserted nests because
they could not find sufficient food.

Snow Buntings in NE Scotland 45 6}

Clutch sizes were unusually low in summer
1992, and as there were slightly greater than
average losses due to unhatched eggs and
the disappearance of small chicks, brood
sizes were also smaller (Table 1). Twenty-
three percent of the 26 females known to
summer on area A were not known to rear
even one brood, in 1992: this was the highest
rate observed during the six summers despite
our greater efforts to find nests and broods in
1992 and 1993. The poor 1992 summer
followed upon a year in which the adult return
rate was only 60% of that averaged across
the rest of the study period, leading to the
largest population decrease on area A during
the study period, from 40 pairs in 1991 to only
26 in 1992. Recruitment of 1991 chicks was
also lower in 1992, although not significantly
so. Interestingly, this drop in overwinter return
rates and productivity followed a particularly
snow-free winter and spring in Scotland (46
snow-free days in the Cairngorm mountains
during January to April 1992, compared to a
mean of 18 days during the rest of the five
winters from 1988 to 1993, R.D. Smith unpubl.
data) and much smaller summer snow beds
than usual (Adam Watson pers.comm.).
Nethersole-Thompson (1966) also noted an
association between higher Snow Bunting
numbers in the Cairngorms and cold winters/
snowy springs although he attributed this to
an increased rate of immigration rather than
to enhanced survival/breeding success. If
the association between decreased
productivity and reduced snow lie is correct,
this may reflect adverse effects on the Snow
Bunting invertebrate food supply and therefore
be of wider conservation and biological
significance.

Acknowledgements

We gratefully acknowledge help with fieldwork
from Ann Marquiss and Keith Duncan. Bob

234 R.D. Smith & M. Marquiss

McGowan (Royal Scottish Museum) provided
details of the degree of incubation of
unhatched eggs. Alonglist of other observers
made useful contributions. Neil Metcalfe and
an anonymous referee commented
extensively on earlier drafts, while discussion
with Adam Watson, Des Thompson, Hector
Galbraith and Phil Whitfield also generated
enthusiasm, ideas and criticism. Substantial
financial assistance was received by RDS
from SNH through the Mountain Plateau
Ecology Project, HIDB, BOU, ASAB andBES.
We are also grateful to Cairngorm Chairlift
Company for providing access to the study
area via their chairlifts. Thanks are also due
to the RSPB and other landowners on whose
ground we worked.

References

Johnson, D.H. 1979. Estimating nest
success: the Mayfield method and an
alternative. Auk 96: 651-661.

Maher, W.J. 1964. Growth rate and
development of endothermy in the Snow

SB 17 (4)

Bunting (Plectrophenax nivalis) and
Lapland Longspur (Calcarius lapponicus)
at Barrow, Alaska. Ecology 45: 520-528.

Mayfield, H. 1961. Nesting success
calculated from exposure. Wilson Bull.
87: 456-466.

Nethersole-Thompson, D. 1966. The Snow
Bunting. Edinburgh: Oliver & Boyd.

Smith, R.D. 1991. Monitoring of breeding
Snow Buntings in 1988 and 1989. In

Stroud, D. & Glue, D. (eds.), Britain’s Birds in
1989-90: The conservation and
monitoring review 112-113. Stretford:
BTO/NCC.

Smith, R.D. 1993. Snow Bunting. /nGibbons,
D.W., Reid, J.B., & Chapman, R.A. (eds.)
The new atlas of breeding birds in Britain
and Ireland: 1988-1991: 430-431.
London: Poyser.

Thompson, D.B.A. & Brown, A. 1992.
Biodiversity in montane Britain: habitat
variation, vegetation diversity and some
objectives for conservation. Biodiversity
and Conservation 1: 179-208.

Watson, A. & Smith, R.D. 1991. Scottish
Snow Bunting numbers in summer 1970-
87. Scott. Birds 16: 53-56.

R.D. Smith, Applied Ornithology Unit, Department of Zoology,
University of Glasgow, Glasgow. G12 8QQ. U.K. .
M. Marquiss, Institute of Terrestrial Ecology, Hill of Brathens,

Banchory, Kincardineshire AB31 4BY. U.K.

(Revised typescript received 15 August 1994)

:
’
}

Scottish Birds (1994)17: 235-238

Short Notes

235

Kestrel predation of Ring Ouzei nestling

On 19 May 1993 during a survey of Ring
Ouzels Turdus torquatus in Glen Mark, at the
head of Glen Esk, | witnessed a male Kestrel
Falco tinnunculus remove a Ring Ouzel pullus
from a nest site. | was trying to count Ring
Ouzel pairs present when! sawamale Kestrel
flying straight towards a ledge. The Kestrel
was about 400m from my position when it
landed and momentarily appeared to entangle
its wings in the surrounding heather. After a
few seconds, it flew off, carrying a nestling in
its beak. Just seconds prior to and during the
attack, atleast 5-6 adult Ring Ouzels mobbed
the Kestrel and made frantic efforts to distract
it with loud alarm calls. The pullus appeared
to be 5-8 days old.

Until the attack the nest was unknown to me,
although | had earlier seen a male Ring Ouzel
perched on a stunted birch nearby. When |
approached the site about an hour later, |

found the nest on a rocky ledge about 4m
above ground level and apparenily
undamaged. | could not see whether any pulli
remained in the nest, as it was inaccessible.
During a visit eight days later, both parents
were seen to carry food into the nest site,
suggesting that some of the brood had
survived.

In several years of observing Ring Ouzels in
Glen Esk, the main cause of alarm has been
the appearance of a hovering Kestrel, and
this kind of predation is probably understated.
In Derbyshire, Fox (1900. Zoologist 4: 1-10)
described how he observed a pair of Ring
Ouzels drive a Kestrel from their territory or
nest site. Very few instances appear to have
been recorded of nestling predation by raptors,
and Cramp & Simmons (1980. BWP Vol. Il)
found that raptors seldom preyed on nestlings.

David Arthur, 12 Dundee Street, Carnoustie, Angus DD7 7PD

Interaction between Red Grouse and Osprey

On6 June 1991, | watched an Osprey Pandion
haeliatus hunting over a highland loch at 300
metres a.s.l., Surrounded by heather

moorland. The Osprey caught a large trout ~

and then flew over nearby moorland at a
height of about five metres, disturbing a pair
of Red Grouse Lagopus lagopus which may
have had a brood nearby. The male grouse
flew up at the Osprey and appeared to strike
it, causing the Osprey to drop its prey. The

Osprey circled quickly, dropped to the ground
and having retrieved its fish flew off in its
Original direction.

Brood defence interactions between Red
Grouse and Hen Harrier Circus cyaneus are
well documented (S.M. Redpath. 1992. Ornis
Scand.). In this case, it seems probable that
the low-flying Osprey may have been mistaken
for a quartering harrier.

Allan Mee, 70 Busby Road, Carmunnock, Glasgow G76 9BL.

236 Short Notes

Merlin follows prey underground

On 13 August 1993 | was driving along a
country road near Cabrach, Banffshire, which
passed through rough grazing on the fringe of
heather moorland, when an adult male Merlin
Falco columbarius flew from a roadside fence
post 100 metres ahead of me across the
rough grass and landed behind a stonewall.
The road at this point turned at right-angles,
so | drove round the corner and stopped my
car at a point directly adjacent to where | had
seen the Merlin land on the ground and
cautiously looked over the fence. There was
a drop of about one metre to the field below
but no sign of the Merlin. However, on closer
inspection, to see if there were any signs of a
kill, | heard a fluttering noise coming from the
entrance of a rabbit burrow at the base of the
wall and the Merlin appeared, but on seeing
me it immediately flew off across the field,
calling in alarm.

A few seconds later, an immature Starling
Sturnus vulgaris flew away from the base of
the wall in an erratic manner as though

SB 17 (4)

impaired in one wing. | climbed over the
fence, down into the field, and checked the
place from where the Starling had flown,
thinking that the Merlin had flushed it from the
main rabbit burrow through a ‘pophole’ or an
escape tunnel, in the manner of a ferret.
There were holes in the turf-topped wall, but
none appeared to go any distance. Getting
down on my hand and knees, | looked into the
main rabbit burrow to check for other exists
and was surprised to see another juvenile
Starling at the end of the short tunnel,
approximately 45cm long and 10cm in
diameter at the entrance. The Starling was
standing up on its feet at the far end of the
tunnel and there were no other exits from the
tunnel. | reached in and removed the now
screeching Starling, which appeared perfectly
healthy and unharmed and when released, it
flew strongly away.

There is no mention of Merlin pursuing prey
underground in BWP.

James K Craib, 5 Rashcrook Walk, New Elgin, Elgin, Moray 1V30 3EZ

Sparrowhawk exploiting a Sand Martin colony

In 1975, the late Tom Irvine guided me to a
Sparrowhawk Accipiter nisus nest in
coniferous woodland near to the river Tarras
at Langholm, Dumfriesshire. The hawks were
rearing four young and prey items collected at
the nest and from the male’s plucking post
indicated that at this stage the hawks were
significantly exploiting a Sand Martin Riparia
riparia colony, located some 440m distant.

During the initial visit the remains of 22 adult

martins were collected, ten days later a further
13 were retrieved and subsequently four more
were found. A feature of the prey at the
male’s plucking post was that the wings were
not plucked out and remained attached to the
sternum, while debris at the nest indicated
that the female typicaliy took them apart. A
watch atthe colony showed that only the male
hawk attempted to catch martins; of 14
observed passes within 37 hours of
observation only three resulted in kills. Usually

ee ae

1994

the martins avoided capture by twisting in
flight and by ‘towering’, by this time of course
the colony had been depleted and fewer
martins were available to the hawk. The
mode of attack was similar in all cases: a swift

_ low level approach. Although being more
| visible, the hawk made no attempt to attack
_ the martins while they fed at higher altitudes.

| was unable to ascertain if juvenile martins
were more vulnerable as, quite dramatically,

_ the whole prey spectrum changed at this

stage with the female bringing in larger items
to feed the brood and the male hawk reverting
to typical woodland species. Juvenile Sand

Short Notes 237

Martins are known to be vulnerable and were
seen to be taken by a male Sparrowhawk at
Barbush near Dunblane in the early 1980s as
they sat at the burrow mouths. (I. MacGowan
pers. comm).

At the Dumfriesshire site, | estimated from
counts of occupied burrows that the hawk
killed 58% of the available adult martins. To
put this record into perspective, | have not
found Sand Martin remains at any of the other
1247 active Sparrowhawk nests | have visited
during the past two decades.

John G. Young, SNH, West Lodge, Airlie, by Kirriemuir, Angus.

_ A successful artificial Sand Martin banking

Sand Martins Riparia riparia, conventionally,
as the name implies, prefer to excavate
breeding tunnels in soft sand or in lighter,
loamy soils. Over the years, there has been
a proliferation of records where they have
been seen to excavate into more difficult or
unusual strata. They have, for example,

_ utilisedtemporary dumps of building materials
_ andcompressed heaps of coal spoil, sawdust,
_ manure, as well as exposed peat banks (T.

Holden, J.G. Young pers. comm.).

Sand Martins are also known to have exploited
man-made or eroded holes in masonry in, for
example, harbour walls and especially in the
support walls of buildings and railway

_ embankments where clay drainage or ‘weep’
. pipes have been inserted to alleviate a build-
up of hydrostatic pressures. At one such site

in the centre of Cumnock, Ayrshire, up to 12
pairs have bred intermittently in large clay
pipes since at least 1967 (J.G. Young pers.

_~comm.). Ithas also been noted from trials at

Loch Leven and New Cumnock, Ayrshire,
that where visual stimuli are induced by

forming holes either neatly with a soil auger,
or even crudely with a walking stick, Sand
Martins will be attracted to breed provided
that the exposed strata are conducive to
further excavation and that the vital insect
food sources are within reasonable flying
distances. (A. Allison, T. Holden, J.G. Young
pers. comm). | know of no other examples,
other than by the deliberate exposure of planes
in sandy bankings, where an artificial site has
been especially constructed to house Sand
Martins.

While developing a small private aquatic
nature reserve near Lockerbie in
Dumfriesshire, | experimented with a

reinforced concrete banking. The mode of

construction was simple. On a stable
foundation relevantto height, were built some
seven courses of high density concrete blocks,
on top of which concrete was poured into
shutters (see photo). Martin holes were
preformed within the shuttering using either
removable tubes or by the insertion of clay
drainage tiles at the diameter, length, angle

238 Short Notes

SB 17(4)

and distribution normally found in a natural
site. Behind the concrete were also formed,
a compact area of coarse grained, riverside
sandy soil was firmly packed to allow the
Martins to complete excavation and to form
nest chambers. Other apertures of different
dimensions to encourage occupation by water
shrews, Swifts Apus apus, Pied Wagtails
Motacilla alba and bat species.

The banking was completed in the autumn of
1989. The next season two pairs of Sand
Martins bred init. Sixteen broods were raised
successfully in 1991, and in the three season
since then, all the available holes have been
occupied. At 136 pairs, the size of the colony
is higher than the British average (37.6) for
natural sites. (BWP Vol. V). The concrete
banking is stable and not prone to the erosion
which destroys many river and lochside sites.
Natural sites are known to be suffering
increasingly from overgrazing and trampling
by farm stock, and from damage by rabbits,
which may burrow into soft soils. Because of

Robert T. Smith, Knowetop, Applegarthtown, Lockerbie, Dumfriesshire.

the tendency to severe, rapid flooding at
many sites, natural colonies are continually at
risk. An important additional feature of the
site is that there is smooth concrete for some
two metres below the nestholes, which makes
itextremely difficult for ground predators such
as rats, stoats, weasels, mink and feral cats to
gain entry to the nest chambers, while laterally
placed, small mesh netting inhibits vertical
burrowing.

During the winter of 1993, the number of nest
sites has been doubled with significant
modifications to the design. Should these
prove successful, a more detailed note on
construction currently being prepared will be
available from the North Solway Ringing
Group. The provision of relatively safe and
stable artificial breeding areas, strategically
placed for Sand Martins, may well prove
significant in the conservation of a species
that shows strong site fidelity and is declining
markedly in Scotland.

Scottish Birds (1994) 17: 239

Correspondence

The influence of the weather on
seabird movements across central

Scotland.

It is surprising that during their discussion of
seabird movements across central Scotland

| neitherC.J.Henty nor R.D.Murray (Scott. Birds
| 17: 107-110) consider whether they may be

due to the weather. | have discussed the

_ main features of seabird migration elsewhere
| (inCramp, S., Bourne, W.R.P. and Saunders,
_ D., Seabirds of Britain and Ireland, Collins,
|| London, 1974: 28-30). In general, birds of the
| coastandinland waters, such as the pelicans,
| cormorants, smaller skuas, gulls and terns,
_ may regularly perform long journeys overland,
|! which are liable to be missed because, as in
' the case of the massive eastward spring
|| migration of the Common Gull Larus canus
' across Scotland, they tend to fly high over
| land (Scott. Birds2: 3-17); ithas since emerged
|| from observations at oil installations that the
| autumn migration is in turn missed by radar
|, because at that season the birds fly lower
|! over the sea. The more marine species,
| including the tubenoses, tropicbirds, gannets

and boobies, larger skuas, Sooty Tern Sterna
fuscata and kittiwakes Rissa sp., normally
avoid the land except when visiting the
breeding places or carried there by the wind,

as discussed for the north-east coast of
|}. Scotland by Bourne (/bis 124: 81-88) and for
|| Islay by Verrall & Bourne (Scott. Birds 12: 3-
|} 11).

On a number of occasions in the autumn

| coastal birds have flown south-west from the

north-east coast, ascending as they went

Correspondence 239

inland, including small skuas from the Moray
Firth, and parties of terns from the Ythan
estuary. Further inland | have also seen
Larus gulls flying south over the Grampian
mountains, and traced what from the timing of
the movement appeared to be shore and
water birds flying south to south-west for long
distances with radar. But, as deduced by
Henty, there was no reason to suspect that
Kittiwakes Rissa tridactyla were included. If
one examines the daily maps in the journal
Weatherthere is usually some meteorological
explanation for the appearance of such
species offshore or inland. For example, the
movements of 500 Kittiwakes per hour west
in the Firth of Forth on 16 November 1973 and
1000 per hour west on 28-29 October 1974
described by Sandeman (Scott. Birds 8: 77-
78, 324-325) both occurred with the cold
northerly airstream behind adepression. This
is normally associated with massive
southward movements of seabirds down both
coasts of Britain at this season, and may have
led to an accumulation of birds in the Firth of
Forth. Similarly, the eastward movement up
the Clyde on 11 March 1990 occurred with the
west winds during the passage of a depression
to the north which were also associated with
some of the largest movements past Islay.
The accumulation of birds in the Forth on 18
October 1990 occurred with the east winds
associated with misty, overcast weather north
of an occluded front. Some birds taking part

in such movements have been seen to

continue overland in such places as the Wash
in the past (Seabird 5: 18-21), though if
watched carefully most eventually appeared
to follow the coast back out to sea.

W.R.P. Bourne, Department of Zoology, Aberdeen University,

Tillydrone Avenue, Aberdeen AB9 2TN.

240 Scottish Birds (1994) 17: 241-243

ltems of Scottish interest

Most of the following papers and report on
birds in Scotland are available in the Waterston
Library at 21 Regent Terrace for reference,
and include all that have come to notice in the
period March to September 1994. The
librarian would be glad to learn of anything
that has been missed, and to receive reprints
or copies of papers on any aspect of
ornithology or natural history. Bird reports
marked with an asterisk are available from
the SOC at the prices quoted, but please add
50p per order for postage and packing.

Scientific papers

Calladine, J. & Mann, N. (1994). Isle of May
report for 1992. 47 pp. Published by
Scottish Natural Heritage (SE Region).
Includes biological and warden’s reports.

Calladine, J. & Robinson, A. (1994). Isle of
May report for 1993. 38 pp. A report
by Scottish Natural Heritage (SE Region).
Includes biological and warden’s reports.

Carss, D.N. 1993. Osprey predation ona
simple fish community. /nst. Terrestrial
Ecol. Rep. 1992-93: 76-78.

Carss, D.N. 1993. Shags Phalacrocorax
aristotelis at cage fish farms in Argyll,
Western Scotland. Bird Study 40: 203-
ZAP

Catt, D.C., Dugan, D., Green, R.E., Moncrieff,
R., Moss, R., Picozzi, N., Summers, R.W.
& Tyler,G.A. 1994. Collisions againstfences
by woodland grouse in Scotland. Forestry
(Oxfd) 67: 105-118.

Craik, JU.C.A. 1994. Aspects of wing moult in
the Common Tern Sterna hirundo.

Ringing & Migration 15: 27-32. A study in the
west of Scotland.

Cresswell, W. 1994. Flocking is an effective
anti-predation strategy in Redshanks
Tringa totanus. Anim. Behav. 47: 433-

SB 17 (4)

442. A study in Scotland.

Cresswell, W. 1994. The function of alarm
calls in Redshanks Tringa totanus. Anim.
Behav. 47: 736-738. A study in Scotland.

Cutts, C.J. & Speakman, J.R. 1994. Energy
savings in formation flight of Pink-footed
Geese Anser brachyrhynchus. J. Exper
Biol. 189: 251-261.

Donald, P.F., Wilson, J.D. & Shepherd, M.
1994. The decline of the Corn Bunting.
British Birds 87: 106-132.

Evans, |. 1993/94. The experimental re-
introduction of the Red Kite Milvus milvus
to England and Scotland. Raptor21: 22-
25.

Fox, A.D., Bell, D.V. & Mudge, G.P. (1994).
A preliminary study of the effects of
disturbance on feeding Wigeon grazing
on Eel-grass Zostera. Wader Study Gp.
Bull. 68: 67-71. Part of this study took
place in the Moray Firth.

Furness, R.W., Thompson, D.R. & Harrison,
N. 1994. Biometrics andseasonal changes
in body composition of Common
Guillemots Uria aalge from north-west
Scotiand. Seabird 16: 22-29.

Galbraith, H., Murray, S., Rae, S., Whitfield,

D.P. & Thompson, D.B.A. 1993. Numbers _|

and distribution of Dotterel Charadrius
morinellus breeding in Great Britain. Bird
Study 40: 161-169.

Grant, M.C. 1992. Effects of moorland
fragmentation on breeding Curlew
Numenius arquata.in Orkney. Wader
Study Gp. Bull 66: 30. Abstract of a talk
given at IWRB/WSG Feeding Ecology
conference in Hungary, September 1992.

Grant, M.C. 1992. Factors influencing
productivity in a breeding Whimbrel
Numenius phaeopus population. Wader
Study Gp. Bull. 66: 26. Abstract of a

talk given at the annual meeting of WSG |

in Hungary, September 1992.
Halley, D.J. & Harris, M.P. 1994. Age-

1994

related changes in the agonistic
behaviour of Common Guillemots Uria
aalge. Seabird 16: 8-14. A study on the
Isle of May in 1990 and 1991.

Harris, M.P. (1993). Isle of May seabird
studies in 1993. Joint Nature
Conservation Committee Rep. 180: 37pp.

Harris, M.P. & Wanless, S. 1994. Ingested
elastic and other artifacts found in Puffins
in Britain over a 24-year period. Marine
Pollution Bull. 28: 54-55.

Harrison, N.M. Webb, A. & Leaper, G.M.
1994. Patterns in seabird distribution
west of Scotland. Aquat. Conserv. Mar.
Freshwater Ecosyst. 4: 21-30. A paper
from the Seabirds at Sea Team,
Aberdeen.

Hill, J.K. & Hamer, K.C. 1994. Do Great
Skuas Catharacta skua respond to
changes in the nutritional needs of their
chicks? Seabird 16: 3-7. A study on
Foula in 1991.

Hughes, J.l. 1994. The Royal Air Force
Ornithological Society's expedition to
Beinn Eighe and Letterewe, June 1991.
RAFOS J. 23: 30-45.

Meek, E.R., Sim, I.M.W. & Ribbands, B. 1994.
Breeding skuas in Orkney: the results of
the 1992 census, Seabird 16: 34-40.

Monaghan, P., Walton, P., Wanless, S., Uttley,
J.D. & Burns, M.D. 1994. Effects of prey
abundance on the foraging behaviour,
diving efficiency and time allocation of
breeding Guillemots Uria aalge. Ibis 136:
214-222. Astudy carried out at Sumburgh
Head, Shetland.

O’Nians, C.S. 1994. St. Kilda: Island on the
edge of the world. Sanctuary 23: 2-4.
Ministry of Defence Conservation
Magazine.

Orchel, J. 1994. Forest nesting Merlins.
Scot. Wildlife 22: 18-21.

Owen, M. (1994). The United Kingdom
shooting disturbance project. Wader

Items of Scottish Interest 241

Study Gp. Bull.68: 35-46. Astudy, partly
in Scotland, of the effects of establishing
wildfowl refuges.

Paice, D. (1993). Monitoring of breeding
success of cliff-nesting seabirds in
Orkney. Joint Nature Conservation
Committee Rep. 190: 12pp.

Parr, R. 1993. Nest predation and numbers
of Golden Plover, Pluvialis apricaria and
other moorland waders. Bird Study 40:
223-231. Astudy in north-east Scotland.

Parr, R., Watson, A. & Moss, R. (1994).
Changes in the numbers and interspecific
interactions of Red Grouse Lagopus |.
scoticus and Black Grouse Tetrao tetrix.
Avocetta 17: 55-59. A study in north-
east Scotland.

Rebecca, G.W. 1994. Hen Harrier Circus
cyaneus laying clutch while still building
nest. British Birds87: 232. Anoccurrence
in Perthshire.

Riddiford, N. 1994. Daurian Redstart and
Daurian Starling in Scotland. British
Birds 87: 190-191.

Rideout, K.J. 1994. Birds at St Abbs Head
in 1993. Hist. Berwickshire Nats’ Club
46: 80-85.

Rideout, K.J. & Drew, T.P. (1994). St Abbs
Head NNR Seabird Report 1993. 26pp.
A report from Scottish Natural Heritage
(SE Region, Galashiels).

Smith, R.D., Marquiss, M., Rae, R. & Metcalfe,
N.B. 1993. Age and sex variation in
choice of wintering site by Snow Buntings
Plectrophenax nivalis: the effect of
altitude. Ardea 81: 47-52. A study in
Scotland.

Smith, R.W.J. 1994. Forth Island bird
counts. Edin. NHS J. 1993: 18-19.
Suddaby, D., Shaw, K.D., Ellis, P.M. & Brockie,
K. 1994. King Eiders in Britain and
lreland in 1958-90: occurrences and
ageing. British Birds 87: 418-430.
Published on behalf of the Rarities

242 W.G. Harper

Committee. A large proportion of these
occurrences have been in Scotland.

Summers, R. 1994. Diurnal and nocturnal
activities of a Purple Sandpiper Calidris
maritima. Wader Study Gp. Bull. 72: 33-
34. A study on the Isle of May of a radio-
tagged bird.

Swann, R.L. (1993). Canna seabird studies
1993. Joint Nature Conservation
Committee Rep. 181: 9pp.

Swann, R.L., Aiton, D.G., Carruthers, J.,
Graham, R.J. & Ramsay, A.D.K. 1994. An
analysis of Shag Phalacrocorax aristotelis
ring recovery and breeding success data
during a period of population change on
the Isle of Canna. Seabird 16: 50-56.

Tasker, M. 1994. East coast seabird wreck
February 1994. Seabird Gp. News68: 1.

Thomson, D.L. 1994. Growth and
development in Dotterel chicks
Charadrius morinellus. Bird Study 41:
61-67. A study in the Cairngorm
mountains of Scotland

Uttley, J.D., Walton, P., Monaghan, P. &
Austin, G. 1994. The effects of food
abundance on breeding performance and
adult time budgets of Guillemots Uria
aalge. Ibis 136: 205-213. A study carried
out at Sumburgh Head, Shetland.

Walsh, P.M. (1993). Counts of breeding
seabirds on the Grampian coast in 1992.
Joint Nature Conservation Committee
Rep. 151: 54pp.

Wells, M.J. 1992. Outer Hebridean Ringed
Plovers Charadrius hiaticula in winter:
feeding rates in territorial and non-
territorial individuals. Wader Study Gp.
Bull. 66: 36. Abstract only.

Withers, B.R. 1994. The Royal Air Force
Ornithological Society’s expedition to
Benbecula, June 1981. RAFOS J. 23: 1-
18.

Yalden, D.W. & Dougall, T.W. 1994. Habitat,
weather and growth rates of Common

SB 17 (4)

Sandpiper Actitis hypoleucos chicks.
Wader Study Gp. Bull. 73: 33-35. Growth
rates were similar in streams in the
Peak District of England and in the
Scottish Borders, but varied between
years.

Composite report

Davidson, N. & Rothwell, P. (eds). 1993.
Disturbance to Waterfowl on Estuaries.
Wader Study Gp. Bull 68: 106pp. A
collection of 15 papers, two of which are
listed above. Available from RSPB,
Sandy for £15 inc. p&p.

Bird reports

Arran Bird Report for 1993. Audrey Walters
(ed) 1994. 24pp. Includes an updated
checklist of the island’s birds by Tristan
ap Rheinallt.

Ayrshire Bird Report for 1993. Angus Hogg &
Andrew Stevenson (eds). 68pp. * £2.75.
Anew addition to this long-running series
is an Ayrshire butterfly report.

Clyde Birds (Clyde Bird Report for 1992). lain
P. Gibson (ed) 1994. 78pp. Available
from lain Gibson, 2 Fulton Crescent,
Kilbarchan, Renfs. PA10 2EB.

Highland Bird Report for 1992. Colin
Crooke (ed) 1993. 40pp.

Islay Bird and Natural History Report for 1993.
Malcolm Ogilvie (ed). 32pp. * £1.50.
Covers birds, mammals, butterflies,
moths, dragonflies and flowering
plants.

Livingston Bird Report for 1993. Livingston
Countryside Ranger Service (ed). 33pp.
Includes a 24-page species list.

Moray and Nairn Bird Report for 1993. Martin
Cook (ed). 1994. 87pp. * £3.75. Includes
a 60-page systematic list, a ringing report
and two short papers.

Orkney Bird Report for 1993. Chris Booth,
Mildred Cuthbert & Eric Meek (eds) 1994.

1994

83pp. A 58-page systematic list and
several short reports including
“Corncrake survey in Orkney in 1993”,
anda North Ronaldsay Bird Observatory
Report. * £3.50.

Perthshire (Central/Southwest) Peregrines
and Ravens in 1993. P. Stirling-Aird

European journals in the
Waterston Library

The following selection of articles appeared
in European journals received inthe Waterston
Library between March and August 1994
inclusive, thus following on the list published
in Vol. 17 No. 3. Articles are arranged in
species order; square brackets indicate that
the article is in the original language, other
articles being in English. Journals quoted are
as follows :

Belgium: Oriolus, Aves

Netherlands: Dutch Birding, Limosa
France: Ciconia, Le Bievre, L’Oiseau,
Alauda, Le Cormoran

Switzerland: Der Ornithologische
Beobachter, Nos Oiseaux, Ornis
Germany: Limicola, 6kologie der Végel,
Corax, Vogelwelt, Seevégel

Poland Acta Ornithologica, Zpravy MOS
Croatia: Larus

ltaly: Rivista Italiana di Ornithologia,
Avocetta

Spain: Ardeola, Butlleti del Grup Catala
d’Anellament (in Catalan)

Iceland: Natturufree ingurinn, Bliki

Items of Scottish Interest 243

1994. 3pp. An unpublished report.

Shetland Bird Report for 1993. Kevin
Osborn (ed). 126pp. Includes reports
on the Braer Oil Spill, on the 1992
survey of Arctic and Great Skuas in
Shetland, and on the rise and fall of the
Fulmar in Shetland.

William G. Harper.

Denmark: Journal of Avian Biology, Dansk
Ornitologisk Forenings Tidsskrift

Norway: Var Fuglefauna

Sweden: Var Fagelvarld, Ornis Svecica
Finland: Linnut, Ornis Fennica, Suomen
Riista

General

Kjellén, N. Moult in relation to migration in
birds - a review. Orn. Svec. 4: 1-24.

Hazevoet, C.J. Species concepts and
systematics. Dutch Birding 16: 111-16.

Kempenaers, B. [Mating behaviour among
birds: an overview of the pair system].
Oriolus 59: 25-30.

Vansteenwegen, C. et al. [A comparison of
census methods: quadrant mapping
and capture-ringing-recapture]. Aves
30: 105-108.

Radovic, D. et al. [Results of bird ringing
and recoveries of ringed birds in 1991
and 1992]. Larus 44/45: 1-32

Vansteenwegen, C. [Geographical
variation in sedentary behaviour of
partial migrants in France: an
analysis of ringing results - Part 1].
L’Oiseau 63: 163-177.

244 Scottish Birds (1994) 17: 243-245

SB17 (4)

Saurola, P. [Trans-Saharan recoveries of
Finnish-ringed birds]. Linnut 3/94:
8-14

Divers to ducks

Walser, B. & Barthel, P.H. [Plumages of
Red-necked Grebe]. Limicola 8:
101-120

Lang, B. [Geese in Normandy 1971-1993].
Le Cormoran 9: 29-36

Markkola, J. & Peltomaki, J. [The threat
ened Lesser White-fronted Goose].
Linnut 3/93: 27-30

Aarvak, T. & Gien, |.J. [The Lesser White-
fronted Goose : a threatened species.
Developments in Norway 1987-93].
Var Fuglefauna 17: 70-80

Leivo, M. et al. [Migration of Arctic water
fowl in north Baltic , Spring 1993].
Linnut 2/94: 12-19

Samwald, O. etal. [Pochard x
Ferruginous Duck hybrids in Austria].
Egretta 37: 28-32

Staav, R. [Arctic Eiders in North Norway].
Var Fagelvarld 2/94: 24-25

Birds of prey

Various. [Papers presented at raptor and
Owl conference at Prerov in 1991].
Zpravy MOS 50: 7-74 |

Muller, W. [A European brings it off : the
Red Kite on the increase]. Ornis 4/94:
35-39

Steen, O.F. [The Hobby in SE Norway
1979-93]. Var Fuglefauna 17:81-90

Grouse to cranes

Valkeajarvi, P. & ljas, L. [Comparison
between breeding success of artificially
fed and unfed Black Grouse in central
Finland]. Suomen Riista 40: 98-109

Grandjean-Thomsen, A. [Significance of
some factors on display activity of
Black Grouse in Denmark]. Dansk
Orn. For. Tidss. 88: 85-90

Parr, R. et al. Changes in the numbers
and interspecific interactions of Red
Grouse and Black Grouse. Avocetta
17: 55-59

Schaffer, N. [Methods of ascertaining
breeding in Corncrake]. Vogelwelt
115: 69-73

Jedraszko-Dabrowska, D. & Debinska, D.
Ethological and ecological aspects of
adaptation of Coot to breeding in urban
conditions. Acta Ornith. 28: 91-96

Waders to auks

Pérez-Hurtado, A. et al. [Importance of the
bay of Cadiz for wintering shorebird
populations]. Ardeola 40: 133-142

Ullman, M. [field identification of
pratincoles in flight]. Var Fagelvarld
4/94: 28-30

Brunner, H. [Juvenile development of
Dotterel]. Limicola 8: 15-27

Gudmundsson, G.A. Spring migration of
Knot over S Scandinavia, as recorded
by radar. J. of Avian Biol. 25: 15-26

Mouritsen, K.N. Day and night feeding in
Dunlin : choice of habitat, foraging
technique and prey. J. of Avian Biol.
25: 55-62.

Brathel, P.H. [Identification of Great Black-
headed Gull]. Limicola 8: 64-78

Hario, M. Reproductive performance of
nominate Lesser Black-backed Gull
under pressure of Herring Gull
predation. Orn. Fenn. 71: 1-10

Volet, B. [Arctic Terns in the port of
Geneva : notes on bill colouring in
juvenile plumage]. Nos Oiseaux 42:
335-340

Lyngs, P. [The Great Auk : a 150-year

1994

memorial]. Dansk Orn. For. Tidss.
| 88: 49-72

| Pigeons to woodpeckers

| Various. [Papers on owls presented at

Raptor and Owl conference at Prerov

| in 1991]. Zpravy MOS 5: 7-74

| Lode, T. [Seasonal variations in Long-

| | eared Owl diet in relation to variations

i in population densities of small

| rodents]. Alauda 62: 91-100

, Sudmann, S.R. et al. [Short-eared and
Long-eared owls as predators in

| Common Tern colonies]. Vogelwelt

115: 121-126

Bar-tailed Desert and Desert larks.
1 Dutch Birding 16: 1-9

| 2/94: 30-32

| Rebstock, H. & Maulbetsch, K-E.

| [Observations on juvenile development
of Whinchat]. 6k. der Végel 15: 137-
153

_Flinks, H. [Ageing of rubicola Stonechats
| by plumage characteristics]. Limicola
Ii 8: 28-37

|| Sandberg, R. [Wheaters and the Earth’s
magnetic field]. Var Fagelvarld 3/94:
18-19

European Journals 245

Spaar, R. & Hegelbach, J. [Nest site and
breeding biology of the Song Thrust in
the Zurich area]. Orn. Beob. 91: 31-41

Alstrom, P. et al. [Identification of small
Acrocephalus warblers from the Far
East]. Limicola 8: 121-131

Mild, K. [Field identification of ‘black and
white’ flycatchers]. Var Fagelvdrld 3/
94: 29-36

Kooiker, G. [Influence of Magpie on urban
bird populations in Osnabruck, north
west Germany]. Vogelwelt 115: 39-44

Senar, J.C. et al. Wing shape variation
between resident and transient
wintering Siskins. J. of Avian Biol.
25: 50-54

Thorstenson, S. & Peterson, AE. [Breeding
biology of Redpolls in north Iceland].
Bliki 14: 1-13

Borras, A. et al. Simultaneous capture of
several Common Crossbills with
whitish wing bars]. B. del Grup Cat.
d’Anellament 10: 15-17

Olafsson, E. [Vagrants in Iceland part 10:
buntings, vireos and icterids].
Natturufree ingurinn 63: 87-108

Kempenaers, B. [Extra-pair relations and
paternity in Blue Tit]. Aves 30: 167-
172

Alstrom, P. [Field identification of Pechora
Pipit]. Var Fagelvarld 5/94: 29-30

Hillstrom, L. & Olsson, K. Advantages of
hatching synchrony in Pied Flycatcher.
J. of Avian Biol. 3: 205-214

Michael Murphy

246 Scottish Birds (1994) 17: 246

Advice to Contributors

Authors should bear in mind that only a small
proportion of the Scottish Birds readership is
science-trained, and should aim to present their
material concisely, interestingly and clearly.
Unfamiliar technical terms and symbols should be
avoided wherever possible and if deemed essential
should be explained. Supporting statistics should
be kept to a minimum. All papers and Short Notes
are accepted on the understanding that they have
not been offered for publication elsewhere and that
they will be subject to editing. Papers will be
acknowledged on receipt and will be reviewed by at
least two members of the editorial panel and in
some cases also by an independent referee before
being accepted. They will normally be published in
order of acceptance of fully revised manuscripts.
The editors will be happy to advise authors on the
preparation of papers.

Reference should be made to recent issues of
Scottish Birdsfor guidance on style of presentation,
use of capitals, form of references, etc. Papers
should be typed on one side of the paper only,
double-spaced and with wide margins; two copies
are required and the author should also retain one.
Headings should NOT be underlined, nor typed

ERRATUM: Caption for colour print of female Mandarin Aix galericulata in Summer 94 issue

should read first breeding record in Argyll.

Unfortunately space was restricted and the Research Index which normally appears in

SB 17 (4)

entirely in capitals. Scientific names in italics
should follow the first text reference to each
species and should follow Voous ‘List of Recent
Holarctic Bird Species’ as given in the The British
Birds’ List of Birds of the Western Palearctic
(1984). Only single quotation marks should be
used throughout and numbers one to ten should
be written out whereas 11 and above should be
written as numerals. Dates should be
written:.......... On S AUGUSTMISSNEe es. ---.: but on
the 5th (if the name of the month does not follow).
Please note that papers shorter than 700 words
willbe treated as Short Notes where all references
should be incorporated into the text, and not listed
at the end, as in full articles.

Tables, maps and diagrams should be designed
to fit either a single column or the full page width.
Tables should be self-explanatory and headings
should be kept as simple as possible, with
footnotes used to provide extra details where
necessary. Each table should be on a separate
sheet. Maps and diagrams should be in Indian ink
and be camera ready, but drawn so as to permit
reduction to half their original size.

For details of writing Research Progress Reports, .

please contact the editor in advance.

December issue will now appear in the June issue.

NEOTROPICAL
BIRD CLUB

Neotropical bird club launched

A club has been launched to promote the study and conservation of
the birds of the Neotropics (South America, Central America and the
Caribbean). It is currently seeking founder members to help reach
the launch budget of £2000, which is required to get the club running
and to publish the two first issues of its intended journal ‘Continga’.
Founder members will be asked to pay a minimum of £25, and will
be formally acknowledged in the first issue of ‘Continga’, planned for
January 1994. ‘Continga’ will provide a colourful and much needed
forum for exchange of information on the avifauna of this extremely
rich and diverse area, and will contain papers and features on the
birds and their conservation as well as news of recent observations
and discoveries (at present, new species are still being discovered
at the rate of more than two a year). It is hoped that in due course
the club will be able to provide direct funding and support for
practical conservation programmes.

For further details and membership forms,
please contact:

Rob Williams,

Publicity Officer,

Neotropical Bird Club,

c/o The Lodge,

Sandy,

Bedfordshire SG19 2DL

Scottish Birds

Volume 17 Part 4 December 1994

Contents

Research Progress Reports

A ten year study of Barn Owl conservation in conifer forests.
G. Shaw

Main articles

Changes in tens numbers of Kittiwakes in Shetland, 1981-1994.
M. Heubeck & R.M. Mellor

Densities of breeding Magpies and Carrion Crows in south-east
Scotland in 1992-93. H.E.M. Dott

The breeding performance of Ravens from a sample of nesting
territories in Shetland during 1984-1993. P.M. Ellis, J.D. Okill,
G.W. Petrie & D. Suddaby

Breeding seasons and nesting success of Snow Buntings in north-east
Scotland. R.D. Smith & M. Marquiss

Short Notes ©
Kestrel predation of Ring Ouzel nestling. D. Arthur
Interaction between Red Grouse and Osprey. A. Mee
Merlin follows prey underground. J.K. Craib
Sparrowhawk exploiting a Sand Martin colony. J.G. Young
A successful artificial Sand Martin banking. R.T. Smith

Correspondence

The influence of the weather on seabird movements across
central Scotland. W.R.P. Bourne

Items of Scottish Interest. W.G. Harper
European Journals in the Waterston Library. M. Murphy

Erratum

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