- ^ 71 British Birds AN ILLUSTRATED MONTHLY JOURNAL Edited by P. A. D. Hollom E. M. Nicholson I. J. Ferguson-Lees Stanley Cramp Photographic Editor : Eric Hosking Hon. Editors: W. B. Alexander N. F. Ticchurst Volume 55 H. F. & G. Witherby Ltd 5 WARWICK COURT LONDON WCI List of illustrations Plates 1-2 Plates j-j Plates 6-7 Plate 8 Plate 9 Plates 10-17 Plate 18 Plate 19 Plates 20-21 Plate 22 Plate 29 Plates 24-28 Plates 29-71 Dollis Hill: aerial photograph and typical road and garden (Aerofilm and Aero Pictorial Ltd., and B.B.C.) . . facing Honey Buzzard ( Pernis apivorus), standing by excavated wasps’ nest, excavating nest, section of comb and decapitated wasp, Denmark (lb Trap-Lind) Crested Lark ( Galerida cristata), at nest, Denmark (lb Trap-Lind) Upper: Nest-box damage by Great Spotted Woodpeckers ( Dendrocopos major), Sussex (Guy Mountfort) Lower: Rook ( Corvus frugilegus), female with lower mandible stuck through skin of upper breast, Kent (Gordon Clemetson) . . . . . . . . . . . . facing Upper: Hawfinch ( Coccothraustes cocco/hraus/es), juvenile male with incomplete bill, Switzerland (Willy Pfeiffer) . . Lower: Starling ( Sturms vulgaris), adult male with elongated bill (Eric Hosking) . . . . . . . . . . facing Swifts ( Apus apus), leaving and returning to nest-hole, with young, feeding young, Radnorshire, Hertfordshire, Oxford, Glasgow (Arthur Brook, C. C. Doncaster, H. N. Southern, C. Eric Palmar) . . . . . . . . facing Party of Swifts, Glasgow (C. Eric Palmar) . . . . facing Black-headed Gulls ( Lams ridibundus), development of wing-stretches in young (Miriam Rothschild) . . facing Black-headed Gull (Larus ridibundus), lifting egg-shell and rolling model egg into nest, model eggs and egg-shells used in experiments, Cumberland (N. Tinbergen, [ohn Haywood) Scarlet Grosbeak ( Carpodacus erythrinus), young male at nest, Finland (Eric Hosking) . . . . facing Top: River Warbler (Locus tella fluviatilis). Fair Isle (Angela Davis) Centre: Radde’s Bush Warbler ( Phylloscopus scbwaryi) Norfolk (P. R. Clarke) . . . . . . _ _ Bottom: Blackbird {T Urdus merula) with punctured eve (C. Stockton) ..facing Rock Buntings ( EmberiZa cia), at nests with young, and habitats, Spain (Arthur Gilpin, H. R. Lowes K 1 Carlson, R. G. Carlson) L facing Rock Sparrows (Petronia petronia), adults and nest-site Spain (Arthur Gilpin, H. R. Lowes) . . . . facm\ PAGE 24 25 49 72 96 1 16 117 137 M2 H3 LIST OF ILLUSTRATIONS Plates 32-40 Plates 41-47 Plate 48 Plate 44 Plates 40 -37 Plate 48 Plate 44 Plates 60-64 More examples of the best recent work by British bird- photographers: Long-tailed Tit (. Aegitbalos cauda/us), Lancashire (J. B. and S. Bottomley); Bee-eater ( Merops apiaster), France (S. C. Porter); female Great Spotted Woodpecker ( Dendrocopos major), Lancashire (J. B. and S. Bottomley); Magpie {Pica pica), Yorkshire (Morley Medley); Blackbird (7" urdus merula) and Starling {Stumus vulgaris), Glamorgan (C. Stockton); Knot ( Calidris canutus) and Redshank {Tringa totanus), Denmark (C. C. Doncaster); immature Ringed Plover {Cbaradrius biati- cula), Cheshire (D. M. Turner- Ettlinger) ; female Kestrel {Falco tinnunculus), Norfolk (R. Jones); female Pintail {Anas acuta), Hebrides (A. Winspcar-Cundall); female Red-breasted Merganser {Mergus senator), Cumberland (E. K. Thompson); Barn Owls {Tyto alba), Ayrshire (William S. Paton) ; Little Gull {Par us minutus), Denmark (Guy B. Farrar) . . . . . . . . . . facing Examples of albinism and other plumage abnormalities: Blackbird {Turdus merula), Essex (C. W. Teager); Red- necked Grebe {Podiceps griseigena), Switzerland (A. Schifferli); Blackbird {Turdus merula) (G. W. Temperley); mounted specimens of Corncrake {Crex crex), Derbyshire, and Curlew {Numenius arquata), Northumberland; xanthistic Wood Warblers ( Pbylloscopus sibilatrix), Wales (Eric Hosking); Lapwing ( V'anellus vanellus), Yorkshire (Walter Higham) ; dilute Oystercatcher {Haema/opus ostra/egus), Cheshire (Eric Hosking); melanistic Great Tit {Parus major), Surrey (K. F. W. Doughty) . . . . facing Upper: Deformed bill of Short-toed Lark {Calandrella cinerca) (George E. Watson) Power: Deformed bill of Herring Gull {Parus argentatus) (C. Stockton) . . . . . . . . . . . . facing Turnstone {Arenaria in/erpres), by carcass of Wolf, Canada (D. Muir) . . . . . . . . . . . . facing Habitats in the Barycz valley, Poland, and typical birds including Crane {Megalornis grus), Black Stork {Ciconia nigra). Ferruginous Duck {Ay thy a nyroca). Red-necked Grebe {Podiceps griseigena). Grey Lag Goose {Anser anser), Penduline Tit {Rem if pendulinus). Lesser Spotted Eagle {Aquila pomarina), Savi’s Warbler (Pocuste/la luscinioides), (M. D. England, Eric Hosking, W. Puchalski, Philippa Scott, J. Witkowski) .. .. .. ..facing Golden Eagle {Aquila chrysaetos), young in nest, Co. Antrim (C. D. Deane) . . . . . . . . facing Parts of letter dated }oth June 1916 from George Bristow to H. F. Witherby on rare birds in the Hastings area . . facing Great Grey Owls ( Strix nebulosa), in flight, perching, with young at nest, Sweden (Goran Hansson and Hilding Mickelsson) . . . . . . . . . . . . facing 184 220 221 241 260 280 281 404 Plates 6j-66 Plate 67 Plate 68 Plates 67-70 Plate 71 Plates 72-79 Plates 80-88 LIST OF ILLUSTRATIONS Radar displays of diurnal hard-weather movements and departures and arrivals (Marconi’s Wireless Telegraph Company Limited) Upper: diseased foot of Chaffinch ( Fringilla coelebs ), Somerset (R. Hood) L over: deformed feet of Ovstercatcher (. Haematopus ostralegus), Flintshire (Ronald Thompson) . . facing Ivory Gull ( Pagophila eburnea), adult at rest and in flight, Shetland (J. Peterson and C. J. Williamson) . . Jacing Destruction of wild life habitat on farmland, Cambridge and Huntingdon (N. W. Moore) Black-headed Gull (Lams ridibmdus), adult combining melanism with albinism, Kent (Pamela Harrison) . . facing Great White Herons (Egretta alba), preening, at nest, in reeds, greeting ceremony, with young, habitat, Hungary (Eric Flosking) . . . . • • • • • • facing Studies of waders at Minsmere: Grey Plover ( Cbaradrius squatarola), juvenile Lapwing ( Vanellus vanellus ), Ringed Plover (Cbaradrius biaticula ), Snipe (Gallinago gallinago). Black-tailed Godwit (Limosa limosa), juvenile Ruff (Philomachus pugnax), Avocet (R ecurvirostra avosetta). Common Sandpiper (Tringa hypoleucos), Green Sandpiper (T. oebropus ), Greenshank (T. nebularia). Redshank (T. to/anus). Spotted Redshank (T. erythropns ), Curlew Sand- piper (Calidris testacea ), adult and first-winter Dunlin (C. alpina ), juvenile Little Stint (C. minuta), juvenile Sanderling (Croccihia alba), Turnstones (Arenaria inter- pres) and Knots (Calidris canutus) (Eric Hosking) . . facing 405 442 443 476 576 Printed in England by Dicmer & Reynolds Ltd., Bedford British Birds A study of suburban bird-life at Dollis Hill Eric Simms (with two plates) Observations on a Honey Buzzard digging out a wasps’ nest lb Trap-Lind (with three plates) Studies of less familiar birds : 116 — Crested Lark I. J. Ferguson-Lees and lb Trap-Lind (with two plates) Principal Contents Notes Recent reports and news Three Shillings January *2 JAN 1962 British Birds AN ILLUSTRATED MONTHLY JOURNAL Edited bj P. A. D. Hollom E. M. Nicholson I. J. Ferguson-Lees Stanley Cramp Photographic Editor: Eric Hosking Hon. Editors: W. B. Alexander N. F. Ticehurst Editorial Address: 30 St. Leonard’s Avenue, Bedford Contents of Volume 55, Number 1, January 1962 Page A study of suburban bird-life at Dollis Hill. By Eric Simms (plates 1-2) . . 1 Observations on a Honey Buzzard digging out a wasps’ nest. By lb Trap-Lind (plates 3-5) .. .. .. .. .. .. .. 36 Studies of less familiar birds: 116 — Crested Lark. By I. J. Ferguson-Lees. Photographs by lb Trap-Lind (plates 6-7) . . . . . . . . . . y 7 Notes: — Golden Eagle attacking Reindeer (M. P. Harris and R. Price) . . . . 42 Kingfisher ducking Kingfisher (G. H. Forster) . . . . . . _ _ 4j Further notes on Great Spotted Woodpeckers attacking nest-boxes (Guy Mountfort) (plates 8a and 8b) . . . . . . . . Calandra Lark in Dorset (Dr. J. S. Ash) . . . . . . ^ Rook with unusual bill deformity (W. S. Nevin) (plate 8c) 46 Recent reports and news. By I. J. Ferguson-Lees and Kenneth Williamson 46 Annual subscription £ 2 (including postage and despatch) payable to H. F. & G. Withcrby Ltd., 3 Warwick Court, London, W.C.i Bird- Song W. H. THORPE A serious, scientific account of the biology of vocal communication and expression in birds. Dr Thorpe discusses how and why bird songs differ, what different songs mean, how birds learn their individ- ual songs, and how the sounds they make are produced. Cambridge Monographs in Experimental Biology. 20s. net from all booksellers CAMBRIDGE UNIVERSITY PRESS Choose a lightweight glass for your watching ROSS 9 X 35 STEPROVA Also available ROSS 8 X 30 A well-balanced, compact glass, weighing only 15 oz. Price \\ ith case £32 .11.0 or £6 . 10 . 3 deposit, balance over 12 months Can be carried all day without discomfort All optics hard coated to provide a bright image. Price with case £36 .8.3 or £7 . 5 . 8 deposit, balance over 12 months HERTEL & REUSS 7 X 25 Weighs only 6 oz., yet has wide field of vision. Price with case £23 .0.0 or £4 . 12 .0 deposit, balance over 12 months H COGSWELL & HARRISON LTD. MASTER GUNMAKERS SINCE 1770 We stock all the well-known makes Write for lists DEPT. BB, 168 PICCADILLY, LONDON, W.l (opposite Bond Street) A NEW AID FOR ORNITHOLOGISTS Photo by Eric Hosking attracts all garden birds Swoop wild bird food is an excellent aid to bird study. Its balanced formula of ten different foods — each carefully tested for acceptance by granivorous, insectivorous and omnivorous birds— has been shown to attract a remarkable variety of species, including migrants. Apart from its obvious use on the bird table, Swoop will be found in- valuable as bait for bird photography. Recommended by the r.s.p.b.. Swoop is available at all grocers and pet shops. Price 1/11 per pack BALANCED -FORMULA WILD BIRD FOOD British Birds Vol. 55 No. i January 1962 A study of suburban bird-life at Dollis Hill By Eric Simms (Plates 1-2) INTRODUCTION Until the present time no thorough or systematic survey of the distribution and behaviour of the birds of a suburban area has appeared since F. D. Power’s Ornithological Notes from a South London Suburb, 1S/4-1909, published in 1910. This paper sets out the results obtained by the author from the study of Dollis Hill, a suburban area in north-west London. It is based on detailed observations carried out over a period of more than ten years from January 1951 to the summer of 1961, when I lived in the district, as well as on spasmodic observations from August 1943 to December 1950, when I was a frequent visitor. The area chosen for study lies within 1,250 yards or less of my home and can be comfortably managed by one observer; it contains five major habitats forming a fascinating, almost exclusively man-made, ecological unit. DESCRIPTION AND HISTORY OF THE AREA The study area lies some five miles north-west of Marble Arch. It consists of approximately 546 acres (or five-sixths of a square mile) and is contained in a rectangle formed to the north by the North Circular Road, to the west by Dudden Hill Lane, to the east by the Edgware Road and to the south by the Midland Region railway fine of British Railways (formerly part of the Midland and South-Western Junction Railway). This rectangle of land is just over a mile across from west to east and slightly more than three-quarters of a mile from north to south (see Fig. 1). The area has the form of a shallow cone on the London clay. The land rises from between 115 and 172 feet above sea-level on the periphery to the highest point of 25 1 feet immediately to the east of the Post Office Research Station. 12 JA 1 BRITISH BIRDS Authors Hook BREWT RESERVOIR John Kelly School Ed&ware l Road P.0. Research Station S SHOPS Ys\ FACTORY AREAS FH ALLOTMENTS □uyy^=^^^tes“‘i Gladstone Park St Andrew's Hospital Fig. i . Map of the area studied at Dollis Hill, London, during 195 1-61, showing the major buildings, residential parts, factories, parkland and allotments Immediately to the north lies the Brent Reservoir and, although it has some effect on the bird-life of the selected area, it was deliberately excluded so that undue weight would not be given to any birds occur- ring in this rather specialised habitat. The ways in which the reservoir has any clear influence on the birds of Dollis Hill will be examined at various points in this paper. An aerial photograph of the study area and the reservoir is reproduced on plate 1. At the time of the Enclosure Award of 1816, the study area consisted of a 1 6th century farm at Oxgate (still in 1961 the oldest building in the Borough of Willesden), another farm at the top of Dollis Hill, a mansion known as Neasden House and some 75 fields resulting from the enclosure. The region was typical open farming country and the only road across the area was Dollis I lill Lane which traversed it from east to west. Dollis Hill House was built in 1825 and the railway which provides the southern boundary to the area in 1868. Bv 1895 the south-western corner had become occupied by a golf-course. 2 SUBURBAN BIRD-LIFE AT DOLLIS HILL Fig. 2. The study area at Dollis Hill, London, at intervals from 1875 to 1961, with the built-up parts in black Residential building really started in the south-east from 1907-08, with a few houses as well in the south-west corner. At this time breeding birds of the area included such species as Sparrowhawk,* Partridge, Corncrake, Cuckoo, Wryneck, Skylark, Swallow, Magpie, Treecreeper, Blackcap, Garden Warbler, White- throat, Lesser \\ hitethroat, Bullfinch and Yellowhammer (Dixon 1909 and Kendall 1907). Of the major landmarks constructed in the first quarter of the century, the two most noteworthy are St. Andrew’s Hospital, built in i9ij, and the Post Office Research Station which rose in 1923 on the site of the old Dollis Hill Farm. In the mid- 19 20’s Edgware Road was developed and there was some small-scale building in the middle of the area. So far a large part of the study area still retained much of its rural character, but a great transformation took place between 1928 and *The scientific names of all birds mentioned in the text can be found in the summary appendix on pages 35-36; otherwise they arc given only in the tables. 3 BRITISH BIRDS 1930 when 29 new streets were laid out in the centre and there was further development in the two southern corners; this was also the period in which the North Circular Road was built. From 1930 to 1932 further building pushed into the western end and into the factory area of the north-east. Within the next three years the total develop- ment of the western side of the area was completed. Since then there have been some extensions to factory premises, and a few houses and small blocks of flats were built after the war. The John Kelly Schools went up in 195 8 on open land north of the Research Station. Fig. 2 shows the dramatic changes that took place in the area between 1928 and 1961. HABITAT Today the study area can be conveniently divided into five main habitats and these will be described in order of size. 1. 'Residential area This comprises private houses and their gardens, roads and a few small blocks of flats, and represents some 60% of the total area. In all, there are slightly more than 3,600 houses in the 330 acres of the residential district. Most of these houses are either terraced or semi- detached with small front gardens typically bordered by low walls, railings, fences or privet hedges. Many have some grass in the front, often with hydrangeas, roses and perennials, but increasing numbers of front gardens have been concreted in. This has generally been to save labour or, during the last decade, in the case of terraced houses, to give parking space for the cars that have come with increased affluence. The effect of this is to concentrate birds in feeding areas; it has certainly not yet resulted in a decrease in numbers. Plate 2 shows a typical road and front garden in the residential area. The average back garden is some 20 feet wide and varies from 50 to 100 feet in length. Exceptionally, a few semi-detached and detached houses have back gardens of 200 feet in length Most of the back gardens are separated from each other by wooden fences or palings, chain-link or walls, and there has been a slow but steady reaction against the privet hedges so popular 25 years ago. The most striking thing about the majority of these gardens is that the top layer of tree or shrub growth is only about 20 feet high and in many gardens is far lower than this. Many I have seen, although they are 30 years old, have no vegetational growth above six feet; one had a black currant bush as the tallest plant within it! The higher growth to 20 feet or so is largely-accounted for by ash-trees, flowering cherries, laburnums, lilacs, sycamores and by fruit-trees such as apples, pears' 4 SUBURBAN BIRD-LIFE AT DOLLIS HILL plums and damsons. A small number of ancient oaks, mostly stag- headed, were incorporated in the estate when it was laid out; these raise their strange archaic forms above the red-tiled roof-tops and provide occasional perches for Carrion Crows, Common Gulls, Black-headed Gulls and Starlings. There are also a few elms and Lombardy poplars in the garden areas. Quite a number of the roads in the residential area have trees planted on both sides. The estate builders who began this were responsible for some not really suitable species that were included. The commonest trees in the roads are two species of elm (including the Jersey elm), three varieties of mountain ash, the London plane, the horse chestnut, the tree-of-heaven, the sycamore, two species of acacia and four varieties of Norway maple. Other trees include the silver maple, the native silver birch, seven species of Crataegus , the laburnum, the white and necklace poplars, three species of Prunus , the white beam, the crab apple, the white willow, the broad-leaved lime and a variety of ashes. A few, ancient indigenous elms survive along Dollis Hill Lane, the pre-estate road north of Gladstone Park. The greater part of the residential area, as will be seen in Fig. i, lies in the centre and west of the district. The typical breeding birds here are the House Sparrow, Starling, Blackbird and Dunnock. A few pairs of Woodpigeons breed in roadside trees, especially elms and horse chestnuts, and in garden trees of sufficient height. Tits, Wrens and Robins cannot usually find nesting sites in these gardens, and the Song Thrush — no more than an occasional winter visitor to some of them— will only rarely attempt to nest, since there are few evergreens or shrubs of sufficient height or density to give it the protection it needs. 2. ¥ acton area The second habitat is made up of the northern block of factories along the North Circular and the Edgware Road, as well as the Post Office Research Station which I have included here because of its massive and extensive nature. These and their surrounds represent some 15% of the total area. Most of the factory structures are slab-like and up to 60 feet in height; they usually have mown or unmown grass or rough ground in their immediate neighbourhood. The research station is an agglomeration of buildings; some of concrete or brick are of great height and dominate the top of Dollis Hill while other buildings are lower and of a less permanent nature. There is a small lake in the grounds frequented by Mallard. The typical nesting species of this area are the Feral Pigeon, House Sparrow, Starling and Pied Wagtail. Carrion Crows use all these high buildings as perches or meeting places; one of their favourite assembly 5 BRITISH BIRDS points is on the radio-masts of the research station. Blackbirds will occasionally sing from factory roof-tops and a pair once bred in a workshop. Parkland Included in this section are some 70 acres of Gladstone Park (north of the railway line) and a small part of the grounds of St. Andrew’s Hospital with tall trees, some hollies and grass; these together repre- sent 13% of the total area. Gladstone Park is most pleasantly sited on the southern slopes of Dollis Hill. The park incorporates Dollis Hill House— a favourite resort of W. E. Gladstone as the guest of Lord Aberdeen— as well as a swimming pool, a small lake near the house, tennis courts, playing fields, a bowling green and a formal walled garden. For some years after the last war much of the lower part of the park was under cultivation and a pair of Skylarks bred there every year from 1946 to 1951. The land was then rehabilitated and the larks disappeared. Today most of the park consists of grass, intersected by several fine avenues of London planes up to 70 feet in height. A number of the original oaks and elms, dating from the period of the private house and including some magnificent trees, are scattered over the grass. There are also black poplars, horse chestnuts, and a few cherries, almonds, hawthorns, Lombardy poplars, willows and other trees. Shrubberies are few and easily penetrated by children. Only one shrubbery has any real cover and this is made up of laburnums, cherries, laurustinus and tamarisk growing through a thicker layer of berberis, flowering currant and Cjdonia japonica. This is an important roost for thrushes. The typical nesting species of this habitat are Mallard, Woodpigeon, Tawny Owl, Carrion Crow, Great Tit, Blue Tit, Wren, Mistle Thrush, Song Thrush, Blackbird, Robin, Spotted Flycatcher, Dunnock, Starling, Greenfinch, Chaffinch and House Sparrow. A single pair of Stock Doves held on until 1952, bred in 1954 and may have done in 1953, 1956 and 1957 as well. Since 1957 I have not seen a single bird in the park. The shooting of Woodpigeons from 1 960 onwards would perhaps have provided too much disturbance for them had they stayed. 4. Allotments There are five areas of allotments in the district. One is too small to have any significance and another has reverted to rough grassland. The other three are of considerable importance and can be seen in Fig. 1. The largest is in the eastern corner between Dollis Hill Lane and the railway line: the second lies on two sides of St. Andrew’s Hospital and the third is immediately to the north of the Post Office Research Station. These allotments make up 10% of the total area. 6 SUBURBAN BIRD-LIFE AT DOLLIS HILL The allotments in varying stages of cultivation, with their occasional dense hawthorn, elder and bramble bushes are important feeding areas for many birds especially thrushes, Woodpigeons, Wrens, Robins, finches and sparrows. Mallard breed in some of the grass tussocks, Song Thrushes and Blackbirds in the bushes, Wrens and Robins in low cover and against wooden fences. In the migration seasons, warblers of several species are regular visitors. A small shallow pond on the allotments immediately to the west of the hospital, still with Iris pseudacorus and Tjpba latifolia growing in it, is often visited by Mallard and provides a drinking place in all winters and some summers for many different species. /. Special area This, the fifth habitat, comprises only 2% of the study area and yet it is one of the most important. It consists of three parts: the first is a belt of sycamores, elms, limes, ashes, horse chestnuts and ancient oaks, with a ground cover of cow parsley, bluebells, nettles and ivy and a tangled mass of hawthorn, privet, elder and willow at one end ; the second is an orchard with rough grass; and the third consists of work- ing or disused chicken-runs. This special area with its rural qualities is a veritable bird sanctuary. The breeding species include Woodpigeon, Carrion Crow, Great and Blue Tit, Wren, Song Thrush, Blackbird, Robin, Dunnock, Starling, Greenfinch, Goldfinch, Chaffinch, Tree Sparrow and House Sparrow. Here the Blackcap and the Willow Warbler have also nested. NUMBER OF SPECIES RECORDED IN STUDY AREA Since observations first began I have recorded 70 different birds in the area, and it is interesting to note that 52 of these have occurred in or over my own garden in Brook Road. The total of 70 species can be sub-divided in the following way: Regular breeders 21 Former or occasional breeders 4 Present in summer but not breeding 3 Winter visitors 6 Passage migrants 21 Occasionally flving over 3 Vagrants 12 This figure over a period of nearly eleven years compares favourably with the total of 63 species that I recorded in Ladbroke Square, Ken- sington (west London), over thirteen years. 7 BRITISH BIRDS SUMMER POPULATION Table i shows the species breeding or present in the breeding season during each year from 1951 to 1961. It can be seen that the losses in this period have been the Stock Dove and the Skylark. The Jay has only recently come into the district: I have always wondered at the previous absence of this bird since it has for so long frequented the central London parks and squares, Paddington Cemetery and the northern bank of the Brent Reservoir. Table i — Species breeding or present in breeding season at Dollis Hill, London, 1951-61 B indicates breeding and p present but not breeding Mallard ( Anas platyrhyncbos) Kestrel ( Falco tinnunculus) Stock Dove ( Columba oenas) Feral Pigeon (C. livid) Woodpigeon (C. palumbus) Tawny Owl ( Slrix aluco) Swift ( Apus apus) Skylark ( Alauda arvensis) Carrion Crow (Corvus corone ) Jay ( Garrulus glandarius) Great Tit (Partis major) Blue Tit (P. caeruleus ) Wren ( Troglodytes troglodytes) Mistle Thrush (Turd/ is viscivorus) Song Thrush (T. pbilomelos) Blackbird (T. meruld) Robin (Er it haem rubecula) Blackcap (Sylvia atricapilla) Willow Warbler (Phylloscopus trochilus) Spotted Flycatcher (Muscicapa striata) Dunnock (Prunella modularis) Pied Wagtail (Motacil/a alba) Starling (Sturnus vulgaris) Greenfinch (Cbloris chloris) Goldfinch (Carduclis carduelis) Chaffinch (Fringil/a coelebs) House Sparrow (Passer domesticus) Tree Sparrow (P. mon/anus) w cq crv vv NO L" CO ON O NO CN NO CN CN G\ CN CN CN CN CN CN CN M M M HH t-* B B B B B B B B B B B P P P P P P B B B? B P B? B? B B B B B B B B B B B B B B B B B B B B B B B B B B B B B B B B B P P P P P P P P P P P B B B B B B B B B B B B B B B P B B B B B B B B B B B B B B B B B B B B B B B B B B B B B B B B B B B B B B B B B B B B B B B B B B B B B B B B B B B B B B B B B B B B B B B B B B B B B B? B? B? B B? B? B B B B B B B B B B B B B B B B B B B B B B B B B B B B B B B B B B B B B B B B B B B B B P B? B B B B B B B B B P B? B B B B B B B B B B B B B B B B B B B B B B B B B B B B B B B P P B B B? B B B B B B From Table 1 it will be seen that the average number of breeding species during 1951-61 was 21, with a minimum of 20 and a maximum in 1954 of 23. These figures may be compared with the total of 22 nesting species discovered by E. C. Rowberry in 1936 during a census 8 SUBURBAN BIRD-LIFE AT DOLLIS HILL of a built-up area in south-west London (Homes et al. 195 7). Similarly, during 1954-59 the average breeding figure for Regent’s Park and Primrose Hill was 25 species (Wallace 1961), and for Hyde Park and Kensington Gardens 19 species, while the average for St. James’s and the Green Parks during 1954-58 was 16 {Rep. Comm. Royal Parks, 1953- 54, 1955-56, 1957-58). The inclusion of the Brent Reservoir, which adjoins the study area, would have added only five more. It is clear, too, that the number of species is fairly static from year to year. NUMBERS OF BREEDING PAIRS AND SELECTION OF NESTING SITES In 1951 onlv two pairs of Mallard bred in the area; by 1961 the total had risen to seven or eight pairs. About 90% of all their nests have been in rough grass on allotments, in gardens or in the grounds of the Post Office Research Station. The remaining 10% have been in holes in elm-trees some 15-20 feet above the ground. When the ducklings hatch, the adults usually take them down to the Brent Reservoir, sometimes after journeys of more than 1,000 yards. A very different bird which overlaps the breeding habitats of the Mallard is the Tawny Owl. From 1951 to 1956 two pairs nested in Gladstone Park and one pair in the hospital grounds. There was a fourth pair in the park from 1957 to 1959, but by i960 the total breeding population in the area was reduced to two pairs. All the nests have been in holes in elms 20-25 feet above the ground. Of the doves, some 14- is pairs of Feral Pigeons breed (a rise since 195 1 of 7-8 pairs), and about 36-40 pairs of Woodpigeons (nearly three times the number in 1951). The former species nests in roof-ventila- tors on the research station and on high ledges on a factory facade near Staples Corner; there are few available nesting sites in a comparatively modern estate. Woodpigeons have built in acacias, elms, London planes, ashes, horse chestnuts and several species of Primus, but I have no records of buildings being used for breeding sites. Of 187 nests examined, one was six feet above the ground, eight were 10-15 feet, 132 were 15-20 feet and 46 above 20 feet. Woodpigeons sometimes nest in such dense foliage that access is difficult. Nests have sometimes been started in mid-March and I have known unfledged young in early October. A single pair of Carrion Crows bred in Gladstone Park from 1943 to 1961, and a second pair in 195 3 and 1958. Another pair also nested in the grounds of St. Andrew’s Hospital during 1951-56 and 1960-61. Of the 29 nests seen, 20 have been in elms, eight in sycamores and one in a black poplar. Crows forage over a wide area and it would seem unlikely that the status of this species will alter much in the immediate future. 9 BRITISH BIRDS Only two species of tit nest regularly. The annual breeding popula- tion of Great Tits varies from five to six pairs; most of the nests are in stack-pipes, hollow trees and old walls. The number of breeding pairs of Blue Tits remains fairly constant at about nine pairs. Nesting sites are similar to those of the Great Tit, but the Blue Tit will more readily use nest-boxes in private gardens, and for this reason the larger species is almost entirely absent from these areas in the summer. The Wren is confined in the breeding season to Gladstone Park, St. Andrew’s Hospital and the adjoining allotments. Here some seven pairs nest each year amongst creepers and ivy on fences and sheds, and in holes in old walls. At Dollis Hill the Mistle Thrush, is a marginal species. Its main stronghold is in the park where two pairs bred from 1951 to 1954 and one pair only from 1955 to 1961. There has been one attempt to extend this range and that was when a pair nested successfully some 25 feet up in a tall Lombardy poplar in a private garden near my home; this tree was felled the following winter. All the nests have been built between 18 and 30 feet above the ground, usually in London planes, but sometimes in elms, oaks and hawthorns. The Song Thrush, on the other hand, is represented by six to eight breeding pairs. The chief limiting factor on its distribution is its conservative choice of nesting sites; all the nests examined have been five to 1 5 feet above the ground and, with one exception, in hollies or hawthorns. Dixon (1909) called the Song Thrush “the commonest thrush in north-west London, but now the Blackbird easily out- numbers it by 26 or 27 to one. During 1951-57 and 1959-61 between 185 and 195 pairs of Blackbirds bred at least once each year in the area, and in the very wet summer of 1958, when insect food was plentiful' the total rose to more than 200 pairs. With the Blackbird, two broods are regular and three not uncommon; in 1958 a pair that had built on top of a partially finished House Sparrow’s nest on a rain-pipe beneath the gutter of a neighbour’s house successfully raised four broods in the same nest. At one stage the male of this pair was simul- taneously feeding the fledged young of the third brood and the newlv hatched nestlings of the fourth. Most of the nests have been in trees and bushes, especially ashes, London planes, pears, plums, ornamental cherries, horse chestnuts, hawthorns, elders, almonds, syringas weep- mg willows, and roses on stumps and fences. A pair once built on top of a clock in a workshop at the Post Office Research Station. Table 2 summarises the heights above ground and the situations of all the blackbird nests found in the area. The Robin is confined in tbe breeding season to Gladstone Park the grounds of St. Andrew’s Hospital ant', some allotments Seven to e.gl.t pairs nest each year in wall cavities or dense creeper, or in grassy IO SUBURBAN BIRD-LIFE AT DOLLIS HILL Table 2 — Heights and situations of 61 i Blackbird (T urdus merula) NESTS AT DOLLIS HlLL, LONDON, 1951-61 0-5 feet 5-10 feet 10-15 feet 15-20 feet 20-25 feet 25-30 feet 4 510 56 22 l6 3 In trees and bushes In creeper on walls On pipes on walls On ledges of fences On stacked ladders In sheds and buildings 497 l6 1 5 76 3 4 hanks on the allotments. Robins avoid the private gardens in the summer as there are no suitable nesting sites for them. In 1958 a pair of Blackcaps built six feet up in an elder and in 1957 a pair of Willow Warblers brought off a brood in a nest in rough grass. The Spotted Flycatcher, however, has changed its status little since Kendall (1907) reported two pairs at Dollis Hill. During 1951-61 a pair has come each year and usually nested about six feet up against a wall in the north-eastern corner of Gladstone Park; a second pair bred in the grounds of the research station in 1956. Two pairs of Pied Wagtails, separated by about half a mile, nest at the research station and at one of the factories along the North Circular Road; these depend on the Brent Reservoir and a small lake by the research station for access to water. The next two breeding species are closely associated with man. The Dunnock is widely distributed, with the annual number of breed- ing pairs varying from 45 to 50. It is essentially the bird of the privet and 99.5% of all the nests have been in hedges of this kind; tne other nesting sites have been in hawthorn and lilac. Of the 214 nests I have found, 84.6% have been between three and five feet off ground level and the remaining 15.4% between five and eight feet. The Starling is also a common resident and from 250 to 275 pairs nest each year in the study area; this gives a density of about 50 nests per 100 acres. However, as Nicholson (1951) pointed out, densities of 120 nests per 100 acres are known. Of the Starling nests at Dollis Hill, 92% have been in houses and buildings and only 8% in holes in trees. From 1952 to i960 Starlings entered my own loft through a small gap under the lead covering to a bay window; it was necessary for the birds to squeeze and struggle for some five to eight seconds before they could get through, but each year a brood was successfully reared in this site. Three species of finch breed in verv small numbers each year and are strictly confined to the area of the park and the hospital. Three, sometimes four, pairs of Greenfinches nest in overgrown hedges or 1 1 BRITISH BIRDS shrubberies. One pair of Goldfinches has bred in every year since 1953 and may well have done so in the two preceding years: in 1956 and 1959 a second pair also nested. All the nests have been in haw- thorns or apple-trees. Two pairs of Chaffinches breed in almonds or hawthorns in Gladstone Park and one pair in an apple-tree near the hospital. The finches are entirely dependent on the conditions available in these two areas and anv changes in them could adversely affect the status of all three. About 900 pairs of House Sparrows breed every year in the area, which gives a breeding density of 3.3 birds per acre. This figure can be compared with the density of 4.3 birds per acre found by S. Cramp in 43 acres of Bloomsbury in 1950 and with the 4.0 birds per acre counted in Lambeth by W. G. Teagle (Homes et al. 1957 ); however, in a suburb of Stockton-on-Tees, Co. Durham, Summers-Smith (1959) found a density of only one bird per acre. The total number of House Sparrows at Dollis Hill has remained constant throughout the decade, although S. Cramp has recorded a slow decline in central London. Nearly all the nests have been built in holes in roofs, ventilators and pipes. I also have records of five nests in hawthorns in Gladstone Park, of seven nests among creepers on walls and of one nest which was constructed in the open, resting on a rain-pipe where it curved towards the wall from the sheltering gutter above. Nests in my own loft have sometimes been built on the floor with open cups or suspen- ded from the underside of a tile with the classical domed form. The chief materials used have been dried grass, especially common couch and annual meadow grass, roots and, from my own garden, the dry- stringy leaves of the lily-of-the-valley. Feathers are often used for nest-linings and House Sparrows may travel as much as 400 yards to bring feathers from the hospital chicken-runs. Dog hairs are also collected. Breeding has taken place in every month of the year at Dollis Hill and two or three broods are usual. I have records of 1 5 3 broods being fed in October, 52 in November, 24 in December, 20 >n January, 12 in February and 316 in March. Dead featherless nestlings are often found lying in the street. Tree Sparrows were present in the summers of 195 x and 1952 in the special habitat area (page 7), but breeding was not proved until 1053 Since then two pairs have certainly nested in every year up to 1961. The nests have invariably been in holes in old oaks 'some 16-20 feet Km, In T T' |,Criod Trce SP”°™ have nested a, Barn Hill, Mill Hill and the Brent Reservoir, but the tiny Dollis Hill colony ts the nearest to the centre of London in this direction The nrds are sedentary all the year round and feed regularly on the allot- 1 2 SUBURBAN BIRD-LIFE AT DOLLIS HILL SIZE OF BREEDING POPULATION Many censuses were regularly and systematically carried out each year to check and re-check the size of the breeding population, most being undertaken in the evenings or early mornings. In fact, more than 2,000 such counts were made during 195 1-6 1, in order to arrive at as close as possible an estimate of the annual breeding population. In 195 1 the total number of breeding pairs of all species was between 1,445 and 1,500, giving a density of 52-53 birds per ten acres. The i960 total was slightly higher — from 1,480 to 1,525 pairs — but this also gave a density of 52-53 birds per ten acres. This density figure can be compared with 19-22 birds per ten acres in Regent’s Park (Wallace 1961), and my own records of 48 birds per ten acres in an area of north Oxford gardens in 1946 and 98 birds per ten acres in the Ladbroke Square district of Kensington before the last war. Some of the national averages for breeding densities of birds per ten acres are as follows: Rough grazing 7 Permanent grass 20 Deciduous woodland 40 Mixed woodland 50 Built-up areas 5° Parks 100 The figures for Dollis Hill are therefore comparable to those for mixed woodland and built-up areas. It would be most valuable to have a wide series of figures available for different kinds of area of houses and gardens. The high figure for Kensington suggests that more densely built-up areas with some open spaces may be more attractive to birds than suburban districts. Wallace’s low figure is due largely to the presence of many open grass swards in Regent’s Park. An example of the kind of density that exists in Dollis Hill is as follows. In i960 there were within 180 feet of my own house 17 Blackbird nests, 15 Table 3 — Figures showing the tendency for communities TO CONSIST OF UNRELATED SPECIES °o of genera with only Average number of Author Locality one species present species per genus Elton (1946) Several communities 86 1.38 Cramp (1949) Regent’s Park (1947) 87 1. 18 Wallace (1961) Regent’s Park (1959) 78 1.26 Simms Ladbroke Square (1937) 75 *•37 Simms Dollis Hill (195 1) 75 *•37 Simms Dollis Hill (i960) 73 *•33 *3 BRITISH BIRDS House Sparrow nests, four Starling nests, two Dunnock nests and one Woodpigeon nest. Cramp (1949) and Wallace (1961), in their studies of the birds of Regent’s Park, correlated their data with those of Elton (1946) who, in a wide survey of ecological communities, found a high and fairly constant percentage of genera with only one species present. Table 3 compares their figures and Elton’s with mine for Ladbroke Square (1937) and Dollis Hill (195 1 and i960). HEIGHTS OF NESTS Records were also kept of the heights of 4,266 nests of 23 different species. This part of the survey covered all natural and man-made sites in order to find out where the altitudinal weight of the breeding population was to be found. Table 4 gives the percentage distribu- tion of nests according to height. It will be seen that two layers— those of 5-10 and 20-25 feet — account for more than 89% of all the nests recorded. The lower layer is largely occupied by the Blackbird/ Dunnock community and the higher layer by the Starling/House Sparrow one. Table 4 — Percentage heights op 4,266 nests of 23 species at Dollis Hill, London, 1951-61 Ground 0-5 feet 5-10 feet 10-15 feet 15-20 feet 20-25 feet Over 25 feet °-5% 3-2% I3-6°o 2.3% 3.7% 75.8% 0.9% SONG AND DISPLAY Full records were kept of song seasons and any displays that were seen. The paragraphs which follow summarise the more interesting aspects of these observations. Beginning with the doves, song from the male Stock Dove often present in Gladstone Park during 1951-1956 was very infrequent, as might be expected, since there were no adjoining territories of other birds of this species. Feral Pigeons sing and display in every month of the year, and I have also heard song from Woodpigeons in every month though it is most regular from mid-February to mid-September The only other non-Passerine that should be mentioned here is the Tawny Owl: hooting is at its height in late September and October when territories are set up. ODer wnen Great lit song normally begins towards mid-December and early January, and lasts until July; there is then a partial resumption in 2 autumn. Similarly, Blue Tits often sing from December to July with a resumption m September. I have heard song from Coal fit! in 14 SUBURBAN BIRD-LIFE AT DOLLIS HILL March, April and August. Wrens sing in every month of the year but most strongly from February to July; the song gives a clear indica- tion of the autumn spread of this species into private gardens away from the breeding territories. Turning now to the thrushes, 1 have heard sub-song from Mistle Thrushes from December to March and full song from December to May. In the case of the Song Thrush, my earliest autumn date for full song is 6th October and this is then maintained through until early July; sub-song is frequent in September and October. Blackbirds may begin in December, but they normally start up in mid-February and go on until July. For three consecutive Februaries a male began his sub-song on the ground under some dense rhododendrons in my front garden; then after a day of full song in this strange location he moved up to the gutters and chimney of my house and these became his regular song-posts for the rest of the season. By making extensive tape recordings of this individual I was able to trace the development of his song. Sub-song in his third year -was comparable, for example, to full song in his second year; it was not until his third season that his song assumed its fullest range, variety and beauty. The autumn song of the Robin begins each year between ioth and 20th August. I have heard full song from Dunnocks in every month of the year; display is at its height in March and I have several spring records of the curious cloaca-pecking which was first described in 1933 by Edmund Selous. In the case of the Starling, song is regular in every month of the year but most frequent from mid-July to early June. Indirect evidence of Continental immigration came from one which gave perfect imitations of the fluting song of the Golden Oriole in my garden in February 1952; Starlings in the area have also produced imitations of Buzzard and Little Owl which they must have heard elsewhere. In addition, I have records of Starlings mimicking the song and low alarm of a Blackbird, the song of a Song Thrush and the calls of Chaffinch, Carrion Crow, Greenfinch, Mallard and Tawny Owl. Other imita- tions have included the miaows of Cats, the squeals of brakes and, on one occasion, a duet with a crying baby which was so good that it was almost impossible to separate the rwo performers. Turning to the finches, Greenfinch song lasts from late February to early August, while full Goldfinch song begins in mid-March and continues until mid-July. The first Chaffinches in full song can be heard each year between 6th and 17th February, with the 14th as the average. For the House Sparrow I have records of song and com- munal display in every month of the year, but the latter, occurring strongly in January, reaches a peak in April and then becomes less frequent each month until December. 1 5 Houses Gardens — —Streets I I i l u I sopd qdBaSspj, SpjBpUBJS dtUB'J S33J3 JSSIJg I I I I I I I I I < u I lull O O I "0 I ■- I I I i ^ I I I I I I I | | <%3 I ^3 I i I 2 B g in J « -5 _5p §>'§ a 2 o ^ ^ ^T- r-C os Cl/D bb •5J..S -C aj w p. 03 — ' 3^ >« ^ fa fa w H VO i fa ^ O ^ W fa *J* >-» H O H S 2 ? S3 fa „ fa fa fa fa 3 x O 2 ™ J 2 o 2 Q H > c4 fa & >-» w ^ i c u O U rt a, c >* o Y &o X £ t) a >> o X E u S a-c £ m Y ^ T* Cl. — 3 O -* .9- g a X o cu 3 Z -5 W ►a A -a § -5 ■S I 0 o a to 'a -a o o $ •5? £ § ■G, 1 | ? -S' 0*, 2 £ V-' v. £ V-i JJ £ X rj X cS C/5 3 w 03 V ' *-» L rC HD IH £ P P IS £ 60 c fa4 U 03 jo s o c/3 SQ N I I I CN N ’T N N I I PT\ \ss o o o I I so cs + O O o I ^ I I N o oo 1 I Ga fa4 u O C a 3 r \ 6fi .£ ’~C- 03 c/5 c v- O £ c v-. u. 03 CL c n CO 3 O BRITISH BIRDS SONG POSTS Very little has been published to date about the choice of song posts in built-up areas, though Fitter (1949) described Blackbirds and Song Thrushes as occasionally singing from roof-tops in London and Hulme (19^ 5) reported eight different species using buildings as song posts in one built-up part of the Midlands; in the London area, too, the Wood- pigeon has been regularly noted as using buildings for singing and displaying (Homes et at. 1957). At Dollis Hill the Blackbirds quite regularly, and the Song Thrushes not infrequently, use buildings as song posts and I have noted 14 other species taking advantage of some part of a permanent building (including radio and television aerials) as a point of vantage for singing. Table 5 summarises my records of song posts over a period of ten years. A bird had to sing at least one full phrase of song to qualify for inclusion. Television aerials certainly represent ideal song posts for such species as Blackbird, Starling and House Sparrow and they are, on occasion, used by much less likely birds (Table 6). In 1951 television aerials were infrequent at Dollis Hill and it has been most interesting to trace, with the growth in their number, their increased use as vantage points for singers. (Incidentally, in 1961 I saw a Corn Bunting begin to use a television aerial on a new housing estate at Peterhead, Aberdeenshire, shortly after it was erected.) Of the nine chief perching places associ- ated with aerials, only the Starling has so far been able to use all of them as song posts. The House Sparrow has used seven and the Blackbird six. Of course, in the London area the television aerials are normally vertically polarised. WINTER POPULATIONS With the coming of winter there is a change in numbers of some of the resident species, as well as the arrival of several winter visitors. Since the beginning of the present century the Mallard has increased enor- mously at this season in the London area. In the winter of 1951 it was r.ot unusual to see a handful of these birds by the small lake in Gladstone Park, but there were never more than 20. By the winter of 1952 the maximum had risen to 33, by 1956 to 52, by i957 to 67 and by 1961 to ~j \ . It should be added, however, that this local increase can to some extent be directly correlated with the increase in human visitors feeding them. Mallard flight twice a day between the park and the Brent Reservoir and pass over my house while doing so, a habit which has enabled me to watch the steady rise in numbers throughout the decade in addition to making regular counts in the park itself. In late winter it is also interesting to watch the dispersal of Mallard into gardens and allotments, and throughout the park, in their search for 18 SUBURBAN BIRD-LIFE AT DOLLIS HILL breeding sites; I have seen up to 21 birds at a time sitting in elms, oaks and plane trees in Gladstone Park in the early morning. There is also a dispersal of some of the other breeding species into parts of the study area where they are rare or unknown in the summer. From September to February each winter up to five Great Tits will visit my garden and bird-table, and forays into other private gardens are frequent during this period. Blue Tits are also regular visitors; in December 1957 more than a dozen were present in my garden and by 3rd February 1958 the party had grown to 20. During this time increased numbers of Blue Tits were reported from Inner London— survivors of the autumn irruption of 1957 — but it is interesting to note that there were no attacks on milk-bottles, paper or putty at Dollis Hill, such as those which occurred in central London, Hampstead and Balham. Greenfinches, Goldfinches and Chaffinches come in winter to quite small gardens in search of plant seeds and there is also a dispersal of Wrens and Song Thrushes. In addition, Robins will appear in gardens to take up winter territories. A single Robin arrives in my own garden each year between 23rd July and 3rd August; it sings regularly, visits the bird-table, fights off intruders and remains until mid-March. In winter, too, resident birds are often concentrated in areas where the cover is good. For example, in any five-minute period from dawn to dusk on 20th January 1958 there were never less than 16 individuals of four species in my own garden; at one time the number rose to 39 individuals of eight species. On 21st January 1958 there were never less than 14 House Sparrows in my garden (20 feet by 180 feet) at any one time from 8 a.m. to 4.1 5 p.m. and for more than twrentv minutes in the afternoon there were over 200. The six regular winter visitors to Dollis Hill are the Meadow Pipit, wffiich at this season can be flushed from the grass in Gladstone Park or on the allotments, and five species of gull. Until the winter of J9 56-57 the Black-headed Gull was the commonest of these. Even fifty years ago Kendall (1907) described it as “of frequent occurrence” and so it would seem to have been a regular winter visitor for the last half century. The Black-headed Gulls have derived benefit from the increasing number of people who feed them regularly, but they are much harassed by Common Gulls. Black-headed Gulls normally appear in numbers in the study area in late August and early September and remain until early April, but in 1952 and 1961 advance arrivals came in strength in July. I have watched as many as 70 in the air at one time, and several daily watches of 10 hours’ duration each in January 1958 showed that at least one and sometimes as many as 24 were in sight from my house in every five-minute period. Black- headed Gulls also regularly use oaks, roof-tops and chimney-pots as BRITISH BIRDS resting places. They cover the private gardens most diligently in their search for scraps and often assemble on the grass in Gladstone Park to hunt for worms. The Common Gull occurs in winter on the Brent Reservoir but during 1947-52 I had only a single isolated record of one at Dollis Hill (1st November 1947). Then a few appeared in the winter of 1952-53 and by 1955-56 the number had risen to 20. These Common Gulls were shy and always obtained their food indirectly by harrying Black-headed Gulls which had picked up scraps from the ground. By 1956-57 Common Gulls outnumbered the smaller species and, besides parasitising the latter, they also obtained their own food direct. In 1960-61 it was not unusual to see up to 30 Common Gulls sitting on stag-headed oaks, roof-tops and chimney-pots. They arrive in September or October and remain until March. Since February 1958 quite large congregations have appeared temporarily on the grass in Gladstone Park, for example on 2nd February 1958 (300), 10th February 1959 (163, and on this day there were also 830 on the Brent Reservoir), 13th February i960 (180) and 21st February 1961 (85). Sage (i960) has shown that “there must be a large influx of Common Gulls into the London Area during the period February to April to augment the winter population”. Like the Herring Gull, this species has added another new habitat — that of suburban built-up areas — to those of freshwater and grassland. Its adaptation took little time and was most successfully accomplished. Until the winter of 1957-58 the Herring Gull was a July migrant flying across the survey area. From that time small numbers (up to 14) have wintered and others have appeared in Mav, June and August. There have often been Flerring Gulls on the Brent Reservoir, but it is onh m the last three years that they have become regular visitors to the built-up area, searching for food in gardens, chicken-runs and other open spaces, and occasionally perching on roof-tops. This is certainly a movement into a new habitat. The wintering birds arrive in Septem- ber and leave again in mid-March. 1 have several times heard their massed trumpeting displays over Dollis Hill in early March The Lesser Black-backed Gull is best known in the area as a late summer and autumn migrant with movements beginning in the last week of May or early June and lasting until September. Since the winter of 1957-58 a few have appeared each December and these can be seen quartering gardens until March or April. 1 have seen several bf,the Bre"t Reservoir between July and November, but the/ stay in the immediate vicinity of this piece of water. It is interest- ing to note that Harting (,866) described this gull as “a ram bh-d'in Middlesex” and Kendal. (w) used the satne ternaTfo Tsta ^ n north-west London a, the beginning of the century. An indivalu)" 20 SUBURBAN BIRD-LIFE AT DOLLIS HILL of the Scandinavian form ( L.f fuscus ) used a flag-pole near the hospital as a perch in September 1951 and 1952. During 1940-50 the Great Black-backed Gull increased greatly in the London area, but at Dollis Hill only rare individuals appeared in the winter months up to October i960 when there was a definite increase. Some were then present until February 1961 and, with other species of gull, visited the chicken-runs at the top of the hill. At least four-fifths of the birds of this species have been adults. ROOSTS Most of the roosts in the study area are features of the winter months, but some are established or maintained during the summer as well. Feral Pigeons roost on the Post Office Research Station and one or two of the factories. Woodpigeons almost invariably choose the taller elms and London planes in Gladstone Park and here I have seen as many as a hundred. The only Tawny Owl roosting places I have found have been in elms. The most important communal winter roosts for Song Thrushes and Blackbirds are a clump of bushes in the park and a hedge near the hospital, but I know many smaller Blackbird roosts of from three to twelve birds and these are, in fact, more typical of the district. I have found these small roosts in tall overgrown privet hedges, almonds and hawthorns. Every winter there is a small Blackbird roost of three to five birds in a tall syringa in my own garden. Dunnocks I have onlv found roosting in privet and snowberry hedges, from which bursts of nocturnal song are then not uncommon. Dollis Hill lies well within the catchment zone of the central London Starling roosts. Certainly a number of birds from the area and also from the north-west as far out as Stanmore and Edgware fly into the centre of the Metropolis. For at least nineteen years one of the flight- lines has passed south-east over the Post Office Research Station and another has followed roughly the course of the Edgware Road, just inside the study area. However, some 3,500 Starlings from the latter flight-line once set up a subsidiary roost in some Lombardy poplars in the factory area, instead of going on into central London. The roost was started in August 1951 and lasted until the leaves began to fall from the trees in October of that year. It was interesting to see that a number of Starlings from the Edgware district flew steadfastly on over the new roost on their way to central London, though from time to time the whistles and chatters of the birds in the poplars below would entice a few down from the passing flocks. No other communal Starling roost has appeared in the study area, but some Starlings roost in their nesting holes during the winter months. One pair regularly spent their nights in the roof of my house, after breeding there, for 2 1 BRITISH BIRDS three consecutive winters. It has been suggested that it is unlikely that many adults begin to roost in their nesting holes as early as November, but my own pair came in every night summer and winter without a break; there was certainly not even any question of the male roosting elsewhere during incubation. There are many small House Sparrow roosts in the district, chiefly in creepers on houses, and numbers may reach as high as 50. A larger roost of up to 100 occurred in hawthorns in the grounds of St. Andrew’s Hospital during the winters of 1950-51 and 1951-52. During the period under review, however, the really great House Sparrow roosts have been outside the study area. The first was in some plane trees in the Edgware Road about 400 yards south of the railway line and this drew to itself the greater part of the winter popula- tion of House Sparrows in Dollis Hill. In the winters of 1957-58 to 1960-61 the roost moved to dense hawthorns by the far side of the Edgware Road near Dollis Hill Lane and only five yards outside the study area. This group of thorns also drew most of the Dollis Hill birds over a radius of just over a thousand yards. Counts showed a maximum of 750 sparrows at this roost in January and February, but smaller numbers use it in every month of the year. In the winter of 1960-61 there was an overspill across the Edgware Road into two or three thorns in some front gardens just inside the study area, but in September 1961 the whole roost moved back to its original site 400 yards outside the survey area. A curious phenomenon is the setting up of short-term summer roosts by House Sparrows. It first came to my notice at the beginning of May i960 when some 30-40 adults began to roost in the syringa in my garden; this lasted for just over three weeks and was used every night. The same thing happened again on the evening of 29th April 1961, with a dozen birds assembling, and lasted for a fortnight. PASSAGE MOVEMENTS Systematic observations have also been made of the various migrants which appear in the study area. The total of migrant species noted is 21, of which nine have been represented by only single records. The remaining 12 species have been of more or less regular occurrence. Some of the species listed previously as summer or winter visitors mav also appear as migrants, especially gulls and Starlings. The first true migrants of the year pass in February; these are night- flying Redwings (whose movements continue until the first week of April) and day-flying Rooks and Jackdaws. All the Rooks 1 have seen have been going east or south-east, but the Jackdaws make for points between north and east. Chaffinches in small numbers move north in the early morning in April; and Swallows and House Martins 22 SUBURBAN BIRD-LIFE AT DOLLIS HILL generally appear from the first week of the month, though they do not turn up every year. An occasional Cuckoo and a regular sprinkling of Willow Warblers occur in April, but 1 have only one spring record of a Chiffchaff. In late April and early May the summer population of Swifts and Spotted Flycatchers arrives. The average date for the Swift is 2nd May (though it may be as early as 25th April or as late as 6th May), while the Spotted Flvcatcher returns between 6th and 10th May. In May and early June there are sometimes northerly movements of Hirundines and large influxes of Swifts. In some years Lesser Black- backed Gulls can be seen on the move in May, but their true migration normally starts in late June. There are two species which reveal mid-summer movements. Firstly, I have records of parties of 1 1 Lapwings on the move on 1 2th July 1956, six on 24th June 1959 and four on 29th May i960; it is possible that these originated on the Continent. Secondly, in thun- dery and disturbed weather in late June and July the numbers of Swifts may temporarily rise in a spectacular manner, and I have sometimes seen as many as 400 under these conditions. July and August are usually marked by passages of Lesser Black- backed Gulls, Willow Warblers and a Cuckoo or two. The autumn movements of the Willow Warbler take place between 17th July and 29th August, often with two peaks about 6th and 2 5th-29th August; birds not only appear in the park, on the allotments and in the hospital grounds, but in private gardens and even in trees in the streets. The season of the Chiffchaff ’s autumn passage is later and lasts from 1st August to 20th September. Chiffchaffs especially favour the brambles and black currant bushes of the allotments; here one September morning there were more than 100, about ten of them being in song. Linnets and Whitethroats may also appear and the Swifts have usually left Dollis Hill bv about 24th August (dates range from 15 th August to 2nd September). In September and October I have seen movements of Lapwings, Stock Doves, Woodpigeons, Rooks and Jackdaws, Pied and Grey Wagtails, Greenfinches, Siskins and Tree Sparrows. The Swallow is regular on autumn passage; movements begin about nth September and continue into October with a peak about 20th September; my latest record is 5 th October. These Swallow passages are almost invariably into the wind and the birds fly low and in a narrow line across the top of the hill. Thev occur most frequently from one to three hours after dawn, but in exceptional instances, for example on 20th September 1952, may last until the afternoon. The movements of the House Martin begin in late September and reach their peak in early October; on 4th October 1952 as many as 700 passed through. 23 BRITISH BIRDS All the passages of this species have been into winds of light or moderate strength. Blackbirds can sometimes be heard calling at night as they pass over the area in October and I once saw 13 flying SW in daylight on 22nd October 1953. Most records of the Fieldfare are in October and November; typical examples are of parties flying SW (with small numbers dropping down to feed) on 9th and nth November 1951 and groups flying NW on 16th October 1955, the latter being part of a widespread movement which was also noted in Essex, Kent and Surrey. The autumn migration of the Redwing lasts from the first week of October to the first week of November. The three heaviest Redwing nights of the many on which I carried out counts were 20th October 1952, 16th October 1955 and 17th October 1958. On the last of these I heard more than 2,000 calls between 6.30 p.m. and 1 1. 10 p.m. and similar reports came in from Addington in Surrey and from two places within the City of London. Diurnal movements of Redwings sometimes take place in October and these can, of course, be watched. Quite heavy ones occurred on 16th October 1955, 14th October 1957 and 16th October i960. On the last date 472 passed over between 7.45 a.m. and 11.30 a.m., all travelling between NW and north from 5 o to 150 feet above the ground. Skylark movements begin in mid-September and go on until the end of October; most of them are in directions between SW and NW and would seem to be of Continental origin. There was a consider- able NW passage of these birds over Dollis Hill on 27th October 1956 and similar flights were seen that day at Staines reservoirs in Middlesex and at three places in Essex. Another autumn passage migrant is the Meadow Pipit ; this can be seen on the move from 14th September to 4th October, with a peak generally about 21st September. Most Meadow Pipit movements take place in the early morning and I have many records of birds passing over either singly or in flocks of from two to nine in size. 81.5% of migrating Meadow Pipits have been flying between SW and west, 1 1.1% between NW and north, and 7.4% between NE and SE. I have no observations of migration continuing throughout the day, as not infrequently happens along the Cotswolds in autumn. Of the many Starlings in evidence in the autumn it is possible to separate the true migrants from the birds flying from their roosts bv the times of movement. For example, on 4th November 1951 over a hundred flew SW over Dollis Hill some 1 J hours after the last ones had arrived from the central London roost. The heaviest passage I have recorded was on 16th October i960 when 3,290 birds passed over between NW and north from 7.15 a.m. to 11.15 a.m. The peak lay between 8.0 and 8.15 a.m. when 1,100 flew over; parties varied in Plate i. Aerial photograph showing Dollis Hill and the Brent Reservoir, Middlesex, 1949. The width of this reproduction covers about i| miles. The limits of the area described in the paper on pages 1-36 can be seen from Fig. 1 on page 2. The allotments in Gladstone Park, now reclaimed, and those on the site of the John Kelly School arc distinctly shown (pbo/o: AerofUm and Aero Pictorial Ltd.) Plate z. A typical road and garden in Dollis Hill, Middlesex, illustrating the residential part of the survey area (pages 4-5). Above, a view north along Brook Road towards the Brent Reservoir, September 1 960 ; the majority of the houses arc semi-detached. Below, a front garden in Brook Road, June i960 {photos: B.B.C.) Plate 3. Honey Buzzard (Pern is apivorus) standing by a hole ten inches across and 1 6 deep, from which it has excavated a wasps’ nest, Denmark, September 1959 (page 36). This chiefly insectivorous species has small scale-like feathers on its forehead and lores, a very large cere and a tiny bill (photo: lb Trap-hind) 'j Plates 4 and 5. Honey Buzzard (Pern/s apivorus) excavating wasps’ nest, Denmark, September 1959 (page 36). Left, the ten-inch hole. Below, the bird with a piece ot comb it has just dug up; a wasp is on its neck and bits of Comb are lying around. Above, a section of the comb and, inset, one of the many decapitated wasps (species I 'espa vulgaris) which were left behind by the bud(pbotos: IU Trap-Liud ) Plates 6 and 7. Crested Lark ( Qalerida cris/a/a) at nest, Denmark, July 1961. Both pictures show the stocky shape, the long and slightly dccurved bill, the sparsely streaked upper-parts and the conspicuous upstanding crest. The short, dark-centred tail with pale (actually buff) edges can be seen on the left, and the breast markings are well illustrated above (pages 37-42) ( pbo/ns : lb Trap-Lind ) Plates 8 a and 8 b. Nest-box damage by Great Spotted Wood- peckers ( Dendrocopos major), Sussex, 1961. Left, concrete box with the hole enlarged by nearly a fifth. Above, several wooden boxes with the part from hole to lid hacked out (page 43) ( photos : Guy Mom/fort) Plate 8c. Female Rook ( Corviis frugilegus) with lower mandible stuck through skin of upper breast, Kent, spring 1961. It could not close its bill and both mandibles were elongated. In good condition, it may have been fed by other Rooks (page 46) ( photo : Gordon C kmc /son) SUBURBAN BIRD-LIFE AT DOLLIS HILL size from 20 to 600. The cloud base was at 100 feet, lifting at 9.07 a.m., and there was a light breeze from NNE to NNW. The Chaffinch is undoubtedly one of the most regular of the diurnal autumn migrants. The period of autumn passage lasts from 19th September to 27th October and in such years as 1955, 1956 and i960 the peaks have been quite impressive. On 27th October 1956 more than 500 Chaffinches flew NW between 8.35 a.m. and 11.10 a.m., at the same time as big movements were also reported from Harold Wood and Sewardstone in Essex. On 16th October i960 1,517 Chaffinches flew between NW and north over my house from 7.45 a.m. to 11.45 a.m.; parties varied in size from single birds up to 35 and as they passed by 50 feet or so above the ground my wife and 1 had no difficulty in counting them. The movement was certainly on a broad front and it was likely that more than 30,000 Chaffinches passed over the whole area that morning. In every year there is always a certain amount of broad-front migra- tion to be seen and sometimes, as on 16th October i960, it may be very heavy indeed. On that day, from 7.15 a.m. to 11.45 a.m., we counted 5,889 birds of seven species flying north or north-west over Dollis Hill. These seasons of migration are always of outstanding interest and Dollis Hill can, in fact, sometimes offer examples of visible migration comparable in weight to those that occur along hill-escarp- ments or river- valleys. On 5 th November 1961, for example, when a huge immigration of Blackbirds and Fieldfares was noted on the east coast, more than 1,000 Fieldfares flew NNW over my house between 8.10 a.m. and 3.52 p.m. During the early years of my migration watches at Dollis Hill 1 was reasonably certain that all the movements I saw were on a broad front and this has been largely confirmed by parallel observations in the London area. Yet it would now seem that Swallows and House Martins in the autumn and Rooks, Jackdaws and Chaffinches in the spring use the conspicuous top of the hill as a landmark, since the parties are always seen flying over the summit and not the lower slopes. All five species travel over the highest point in a narrow stream. SPECIES OCCASIONALLY FLYING OVER THE AREA Apart from the Swift and Kestrel, which nest outside but near to the area, there are three species in this category — Heron, Mute Swan and Lapwing. Herons and Lapwings pass over at many different times of the year. Any Mute Swans flying over come invariably from the Brent Reservoir. VAGRANTS AND RARE PASSAGE MIGRANTS This group includes such species as the White-fronted Goose, Sparrow- 25 BRITISH BIRDS hawk. Hobby, Peregrine, Pheasant, Curlew, Whimbrel, Bar-tailed Godwit, Greenshank, Glaucous Gull, Turtle Dove, Little Owl, King- fisher, Great Spotted Woodpecker, Sand Martin, Coal Tit, Redstart, Grey Wagtail, Crossbill, Yellowhammer and Serin. The Serin may have been an escape like the 12 Budgerigars, one Lovebird and one African Grey Parrot which have visited my garden over a period of ten vears. HARD-WEATHER MOVEMENTS The coming of cold weather often brings about an increase in the numbers of some species and it is also possible to watch movements of birds across the district. A spell of severe weather may result in a temporary increase in Greenfinches, Goldfinches, tits and gulls. During the cold weather of January 1955 two Fieldfares appeared in my garden for one day; and on 20th February 1955 another, on its own and very hungry, arrived and fed for five hours on some of the apples I had put out in the snow for the Blackbirds. This individual remained until 1 3th March 1955; it fed and roosted in my garden and spent many hours chasing Blackbirds up to distances of 1 50 yards from the garden before returning to feed again. On 24th January 1958 12 Fieldfares flew SSE over my house on a day when others were recorded at Dulwich Park and Sutton in Surrey and St. James’s Park in Inner London. In the cold conditions of January 1958 a party of 40 Redpolls visited my garden; this visit could not be explained by the presence of any food source and it would seem that these tired birds were temporarily attracted to the shelter of my well-developed fruit-trees. Of visible weather movements, the most important have all been in the month of January — in 1955, 1958 and i960. In a short cold snap in 1958 from 22nd to 27th January there were movements of Lapwings, Chaffinches, Fieldfares, Stock Doves and White-fronted Geese. More striking, however, were the events of January i960. The weather of 10th January that year was very cold indeed and the skies were clear. At 3.25 p.m. a party of 40 Lapwings flew SSW some thirty minutes in advance of a snow-storm which soon brought visibility down to less than a hundred yards. Two days later 1 watched Redwings flying by day over Willesden and the B.B.C. Television Centre in Wood Lane and there were more on the following day. Then on the 14th a strong movement took place from 8.50 a.m. Redwings were passing over at the rate of 600 an hour until 1.30 p.m. and with them were scores of Fieldfares, Skylarks, Lapwings, Green- finches and Linnets, all moving SVV. This was the peak day for hard- weather movements in England and large numbers of these species were seen passing through in Sussex and Hampshire where the total 26 SUBURBAN BIRD-LIFE AT DOLLIS HILL was described as “terrific”. This period of cold weather may well have accounted for the presence at Dollis Hill of the Glaucous Gull I saw on 23rd January i960. PREDATION Both avian and mammalian predators have some efiect on the bird-life of the survey area. The mammalian predators have been introduced by man — Brown Rats ( Katins norvegicus ) and Cats (Felis coins). Brown Rats have sometimes decimated the ducklings hatched on the allot- ments and I have also known them to take the young of Blackbirds and the eggs of Dunnocks, but their total effect is small since their numbers are severely controlled. The Cat is by far the more important enemy of birds in the district. Hitter (1949) estimated that the total Cat population of London was of the order of 550,000. In the study area at Dollis Hill it has been impossible to arrive at an exart figure, but a wide series of sample counts in different parts in 1951 suggested that there were then about 700. By 1961 the figure had fallen to around 300 and there is little doubt that at Dollis Hill the Cat has steadily lost ground as a household pet. I know of many homes which have lost a Cat in the last decade and never replaced it. The presen" figure of 300 means that there is one Cat to every 12 houses; in 1951 there would have been one to every 5 houses. This decrease is not reflected in anv changes in the avian breeding population, however, since the limiting factor on the total number of breeding birds is clearly the availability of nesting sites. It would seem that Cats in the area fill the ecological niche occupied in the country by Adders ( Vipera herns ) and our native carnivores and squirrels. There are, of course, no Grey Squirrels (. Scinrns carolinetisis) in the area although they occur at Hampstead and Golders Green. I have records of Cats in the survey area taking adults of Feral Pigeon, Blue Tit, Song Thrush, Mistle Thrush, Blackbird, Starling, Chaffinch and House Sparrow — as well as the young of Mallard, Woodpigeon, Blackbird, Dunnock, Starling and House Sparrow. On occasions I have watched Cats stalking adult Dunnocks and Wrens, but timely intervention on my part has prevented these two species from being added to the list. In connection with Cats, it is interesting to note that adult Starlings strive valiantly to encourage their newly fledged young from the lawns and flower-beds back to the safety of the gutters and roof-tops. This I have never seen House Sparrows attempt and it would seem that this is a case of adaptation in the Starling for the practice is regular in Dollis Hill but not so in country districts. The avian predators are the Tawny Owl, the Carrion Crow and once 27 BRITISH BIRDS a Peregrine. Owls have often taken House Sparrows, and Carrion Crows have fed on the eggs and young of Blackbirds, the eggs of Woodpigeons and the young of House Sparrows. The Peregrine was a tiercel chasing Feral Pigeons around the Post Office Research Station. Since the Jays arrived in the district I have not yet seen them at work; this is also true for the occasional Sparrowhawks and Kestrels that appear from time to time. Parasitism among birds is quite common, of course, and many species will chase and rob others of their food. The best example in Dollis Hill is that of the Common Gulls which regularly chase Black-headed Gulls, forcing them to give up their food by sheer speed and persistence of pursuit. Table 7 summarises my observations on birds chasing, attacking and robbing other species of food. Table 7 — Food-parasitism among birds at Dollis Hill, London, 1951-61 Parasite Victim Mallard (Anas platyrhynchos ) Common Gull (Earns canus) Black-headed Gull (L. ridibundus ) Woodpigeon ( Columba palumbus ) Blue Tit ( Partis caertdeus) Fieldfare ( T urdus pilaus') Blackbird (T. merula) Robin (Eritbacus rubecula) Starling ( Sturnus vulgaris) House Sparrow ( Passer domesticus) Feral Pigeon, Woodpigeon, Blackbird, House Sparrow Black-headed Gull Mallard, Feral Pigeon, Woodpigeon Blackbird, House Sparrow Great Tit, House Sparrow Blackbird Dunnock, House Sparrow Dunnock, House Sparrow Blackbird, Dunnock, House Sparrow Blackbird, Greenfinch, Chaffinch THE EFFECTS OF MAN Some human activities represent an intervention by man in favour of the birds; others may have either direct or indirect, but nevertheless adverse, effects upon bird-life. In the broadest sense, all birds which breed, roost or feed in and around buildings and gardens receive indirect but valuable benefits from man’s way of life. There are however, certain aspects in an urban area which can be studied quite closely. Buildings provide convenient perching and resting sites, song posts and, for some species, safe places in which to nest. Poor maintenance of properties often allows birds to gain access to roofs and lofts. Starlings and House Sparrows may get in under loose tiles, under the lead covering over bay windows and through holes under the roof- ridges where mortar has become loosened or has disappeared. There is also a superabundance of material left about by man which 28 SUBURBAN BIRD-LIFE AT DOLLIS HILL birds may use in the construction of their nests. I have seen trans- parent cellophane wrappings from cigarette packets, sweet papers, pieces of newspaper, bits of rag and wood shavings in the nests of Starling, Blackbird and House Sparrow, while pieces of string, some- times of phenomenal length, have been used by Starling, Mistle Thrush, Song Thrush, Blackbird and House Sparrow. There are now only a few chicken-runs in the area, but these supply feathers for Starlings and House Sparrows. 1 have watched a female Dunnock assiduously collecting up the white hairs blowing about on my lawn while 1 was still grooming my dog; and in May 1961 I saw House Sparrows performing the same function in a neighbour’s garden. Once a Blue Tit spent ten minutes extracting white hairs from my dog’s blanket which had been put out for brushing and airing. With more enlightened and interested attitudes to birds there has been some increase in the provision of nest-boxes as well as an in- creased desire not to disturb nesting birds. Tnere are always volun- teers at hand to escort a duck Mallard and her brood across the estate and over the dangerous North Circular Road to the safety of the Brent Reservoir. The cultivation of gardens and allotments in which the soil is regularly kept open benefits such birds as Song and Mistle Thrushes, Starlings, Robins and Dunnocks, which are primarily insect-eaters. The regular cutting of grass provides the short turf which is an import- ant feeding area for thrushes, Starlings, Mallard, crows, pigeons. Pied Wagtails, Dunnocks, House Sparrows and gulls. Feral Pigeons and Woodpigeons regularly feed on the shoots and seeds of grasses and also take the seeds of plantains, clover and knotgrass. I have seen a Skylark in April feeding on the close-cut grass of the bowling green in Gladstone Park. House Sparrows in the summer take many different kinds of flies, aphids, swarming ants, moths such as the Yellow Underwing ( Triphaena pronuba), and butterflies such as the Large, Small and Green-veined Whites ( Pieris brassicae, rapae and nap'i) and Small Tortoiseshell ( Aglais urticae). On the other hand. House Sparrows can be very destructive and they have ripped up the flowers of yellow crocuses, wild primroses and thrift in my own garden. Starlings in the breeding season take many insects and other inver- tebrates and, unlike House Sparrows, largely ignore bread at this time. On warm days in late summer it is often possible to watch scores of Starlings, often with House Sparrows, rising from roof-tops to heights of 60-150 feet to catch flies and ants; their methods are cumbersome but very successful. They also take advantage of man’s planting of fruit-trees and will feed on black currants, raspberries, loganberries, plums, pears and apples. They are particularly prone to attack pear- 29 BRITISH BIRDS trees in long dry seasons, and in 1955 and 1959 stripped one in my garden of all its fruit, leaving just the cores still attached to the tree. The reverted allotments and the more poorly tended gardens attract many birds, for here the commonest weeds are groundsel, broad- leaved plantain, chickweed, dandelion, sowthistle, creeping thistle, creeping buttercup, couch grass, white dead nettle and shepherd’s purse. Goldfinches favour the seeds of thistle, groundsel, Oxford ragwort and Michaelmas daisy, Dunnocks take chickweed and plantain seeds and House Sparrows will take all. There has been a marked increase in the deliberate feeding of birds in Dollis Hill in the last decade and, as already mentioned, the great rise in the winter population of Mallard in the district is directly due to regular feeding in Gladstone Park. It would also seem to be a con- tributory factor in the increased numbers of Common Gulls. The greater part of the food given to birds consists of bread and I have seen this taken by the following 20 species in the survey area: Mallard, Herring Gull, Common Gull, Black-headed Gull, Lesser Black-backed Gull, Feral Pigeon, Woodpigeon, Carrion Crow, Jay, Great Tit, Blue Tit, Song Thrush, Blackbird, Robin, Dunnock, Starling, Greenfinch, Chaffinch, House Sparrow and Tree Sparrow. I have one record of polyneuritis through Vitamin B deficiency in the Feral Pigeon. Bones and fat attract the two commoner species of tit, as well as Starlings and Robins. A single Fieldfare came to my garden, attracted by the apples I had put out for the Blackbirds in severe weather. Man’s adverse effects upon the bird-life of Dollis Hill are small in relation to the benefits. Numbers of Woodpigeons are systematically shot in Gladstone Park in winter, but apart from these control measures I personally know of only three direct actions against birds in ten years. The first was a boy who took a pot-shot at a House Sparrow with a catapult, the second was another boy who ragged a Blackbird’s nest and the third was a youth who fired at a Starling in Gladstone Park with an air-pistol. Nets, muslin, black cotton, free-blowing metal strips, rotating propellers and skeletal scarecrows may be used to protect fruit-trees and bushes, peas and other crops from the depreda- tions of birds. Allotment holders have had many occasions to com- plain of attacks by Woodpigeons on peas and Brassica crops. The heavy pruning of street trees often restricts the number of breeding sites, but some species, such as the Blackbird and Wood- pigeon, may take advantage of the pollarded condition of London planes. On the other hand, Woodpigeons also feed widely on the buds and flowers of elm, ash and plane, and the young leaves of ash and hawthorn, as well as on acorns and haws, and the periodic cutting of trees may reduce these sources of food. Rehabilitation of cultivated ground in Gladstone Park forced the Skylark from one breeding 3° SUBURBAN BIRD-LIFE AT DOLLIS HILL ground and the building of the John Kelly Schools destroyed its last nesting site in the survey area. The felling of a small group of Lombardy poplars near my house also removed one safe breeding site for the Mistle Thrush. There has been some grubbing up of privet hedges to be replaced by walls and fences, but not yet on such a scale as materially to reduce the numbers of breeding Dunnocks. The periodic trimming of hedges causes some disturbance to breeding birds, especially Blackbirds and Dunnocks, but the latter species is surprisingly tolerant of this kind of activity provided the nest is not completely exposed to the air. Incidentally, I have no records of birds being killed on the roads by vehicles ; this must surely be due to the range of vision available to a flying bird in the Dollis Hill area, where most roads are wide and few front gardens have much high cover, as well as to the town bird habit of rising up above an approaching car and often being carried over it by the slipstream. It is the bird crossing the narrow country road with high hedges which so often dives down low above the road surface and is struck by a vehicle. NOTES ON SELECTED SPECIES Heron There were two Herons on 26th July 1950 and single birds on 2nd April 1956, 18th October 1957, 26th May 1958, 28th January 1961 and 3rd April 1961. Mrs. Irene Rutherford reported to me that a Heron once dropped out of a tree in her garden in Dollis Hill Lane. Herons are not infrequent visitors to the Brent Reservoir and some must cross the area on their foraging expeditions. White-fronted Goose This is the grey goose most often reported in south-east England. At 11.56 a.m. on 23rd January 1958 a flock of about 40 White-fronted Geese flew over the top of Dollis Hill in a NNW direction some two hours in advance of a snow-storm. In addition, R. E. Jones reported 8 grey greese near Neasden on 4th January 1952 and I saw 16 flying NW over the area on 29th March 1958; these flocks were probablv also of this species. Sparrow hawk Kendall (1907) recorded that the Sparrowhawk still bred in this part of London and Dixon (1909) said that it could be seen “frequentlv in the vicinity of Neasden and Dollis Hill”. This is a lost breeding species and I have only two records of single birds on 2nd February 1953 and 9th October i960. 5 1 BRITISH BIRDS Peregrine The Peregrine is primarily a rare winter visitor. A single bird over Staples Corner on 7th January 1958 and over my garden on 8th, 20th and 22nd January 1958 was sometimes heavily mobbed by Black- headed Gulls. Others flew over my house on 13th November i960 and 5 th November 1961. There are also two late summer records of a falcon flying east on 21st July 1961 and of a tiercel chasing Feral Pigeons over the Post Office Research Station on 9th August 1961. Kestrel Kestrels have not bred in the area during the period of the survey. These falcons have certainly nested at Hampstead and Harrow during this time, however, and it may well be that the single birds or pairs that are seen over Dollis Hill come from one or other of these districts. Most of the records are from January to April and from July to September. Although Kestrels can occasionally be seen hovering over factory surrounds, allotments and gardens, most of them cross the area fairly quickly. Cuckoo Some 60 years ago the Cuckoo used to appear each summer at Kensal Rise and Kilburn, both of which are nearer to the centre of London than Dollis Hill. In the period under review, however, there have been only single birds in six of the years from 1951 to 1961. My own records include one in the grounds of St. Andrew’s Hospital for the first two weeks of May 1952; one calling in Brook Road on 19th April 1953; one flying east over my house on 4th July 1958 and another on 9th August 1959; and one calling near the hospital on 6th May i960. In The Willesden Chronicle of 19th May 1961 Miss E. C. Hodge reported that she heard a Cuckoo in Gladstone Park on 20th April and 13th May 1961. Swift The Swift is present every summer, but does not breed in the area through lack of suitable nesting sites (it will be remembered that most of the houses have been built within the last thirty years or so). Swifts certainly nest in adjacent Cricklewood and Brondesbury, however, for there are many Victorian villas there, and these birds come on daily forages over Dollis Hill. The most favoured feeding areas are the southern slopes of Gladstone Park, the top of the hill and, as one might expect, that part of the area which is closest to the Brent Reservoir; this last district is frequented by many Swifts in May and August when migration is under way. 32 SUBURBAN BIRD-LIFE AT DOLLIS HILL Great Spotted Woodpecker Great Spotted Woodpeckers were present only in 1957. There were single ones in Gladstone Park on 13th July and 24th August, and a pair in the same place on 5 th August. I also saw one near the hospital on 14th August. J*y Before i960 there was only one record of this species and that was of a bird found dead in a water-butt in a Brook Road garden on 2nd September 1955. On 14th September i960, however, I discovered a live Jay in Gladstone Park; this travelled widely round the area and was joined in the early part of 1961 by a second. The pair spent much of the ensuing summer in gardens near the park, but there was no evidence of breeding. blackcap Singing male Blackcaps were regularly heard in one area in 1952, 1955 and 1956; a hen was also occasionally seen, but there was no proof of breeding. A pair nested in an elder in 1958, however. POSTSCRIPT At the time of going to press there would seem to be some uncertainty about the future of one group of allotments and part of the special habitat area, both of which may be built over. If this happens the pattern of bird-life at Dollis Hill will be verv much affected. acknowledgements I would like to thank Mr. J. T. Gillett, the Borough Librarian of Willesden, for undertaking numerous pieces of research on my behalf and for the loan of manuscripts and maps. I am also indebted to Mr. J. G. Green, Public Relations Officer to the Borough of Willesden, for his assistance in my investigations. The editors of British Birds have also made many valuable suggestions during the preparation of this paper. SUMMARY (1) Detailed observations were carried out on the bird life of the London subur- ban area of Dollis Hill from 1951 to 1961. (2) The resulting account opens with a history of the land development from 1816. (3) The live main habitats in the study area are then described, with summaries ot the species that occur within them. 33 BRITISH BIRDS ^4) It is shown that the average number ot breeding species each year trom 19s 1 to 1961 was 21; and that the total population of breeding pairs of all species in 1961 was about 1,500, a density of 52-53 birds per ten acres. (5) The numbers of breeding pairs of each species are given, together with a description of the nesting sites. (6) It is shown that 89'', , ot the nests examined were in two layers, 5-10 teet anil 20-25 teet above the ground. (7) Details of song and display are given, with a description ot the song-posts used by 22 species. The specialised use of television aerials as song-posts is also discussed. (8) \\ inter populations, roosts, migration and hard-weather movements are described. (9) The chief predators of birds are considered to be Cats (which have decreased in numbers during the period), Carrion Crows and Tawny Owls. (10) The influence of nvan on the birds of Dollis Hill is examined: in recent years it has been almost wholly beneficial and there has been a marked increase in the number of people feeding them. (11) Additional notes are given for ten selected species. (12) Altogether 7c species have been recorded in the area; these are listed in broad categories in an appendix. REFERENCES Cramp, S. (1949): “The birds of Kensington Gardens and Regent’s Park”. London Bird Report, 13: 37-45. (1960): “The irruption ot tits and other species in the London area, 1 95 7-1 95 8”. London Bird Report . 23: 62-69. and Teagle, W. G. (1950): “A repeat bird census of Kensington Gardens”. London Bird Report, 14: 41-8. (1952): “A bird census ot St. James’s Park and the Green Park”. London Bird Report, 15: 48-52. Dixon, C. (1909) : The Bird Life of London. London. Elton, C. (1946): “Competition and the structure ot ecological communities”. J. Anim. Leo/., 15: 54-68. Fitter, R. S. R. (1949): London's Birds. London. Goodwin, D. (i960): “Comparative ecology of pigeons in inner London”. Brit. Birds, 53: 201-2 1 2. Harting, J. E. (1866): Tbe Birds 0/ Middlesex. London. Homes, R. C, et al. (1957): Tbe Birds of tbe London Area since 1900. London. Holme, D. C. (1955): "Buildings as song-posts”. Brit. Birds. 4S: 211-215. Kendall, W. B. (1907): “ The birds of Willesdcn”. Unpublished MS. in Willesdcn Public Library. Nicholson, E. M. (1951): Birds and Men. London. Sage, B. L. (i960): “The spring migration of the Common Gull through the London area”. London Bird Report, 23: 69-74. Selous, E. (1933): Tbe Evolution of Habit in Birds. London. Simms, E. (1052): Bird Migrants. London. (1956): “A century of bird-watching in north-west London”. W'i/lesden Chronicle (three articles). Summers-Smith, D. (1959): “The House Sparrow Passer domestins: population problems”. Ibis, 101: 449-454. Wallace, D. 1. M. (1961): “The birds of Regent’s Park and Primrose Hill, 1959”. London Bird Report, 24: 81-107. 34 SUBURBAN BIRD-LIFE AT DOLLIS HILL APPENDIX — SPECIES RECORDED AT DOLLIS HILL, LONDON, DURING I95 I -6 I Birds which stay the summer B regular breeder O former or occasional breeder P non-breeder but present Mallard ( Anas platyrhyncbos) B Kestrel ( Valeo tinnunculus) P Stock Dove ( Columba oenas) O Feral Pigeon ( Columba livia) B Woodpigeon ( Columbus palumbus) B 'l awny Owl ( S/rix aluco ) B Swift ( Apus apus ) P Skylark ( Alauda arvensis ) O Carrion Crow ( Corvus corone ) B Jay (Carr ulus glandarius) P Great Tit ( Parus major) B Blue Tit ( Parus caeruleus) B Wren (' Troglodytes troglodytes) B Mistlc Thrush ( Turdus viscivorus ) B Hobby ( Falco subbuteo) M Peregrine ( Falco peregrittus ) M W Curlew ( Numenius arquata) M Whimbrcl ( Numenius pbaeopus) M Bar-tailed Godwit ( Limosa lapponicd) M Grccnshank ( Tringa nebularia) M Great Black-backed Gull ( l aims marinas) W Lesser Black-backed Gull ( Laras fttsens) M W I lerring Gull ( Laras argentatus) M W Common Gull (Laras canas) W Black-headed Gull (Laras ridibundns) W Turtle Dove (Streptope/ia tartar) M Cuckoo (Cuculas canoras) M Song Thrush (Turdus pbilomelos) B Blackbird (Tardus merala) B Robin (Eri/hacas rubecula) B Blackcap (Sylvia atricapilla) O Willow Warbler (Phylloscopus troebilus) O Spotted Flycatcher (Muscicapa striata) B Dunnock (Prunella modularis) B Pied Wagtail (Mo/acilla alba) B Starling (S/urnas vulgaris) B Greenfinch (Ch/oris cbloris) B Goldfinch (Cardaelis cardue/is) B Chaffinch (Fringil/a coelebs) B blouse Sparrow (Passer domesticus) B Tree Sparrow (Passer mon/anus) B passage migrants M passage migrant Swallow (Hirundo rustica) M House Martin (Delicbon urbica) M Sand Martin (Riparia riparia) Ml Rook (Corvus frugi/egus) M Jackdaw (Corvus monedula) M Fieldfare (Turdus pilaris) M Redwing (Turdus masicus) M Redstart (Phoenicurus phoenicurus) M Whitethroat (Sylvia communis) M Chiffchaff (Phylloscopus col/ybita) M Meadow Pipit (Anthus pratensis) M W Grey Wagtail (Motacilla cinerea) M Siskin (Cardue/is spinas) M Linnet (Cardaelis cannabina) M Winter visitors and W winter visitor Vagrants 1 Icron (Ardea cinerea) White-fronted Goose (Anser albifrons) Mute Swan (Cygnus olor) Sparrowhawk (Accipiter nisus) Pheasant (Pbasianus co/cbicus) Lapwing (Vanellus vanellus) Glaucous Gull (Laras hyperboreus) Little Owl (Athene noctua) Kingfisher (Alcedo attbis) Great Spotted Woodpecker (Dendrocopos major) Coal Tit (Parus ater) Redpoll (Cardaelis flammea) Serin (Scrinus canarius) Crossbill (Loxia curvirostra) Ycllowhammer (Emberiga citrine! la) 35 BRITISH BIRDS Other birds mentioned in the text Bu2zard ( Buteo buteo ) Partridge ( Perdix perdix ) Corncrake ( Crex crex) African Grey Parrot ( Psittacus erithacus) Rosy-faced Lovebird ( Agaporms rosei- collis ) Budgerigar (Melopsit tacus undulatus) Wryneck (Jynx torquilld) Golden Oriole ( Oriolus oriolus) Magpie ( Pica pica) Treecreeper (Cert hi a familiar is) Garden Warbler (Sylvia borin) Lesser Whitethroat (Sylvia curruca) Bullfinch (Pyrrhula pyrrhula) Corn Bunting ( Umber i^a calandra ) Observations on a Honey Buzzard digging out a wasps’ nest By lb Trap -Lind (Plates 3-5) On 22ND and 2 3RD September 1959, I had an opportunity of watching and photographing a Honey Buzzard (. Pernis apivorus ) digging out a wasps’ nest in Utterslev Mose, north of Copenhagen, Denmark. The wasps were of the common species (Vespa vulgaris). On my arrival the bird flew off, but it returned within a quarter of an hour and my hide did not seem to distract it at all. Altogether I watched it at v/ork for about ten hours. On both days it was very busy and stopped digging only for short rests or to eat the larvae it was extracting. The actual unearthing of the nest took up most of the time and if needed only a few minutes to empty each piece of comb that it brought up. Incidentally, I noticed that it did all the digging with its right foot. B. Loppenthin remarked upon the same thing in 1945 (Dansk Orn. Forert. Tidsskr., 39: 187-198). The wasps were swarming round in numbers, but they apparentlv did the bird no harm. They just annoyed it and it snapped at them. Afterwards, when I examined the excavation and the earth around, I discovered a lot of dead wasps and was interested to note that prac- tically all of them were headless. It seemed likely that the bird had been eating only the larvae and pupae from the pieces of comb, and that it had decapitated the adult wasps merely to get rid of them. Plate 3 shows the Honey Buzzard at the excavation, and in plate 5b it is actually holding a piece of comb in its beak as a wasp crawls on the side of its neck. One of the quite large pieces of comb which it was digging up can be seen in plate 5a, and the inset illustrates a decapitated wasp. When the bird had finished digging out the nest, the hole it left was about ten inches wide and sixteen inches deep; some idea of its size can be got from plate 4. 36 Studies of less familiar birds 1 1 6. Crested Lark Bj I. ]. Ferguson-Lees Photographs by lb Trap-Und (Plates 6-7) We have only two photographs of the Crested Lark ( Galerida cristata ) here, but they show the salient features very well. The species gets its name from the long upstanding crest which arises from the middle of its crown and which is conspicuous even when depressed. Many other larks have crests and inexperienced observers are sometimes misled by that on the Skylark (Alauda arvensis ) when they see it raised and at close range, but the crest of the Crested Lark is really of almost comical proportions. The two plates also illustrate several other characters of this species and attention is drawn to these in the caption on plate 7. Crested Larks have a somewhat undulating flight, rather like that of Woodlarks (JLullula arborea), and a characteris- tic outline from their short tails and broad, rounded wings. In Britain the Crested Lark is a surprisingly rare vagrant which has been recorded on less than fifteen occasions. The last two accepted observations were on Fair Isle in 1952 (Brit. Birds, 46: 2x1) and in Devon in 1958-59 (Brit. Birds, 53: 167, 422), though it should be added that the species has almost certainly also occurred in Kent on at least two occasions in the last five years. Thus, while so many other birds tormerly regarded as very rare wanderers to Britain are now known to be of annual occurrence in small numbers — the Melodious Warbler (Hippolais polyglotta) is one such example — the enormous increase in experienced observers has failed to raise the number of records of the Crested Lark. This is all the more surprising when one remembers that it breeds in many parts of the Continent as far north as southern Norway and Sweden (though apparently not now in Finland) and is thus found on the same latitude as Scotland. It also nests in the northern half of Africa and across much of southern Asia to northern India, north China and Korea. In many places the species is resident, but Dementiev and Gladkov (1954) quoted Stanchinski (1926) in saying that it is sedentary in the U.S.S.R. only where the snow is on the ground for less than 144 days in the year, and Vaurie (195 1) men- tioned several published cases of migratory movements. Labitte (1957) cited two recoveries within six months of birds ringed as nestlings; in that time these had respectively travelled 1,500 kilometres SSW from Sweden into France and 750 kilometres SW' from Belgium 37 BRITISH BIRDS into France. Evidence of passage has also been obtained as close to Britain as Cap Gris Nez (Redman 1956). Many geographical forms have been separated. Dementiev (1954) mapped 37 sub-species and Meinertzhagen (1951) was able to list no fewer than 56 which were more or less generally recognised (thougn he himself accepted only 20 of them). Even for a bird with such a wide range across three continents, this is a very high number of distinct races. In general, populations of the Crested Lark become paler, greyer and more sandy from Europe to central Asia and then the cline is reversed; there are similar dines in wing-length and bill-length. Vaurie (1951) suggested that “its geographical variability may be due to a fairly high degree of susceptibility to varying conditions of aridity and humidity and, in some cases, to variations in the coloration of the soil.” The remarkable extent to which the plumages of larks vary from sandy to brown, grey or red according to the habitat in v/hich they are found was also discussed by Vaurie and he referred to a number of other publications on this subject; this correlation with soil colour is particularly marked in Africa. Vaurie (1959) accepted 22 races of the Crested Lark in the Palearctic, of which four are found in Europe. These are the typical cristata, the more faded pallida from Spain and Portugal, the browner meridionalis from the southern Balkans and Italy, and the greyer caucasica from Crete, Rhodes and further east. The Crested Lark is a bird of open country, but it is much less addicted to grassland and crops than, for example, the Skylark. It prefers arid and barren ground, particularly dusty areas, desert edges, dry steppe, arable farmland, railway embankments and the edges of unmetalled roads. In some parts of its range it is found in rocky habitats in quite mountainous country, but it is generally a bird of the lowland plains. It also tends to be absent from places where there is much growth of shrubs and bushes. In central Europe, and in parts of the south, it is particularly common at the edges of villages anti towns where the roads are dusty and rough. In Holland it can be seen near railway stations and demolished houses. In Poland it nests on bomb sites in the centre of Wroclaw. Dementiev and Gladkov (1954) similarly described it as much more common in the U.S.S.R. near human habitation than on the open steppe. There are three other species of Galerida. Two of these, G. dcra and G. malabarica, are confined to India, but in north-west, north and east Africa, and in Spain, Portugal and the very south of France, the range of the Crested Lark overlaps with that of the very similar Thekla Lark (G'. tkeklae). In fact, the two species may be found closely adjacent, though the Thekla appears to be more partial to rocky or scrub-covered plateaux and slopes dotted with bushes and trees. It also seems to extend to quite high altitudes, but is perhaps most common 38 CRESTED LARK STUDIES within a few dozen miles of the coast. Generally speaking, the Thekla is more a bird of hills, hillocks, sea-cliffs, rocks and bushes, but it also frequents sand-dunes and in the semi-deserts of the Coto Dohana in Spain it inhabits the oases near the coast as well as the scrub-covered plain inland. It may be that the presence of the Thekla causes the Crested to contract its choice of habitats, and that otherwise the latter fills the niches of both to some extent. The situation is complicated by the fact that the two species are verv similar in the field. In southern Europe, the Crested is generallv more sandy than the darker and greyer Thekla, but both are so variable that much more than this is needed to separate them. It is, indeed, necessary to take into account a whole series of slight differences, hardly any of which can be regarded as reliable on their own. Niet- hammer (195 5) also emphasised this point, but his choice of characters was misleading. He considered the most reliable features to be the Crested’s larger size, its sandier colouring, the less distinct streaks on its breast and differences in habitat and voice; he also said that the Crested was much more shy. Habitat and colouring are both rather variable, however, as we have seen, and size is notoriously difficult to judge unless a direct comparison is possible; in some parts of Spain, too, Crested (and Thekla) Larks are so tame that they feed at the edge of the road while one walks by. The streakings on the breast are a very useful pointer, however. Those of the Thekla are much more distinct and the marks are quite conspicuous at, sav, 30 yards when those of the Crested Lark appear as little more than smudges. The Thekla also has a smaller and more solid-looking bill, and a less melodious and varied vocabulary, but the best distinction between the two lies in the colour of the underwing. This is strikingly orange- buff in the Crested Lark and grev in the Thekla. Unfortunately, it is often difficult to see the underwing unless the observer gets the bird to fly past when he has the light behind him; however, in such conditions the wings of the Crested Lark seem to have quite a rufous glow and those of the Thekla appear silvery-grey. The normal call of the Crested Lark is a liquid and musical whistle of four syllables (or sometimes three), written in The Handbook as “whee-whee-a^ffoo”. This call was discussed at some length bv Barrett et al. (1948), as a result of their observations during the war in German prison camps, the vicinities of which provided ideal habitats for these birds. They likened the rhythm of the note to “God Save the Queen”. They found that it was used throughout the year, partic- ularly in March-May and August-October, but rather less in winter. It serves to advertise territory and is also uttered in sexual chases, as well as providing contact between feeding pairs and parties. Depending on whether it is a display or contact note, it varies from 39 BRITISH BIRDS shrill and loud to soft and sweet. When uttering the shrill version, the bird stands upright with its crest raised. The normal alarm is a pure-toned whistle of two syllables, a long slow note increased in pitch at the end; this is usually delivered on the ground, the bird crouching low as it normally does before taking flight. Barrett et al. also described three other juvenile, pursuit and challenge calls, in addition to soft and full song. The Handbook describes the song as “lacking continuity and vehemence of Sky-Lark, delivered more haltingly and mostly in brief phrases, produces inferior and somewhat monotonous effect”, but I agree with Barrett et al. in considering it to be intermediate between those of the Skylark and Woodlark, and little inferior to the former, with a silvery and bell-like quality which gives it a character of its own. The Handbook also states that the Crested Lark sings frequently on ground, stone or building, but “less commonly on wing” and that it has no soaring song-flight like that of a Skylark. This gives a com- pletely wrong impression, however. Barrett et al. considered that loud song on the ground was usually a prelude to loud song on the wing and found that song-flights commonly took place at 100-200 feet. Perhaps this song-flight gets overlooked because Crested Larks climb directly and silently, not circling and singing as Skylarks do, and similarly dive in silence back to the ground. Though they live mainly on the ground and roost there like Skylarks, Crested Larks will also perch and sing on buildings and wires, and to a lesser extent on bushes and trees. Bodenstein (195 3) described an interesting war- time observation at a military hospital in Germany; the male of a pair of Crested Larks in the grounds of the hospital used to perch and apparently sing on a single barrage-balloon which was' anchored there at a height of between 40 and 50 metres. Barrett et al. found the Crested Larks in Germany and Poland to be regular mimics and they listed ten species which they had heard them imitate. These included Tree Sparrow ( Passer montanus), House Sparrow (P. domesticus), Siskin ( Carduelis spinets ), Greenfinch ( Chloris chloris), White Wagtail ( Motacilla alba), Whitethroat (Sylvia communis). Black Redstart {Phoenicians ochruros). Marsh Tit ( Pants palustris). Great Tit (P. major) and Partridge ( Perdix perdix). Similarly, Simmons (1951) noted regular imitations of Redshank {Prinpa totanus) in Egypt, while one bird there mimicked Greenshanks (T. nebitlaria) and Green Sandpipers (/’. ochropus) as well as responding to a human whistle. Davis (1949) reported imitations of Red-wattled Lapwings (L obi- vane Hus i ii elicits) in Iraq. Barrett et al. also described various ground displays, including court- ship, territory, threat and possible nest-site selection, while Hartley (1946) gave an account of sexual displays, nests and eggs, incubation, 40 CRESTED LARK STUDIES care of the young, injury-feigning and breeding success, from observa- tions made in southern Palestine. More recently, Labitte (1957) described his observations on the habitat, nest-site, breeding season, nest construction and details of laying, incubation and Hedging. He particularly referred to the preference which these birds showed for the vicinity of railways in his part of France, and he included a photo- graph of a nest built just by a railway track. Nests, which are built by both sexes, are usually on the ground or under banks, but they have been found on the turf roofs of rough sheds. They are usually sited by some clump of vegetation — a small shrub, a large thistle, a potato plant or a thick tuft of grass — and are generally rather loosely constructed cups of grass. They are usually very simple and may or may not be lined with fine roots or hair, though Chappell (1946) described nests in Palestine as “beautifully woven and cup-shaped”; eleven nests that he found were all built under clumps of vegetation and faced north or north-east away from the sun. Clancey (1944) discovered a number of nests under shrubs in Italy, which were “composed of coarse heathland grasses, lined with fine rootlets. Each nest was neatly domed with similar material, the superstructure being roughly woven and incorporating a number of the lower, and generally dead branches of the shrub. The dome was always so constructed as to give the nestlings the maximum protection from the fierce solar rays.” Fresh eggs may be found from late March to mid-July in Eure-et- Loir in northern France and three broods are often reared (Labitte). There are usually four eggs in the clutch in Europe, though sometimes five and occasionally three or six, while fives and sixes are evidently more regular in Palestine and north Africa; one female in northern France, which laid and lost five clutches between mid- April and mid- July, still produced four eggs each time and it was estimated that as high a proportion as 90-95% of the clutches in that region were of this size (Labitte). Parasitisation by the Cuckoo ( Cuculus canorus ) was recorded by Briche (1956). Incubation begins with the last egg (Hartley, Labitte) and is by the female alone. Hartley gave details of the lengths of time for which one individual bird covered the eggs and he found the total incubation period to be 11-12 days (which is shorter than the 12-13 days given in The Handbook). He also noted that the shells of hatched eggs were either eaten by the female or drop- ped a foot or two from the nest as soon as the chick had emerged. The young are fed by both parents and they leave the nest a week or more before they are able to fly; those in the three nests watched to this stage by Idartley left at between eight and 1 1 days old. The young are fed chiefly on insects, especially caterpillars and small grass- hoppers, and various other invertebrates are taken in the breeding 4i BRITISH BIRDS season. Otherwise, however, this species seems to feed mainly on grain and the seeds of grasses, and it is one of several birds which are known to peck grain from horse and cattle droppings in winter. I am most grateful to D. I. M. Wallace for allowing me to include his notes on the separation of Thekla and Crested Larks with mine. REFERENCES Barrett, J. H., Conder, P. J., and Thompson, A. J. B. (1948): “Some notes on the Crested Lark”. Bril. Birds, 41: 162-166. Bodenstein, G. (1953): Orn. Mitt., 5: 191. Briche, L. (1956): “Nid de Cochevis huppe Galerida c. cristata (L.) parasite par le Coucou gris Cuculus c. canorus L.” Alauda, 24: 3 10-31 1. Chappell, B. M. A. (1946): “Siting of Crested Larks’ nests”. Brit. Birds, 39: 278. Clancey, P. A. (1944): “Observations on Crested Larks’ nests in southern Italy”. Brit. Birds, 38: 134. Davis, T. A. W. (1949): “Crested Lark imitating Red-wattled Lapwings”. Brit. Birds, 42: 85-86. Dementiev, G. P., and Gladkov, N. A. (1954): The Birds of the Soviet Union. Moscow. Vol. V. (In Russian.) Hartley, P. H. T. (1946): “Notes on the breeding biology of the Crested Lark”. Brit. Birds, 39: 142-144. Labitte, A. (1957): “Contribution a l’etude de la biologie de l’Alouette huppee en pays drouais (E.-et-L.)”. Oiseau, z~j: 143-149. Meinertzhagen, R. (1951): Proc. Zool. Soc. London, 121: 81-132. Niethammer, G. (1955): “Zur Kennzeichnung von Galerida cristata und G. tbeklae ”. J. Orn., 96: 411-417. Redman, P. S. (1956): “Notes on selected migrants at Cap Gris Nez, North France, in 1955”. Brit. Birds, 49: 396-397. Simmons, I<. E. L. (1951): “Crested Lark imitating calls of Redshank, Greenshank and Green Sandpiper”. Brit. Birds, 44: 92-93. Vaurie, C. (1951): “A study of Asiatic larks”. Bull. Amer. Mus. Nat. Hist., 97: 431-526. (1959) : The Birds of the Palearctic Fauna. London. Notes Golden Eagle attacking Reindeer. — With reference to the recent papers by Dr. K. Curry-Lindahl and Dr. G. Bergman on the food and feeding habits of birds of prey in Fenno-Scandia (Brit. Birds, 54: 297-306, 307-320), it may be of interest to record an attack by a juvenile Golden Eagle (Aqitila chrysaetos ) on a female Reindeer (Rangifer tarandus) and her half-grown calf, which we witnessed at Olderfjord, Troms, Norway, on nth August 1961. The Golden Eagle was first seen circling above a mountain. Suddenly, with feet and talons extended, it swooped towards the two Reindeer which cowered in the face of the attack. The female Reindeer was sheltering the calf, but the Golden Eagle repeatedly tried to press home its attacks and the swoops it was making missed her only by a matter of inches because she was ducking down at the last moment. Altogether the Golden Eagle dived about six times before the two Reindeer were able to retreat 42 NOTES under a large boulder. They were not seen to reappear even when the bird moved away. M. P. Harris and R. Price Kingfisher ducking Kingfisher. — On 4th August 1961, as I was driving alongside the River Bourne at Idmiston, Wiltshire, my eye was caught by what I took to be a fish jumping. The stream was only some six inches deep at that time and about ten feet "wide. I drew to a halt and looked through my binoculars at the object which was still bobbing up and down in the water. To my surprise I found that I was watching a fight between two Kingfishers ( Alcedo atthis). One was hovering low over the water and apparently holding the other by the bill. It was repeatedly ducking the latter and I had the impres- sion that there was a small fish somewhere between the two beaks. Unfortunately, however, the squabble came to an abrupt end almost as soon as I focused my binoculars and the two contestants flew off rapidly into the surrounding bushes. The whole incident was obser- ved for about 25 seconds, during which time the lower bird was being pushed under at least once per second, and it should be remembered that I did not see the beginning. As a sequel to this observation, I erected a mist-net near the spot on 9th September and, almost at once, two Kingfishers hit it in rapid succession. One immediately began to duck the other even while they were entangled in the net and this continued until my companion, F. P. Errington, started to take them out. The one which was being attacked proved to be in first-winter plumage. Unfortunately, the aggressor escaped while being extracted from the net. G. H. Forster Further notes on Great Spotted Woodpeckers attacking nest- boxes. — I have previously drawn attention (Brit. Birds, 52: 270, 54: 1 19) to the damage done to nest-boxes at Possingworth, Sussex, by Great Spotted Woodpeckers (Dendrocopos major). During the winter of 1960/61 further damage was caused to ten more boxes, and between 1st March and 30th June 1961 another twenty-four received sufficiently severe attacks to necessitate the complete replacement of the fronts. Seventeen of these contained nests of Great Tits (Paras major ) or Blue Tits (P. caeruleus ) at the time. One clutch of eight eggs of Great Tits was pulled out with most of the nest. Nestlings killed totalled nine Great Tits and at least one hundred and four Blue Tits (exact brood sizes were not known in one or two instances). In nearly all cases the nestlings were removed and presumably eaten, but a few dead ones were found in the nest remains. In only one instance did a brood survive after a box had been sufficiently opened-up to permit a woodpecker to enter, presumably because the bird had been 43 BRITISH BIRDS disturbed before completing its task. Eight other occupied boxes received less severe damage; in some of these eggs or young were deserted, though it cannot be proved that the attacks caused the desertions. Nearly one third of the 190 nest-boxes in the park have now received some damage from woodpeckers and several have had fronts replaced more than once. So far as I can ascertain, there are not more than four pairs of Great Spotted Woodpeckers in the 150 acres where these attacks occur. Nestling tits therefore appear to have become an established part of the diet of these birds in spring. There is evidence of improved technique in gaining access to the nests, by comparison with previous years. In 1959 and i960 the entrance holes of damaged boxes was merely evenly enlarged and in one instance a hole was made in the side of a box. In 1961 nine-tenths of the damaged boxes showed that the woodpeckers had worked only on the two inches between the top of the entrance hole and the lid. This section was speedily knocked in to the width of the hole and then widened to permit the bird to enter. The wood is three-quarters of an inch thick, with two coats of preservative. Several boxes so damaged are shown on plate 8b. The previously reported attempts by woodpeckers to open my concrete nest-boxes have continued and plate 8 a is an illustration, but so far damage is only slight. An interesting variation, however, was an attack last winter on an open-fronted concrete box designed for Spotted Flycatchers ( Muscicapa striata) ; not only the edges of the open part of this box but also the entire roof were pitted, the marks being identical with those around the entrance hole on an adjacent concrete tit-box. Guy Mountfort Calandra Lark in Dorset. — A Calandra Lark ( Melanocorypha calandra ) was under observation at Portland Bill, Dorset, for much of 2nd April 1961. I first heard it calling at 1 1.30 G.M.T., and then saw it circling overhead with Skylarks ( Alauda arvensis). Its large size and dark underwing, combined with an absence of any pale wing-patch, con- firmed its identification. R. J. Jackson soon joined me and we were able to obtain good views of the bird in flight and on the ground. During the course of the day it was seen by at least 23 observers, and the following description is culled from detailed notes made by F. M. Gauntlett, R. J. Jackson, Dr. K. B. Rooke, M. Terry and myself: Size and build: when flying looked twice as big as Skylark, partly due to large expanse of open wing, and on ground approximately corresponded to Song Thrush (T Urdus philomelos ) with which it was directly compared; bulky, and plump like Corn Bunting (, Emberi^a calandra), usually with short-necked appear- ance. Upper-parts: crown dark with some streaking; nape pale grey with no obvious streaking; mantle dark greyish-brown streaked with darker brown or blackish, as in juvenile Mistlc Thrush (/. viscivorus) (i.c. leathers had dark 44 NOTES brown centres with pale grey fringes), and lacking brownish-buff or olive-buff tinge of Skylark; rump warmer and more buff than mantle, with fewer streaks. Sides of head: grey-brown with pale off-white or greyish-white supercilium starting a little in front of eye and travelling round behind ear-coverts (not broad, but quite conspicuous at a distance, even in flight); darker line through eye angled back at posterior edge of ear-coverts. Under-parts: throat off- white; very conspicuous and almost horizontal patch of dark blackish on each side of neck, about 2$ times as long as broad, sometimes looking blunt-ended and sometimes more pointed at centre of upper breast where the two patches almost met; shadowy area between these and a few distinct spots of brownish below; remainder of under-parts whitish and unstreaked; under tail-coverts pure white. Wings and tail: wings generally dark with two lines of pale huffish tips to coverts forming indistinct bars, and one line of dark centres (to the median coverts?) producing dark bar in front of these, as in Tawny Pipit ( Anthus campestris) ; in flight there was marked contrast between remiges and rest of upper surface of open wing, as in Kestrel ( Valeo tinmmculus) and Turtle Dove ( Streptopelia tartar) ; underwing blackish with prominent white trailing edge, this white being most conspicuous near body but probably extending as far as inner primaries; tail very short and dark brown with whitish outer feathers. Soft parts: bill pale horn or pale yellow with darker tip, short and heavy and reminiscent of finch or Corn Bunting (bill and facial pattern together distinctly bunting-like); gape pale orange; eye dark; estimates of leg colour varied from pink (in strong sun), salmon-pink, flesh- pink and bright flesh to light pinkish-straw and yellowish-orange. When first seen the bird was calling with a succession of loud notes which I rendered as prrrruutip, but which were impossible to describe adequately. After circling for four or five minutes at a height of 50 or 60 feet, it dropped like a stone, uttering a rather long trrrreeeep , and alighted about 20 yards away in one of two small adjoining fields which had recently been drilled. Here it spent most of the rest of the day. It was not heard to call any more and, in general, seemed rather shy and nervous, often flying off and climbing high in a vigorous manner; after circling in typical lark-like flight, it would then plunge steeply with nearly closed wings down almost to ground level, finally planing to earth on outstretched wings. It would crouch for long periods in hollows and often stood still, sometimes on a small ridge or stone, apparently doing nothing. When alarmed it would stand upright with outstretched neck, and it sometimes flew with its neck extended. It hopped, walked and ran. It could usually be picked up fairly readily against the rather dark soil. At times it looked a very grey bird compared with Skylarks; this was very marked in the over- cast light of evening when the head especially seemed grey and the streaking on the mantle appeared as black striations. It left with some Skylarks at dusk and was not seen again. To suth up the salient features, this was a large lark with a very short tail and broad, rounded wings, the undersides of which were black with white trailing edges; it had mainly unstreaked and almost white under-parts with conspicuous blackish neck patches; it had greyish- 45 BRITISH BIRDS brown upper-parts, a bunting-like bill, white outer tail-feathers and no crest. If one accepts the decision of the editors of British Birds to exclude the “Hastings records” (see P. A. D. Hollom, The Popular Handbook of Rarer British Birds , i960, p. vi), this is the first known occurrence of this species in Britain. J- S. Ash Rook with unusual bill deformity.— On 26th February 1961, Mr. Gordon Finn-Kelcey telephoned me to say that a Rook ( Corvus frugilegus ) had been shot on his farm at Old Romney, Kent, because it had a beak so misshapen that it could not possibly feed itself. I inspected the bird later the same day. Both mandibles were very elongated. The upper one was much decurved, while the lower, correspondingly upturned, was embedded through its middle length in the flesh and feathers of the upper breast. The body was plump and well-nourished and we concluded that the bird must have been regularly fed by other Rooks. From the way the lower mandible entered and emerged from the flesh, we thought that the lengthening of the mandibles must have been a consequence of the piercing of the upper breast and in no way a cause of it. Presumably the two man- dibles started to grow in length as soon as the bird was unable to close them properly. On 2nd March Mr. Gordon Clemetson took the photograph which is reproduced here as plate 8c. I arranged for the body to be sent to Dr. James M. Harrison who managed to salvage the specimen although it was by then in a very decomposed state. He found that the bird was an adult female and he likewise commented on the fact that it was not nearly as emaciated as might have been expected, although “feeding must have presented many difficulties”. He measured both mandibles from the gape. The upper was 66 mm. and the lower 71 mm. ( The Handbook gives the measurements of the bills of ten adult females as 31-38 mm. from the nostril). He added that “approximation of the two mandibles fails by 2 mm. at about 34 mm. from the gape”. W. S. Nevin Recent reports and news By I. J. Ferguson-Lees and Kenneth W iUiamson [These are largely unchecked reports, not authenticated records] Our last summary reviewed the occurrences of unusual Passerines and of all American species from early August to November, against a background of the more striking movements of common land birds. 1 he following gives a brief picture of other groups during this same three-month period and is chiefly concerned with the rarities. 46 RECENT REPORTS AND NEWS BIRDS OF PREY A Red-footed Falcon (Fa/co vespertinus ) was seen near Zennor (Cornwall) on 17th September and one was found dead at Hule Moss, Greenlaw (Berwickshire) on 15 th October. Other unusual birds of prey included Kites ( Milvus mi/vus) at Sandwich Bay (Kent) and Minsmere (Suffolk) on 26th and 28th November respectively. Ospreys (Pandion haliaetus) were reported up to 19th November, in various parts of the country from Aberdeen, Northumberland and Yorkshire to Suffolk and Kent, and on the south coast from Sussex to Devon. There were a few reports of Rough- legged Buzzards (Buteo lagopus) on the east coast down to Suffolk and across to Perthshire and Cheshire, but nothing like the number in i960. DUCKS, GEESE AND SWANS Red-crested Pochards ( Nelta rufiria ) were reported from August to November in Kent, Essex, Hertford, Wiltshire, Leicester and Nottingham, and Ferruginous Ducks (Ay thy a nyroca) from September to November in Kent, Stafford, Worcester and Lancashire. A Snow Goose ( Anser caerulescens) appeared on the River Lune, some miles north-east of Lancaster, on 17th September and stayed for some weeks. Meanwhile, another flew over Gladhousc Reservoir (Midlothian) and what wTas thought to be the same bird arrived on the Dumfries side of the Solway Firth later the same day. A blue phase Lesser Snow or “Blue Goose” ( A . c. caerulescens) came to Libbcrton (Lanarkshire) on 13 th October and now seems to be wintering there for the third successive year (cf. Brit. Birds, 54: 182). Another “Blue Goose” was identified in Cheshire in October, but this is more likely to have been a hybrid. Bewick’s Swans ( Cygnns columbianus bewickii ) began to arrive in East Anglia about 29th October, when a party of five also appeared in Somerset, and during the next three weeks there were single birds or parties of up to 45 in Essex, Suffolk, Norfolk, Lincoln, York, Derby, Huntingdon, Middlesex and the Isle of Man. WADERS The early wader movements were discussed in our August summary (Brit. Birds, 54: 333)- Little Stints ( Ca/idris minuta) remained fairly numerous throughout the autumn, but the unusual quantities of adult Curlew Sandpipers (C. tesfacea) in late J uly and early August were followed by a rather below average passage of birds of the year. Grey and, to a lesser extent, Red-necked Phalaropes (Pha/aropus fulicarius and lobatus) began to appear in the second half of August when there were odd ones in Yorkshire, Norfolk, Suffolk and Caernarvonshire, and rather more in western and southern Ireland. Totals of over 40 and over 150 phalaropes were counted off Cape Clear (Co. Cork) on 25 th and 27th August. In September there were small parties in Scillv, Cornwall, Devon, Dorset, Anglesey, Co. Antrim, Northampton, Nottingham and Yorkshire, and several quite sizeable groups of up to 5 5 off Erris Head (Co. Mayo). In October there were gatherings of up to 20 or so in Scilly and Cornish waters and odd ones to almost the end of the month in Dorset, Kent, Norfolk, Lincoln, Nottingham, Stafford and Cheshire. The latest report was of one at Spurn (Yorkshire) on 15 th November. The autumn total was of the order of four or five hundred, but this is nothing compared with the several thousands involved in i960 (Brit. Birds, 53: 529-531). Apart from the American waders mentioned last month, several other rare species were represented. A Sharp-tailed Sandpiper (Ca/idris acuminata) was identified at Burton Marsh (Cheshire) during ist-3rd September and another, an adult in almost full summer plumage, stayed at Bedford sewage farm from 4th to nth September. A Terek Sandpiper (Tringa terek) appeared at Blagdon Reservoir (Somerset) on 6th October, and a Sociable Plover (Cbettusia gregaria) — the second in 1961 — was seen at Wilstone Reservoir, Tring (Hertfordshire), on the 29th. Broad-billed Sandpipers (Limicola falcine/lus) in Co. Durham and Nottinghamshire 47 BRITISH BIRDS have already been mentioned (Brit. Birds, 54: 333) and there was a third near New- castle-on-Tyne, at Seaton Burn, from 12th to 16th August. GULLS AND TERNS The most unusual record in this group concerned an Ivory Gull (Pagopbila eburned) at Porto Bello, Brighton (Sussex), on 19th November. Three of the half dozen reports of Sabine’s Gulls (Xenia sabini ) came from Cornwall— single adults at St. Ives on 19th and 22nd August and at Sennen on 19th September. 1 he others were an adult at Spurn (Yorkshire) on nth September, one at Portland (Dorset) on the 19th and two juveniles on Rathlin Island (Co. Antrim) on the 29th. The number of reports of Mediterranean Black-headed Gulls (Lams melanocephalus ) on the south coast from August to October, and to a lesser extent in November, was remarkable. During this time there were at least two in Kent, some six in Sussex, one in Hamp- shire and two in Dorset, and regular observations of a number of different individuals in Cornwall, particularly at St. Ives, from 31st July to 20th October. There was also one at Spurn (Yorkshire) on 21st October and, of course, the “regular” at Hartlepool (Co. Durham). Little Gulls (L. minutus ) continued to increase. Apart from those on the east coasts of Scotland and England, there was again a spectacular passage of them at Portland Bill from late September to early November, with peaks of 69 and 78 on 14th and 20th October. As many as 33 were also seen on the Exe Estuary (Devon) on 8th October, and there were several other records as far west as Cornwall, Flint and Cheshire, as well as odd ones in inland counties. Reports of Gull-billed Terns (Gelochelidon nilotica) were rather few— at Portland (Dorset) and Dungeness (Kent) on 21st and 24th August. A Sooty Tern (Sterna fuscata), an immature bird, was identified at the mouth of the River Exe (Devon) on 1 2th September. OTHER WATER BIRDS The Little Egret (Egret t a garget la) in Anglesey in August (Brit. Birds, 54: 334) moved to Malltraeth on 2nd September and was still there on 3rd December. Further Purple Herons (Ardea purpurea ) included a young bird at Snargate (Kent) on 9th August and another which stayed at Shotton Pools (Flintshire) from 24th September to 12th October and then reappeared there from 19th to 22nd November. A Little Bittern (Ixobrychus minutus ) was picked up dead at Wcybridgc (Surrey) on 22nd August. Spoonbills (Platalea leucorodia) were reported throughout the autumn from Norfolk to Kent and in Devon and Cornwall. The largest numbers were nine and six at Dungeness (Kent) on 29th and 30th August and the latest was at Abberton (Essex) on 3rd November. Four Cranes (Megalornis grus) were identi- fied in flight not far from Southport (Lancashire) on 1 ith November. What seems to have been a Little Crake (P organa parva ) was seen at Chew Valley Reservoir (Somerset) on 5 th November, and there were a dozen reports of Spotted Crakes (p porzana ) from August to October in places as far apart as Shetland, Cheshiie, Flint and Kent. Black Guillemots (Cepphus grylle) are not often recorded far south of their breed- ing range, so that one in Kent and a scries of observations from Sussex are of no little interest. The first to be reported were off Sclsey Bill (Sussex) and Dungeness (Kent) on nth and 1 2th August respectively. There were then further observations at Sclsey on 3rd and 16th September and 1st October; the state of moult showed that the two September birds must have been different individuals. After some early records of Little Auks (Plautus a//e) in September— including ones in summer plumage at Holy Island (Northumberland) and Great Saltce (Co. Wexford) on the 7th— there was a small influx on the cast and south coasts from Northumberland to Dorset, and to a lesser extent elsewhere, between nth October and 19th Novem- ber. One was picked up exhausted near Salisbury (Wiltshire) on 6th November. 48 ( 7 3 - *3> '.XkM i-G IBird life features in tevery issue of . . . 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Supplied complete with leather case and straps. £23 .0.0 6 X 30 ARMY BINOCULARS An excellent general purpose binocular of good performance, which will stand up to a great deal of rough usage. Cost approx. £20. £7 . 15.0 7 x 50 PRISMATIC TELESCOPE Tripod mounted. A heavy instrument of superb performance. Estimated cost £120. £9 . 15 . 0 10 X 70 ROSS BATTLESHIP BINOCULARS Tripod mounted. Cost over £200 £45 . 0 . 6 Ex-Admiralty 7x50 CANADIAN & U.S. NAVAL * BINOCULARS 1 Printed in England by Diemcr & Reynolds Ltd., Eastcotts Road, Bedford Published by H. F. & G. Witherby Ltd., 5 Warwick Court, W.C.i British Birds Some photographic studies of the Swift Arthur Brook, C. C. Doncaster, C. Eric Palmar and H. N. Southern (with nine plates) South-eastern rarities at Fair Isle Principal Contents Birds with abnormal bills D. E. Pomeroy (with one plate) I. C. T. Nisbet Notes Reviews Letters FEB 1362 Three Shillings February British Birds AN ILLUSTRATED MONTHLY JOURNAL Edited by P. A. D. Hollom E. M. Nicholson I. J. Ferguson-Lees Stanley Cramp Photographic Editor: Eric Hosking Hon. Editors: W. B. Alexander N. F. Ticehurst Editorial Address: 30 St. Leonard’s Avenue, Bedford Contents of Volume 55, Number 2, February 1962 Page Birds with abnormal bills. By D. E. Pomeroy. Photographs by Willy Pfeiffer and Eric Hosking (plate 9) • • • • 49 Some photographic studies of the Swift. Photographs by Arthur Brook, C. C. Doncaster, C. Eric Palmar and H. N. Southern (plates 10-18) .. 72 South-eastern rarities at Fair Isle. By Dr. I. C. T. Nisbet . . . . . . 74 Notes 1 — * British-ringed Manx Shearwater recovered in Australia (Robert Spencer) 86 Spotted Redshanks up-ending to catch Sticklebacks (Dr. R. J. Raines) . . 87 Barn Owl apparently killing Weasel (J. M. Last) . . . . . . . . 87 Passerines feeding on blackberries (R. E. Scott) Pre-coital display of Magpies (T. M. Clegg) Notes on the food of the Marsh Tit (Bryan L. Sage) 89 Song Thrush incapacitated by seed heads (L. P. Alder) 89 Blackbird dead on nest after grass fire (N. L. Hodson) 90 The field identification of Sardinian, Subalpine and Spectacled Warblers in autumn (J. T. R. Sharrock) . . • ■ • • • • • • • • 9° Bonelli’s Warbler in Co. Cork (J. T. R. Sharrock) 92 Down the Long Wind. By Garth Christian. Reviewed by Robert Spencer 93 The New Wildfowler. Edited by Noel M. Sedgwick, Peter Whitaker and Jeffery Harrison. Reviewed by Dr. John Berry . . . . . . . . 94 Birds of River Tama. By Sakac Tamura. Reviewed by Eric Hosking .. 95 Letters: — What is a British bird? (Dr. Bruce Campbell) Animals trapped by plants (J. V. Morley) . Request for information: — Cold weather migrations 96 96 96 Annual subscription £2 (including postage and despatch) payable to H. F. & G. Witherby Ltd., 5 Warwick Court, London, W.C.i n British Birds Vol. 5 5 No. 2 February 1962 Birds with abnormal bills By D. E. Pomeroy — ^ (Plate 9) INTRODUCTION (Close correlation of the shape and size of a bird’s bill with its : feeding preferences has been demonstrated even within a species (see Lack 1947, Snow 1954). But individuals with bills differing con- siderably from the normal also occur, even though rarely, and prompt certain questions. How do these abnormalities arise ? Do they survive and, if so, how in view of their marked divergence from the type produced by selection? Many birds with abnormal bills are unable to feed in the usual way and, at least in some cases, they acquire feeding mechanisms appropriate to the beaks uffiich they possess. Thus it may be that, in normal birds too, the feeding mechanisms which are seen are acquired as a result of having a particular type of bill; and the fact that normal members of a species show a “lack of indivi- dual variation in the motor pattern can ... be ascribed in part to lack of variation in the relevant effectors” (i.e. bills) (Hinde 1959). It was shown by Spalding, as long ago as 1873, that the motor patterns of a chick in pecking at small objects are well organised at the first peck; but later work has revealed that these patterns are improved with practice (Koenig 1951). Thus a learning process is involved. It has only recently been accepted (e.g. Hinde 1959) that birds’ behaviour does show plasticity; in other words, it is less stereotyped than was once thought. The adaptability now suggested enables birds to survive even with abnormal bills. It also makes Plate 9 (opposite). Upper, juvenile male Hawfinch (Coccothraustes coccothraus/es) with incomplete bill, Switzerland, August 1949. Although its two mandibles met only at the base, an apparently congenital deformity, its weight was normal and it covered 460 km. in 43 days (page 65) (photo: Willy Pfeiffer). Lower, adult male Starling (Stumus vulgaris ) with elongated and down-curved bill 42 mm. long; this symmetrical deformity is not uncommon among Starlings, lengths up to as much as 2-1 inches (over 60 mm.) having been recorded (page 57) (photo: Eric Hosking) 49 BRITISH BIRDS possible the acquisition of different feeding mechanisms within a species, which may be of importance in enabling birds to take advan- tage of locally abundant food supplies. Hence, plasticity in feeding mechanisms may have a positive evolutionary value — unlike, for instance, reproductive mechanisms, where selective pressures will tend to favour uniformity within the species. Thorpe (1956a and b) has shown that individual Passerines may acquire unusual feeding methods; these are more easily acquired by some species than others. There is some evidence that the ability to acquire new feeding mechanisms also varies from species to species : examples will be given in which the behaviour varies considerably from the normal. The Starling ( Sturms vulgaris ) shows considerable adaptability, but this may be correlated with the wide range of foods taken by normal members of this species. Deformities may develop slowly — over a period of a year or more in some cases — or rapidly, as the result of an accident. Clearly the latter type requires much greater plasticity of behaviour if the bird is to survive, and this must be taken into account in the interpretation of differences in behaviour. The number of deformities due to injury is rare, however, and when behaviour is mentioned it may be assumed that the abnormality was not the result of a sudden injury unless other- wise stated. The information in this paper is derived mainly from the results of an enquiry published in four ornithological and agricultural journals, from published records, and from correspondence. Full acknowledge- ments are given at the end or in the body of the text. THE NORMAL BILL* The underlying bony structure of the normal bill is shown in Fig. 1. This differs considerably in shape in different species, but the basic structure does not vary. Immediately overlying the bones is a cutane- ous laver, or dermotheca, which is continuous with the skin or epider- mis over other parts of the bird. The dermotheca is thin, and contains blood vessels and nerves. From it arises the horny sheath, or rhamphotheca, which forms the externally visible part of the bill. The rhamphotheca is produced from proliferating cells in the der- motheca which, as they divide, move outwards, at the same time becoming keratinised and, therefore, hard (Rawles i960). The rhamphotheca may form a continuous sheath, as in most birds, or be made up of a number of separate plates, as in the Procellariiformes and some other groups. There are also differences in the degree of hard- ness found in the rhamphotheca : in a few species (e.g. some parrots) ♦The author is very grateful to Sir A. Landsborough Thomson for help with the information contained in this section. 50 BIRDS WITH ABNORMAL BILLS Nasal I the cere appears to be ordinary skin, and may even bear feathers. In i the Puffin ( Yratercula arctica) the outer part of the rhamphotheca is . grown and shed seasonally. As far as is known, the bill grows throughout life (Rawles i960), although the rate at which this occurs must vary from species to species. Moreover, there appears to be some individual variation within the species. Fox (1952), Moltoni (1949, 1950) and others have suggested that in most birds the growth of the bill is opposed by wear and tear, and by the opposition of the mandibles to each other; provided that both processes occur at an equal rate, the correct form of the bill will be maintained. This mechanism appears to explain some of the commoner abnormalities which occur (see later). U However, it should be mentioned that in some species the ends of the mandibles (where most growth occurs) are never opposed to each other. This happens in the majority of birds of prey and in all psittacine birds, as well as a few members of other groups, e.g. the adult Scissor-bill ( Rjtichops flavirostris). It is well known that the range of bill types found amongst the ten thousand or so living species of birds is considerable. However, as will be seen, the range found in abnormal bills is even more remark- able. Various attempts have been made to classify normal bill types, perhaps the most satisfactory being that given by Van Tyne and Berger (1959). Finally, it should be mentioned that variation of bill, other than that dependent on age, can occur within the species. The seasonal dimorphism of the Puffin has been mentioned; in the New Zealand wattle-birds ( Neomorpha ) there is a sexual dimorphism (the bill of the male being longer and more decurved than that of the female). Colour differences also occur, e.g. seasonal changes and sexual differences in the Starling and Blackbird (Turdus merula ). 5 1 BRITISH BIRDS Table i — Variation in the direction of the crossing of the mandibles of the Crossbill (Loxia curvirostra') Country Lower mandible crossed left crossed right % left % right France (Mercier and Poisson 1924) 10 (7^ 3$) 5 (3d1 2$) 67 Norway (P. P. G. Bateson in litt.) 34 (i8d 16$) 25 (i4<$ u$) 5 8 44 3° 59 33 42 4i The bill of the Crossbill Only two genera of birds normally have crossed bills — the crossbills of Eurasia and North America and the Loxops of Hawaii (Landaeur 1938). In the young Crossbill ( Loxia curvirostra ) the tips of the mandibles are coincident (Witherby et al. 1941), and in the adult the direction of crossing varies. This is illustrated in Table 1 (see also Ludwig 1932); the apparent preponderance of those with the lower mandible going to the left (59% of the total) might well disappear if a larger sample were available. The fact that the ratio is similar in both sexes shows that the direction of cross is not a sex-linked character. OCCURRENCE OF ABNORMALITIES An abnormality may be defined as any irregularity in the bird’s bill which is sufficiently different from the normal to attract the observer’s attention. Such abnormalities are those which are likely to affect the bird in some way. Birds with abnormal bills are rare in the wild state (see Table 2). This could be due either to a low incidence of the causes of abnormality, or to a low survival of birds with abnormal bills. Deformities that are not the result of injury have been recorded in about sixty species of wild birds, but their actual occurrence is doubt- less much wider. There are, of course, more records for those species which are more readily observed, e.g. the House Sparrow (. Passer domsticus), or trapped and handled in large numbers, e.g. the Starling. It is tempting to suggest that deformities occur more frequently in some species or families than others, but this would be very difficult to prove and, on the whole, there is little evidence to , support it, except possibly in the case of the Starling. Over sixty i cases have been recorded in this species — the next largest number in any one species being fifteen. Nevertheless, Table 2 (which contains all the available information) suggests that the occurrence is not significantly higher in the Starling than in other species. With regard to frequency of deformity, then, all that can be said is that it is well below 1% in wild birds. In cage birds, however, deformities appear to be much more frequent— although no accurate quantitative infor- j mation is available. 52 i E 3 E 3 -3 S -a " p Z “ '■3" T) H u .12 <12 := ^ 2 _2 ;_- -- U G3 X -'-a, " 3 S cL J3 o « r* C > i2 -2 1 u « : G3 .G » tu .tj 3 0 5 TJ 3 co ^ u ■ T3 00 TJ S u V - . o g 3 y '2 E U <2 cj Q 3 g S g J ** ^ _Q . i8 3^ E Cl CO ■v tj u 3 -s o u CO co « e- ■ C O a c o c' £ 33 y c _Ol, 2 . ^ u I D w ^ C CO CO CJ Cl CO CJ £ JZ ■a « >* o 0 ... :8 m -r •*- cs = ! -a £ f-II p T3 o ^ M TJ ** G T3 2 o JG « v-« a, — . Cl - — -C Vh _C t to % % S.£S^ -n y CC ■“ ^ G JC „ o ~ *3 4-. 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H -r( H E o .ii £ ~ CT o r ._ « w ^ 10 u ; 2 ^ cj > .y ^ G JG CO *-> 2 3 -C o U cg . o Q ^ '-' jC c u O VZ z a: >_ u 33 < ■6 . « CJ v co CO TJ X Wj co ^ 2 w J5 C3 W CJ TJ CO ^ X ^ .S2 « G ■*-* co G O' CS ° * CN P ^ w n, ^ O y ^ o cn s >> C3 Cl !* CJ H G ^ « JS M 2 c o W Z s -s p o * u TJ O u PO >V G O to d TJ o bO G O S o> u cl o CO 1> x; 4-* o u G CO * «-» G 5: .0 ^ ^ I 5 § § I §■! ^ Q> ?N ^ V. ^ ^ ^ O, S* w S H Jd 5 u T -O OG "Ij i_- w. 1,-^ § § ^ 5 w H 8 « u O CQ ci ^ V ^ Cl v V n toS! JP TJ T Oh 5 '-'to ta -T 2 to r-G /-* & =5 U C/2 >3 a. Cl Q- CO i o E BRITISH BIRDS TYPES OF DEFORMITY The most satisfactory classification of deformities would be one based on their causes, but these are otten unknown. Hence the system used here is mainly morphological, but inevitably there are some examples which do not fit into anything but a “miscellaneous” section. (a) Temporary According to Wilkinson (1953), temporary deformities have been recorded several times amongst cage birds. He attributed this to faulty feeding, but gave no actual examples. The only specific record which I have found concerns a Zebra Finch (T aeniopygia castanotis') in which the cock “continually developed the upper mandible until it had increased by nearly a quarter of an inch, in a downward curve. The abnormal part would then drop off, and growth continue as before” (Rankin 195 3). A wild male Great Tit ( 'Varus major ) observed by Howard (1951) had a bill which was normal up to the age of four years ; the upper mandible then began to grow until after four months it was double the length of the lower, which remained normal. Ex- ceptionally fierce bill-wiping (which had not been seen before) took place on the two days before the young of this bird were due to hatch; when they did hatch, the bird’s bill appeared to be normal again. However, the upper mandible began to grow again a few months later, and in six months had reached the same size as before. (b) Permanent Crossed mandibles. This is a relatively common abnormality which has been recorded in a wide range of species — for example, the Linnet ( Carduelis cannabina), Hooded Crow ( Corpus corone cornix). House Martin (Delichon urbica) and Robin ( Erithacus rnbecula), to name but a few. Typically, the bill appears as in the Crossbill with the upper mandible decurved, the lower mandible upcurved, and the two crossing towards the tip, but without any significant elongation. However, elongation does occur in some instances, the Blue Tit (Paras caeruleus ) shown in Fig. 2 being an example. As in the Crossbill itself, crossing may be left to right or right to left (see page 52). It is interesting to note that Fig. 2. Blue Tit (Paras caertdem ) with crossed mandibles and some elongation. Great Tit ( Paras major) with the upper mandible slightly decurved 54 BIRDS WITH ABNORMAL BILLS tFiG. 3. Twenty-eight Parrot ( Barnardius 3 onarius semitorquatus) \with the upper mandible extremely decurved a straight bill has been observed as an abnormality in the Crossbill (Rzehak, quoted by Duerst 1909). Upper mandible decurved. This too is a fairly common deformity, affecting such varied species as the Rook (Corpus frugilegus) and Corn Bunting (Emberi^a calandra ), and the Feral Pigeon ( Columba livia \ ar.), in the last of which it is particularly common (D. Goodwin). The extent of the overgrowth of the upper mandible varies considerably . in the Continental Great Tit (P. m. major) shown in Fig. 2, it was only slight (15 mm; 10-11 mm. being the normal length for this race), in the Australian Twenty-eight Parrot (Barnardius % onarius semitorquatus) shown in Fig. 3, however, it was extreme. This bird suggests that the overgrown part continues on the same curve as the normal part of the bill. In Passerines, therefore, one would expect the curvature to be slight, as it was in the Great Tit already mentioned; and this appears to hold good in most cases (cf. Engels 1 940). In Feral Pigeons, however, overgrown upper mandibles appear to be strongly hooked in most instances (D. Goodwin, W. Shipp). In most cases where definite information is available, overgrowth and downcurving of the upper mandible is associated with the tip of the lower mandible being broken off or otherwise damaged (e.g. the Starling in Fig. 4); or. Fig. 4. Starling ( Sturnus vulgaris) with the upper mandible decurved, probably because the tip of the lower has been broken off 55 BRITISH BIRDS Fig. 5 . Starling ( S/ttrnus vulgaris ) with the lower mandible upcurved alternatively, the two mandible tips not corresponding (e.g. the Blue Tit and Great Tit in Fig. 2). In other words, this type of overgrowth occurs when the tips of the two mandibles do not approximate (see below) and a rather unusual illustration of this fact was the recent case of a female Rook whose lower mandible had become stuck through the skin of her upper breast, with the result that she could not close her bill and both mandibles became elongated and slightly curved (Nevin 1962). The exceptions to all this are those species in which the tips do not approximate normally— e.g. Psittacines and raptors, in which no cases of overgrowth are known in wild birds. Lower mandible upcurved. This is rare, apparently only occurring when the tip of the upper mandible is missing. The only certain cases seem to be a Starling in the British Museum (Natural History) (Fig. 5) and a Great Crested Grebe ( Podiceps cristatus ) seen on Queen Mary Reservoir, Middlesex (Bruce 1952); a record of a Rook quoted by Groebbels (1932) is probably of a similar kind. There is also one record of the whole bill being upcurved slightly, in a Snipe ( Gallinago gallinago), no elongation being involved in this case (Bottomley 1957 and in lilt.). Upper mandible upcurved and/or lower mandible decurved. This can be one of the most spectacular types of deformity, as in the House Sparrow shown in Fig. 6 (Donark 1950) where the lower mandible was 31 mm. long, the upper one 44 mm. long and the tips of the mandibles 5 1 mm. Fig. 6. Male House Sparrow {Passer domesticus) with the upper mandible upcurved and the lower mandible decurved 56 BIROS WITH ABNORMAL BILLS apart! Another House Sparrow (Petit 1926) had the upper mandible normal, whilst the lower one was decurved and reached a length of 40 mm. A third House Sparrow (Hantzach 1902) had the upper mandible upcurved and 31 mm. long, the lower being straight and only half as long; and a fourth (Piechocki 1952) had the upper mandible normal whilst the lower was downcurved and reached 30 mm. in length. Although most frequently recorded in the House Sparrow, :this type of deformity does occur in other species. For instance, a : Song Thrush (Turdus philomelos ) in the City of Leicester Museum has a beak curving over in an almost complete loop, the tip being just above t the nostrils and pointing forwards (T. A. Walden). Another record 1 concerns a Starling whose upper mandible was curved back over its : shoulder, so that when seen in flight it appeared to be carrying a short twig (The Lincolnshire Chronicle , November 1957). F 1 g . 7 . Starling ( Stumus vulgaris) with the whole bill elongated and downcurved Elongation. This, a fairly common deformity, is nearly always associated with a down-curving of the bill, and may therefore be des- cribed as “curlew-type”. Typically, elongation affects both mandibles equally (e.g. Fig. 7 and plate 9b). Deformities of this sort are com- mon in Starlings, a length of two and a half inches having twice been recorded (Dadv 1951; and a specimen in the Royal Scottish Museum, quoted in British Birds, 44: 349). A remarkable case is that of a Californian Thrasher (Toxostoma redid rum) in which the lower mandible was 1 12 mm. long and decurved through about 150°, while the upper mandible had broken off at 69 mm. (Fox 1952). The normal length is 32-39.5 mm. and decurvature about 30° (Engels 1940). As might be expected, the tips of these elongated mandibles are very thin, and therefore become broken quite frequently. In the case of a Nuthatch ( Sitta europaea) whose bill grew to about one and a half times the usual length, the extended part was sufficiently weak for the tips to break off, leaving a bill of normal size (M. Bryant). Occasionally the mandibles become laterally twisted to some extent. The degree of curvature varies considerably, as can be seen from a comparison of Figs. 3 and 7. A pronounced curvature might be expected in a parrot, but in fact it 57 BRITISH BIRDS also occurs elsewhere, as in the Californian Thrasher already men- tioned and a House Sparrow recorded by Moltoni (1949); the latter had a bill which was 30 mm. in length and decurved through more than 90°. Engels (1940), who was studying bill curvature in thrashers in general, found that not only does the degree of arc become greater in longer bills — as would be expected — but the degree of curvature also becomes greater in the more distal part of the bill. This would account for Fox’s Californian Thrasher, and perhaps for some of the other cases, but certainly not all of them. Fig. 8 . Starling (S turn ns vulgaris) with the upper mandible curved to the right Fig. 9 . Red-crested Pochard ( Net/a rufitia) with the bill splayed out at the tip Lateral curvature. Deformities of this kind are very unusual. Groebbels (1932) referred to a Rook in which the upper mandible was broken and the lower turned to the left; he also recorded a Swallow (Hirundo rustic a') which had a bill turned to the right, and a South American parrot of the species Ama^ona leucocephala whose beak “turned outwards”. The only other recorded examples are the Starling shown in Fig. 8, where the lower mandible appears normal, but the upper mandible is turned to the right (R. R. Lovegrove) and a Northern Red-breasted Sapsucker (Sphyrapicus varius ) whose elon- gated upper mandible was curved “far over to the right” (Bowles 1908). Locked bills. Three cases have been recorded (see Field, 1958): the tip of the upper mandible pierced the skin between the two rami of the lower mandible, probably as a result of an accident, such as crash- landing bill first on to a hard surface. The birds concerned were a Pheasant ( Phasianus colchicus), a Partridge ( Perdix perdix) and a Fantail Pigeon. A similar instance involving a Snow Bunting ( Plectrophenax nivalis ) took place on Fair Isle in October 1953 (I. J. Ferguson-Lees). 58 BIRDS WITH ABNORMAL BILLS 1 - 1 c; . io. Female House Sparrow ( Passer domcs/icus) with the lower mandible Elongated in the form of a trough, the tip being as wide as the base and open. (Great Tit (Pants major) with the upper mandible decurved to pierce the check and the lower mandible elongated and twisted Miscellaneous. A few examples will serve to show the range of other abnormalities which exist. The Red-crested Pochard (Netta rrufina ) illustrated in Fig. 9 had a bill which was normal at the base, but splaved out distally in such a way that it could not be closed (Vis- count Chilston) (it is possible that this was a case of the upper mandible being upeurved). One Black-headed Grosbeak ( ' Phene ficus melano- cephalus ) has been described as having a flange of rhamphotheca on the left side of the lower mandible, extending across the side of the upper mandible to such an extent that “the bird could only have fed from the right side, and must have been considerably handicapped'’ (Loye Miller, quoted by Fox 1952). In the House Sparrow shown in Fig. 10, the upper mandible was normal but the lower, instead of coming to a point, was in the form of a trough, which was just as wide at the tip as at the base, the tip being open; and it was 27 mm. long (von Madarasz 1902). A Starling in the British Museum (Natural History) has a similar lower mandible which, although rather worn, is 46 mm. long; this bird’s upper mandible is enlarged at the base and broken off short. Similarly, the lower mandible of the House Sparrow in Fig. 6 also appears to be trough-shaped, as well as decurved, and the same applies to Petit’s House Sparrow mentioned on page 57. It seems possible, however, that each of these “troughs” was the result of the tip breaking oft' from a mandible which had been longer still. A most extraordinarv deformity occurred in the Great Tit represented in Fig. 10, which was killed on 14th December 1891 at Zemplen in Hungary. The upper mandible curved down to such an extent that the tip pierced the bird’s cheek, whilst the lower mandible stuck out forwards and was twisted “like a cow’s horn” (von Madarasz 1902). MORPHOLOGY In most cases, all that is recorded is the outward appearance of the 59 BRITISH BIRDS deformity, with no reference to the underlying structures. However, Fox (1952) stated that X-ray photographs of the deformities of a Scrub Jay (. Aphelocoma caerulescens), a Red-breasted Sapsucker and a Californian Thrasher suggested that the bony portions of the bill were normal; and that the abnormal growth was limited to the dermatheca. He concluded from this that the abnormalities were due to damage of the rhamphotheca, but he presented no evidence as to how such damage might come about. There is, however, one case where a deformity may have been due to damage. An Oystercatcher (. Haematopus ostralegns ) recorded by Rutherford and Wagstaffe (1955) showed evidence of shot-gun wounds at the base of each mandible, which were both overgrown and had the tips crossed. It seems pos- sible, but not conclusive, that this may have been due to the damage caused by the pellets. A few other points seem worthy of mention. In the old cock House Sparrow described by Hantzsch, and already mentioned here on page 57, “the condition of the beak near its base was bony, rather than horny, the colour there being lighter than towards the tip”. Unfor- tunately he gave no further information, except that the feet were in poor condition. There are other records of unusual coloration: for example, a curlew-billed Starling had a broad blackish-brown band halfway down the otherwise normally coloured bill (Huyton 1953). In general, however, the bill coloration seems to be the same in abnormal as normal birds. Little is known about regeneration of broken parts of the bill. Groebbels (1932) recorded an Eagle Owl ( Bubo bubo ) which broke off a bit of its upper mandible ; this then regenerated, after which it was abnormally long. Groebbels also recorded that Bordage noted regrowth of broken edges of the bills of storks (Ciconia) and chickens ( Gallus ). This appears to be all the available information concerning regeneration. In many birds where the mandibles are broken, the damaged part heals off; this would seem to be a protective function. Mercier and Poisson (1927) noted that the tongues of domestic fowls became tougher when the beak was crossed. Stabler (1938) found a similar thing in a Chinese Ring-necked Pheasant which also had crossed mandibles. Presumably this is a result of the sharp edges of the mandible causing fibrous tissue to form in the tongue. CAUSES (a) Genetic Despite the conspicuousness of some bill abnormalities, and the widespread belief that they are inherited, there is little evidence that this is so, although other dermal and epidermal abnormalities, such as albinism and comb formation, have received much attention from geneticists. 60 BIRDS WITH ABNORMAL BILLS Hodges (1952) found that two out of four nestlings of an American FRobin (Turdus migratorius) had crossed bills, whilst the other two nestlings and the parents were normal. An obvious explanation is t:he recombination, in two of the offspring, of recessive factors present un both parents. Mercier (1926) mated a female domestic fowl that mad a crossed beak with a normal male. Thirty-four eggs were laid; rthree were infertile and five chicks died before hatching. Of the rremainder, some were normal, but others showed a variety of defects, including crossed bills (three crossed at hatching and a fourth later), rrickets, brittle feathers and dwarfism. The occurrence of four off- spring with crossed beaks suggests that this anomaly was inherited. However, cage birds often show bill abnormalities, which avicul- ;turists are prone to correlate with nutritional deficiencies. Hutt (1949) in his account of the genetics of the domestic fowl that “only a small proportion of birds homozygous for hooked beak is visibly affected”, and Landauer (1938) found it impossible to produce a true-bred cross- billed fowl, despite considerable inbreeding. So even the case of the American Robins, quoted above, may not be as simple as at first might seem; and further data on this subject are clearly needed. (b) Accident If the bill of a bird is damaged, it may respond in various ways. Damage to the bone can be only locally repaired. However, if only the rhamphotheca is injured, regeneration may occur and this has been recorded occasionally. Hutt (1949) believes that the commonest deformities of the domestic fowl, namely unilateral microphthalmia and anophthalmia, are pro- bably accidental in origin. In microphthalmia the upper mandible is decurved and laterally displaced, the eye is reduced on the same side as the bill displacement and there are other defects. Anophthalmia is a more serious form of the same phenomenon. Both conditions are prenatal and most of the chicks never hatch. The occurrence of these deformities is increased by unfavourable incubation conditions (Landauer 1938). Nestlings falling from the nest often land on their beaks and cause permanent damage which results in a displaced or deformed bill in the adult. This is of concern to breeders, but wild birds falling from the nest are unlikely to survive, of course. Accidental damage to the beaks of adult birds is probably rare, but it does occur. Examples are the Starlings shown in Figs. 4 and 5, where the tips of lower and upper mandibles respectively had been broken off. It is immediately obvious in both these cases that the opposite mandible has overgrown considerably and, as already mentioned, it appears that in most species each mandible owes its usual length to wear on the other. This 61 BRITISH BIRDS wear occurs largely in normal feeding activities. When the tip of the upper mandible is broken off in some way, there is no longer a wearing surface for the tip of the lower mandible, and it therefore lengthens unopposed; and vice versa. Similarly, the tips will continue to grow if they are slightly crossed, as appears to have happened in the Blue Tit in Fig. 2. This slight lateral displacement, which may be accidental (perhaps due to slight asymmetry of the jaw) is probably a purely mechanical effect, and different from the curving of the crossbill-type and the elongation of the curlew-type, both of which are suggested to be genetically caused. In species where the tips of the mandibles do not normally oppose each other, e.g. many raptors, increase in length may be limited by wear and tear during feeding, since the beaks of birds of prey are inclined to overgrow in captivity unless they are given bones to pick (J. J. Yealland). (c) Disease Since the horny covering or rhamphotheca of the bill is produced by the underlying epithelial dermotheca, it is quite possible that diseases of the latter could lead to deformities of the former. However, there appear to be no records in which this has been shown. Another and quite different cause of deformity might be due to parasites damaging the dermotheca. Appleby (1958), referring to Budgerigars ( Melopsittacus mdulatus), stated that Cnemidocoptes pilae (a mite) “may be responsible for damage to the developing beak in nestlings, resulting in later deformity”. This view was supported by Keymer (1958), for the same species. There are no similar records for other species, but this may be due to lack of observation, and it could well be that such irregular growths as that of the Great Tit in Fig. 10 are due to this cause. The irregularity could be due to the parasite attacking the tissues for a relatively short period, causing uneven growth at this time. C. pilae has been recorded from the Hoopoe (Up up a epops) and the Alexandrian Parakeet ( Psittacula nipalen- s is) as well as from the Budgerigar. However, it is the only mite which is known to attack the beak (G. O. Evans per P. N. Lawrence). Some cases occur in which the abnormality appears to be a superficial growth that is presumably due to some disease, and the bill is otherwise unaffected. Schauberg (1901) recorded a remarkable instance of a Curlew ( Numenius arquata) with a swelling on its upper mandible; this swelling resembled a potato in shape and colour, and was suffi- ciently large to be seen with the naked eye at a considerable distance. The bird was later found dead, with an empty stomach. (d) Other causes Birds kept in captivity sometimes suffer bill deformities as a result of 62 BIRDS WITH ABNORMAL BILLS incorrect feeding, lack of grit or related causes. These may be per- manent or only temporary (e.g. Wilkinson 1 9 5 3 > Rankin 1953). However, the processes involved in such deformities are obscure, to quote Groebbels (1932), “Holmgren found that pigeons fed on fibrin and meat grew elongated and downward-curving bills. Brandes, who repeated the experiment, came to an entirely negative conclusion. j. | _ Yealland says that in the London Zoo few birds sutler defor- mities; those that do are principally parrots, but include some birds of prey and waders. Other species which may be aftected in captivity include Choughs (Pyrrhocorax pyrrhocorax ) (B. C. Turner) and various finches (Groebbels 1932). All these are birds whose beaks are, in the wild, subject to heavier wear than those of purely insectivorous species — on food, stones, sand or other abrading surfaces. The effects of what has been called “industrial contamination’' have been suggested as the cause of some deformities (Ash 1958). The birds concerned were a House Sparrow and several Partridges. Their bills were overgrown (three or four times the normal size) and badly mis-shapen. They were examined by Dr. J. M. Harrison who pointed out the presence of warty excrescences which, he said, might have been caused by a carcinogen. Except for the sparrow, the birds were otherwise in good condition, but all showed very dirty plumage. The deformed Partridges were found near a \ orkshire colliery, the sparrow at Gravesend. BEHAVIOUR AND SURVIVAL (a) Behaviour apparently not affected I have received a total of 48 records in which the behaviour of a bird with an abnormal bill was observed, and in only eight was there no apparent alteration in habits. Seven of these eight (including five Starlings) referred to wild birds in which the abnormality took the form of elongation, although in one case (a Blue Tit) there was also some lateral displacement. The last bird, whose bill was not elon- gated, was a captive cock Budgerigar with the lower mandible knocked to one side; this did not prevent him from feeding himself success- fully and his mate “quite well”, however (F. C. Gower). In the case of the seven wild birds, it would probably be more accurate to say that no irregularities in behaviour were seen: on the whole it seems unlikely, for example, that a Starling with a curlew-type bill would be as successful at preening, or feeding its mate, as a normal one. (b) Behaviour definitely affected The forty cases of abnormal behaviour included nineteen Starling records and twenty-one of fifteen other species. In ten different species, ranging from Starling and Blackbird to Green Sandpiper ( T ringa 'oc hr opus), and Chough to Great Tit, the head was turned on one 63 BRITISH BIRDS side to feed. For example, a Starling recorded by Dady (1951) in Regent’s Park, London, with a decurved bill about two and a half inches long, turned its whole head on one side to pick up food at about the same distance from the base of the bill as it would have done if it had been normal. A Starling reported by B. C. Turner, with a very long decurved upper mandible and apparently normal lower mandible, used the long tip as a probe for testing potential food. Its head was then turned on one side, and it picked its food up at the tip of its lower mandible. Another Starling, reported by Warham (1951), had a sharply decurved upper mandible and a deformed or broken lower mandible, and it fed by a series of sideways scooping movements which, however, were not always successful. Warham noted tnat this bird seemed more quarrelsome when feeding than the other Starlings with which it associated. B. Coleman, on the other hand, observed that a Starling with a very long, thin bill would not feed whilst other Starlings were feeding — suggesting some fear of them. Turning the head on one side to feed leads, after a time, to some abrasion. In the case of a Green Sandpiper (Amann 1950) where the upper mandible was 3 mm. shorter than the lower, one side of the bill was worn, showing that the head had been turned to that side when feeding. Two Starlings with elongated bills had the lores bare, presumably for a similar reason (P. A. Rayfield, Williamson 1951). The Red-breasted Sapsucker (Bowles 1908) whose upper mandible was about two and a half times the normal length, and which fed by turning its head on one side, evidently had no difficulty in feeding and was fat and healthy. Similarly, a cock Great Tit with an elon- gated upper mandible learnt to tilt his head on one side to pick up food (Howard 1951). His mate at first hesitated to accept food, but soon learned to turn her head on one side too. The House Sparrow with the incredible bill shown in Fig. 6 survived for a year and a half throughout which period the bill was growing— by scooping up grain with its head turned to one side and flat on the ground (Donark 1950). This was an artificial source of food, of course j it is doubtful whether the bird could have lived in the wild state with such a bill. A similar case concerned a Blackbird with elongated and crossed mandibles, which survived for three years on food given to poultry and came to judge their feeding time with considerable accuracy (W. S. Craster). A remarkable change of behaviour occurred in a Hoopoe which was wounded by gunshot in the upper mandible. It was kept in a large cage, and procured its food by scratching with its feet. “When a worm turned up, it threw it with great skill with its lower mandible into the air, and then caught it in flight” (Count Emilio Ninni, quoted by Moltoni 1949). A cock Blackbird, believed to be ten years old (a considerable age for this species), suffered a broken upper mandible in an encounter 64 BIRDS WITH ABNORMAL BILLS with a cat (J. Burton). This bird also fed by putting its head on one side and scooping up food provided for it in a garden. It drank by ^catching drops of water from leaves or drainpipes. Drinking is clearly a problem for many birds with bill deformities. Captive i Choughs, in which the bill frequently becomes overgrown in such a manner that the tips cross, both feed and drink by turning their heads ■ slightly to one side. In this case, however, the action is part of these birds’ normal behaviour pattern, as apparently the head is also inclined sideways when drinking from very shallow water (B. C. Turner). A Starling with an elongated upper mandible drank similarly (K. G. i Clark per I. D. Woodward). There are no other drinking records. A case of a deformity in one bird leading to an alteration in the behaviour of another has already been mentioned (the Great Tit feeding its mate). A most remarkable case involving more than one bird relates to a male Black-headed Grosbeak which was collected in 1926 by Dr. Loye Miller (Fox 1952). It had a flange of rhamphotheca on the left side of the lower mandible extending across the side of the upper mandible, so that “the bird could only have fed from the right side, and must have been considerably handicapped”. Nevertheless, it was apparently in good condition. Dr. Miller had seen one gros- beak feeding another and presumed that it was the male courtsnip- feeding the female; however, the deformed bird which he shot proved to be the male. Fox continues: “There was no doubt in his mind that a hen had been feeding the cock. It seems probable that the well-fed condition of the cock, and his recent obviously successful migration, had been made possible by the efforts of the hen. At least, as a result of the cock’s handicapped condition and the attention shown to him bv the female, the dependency of the cock on the hen for an extended period seems evident.” This would be quite remarkable and it is unfortunate that its absolute veracity is in doubt. The extraordinary thing about all these birds is that they survive at all. In addition to the cases already discussed, two more deserve attention. The first concerns a Pink-footed Goose ( Anser brachyrbyn- chus ) which had had half of its upper mandible shot away (G. Atkinson- Willes). The injury was obviously an old one, since the damaged part showed a considerable amount of new growth and the tooth at the tip of the lower mandible had become enlarged, presumably from lack of wear. How a grazing goose could survive with such an injury — and it was in good condition when shot — is indeed a problem. So is the case of the young Hawfinch ( Coccothraustes coccotbraustes ) shown in plate 9a. This bitd, whose partial lack of bill appeared to be con- genital, was ringed near Basle, Switzerland, and shot 43 days later about 460 kilometres away in the south of France (Amann 1950). Its weight was normal and it had evidently migrated normally, although onlv for the proximal 2 mm. of the bill did the mandibles meet. 65 BRITISH BIRDS Table 3 — Weights of birds with abnormal bills Those marked with an asterisk were apparently migrants and the “normal” weights for the species have been taken from Browne and Browne (1956) and Turcek (1956), except in the caset the Hawfinch where the “normal” weight is the range of six others caught on the same da; Each of the other three “normal” weights is that given by the authority concerned. The Crests Lark had been refrigerated for several days beforehand and so may have been below its trt weight. K. Williamson described his Blackbird as “abnormally low, even for a migrant” and hi Meadow Pipit as “quite good for a migrant” “Norma! Species Deformity Weight (gm.) weigh (gm-) Bar-tailed Godwit {Limosa lapponica ) Rami of lower mandible unfused (Harrison 1947) 227 340 Crested Lark {Galerida crista/a) Bill elongated (Moltpni 1949) 36 40-45 Magpie {Pica pica ) Upper mandible elongated and decurved (B. C. Turner) 220 210 ♦Blackbird (Tardus merula ) Upper mandible 3.5 mm. short (K. Williamson) 83.27 80-96 ♦Blackcap (Sylvia atricapilla ) Upper mandible elongated and decurved (Ruttledge 1952) 19.81 17-20 ♦Meadow Pipit ( Antbus pratensis) Lower mandible 2 mm. short (K. Williamson) 18.2 19 ♦Hawfinch (Coccofbraas/es coccothraustes) Bill congenitally underdeveloped (F. Amann) 50.2 48.59 Weight can be taken as some indication of general condition. Birds with abnormal bills have been weighed on several occasions and the results are set out in Table 3. It will be seen that only the Bar- tailed Godwit ( Limosa lapponica) had a weight appreciably lower than normal, which is at first sight surprising and suggests that the birds were able to feed themselves quite well, despite their deformities. Nevertheless, it is evident that nearly all the birds mentioned in this section showed some plasticity in behaviour. A number of examples have already been given in which individuals learned to feed themselves by turning their heads on one side. Other aspects of behaviour are also affected: feeding the mate, drinking, and possibly reactions towards, or by, other members of the same species. Greater tameness has been recorded several times: this gives access to readily obtained food, but may be the result of near-starvation, just as birds become tamer in very cold weather. Feral Pigeons, of course, subsist to a very large extent on food provided, intentionally or otherwise, by- man. Overgrowth of the upper mandible is particularly common in these birds, and probably associated with a short lower mandible (D. Goodwin). Changes in feeding habits, especially with regard to the type of food taken, are well known in birds (e.g. tits and milk bottles), and there is clearly an advantage towards survival for a bird with a deformed bill that can adapt its feeding methods. BIRDS WITH ABNORMAL BILLS The ease with which a bird can adjust its motor patterns of behaviour probably depends, amongst other things, on the speed of the onset of tthe deformity. Presumably it is more difficult for a bird to survive if the change is sudden (e.g. due to injury) rather than slow (e.g. due to overgrowth); but there are no data on this point, as yet. It would also be interesting to know whether the chances of survival are higher in juveniles than in adults. Whilst the number of deformed birds which survive is remarkable, inevitably there are many which do not. A minority of those recorded have been described as thin and weak, with the feathers in poor con- dition. D. Goodwin noticed that Feral Pigeons with badly overgrown beaks were characterised by drooping wings (the primaries actually dragging on the ground), uplifted tail and thrown-back head. Never- theless, of the 60 or so records of Starlings with abnormal bills, excluding those “collected”, there is only one in which the bird died and that was nearly two years after it was first seen (P. W. D. Waite). On the other hand, of five Oystercatchers with elongated bills (which in three cases were also crossed and curved), all but one were found dead (J. B. Bottomley, Miss A. M. Mackintosh, W. T. C. Rankin 1953 and in lift., and Rutherford and Wagstaffe 1955); in two cases followed a cold spell. The only other record of death in a wild bird concerns a melanistic Blue Tit with curved and elongated mandibles, which was found drowned in a shallow bowl “from which a normal healthv bird would have had no difficulty in escaping” (Sage 1956). There is also circumstantial evidence in the case of the Great Tit shown in Fig. 2 that it did not survive the winter (P. P. G. Bateson). Four birds actually appeared to gain some advantage from their deformities. A. D. Townsend watched a Great Tit with an elongated and crossed upper mandible (the tip of the lower being broken) and found that it could not only feed normally on fat, but also seemed to extract nuts from their shells faster than a normal bird, although it had some difficulty in picking them up afterwards. W. P. White made similar observations on another Great Tit, which also appeared to gain advantage in threat displays at a Chaffinch ( Fringilla coelebs). The Red-breasted Sapsucker observed by Bowles (1908) used its long upper mandible rather like a nut pick, digging insects to the surface with it, and then picking them up by turning its head to one side. A hen Indian Silverbill ( Euodice malabarica ) belonging to A. FI. Flayes had the mandibles slightly overgrown and crossed; it had difficulty in cracking seeds, but found the sharp points useful in squabbles with other females! Although a number of birds have had their deformities “manicured” with nail-clippers and scissors, there is, regrettably, only one record which throws any light on subsequent behaviour. This concerns a Feral Pigeon which, although free-living, had been hand-fed from the 67 BRITISH BIRDS nestling stage to an age of 19 months (W. Shipp and K. N. Brock- house). Its upper mandible was strongly decurved and there is no doubt that the bird owed its survival to being hand-fed. However, its beak was eventually trimmed to normal length and it was then kept in a cage for several days, during which time it learned to feed itself for the first time in its life. It was finally released, and was still alive four months later. (05.7768, which showed that it was a Manx Shearwater {Procellaria O uffinus ) ringed as a chick on Skokholm, Pembrokeshire, on 9th September i960. Since the first record of a British-ringed Manx '■shearwater in South America in 1951 {Brit. Birds, 45 : 346), seventeen of these birds have been recovered on the coasts of Brazil and Argentina between latitudes i8°S and 37°S, the majority in the second half of October or in November. If the bird under discussion reached Australia from these South American wintering grounds, an east- . about journey across the South Atlantic and Indian Oceans would seem tthe easier, though longer, route, for westerlies prevail throughout the wear south of latitude 40°S. This is apparently the first record of the Manx Shearwater in Australia, although one cannot preclude the possibility that the bird died at sea and drifted as a corpse for the last stage of its journey. It is also the first recovery of a British-ringed bird in that continent. ^Spotted Redshanks up-ending to catch Sticklebacks. — J. H. Taverner has recently recorded the habit of Spotted Redshanks ( Tringa i erjthropus ) up-ending to feed {Brit. Birds, 54: 403-404). I saw similar behaviour on the marshes at Shotton, Flintshire, on several occasions in late September and October 1961. Parties of eight to 22 Spotted Redshanks were habitually feeding bv swimming in the deeper pools and up-ending in the manner of ducks. The food taken was identified as Sticklebacks {Gasterostens aculeatus). These fish were brought to the surface and swallowed with some difficulty, the birds often opening their bills and jerking their necks for several minutes. Even then the outline of a large Stickleback was sometimes visible in a bird’s neck for a considerable while. R. J. Raines Barn Owl apparently killing Weasel. — The note by T. J. Lawes on the killing of Weasels {Mustela nivalis ) by Short-eared Owls {Asio Ham mens') {Brit. Birds, 54: 326-327) prompts me to write of the remains of a Weasel which I discovered in a barn at Corpusty, Norfolk, on 14th August 1961. Only the hind parts of the animal — half of the trunk, the hind legs and the tail — were to be seen and these were lying near several pellets ejected by a Barn Owl {Tyto alba) which regularly inhabits this particular building. It would seem, therefore, that Weasels are occasionally taken as food by Barn Owls, although there is no mention of this in The Handbook. J. M. Last Passerines feeding on blackberries. — With reference to the recent notes on birds eating berries {Brit. Birds, 54: 122, 124-125, 405), it may be of interest that I have personally recorded 24 species feeding on blackberries (R ubus fruticosus) at Dungeness, Kent, during the autumns BRITISH BIRDS of i960 and 1961. Both grounded migrants and local populations make use of the ready supply of food in the expanses of bramble on the shingle there. The birds concerned have been: Wren ( Troglodytes troglodytes ) Mistle Thrush (Turdus viscivorus) *Ring Ousel ( Turdus torquatus ) Song Thrush ( Turdus Philomelas') Redwing (Turdus musicus) ^Blackbird (Turdus merula) Wheatear (Oenanthe oenanthe) Stonechat (Saxicola torquata) Whinchat (Saxicola ruhetra ) Redstart (Phoenicurus phoenicurus ) Nightingale (Luscinia megarhynchos) Bluethroat (Cyanosylvia svecica) *Robin (Erithacus ruhecula ) Sedge Warbler (Acrocepha/us schoenobaenus ) Blackcap (Sylvia atricapilla) Barred Warbler (Sylvia nisoria) ^Garden Warbler (Sylvia boritt) Whitethroat (Sylvia communis) *Lesser Whitethroat (Sylvia curruca) Willow Warbler (Phy/loscopus trochilus) Chiffchaff (Phylloscopus collybita) Spotted Flycatcher (Muscicapa striata) Pied Flycatcher (Muscicapa hypoleuca) *Bulltinch (Pyrrhula pyrrbula) *Blackberry-eating mentioned in The Handbook When one is handling birds for ringing, it is comparatively simple to establish if they have recently fed on blackberries. Juice stains are often present on the plumage and an examination of the bill and inside the mouth usually shows traces of the fruit. The colour of the drop- pings of trapped birds is also a clear indication of the presence of blackberries in the diet, as the stains on many ringers’ clothes will show! R. E. Scott Pre-coital display of Magpies. — In view of the scarcity of published accounts of the pre-coital displays of the Magpie ( Pica pica), the follow- ing notes seem worth recording. The species is quite common in Totley and other well- wooded suburbs of Sheffield, Yorkshire, and a pair which I watched in the spring of 1961 were renovating an old nest in a garden near mine. At 7.20 a.m. on 27th April, when they had been engaged in this work for several days, the birds were feeding together on a patch of bare earth. After a few minutes one of them, presumed to be the female, adopted a position in which its body and tail were flattened to the ground, its head was slightly raised and its wings, held half-open and drooping, were quivering rapidly; it should be emphasised that only the wings, and not the tail, were quivering. This posture and the associated movement seemed to combine elements of begging and soliciting displays. The other bird, presumably the male, was about three feet away at the time but turned and began to approach the female. He hopped towards her with his tail held side- ways at an angle to his head and body and slightly raised, and at the same time vibrated his open wings, which were held stiffly out from his body. The last action was so rapid that the white areas on his wings appeared blurred and, from my view-point in front of and above him, presented a very striking effect. After two or three hops in this position he mounted the female from behind and coition occurred 88 NOTES >riefly. When the birds parted the female hopped a short distance way, apparently feeding, and then flew up to the nest which was bout seventy yards away. The whole sequence of events lasted rather e’ss than two minutes. Unfortunately, I watched the first part of he display through a closed window and if the birds called the sounds were inaudible to me, but during the last stages they were definitely ilent. D. Goodwin, in his paper on the displays of the Magpie {Brit. Birds, P5 : 1 1 3-122), mentioned wing-flirting and fluttering as being used by •irds of either sex towards their mates, but not in terms of a soliciting display by the female, nor do any of his descriptions convey as high a degree of intensity as that of the male in mv observations. Both he ; nd F. J. Stubbs {Brit. Birds, 3 : 334-336) referred to the effective show »f white in the plumage of displaying Magpies and this was the most impressive part of the events which I observed. T. M. Clegg Wotes on the food of the Marsh Tit. — The following notes on the * ood of the Marsh Tit {Pants palustris ) seem worth placing on record. \.t Perham Down, Hampshire, I observed this species eating seeds of he spear thistle ( Cirsium vulgarc ) and upright hedge-parsley {Torilis rponica ) in August 1949, and those of the lesser burdock {Arctium ' 'linns ) on 9th October 1949. At Waterford, Plertfordshire, I saw a ingle bird eating berries of the hawthorn {Crataegus monogyna) on 9th October 1955, and at Little Berkhamsted, Hertfordshire, I watched >ne consume several seeds from the pods of a spindle tree {Euonymus 1 uropaeus) on 29th October 1961; this plant is poisonous. Ernest ! llezard {Trans. Carlisle Nat. Hist: Soc., 8 : 83) found nutlets of the alder Ain us glutinosa ) in the stomach of a male killed at Kentmere, West- norland, on 17th December 1935, and regular feeding on the fallen ruit of a French pear {Pjrus communis) has also been recorded in autumn Brit. Birds, 44: 109). It will be noted that all the above records refer to the autumn or winter months. During the breeding season the species is probably nainly insectivorous. For example, on 13th May 1961, at Northaw, lertfordshire, I spent 45 minutes watching a pair of Marsh Tits feeding oung. Only insects were brought, the most numerous item being aterpillars of the Oak Leaf-roller Moth {Tortrix viridana), but fymenoptera (Cynipoidea) and Diptera (Tipulidae and Asilidae) were Iso represented. Bryan L. Sage long Thrush incapacitated by seed heads. — There was a consider- ble influx of Song Thrushes {Turdus pbilomelos ) and Blackbirds (T. 'serula) on Holy Island, Northumberland, during the night of 2nd/3rd October 1961. The following morning, while walking through the lunes, I came upon a Song Thrush which was unable to flv and, on 89 BRITISH BIRDS catching it, I found that its wings were “glued” to its body by a mass of the prickly seed heads of the alien Acaena anserinifolia which grows in abundance in the dunes. It could not, in fact, move its wings, but I managed to remove all the seed heads before I let it go. The finding of a juvenile Wheatear ( Oenanthe oenanthe ) in a similar state was recorded in the Ornithological Report for Northumberland Durham for igjo\ 122, and James Lilburn, who resides on Holy Island, told me that Redwings (T. musicus) and duckling Shelduck ( Tadorna tadorna ) have been found dead with varying amounts of these seed- heads covering them. L. P. Alder [A number of records of birds trapped by the seed heads of burdocks ( Arctium ) and other plants were recently discussed in British Birds (54: 246) and a letter on a similar fate which befell a bat appears on page 96 in this issue.— Eds.] Blackbird dead on nest after grass fire.— It was with considerable interest that I read the account by P. M. Hope and G. E. Pipe of a Whinchat’s ( Saxicola rubetra ) nest surviving a grass fire (Brit. Birds , 54: 364), for it reminded me of a comparable occurrence at Corby, Nor- thamptonshire, in April 1957 (unfortunately the exact date was not recorded). The fire took place in an area of coarse, dry grass dotted with hawthorn, blackthorn and bramble. Afterwards, in the remains of a small hawthorn four feet high, I found a Blackbird’s ( Turdus merula) nest with the female in the incubating position, but quite dead ! The outside of the nest was partially burned, but the inside was unharmed and still contained four eggs which proved to be in an advanced stage of incubation. Not only does this illustrate the insulating qualities of the nest, but also the suicidal reluctance of the female to desert her ep-reed on the banks of the Tama, the river which flows through Tokyo 5 nd Kawasaki. Like so many rivers which run through large towns, he Tama is subject to increasing pollution as the human population • ises. Mr. Sakae Tamura’s aim was to photograph what was left of :'rhe bird life before it vanished completely. The book opens with an ■ erial photograph of the river and a number of illustrations of the modern development along its banks. The main part is then devoted t o a series of photographs of each of the chief breeding species. The number of different birds seems to be pitifully small, but Mr. Tamura l ias endeavoured to cover every one thoroughly. The Little Tern, I or example, is shown hovering over the river and diving down to catch I ish, incubating its eggs (four photographs illustrate the actual hatch), t aking away the empty shells, feeding the young on fish, and so on r ight the way through its life until it migrates from the area. Among t he other birds treated equally fully are the Little Ringed Plover, Kentish Plover, Long-billed Plover ( Charadrius placid/ts), Fan-tailed 'Warbler, Skylark, Japanese Wagtail (d lotaci/la grandis) and Great Reed 'Warbler, while the Great Tit, Chinese Bamboo Partridge (Bambusicola horacica ) and Eastern Turtle Dove are also portrayed. Thus, seven of the species concerned are familiar to us in Europe while an eighth, the Eastern Turtle Dove, has occurred as a vagrant o Britain on three occasions) and it is useful to see illustrations of hese in habitats on the other side of the world. There are also some nteresting action shots, but by western standards the photography cannot be said to be good. Several of the pictures have been over- :nlarged from the original 35 mm. negatives, with the result that lefinition has been lost and the grain has become obtrusive. Fore- grounds tend to be badly out of focus because the photography has oeen from too low a viewpoint. The shots of the change-over at he nest of both Little Ringed and Long-billed Plovers should have ieen excluded, even though they are interesting, because in one case :he foreground bird is completely out of focus and in the other there s a mass of blurred movement. The eleven colour plates are rather nixed and generally not a success. But, for all its photographic aults, this is a worth-while book because it illustrates the way in which :he Japanese are now beginning to educate the new generation to a greater concern for the animal life of their country. Eric Hosking 95 !!f FEBiS*2 Letters What is a British bird ? Sirs, — The recent note and subsequent correspondence on the occur- rence of a White-throated Sparrow ( Zonotrichia albicollis ) in Hampshire (Brit Birds , 54: 366-367 and 439-440) prompts once more the question: what is a British bird ? I do not oppose the decision to regard ship- assisted passage as a biological factor, but it seems to me difficult, if not impossible, to make distinctions about the “freedom” of such passage. What is the difference, for example, between a bird that lands on a ship of its own accord and is then fed by the passengers and one that is deliberately brought on board and subsequently released ? This leads me to what seems a far greater inconsistency — the recog- nition of records of odd birds that make the passage from America and the failure as yet to make honest Britons of established intro- ductions like the Mandarin ( Aix galericulata ), Egyptian Goose (Alo- pocben aegyptiacus) and Amherst Pheasant (Cbrysolopbus amherstiae). Even though these occur only in restricted areas, their biological influence on the environment is much greater than that of the occasional American Passerine. Once a bird breeds regularly in a free state, surely it is realistic to accept it as a member of our fauna, whatever its origins? Bruce Campbell Animals trapped by plants Sirs, — In view of the recent note and editorial comment on birds being trapped by plants {Brit. Birds, 54: 246), it seems relevant to suggest that small mammals may be open to similar dangers. On 25 th August 1961, in my garden at Stolford, Somerset, I found a newly dead Pipistrelle Bat ( Pipistrellus pipistrellus ) with its left “wing” firmly held by the bristles of some rough bristle grass (Setaria verticil- latci). Probably it had caught on the grass head in flight, perhaps while after insects, as it is most unlikely that it would have attempted to settle there. It seems possible that the Sand Martin ( Kiparia riparid) described by M. Goodman (in the note referred to above) may have become entrapped in a similar way. J. V. Morley [Another note on a bird entangled with seed heads appears on pages 89-90 in this issue. — Eds.] Request for information Cold weather migrations. — The British Trust for Ornithology and British Birds are analysing the unusually impressive cold weather migrations of the week follow- ing 28th December 1961. All records of movements, arrivals and departures at this period arc of interest, including times, species, numbers and directions (also weights of birds caught). Details should be sent to Kenneth Williamson, B.T.O., 2 King Edward Street, Oxford, by 28th February. 96 late 18. Screaming party of Swifts ( Apus apus ), Glasgow, summer 1951. hcsc noisy, clashing gatherings arc a characteristic sight and sound of the colony n warm summer evenings; they arc thought to help to unify the group and. they lay a definite. part in the preparation for migration (page 74) (photo: C. Eric Palmar) Notice to Contributors ifis/j Birds publishes material dealing with original observations on the birds of r 'itain and western Europe, or, where appropriate, on birds of this area as observed other parts of their range. Except for records of rarities, papers and notes are ormally accepted only on condition that the material is not being offered to any her journal. Photographs (glossy prints showing good contrast) and sketches ate elcomed. Proofs of all contributions accepted are sent to authors before publica- 5n. After publication 25 separates of papers are sent free to authors (two more authors of one paper receive 15 copies each); additional copies, for hich a charge is made, can be provided if ordered when the proofs are ! turned. Contributors are asked to observe the following points, attention to which saves ice waste of much editorial time on trivial alterations: Papers should be typewritten with double spacing, and on one side of the sheet ily. Shorter contributions, if not typed, must be clearly written and with similar racing, failure to help in this way may result in delays to publication. , Notes should be worded as concisely as possible, and drawn up in the form in ! lich they will be printed, with signature in block capitals and the writer’s address i ;arly written on the same sheet. If more than one note is submitted, each should ' on a separate sheet, with signature and address repeated. In the case of rarity7 ^;ords, any supporting description which is too detailed for publication should be r eached separately. Certain conventions of style and layout are essendal to preserve the uniformity7 any publication. Authors of papers in particular, especially of those containing ■ stematic lists, reference lists, tables, etc., should consult the ones in this issue as a ide to general presentation. English names of species should have capital dais for each word, except after a hyphen (e.g. Willow Warbler, Black-tailed ndwit), but group terms should not (e.g. warblers, godwits). English names are ose used in The Handbook of British Birds, with the exception of the changes listed in itish Birds in January 1953 (46: 2-3). The scientific name of each species should given (in brackets and underlined) immediately after the first mention of the lglish name. Subspecific names should not be used except where they are evant to the discussion. It is sometimes more convenient to list scientific mes in an appendix. Dates should take the form “1st January 1962” and no aer,f except in tables where they may be abbreviated to “1st Jan.”, “Jan. 1st”, or cn Jan. 1 , whichever most suits the layout of the table concerned. It is rticularly requested that authors should pay attention to reference lists, which terwise cause much unnecessary7 work. These should take the following form : icker, B. W. (1949): “Species and subspecies: a review for general ornitholo- gists”. Brit. Birds, 42: 1 29-1 34. (therby, H. F . (1894): Forest Birds: Tbeir Haunts and Habits. London, p. 34. i rious other conventions concerning references, including their use in the text, ■ Yuld be noted by consulting examples in this issue. Tables should be numbered with arabic numerals, and the title typed above in : : Style used in this issue. The title and any7 headings within the table should t be underlined, because this sometimes makes it difficult for the editor to indicate : : type to be used. It is most important that the layout of each table should be efully planned with an eye to its final appearance; above all, it should be borne mind that tables must either fit into the width of a page, or be designed to fit a ole page lengthways. All tables should be self-explanatory7. Figures should be numbered with arabic numerals, and the captions typed on a iarate sheet. All line-drawings should be in indian ink on good quality drawing 7 >er (not of an absorbent nature) or, where necessary, on graph paper, but this st be light blue or very pale grey. It is best if maps, graphs, etc., are drawn twice size of the final reproduction (ideally, therefore, for the normal 4" width the ginal should be 8' wide); sketches of birds, however, should be only slightly ger than the size at which it is intended they should appear. It is always most Yortant to consider how each drawing will fit into the page. The neat insertion lettering, numbers, arrows, etc., is perhaps the most difficult part of indian ink iwing and, unless he has had considerable experience of this kind of work, an hor should seek the aid of a skilled draughtsman. THE PICK OF THE WORLD’S GREAT BINOCULARS ON 14 DAYS’ FREE TRIAL SEND II x 60 WRAY(o$ illustrated) A remarkable, new, fully coated binocular, which combines good magnification with high light transmission. Including hide case. 638 . 17 . 10 6 X 30 ARMY BINOCULARS An excellent general purpose binocular of good performance, which will stand up to a great deal of rough usage. Cost approx. £20. £7 . 15.0 Ideally suited to bird-watching requirements, this in- strument has many outstanding characteristics which combine to make it one of the world’s greatest binoculars. The advanced optical system produces an extraordinary high light transmission, giving maximum performance even under the dullest conditions. Another feature is the wide field of approximately 660 yards at 3 miles, plus an excellent stereo- scopic or 3D effect. These binoculars are in perfect con- dition and are supplied complete with leather case and straps. Current value estimated at £60. Offered under our 5 years’ free maintenance service at Ex-Admiralty 7x50 CANADIAN & U.S. NAVAL BINOCULARS " FOR NEW ILLUSTRATED CATALOGUE 7 x 50 PRISMATIC TELESCOPE CHARLES FRANK LTD. 67-75 Saltmarket Glasgow C.1 Tripod mounted. A heavy instrument of superb performance. Estimated cost £120. £9.15.0 Phone. BELL 2106/7 Est. 1907 10 X 70 ROSS BATTLESHIP BINOCULARS Britain's greatest stocks of New.Usedand Ex-Govt. Binoculars, Telescopes and Navigational Equipment. Tripod mounted. Cost over £200. £45 . 0 . 0 Printed in England by Dierae. * Reynold, Ltd- I E“,C.C"” Published by H. F. & G. Withcrby Ltd., 5 Warwick Court, VC.C.i - - British Birds Principal Contents , ; . \ Mass mortality among European Common Terns in South Africa in April-May 1961 M. K. Rowan Development of paddling and other movements in young Black-headed Gulls Miriam Rothschild How do Black-headed Gulls distinguish between eggs and egg-shells ? N. Tinbergen, H. Kruuk, M. Paillette and R. Stamm Studies of less familiar birds: 117 — Scarlet Grosbeak Eric Hosking and Kenneth Williamson in January 1962 M. P. Harris Foot-paddling in gulls N. Tinbergen Notes Three Shillings March British Birds AN ILLUSTRATED MONTHLY JOURNAL Edited bj P. A. D. Hollom E. M. Nicholson I. J. Ferguson-Lees Stanley Cramp Photographic Editor : Eric Hosking Hon. Editors: W. B. Alexander N. F. Ticehurst Editorial Address: 30 St. Leonard’s Avenue, Bedford Contents of Volume 55, Number 3, March 1962 Page Weights from five hundred birds found dead on Skomer Island in January 1962. By M. P. Harris . . . . . . . . . . . . . . 97 Mass mortality among European Common Terns in South Africa in April- May 1961. By Mrs. M. K. Rowan . . . . . . . . . . . . 103 Development of paddling and other movements in young Black-headed Gulls. By Miriam Rothschild (Hon. Mrs. G. Lane) (plate 19) .. .. 114 Foot-paddling in gulls. By Dr. N. Tinbergen . . . . . . . . 117 How do Black-headed Gulls distinguish between eggs and egg-shells? By Dr. N. Tinbergen, H. Kruuk, Miss M. Paillette and Dr. R. Stamm. Photographs by Dr. N. Tinbergen and John Haywood (plates 20 and 21) 120 Studies of less familiar birds: 117 — Scarlet Grosbeak. By Kenneth Williamson. Photographs by Eric Hosking (plate 22) .. .. .. 130 Notes: — Peregrine incubating Kestrel’s eggs (Dr. D. A. Ratcliffe) . . . . . . 131 Water Rail killing Wren (H. E. Axcll) .. .. .. .. .. 132 Woodcock alighting on bird table (Frank Norris) .. .. .. .. 133 Distraction displays of Common Gulls (Major Robert F. Ruttledgc) . . 133 Feeding behaviour of Kingfishers (J. T. R. Sharrock) . . . . . . 134 House Martins building nest of cement (Arnold Darlington) .. .. 134 Unusual death of House Martin (G. R. Benne t) .. .. .. .. 133 Hooded Crow asleep on the ground (Dr. P. R. Evans) . . . . . . 135 Rook asleep on the ground (J. C. Manson) . . . . . . . . 136 Probable inheritance of crossed mandibles in Robins (Mrs. V. M. Caird) 136 Annua) subscription £2 (including postage and despatch) payable to H. F. & G. Witherby Ltd., 5 Warwick Court, London, W.C.i Special Announcement We are proud to introduce a new range of lightweight prism binoculars by Jacob Pfeifer of Wetzler, for which we are the Sole Agents for the United Kingdom PFEIFER BINOCULARS First quality glasses, fully coated on all optical surfaces, have a high light intake and by reason of their extremely light weight are ideally suited to the bird watcher. 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The advanced optical system produces an extraordinarily high light transmission, giving maximum performance even under the dullest conditions. Another feature is the wide field of approximately 660 yards at 3 miles, plus an excellent stereo- scopic or 3D effect. These binoculars are in perfect con- dition and are supplied complete with leather case and straps. Current value estimated at £60. Offered under our 5 years’ free maintenance service at THE PICK OF THE WORLD’S GREAT BINOCULARS ON 14 DAYS’ FREE TRIAL ^ v ''w'J SEND FOR NEW ILLUSTRATED CATALOGUE CHARLES FRANK LTD. 67-75 Saltmarket Glasgow G.t. Phone. BELL 2106/7 Est. 1907 Britain's greatest stocks of New, Used and Ex-Govt. Binoculars, Telescopes and Navigational Equipment. II X 60 WRAY (as illustrated) A remarkable, new, fully coated binocular, which combines good magnification with high light transmission. Including hide case. £38 . 17 . 10 6 X 30 ARMY BINOCULARS An excellent general purpose binocular of good performance, which will stand up to a great deal of rough usage. Cost approx. £20. £7 . 15.0 7 x 50 PRISMATIC TELESCOPE Tripod mounted. A heavy instrument of superb performance. Estimated cost £120. £9 . 15 . 0 10 X 70 ROSS BATTLESHIP BINOCULARS Tripod mounted. Cost over £200. Ex- Admiralty 7x50 CANADIAN & U.S. NAVAL BINOCULARS British Birds MI*T Weights from five hundred birds found dead on Skomer Island in January 1962 ' By M. P. Harris Department of Zoology, University College of Swansea KOMER, 722 ACRES, is the largest of the islands off the Pembroke- ire coast and one of the most westerly points in Wales. A visit as made there from 2nd to 5th January 1962, during one of the coldest ells of weather this country has experienced for many years. Large : imbers of birds, which had apparently been forced out from the oinland by snow and ice, were trying to exist on the island, being her unwilling or unable to attempt the crossing to Ireland. The ecies concerned, and some indication of the numbers involved, are wen in Table 1. It was virtually impossible for these birds to obtain food or water, cause the whole island was frozen hard, and many of them were Mr. Harris is to be congratulated on making the most of an interesting, if somc- at sad, opportunity. This paper was received soon after the event and we have dished it as quickly as possible because, although complete in itself, it records integral part of the impressive hard weather movements that took place in the d spell at the turn of the year. We hope, therefore, that it will serve as a reminder he proposed analysis already mentioned in the February issue (page 96). Apart m many sight records of large-scale migrations to the west and SSW (with a few :hc east along the south coast), and records of colossal casualties in Ireland and some coasts of England and Wales, there was also an interesting scries of ringing Dveries from south-west England, Wales, Ireland, northern and western France north Spain at this time. Anyone who has any relevant observations for the :k or ten days beginning 28th December 1961, and has not yet submitted a unary, is asked to write to Kenneth Williamson, British Trust for Ornithology, Cing Edward Street, Oxford, as soon as possible. Information required udes records (however fragmentary) of visible migration, with dates, times, ;ies involved, numbers and directions; details of large-scale deaths; and any ilabie weights of birds caught or found dead, with dates, times and localities.— Eos 97 BRITISH BIRDS Table i— Numbers of birds seen and dead on Skomer Island, Pembrokeshire, 2 nd-jth January 1962 All figures in the “Maximum seen” column are estimates and not counts Maximum Found seen dead Remarks Lapwing (V anellus vanellus ) Golden Plover ( Cbaradrius apricarius ) Snipe ( Gallinago gallinago) Woodcock ( Scolopax rusticola ) Curlew ( Numenius arquata ) Skylark {Alaucla arvensis ) Wren ( Troglodytes troglodytes) Mistle Thrush ( Jurdus viscivorus ) Fieldfare ( T urdus pilaris) Song Thrush (Jurdus phi/omelos) Redwing ( Jurdus musicus) Blackbird ( 'Jurdus merula) Stonechat ( Saxicola torquata) Meadow Pipit ( Anthus pratensis) Pied Wagtail ( Motacilla alba) Starling (St limits vulgaris) Greenfinch ( Chloris cbloris) Goldfinch ( Carduelis carduelis) 10 Linnet ( Carduelis cannabina) Chaffinch (F ringilla coelebs) 20 Brambling (F ringilla mon/ifringilla) 10 10 Many others very weak 1 - No sign of ill effects - No sign of ill effects - Some weak - Many passing through 10 Many had apparently left 6 }6 Many too weak to fly 18 245 Many too weak to fly 3 1 Large decrease from usual 23 1 187 Movement made maximum 4 inaccurate 2 15 2 100 2 500 5° + 100 ? p 15 1 ,000 + 500 + thousands 1,000 p 200 dying from starvation or cold. A search of the boulders in North Haven, South Haven and The Wick, the three accessible beaches on the island, revealed 564 recently dead corpses, which are also recorded in Table 1 ; most of these had apparently died while roosting among the boulders. A few live birds were caught and ringed, but some of these were found dead within 24 hours, the actual numbers being 12 out of 24 Starlings ( Sturnus vulgaris) ringed, five out of 22 Redwings (V urdus musicus) and three out of nine Song Thrushes (T. philomelos). Many other birds were killed by such predators as Buzzards ( Buteo buteo), a Hen Harrier ( Circus cyaneus), a Peregrine ( Valeo peregrinus), a Tawny Owl ( Strix aluco), Ravens ( Corvus corax) and Carrion Crows {C.. corone) . Kestrels (F. tinnmculus ), which two weeks earlier had very frequently been seen on the island, had entirely deserted it, however, as had all the Stonechats ( Saxicola torquata) (except for one found dead) and the majority of the Dunnocks {Prune Ha modular is) and Wrens {Troglodytes troglodytes). The birds most commonly found dead were Redwings, Starlings, Fieldfares {Tardus pilaris). Meadow Pipits {Anthus pratensis). Song Thrushes, Chaffinches (F ringilla coelebs). Lapwings {Vanellus vanellus) 98 M ■ le 2 — Sexes and weights of birds found dead on Skomer Island, Pembrokeshire, 2nd- 5 th January 1962 its are in grams. Weights of “normal” birds have been taken mainly from those quoted 1957), Browne and Browne (1956) and Williamson (1958), with the addition of some led records. The figures in brackets show the numbers of birds on which the “norma!” averages and ranges are based us vane Hus) ’lover ; Iritis apricarius) . iytes troglodytes ) finish viscivorns) pilaris) rush phi/omelos) mnsicus) I merula) Pipit r pratensis) ! retail lla alba) r vulgaris) :h • ch/oris) X V c/3 Total examined Total weighed Weight range Average weight g 0 c be 0 £ Z CZ “Normal’ range 6 3 2 136-145 140.5 9 4 3 1 24-1 3 1 128 210 (1) ? 1 I 140 Total 8 6 I24'T45 134.2 9 I 1 1 14 10 5 5-8 6.4 9.2 (70) 7.4-1 1.7 $ 3 3 72-75 73 9 2 2 62-68 65 Total 3 3 62-75 69.8 146 (1) VO d _ ^ G ~ 2^ d (U op «'a < s d « 05 bi3 d £ X* ^ 8 -o O-i +-» a « < u (50 „, « « d >_j ^ 2 ”0 d o - §£ ^■8'S -7 ■— co “ X O _ £ "0 So * « ° o g M i <*< p « •< X 2 -S* M *T rt (50 £ - a * O «< u c/5 si W -a O ’£ 1 1 1 4-> 4-» 4-> C/5 C/5 C/D b£) M 4J * G 3 15 d O y* 05 Z, [Li 43 Z .2 2 c - & A \> g C *3 G3 S U «S G U O o ^ci Oc > y ^ w .EL -a -§ "S s « § -s O -S ^wi 1 .£* « T3 « « to U O » 3-a a -vc co _2 S OJ 5 c - “ a S ~ 3 f z ^ cu r O O C/D 5 <5 ^ ci dO d i*-* C3 r-r-t s Ul « i u d C/3 JJ 0 n u w « •>, co 0 ^.-^"0 « ^ H u ^ O G 3 O C ts o CO d Ic ^ m Q u pi pi cn ” ^ 1-1 d S C/5 "G G > 3 d CQ C/5 PQ T3 O o o d § pi d 2 *d & o G 05 o V-I O G O C/3 £ d o 4-» G T5 O o hJ u d S pi d T3 O N G £ T3 T5 S C d d G *05 4-> G G d d PQ &■ ^ 5' «' ffl (fl ffl (Z) co CP 2 "2 C « « T3 cj . — 1 X c/5 V G *-1 I ^ ^ 1 C/3 "g "g o o rT3 V-l V-. O O >> d CQ T5 C d T3 _ G d 2 H H "G G d pSfSr8nrH§ 0t-|OOc/3(/5^(/5^ 0 vS vS O vS 0 >o 2 vq VO vq so vq o o 6 r^* m ^ •'3* ^ o rfCN d o 0 rG 05 r- CN i/''. O vq O vq O vq O vq ON ir> O vq d bD vq vq vq 00 vq r^» vq vq Q .9 V-l N M Cv M 21. 00 M NO r^> N IZN N o ON O iz-s vq r^~ sq r^- vd o vq vq CO N tQ W HD (i) U3 u-l W *0 W U3 U WW ' ' - v ^ V r\ r — -rt* CO r"G (D W) G CO CO N M O o v ON CO i-c >Oi l^\ U-\ O M o o co, O VD VD 05 G 3 d N r- M CO pH N u-n O VD M r- o COc N m C o CO G\ ON N N O no no d d 05 k 05 * 05 £ g ^9 'g .9 Y* C/5 C/5 C/5 lu PH Ui Uh T3 G J3 3=1 O * no nO no n3 C G G G d d -9 ^3 O *0 0 0 bC bJ5 bJD bJD G3 33 33 33 05 05 05 05 3 X X K +- "G n3 .9 C G *C/3 C/3 3 ^3 c d a 19 E bX) .9 bo .9 *G E o CJ u D o G C/3 d 43 u 05 bD .9 s * COMMON TERN MORTALITY IN SOUTH AFRICA 'reported from 24th April onwards; and workmen engaged on canalis- ing the vlei outlet thought that they had noticed the first casualties .about the middle of the month. On 30th April Brown counted 80 (.corpses in one place at Strandfontein and 139 at a second. Many j (Others were scattered in between and he estimated the total at 270 to >300 over a two-mile stretch of beach. In a smaller area, less than lhalf a mile long, Winterbottom, Masters and I found approximately 120 sick and dead birds on 1st May; and on 7th May Brown found a further 5 3 newly perished in the same locality. By 1 2th May, however, | this part of the coastline was deserted, and no terns, alive or dead, were I -seen. During the same period (24th April to 1st May) other casual reports '-were received of dead terns near George on the south coast, and at 'Sea Point on the peninsula. On 29th April Broekhuysen found five Mead Common Terns at Langebaan, and one dead Common Tern and ttwo dead Swift Terns (S. bergii ) in a nesting colony of the latter at •Meeuw Island in Saldanha Bay. In a neighbouring area, Velddrift on the Berg River, Chaundy found no evidence of any mortality on 113th May, but noted about 50 Common/Arctic Terns in apparent good health on the river estuary and shore. Further north, at Lambert’s Bay, Winterbottom and I made observa- tions and enquiries during a visit on 23rd and 24th May. At that time, no signs of illness could be detected amongst an estimated 200-300 (Common/Arctic Terns which were frequenting the shore; but the ; Harbour Master, who also acts as superintendent of the neighbouring gguano island, reported that “at least 400” terns had died during the second half of April, chiefly on the island where they roost and to a Lesser extent on mainland beaches. In the Port Elizabeth area, Liversidge recorded mortality among Common Terns towards the end of April and during early May. Fie las kindly made available an interesting report from Captain le Gras, ukipper of a fishing vessel, who noted dead terns in various fishing areas (5-10 miles off Cape St. Francis, off Slang Bay, and off Bird Island it about 34°S, 26°E) between 26th April and 10th May. Altogether ikbout 40 corpses were observed floating on the water over a total area if 20-25 square miles. Le Gras added that “it is unusual to see any lead birds at sea, and the odd one found is a rare event”. He also recorded a sick Common Tern which alighted on deck, refused to fly )r eat, and died two days later “passing a green liquid from the vent”. RINGING RECOVERIES This disaster resulted in 14 ringing recoveries as shown in Table 1, which also lists two further recoveries made later in the year. In the past, Common Terns bearing Finnish, Danish and German rings have 107 BRITISH BIRDS been found on South African shores (McLachlan and Liversidge 1957, Anon i960, Nordstrom 1961), and the present records again suggest that the Baltic region and European North Sea coast supply the bulk of this migrant population. However, the two Russian returns, which have not yet been acknowledged by the ringing station, could refer to birds breeding anywhere in that country, more especially as a Common Tern ringed as a nestling in the Black Sea area in 1955 was recovered a year later at East London (Anon 1956). It is interesting that British- ringed Common Terns, which breed in the same latitudes as the Dutch and German birds, have never been found in South Africa, although the total of over 31,000 ringed in the United Kingdom up to the end of i960 has resulted in 609 returns (1.95%), mainly from southern Europe and West Africa (Spencer 1961). Writing of S. hirimdo in the Americas, Austin (1942) stated that “of all the recoveries made on the wintering grounds eighty per cent at least are birds of the year”. Most of the earlier recoveries of this species in South Africa and eight out of the thirteen returns for which data are available were also yearling birds. However, three were in their second year, one was in its fourth, and the last was in its fifth. LABORATORY INVESTIGATIONS Many of the dead birds seen in the field were damaged, severely dehydrated or decomposed, but about 130 specimens in fair to good condition were obtained between 23 rd April and 1st May. Several of the freshest birds, including some which were found in extremis and destroyed, were reserved for bacteriological and virological tests, while the remainder (111) were examined in the laboratory at the Percy FitzPatrick Institute with the results recorded below. (a) Plumage Various authorities (Murphy 1936, Witherby et al. 1941, Peterson 1947) have indicated that dark lesser coverts, forming a distinct bar on the carpal joint of the wing, serve to distinguish Common Terns in their first winter from birds of greater age, although occasional individuals may retain some deep grey coverts well into adulthood (Cullen 1957). Seventy-eight of the 111 specimens in this series had the carpal bar. Most of these were probably yearlings and three ringed individuals certainly were. However, a fourth ringed bird with the dark shoulder mark had been marked in the nest in Sweden nearly four years before. The extent of the carpal bar was variable: about one-half of the specimens retained most or all of their dark coverts, but the rest were in various stages of replacing these with the paler grey feathers typical of adult summer plumage. 108 COMMON TERN MORTALITY IN SOUTH AFRICA Most of the “first-winter” birds (those having the carpal bar) had white foreheads, but in four the feathers of this area were largely .•lack. Among the 33 “adults” (those lacking the carpal bar), there vere 1 5 with wholly black foreheads, eight with white foreheads and tine at an intermediate stage. The remaining two specimens were lightly damaged about the head so that the colour of the feathers ould not be certainly determined. Forty-five of the 78 specimens with dark carpal bar were completely white below, but the remainder of this group and all the “adults” had -rev feathering from throat to vent, the tone varying individually from pale wash to a much deeper shade with a warm mauve tinge. In nearly all specimens (whether with or without shoulder patch), hhe first or second pairs of outer retrices, or both, were either missing itr in process of development. The only exceptions were five birds in cdult dress in which the tail moult was recently complete. Most interesting was the state of the flight feathers. Of the 78 jpecimens with carpal bar, the primaries had been completely and iccently renewed in ten (including the four-year-old bird mentioned bove), more than half of the primaries had been replaced in 52, and tiss than half in 16; secondaries had been fully replaced in 61 and were n.1 process of renewal in 17, all except one of these being birds in an arly stage of primary moult. By contrast, in all 33 “adults” the wing moult was complete, but the feathers were fresh, showing no more signs of wear than did the new primaries and secondaries of irds in the “yearling” group. This was surprising, since, according 0 Witherby et al. (1941), the adults of British-breeding Common ”erns replace their flight feathers in a post-nuptial moult which begins 1 July-August, but do not appear to moult their primaries or secon- daries twice in one year. The “first-winter” birds, on the other hand, onformed to the statement by Witherby et al. that yearlings undergo heir first complete moult in the February-June following their birth. I ’wo possibilities thus exist: (i) that the entire series of specimens onsisted of first-year birds, with the exception of the five ringed ones 1 f known greater age; or (ii) that the moulting pattern in the popula- ons reaching South Africa differs slightly from that in British birds. f >) Soft parts ’he colouring of the soft parts was recorded only for those specimens 'diich had not suffered any noticeable dessication. Fifty birds with ie dark carpal bar had wholly black bills, nine showed some red at the ase of the lower mandible, and two had lulls which were wholly red xcept at the tip. Five of those in adult dress had wholly black bills, ve had bright red bills with black tips, and 13 showed a variable mount of red, mainly on the lower mandible. 109 BRITISH BIRDS Greater variation was observed in the colouring of the feet and legs of both “adults” and “first-winter” birds. For about half the fresh specimens, various shades of “dull”, “dark” or “brownish” red were recorded, while the remainder ranged through orange-red, coral, true scarlet and bright crimson. These differences appeared to be purely individual and showed no correlation with the stage of moult. (V) Sex ] Because of internal decomposition, dehydration or damage, sex could not be certainly determined in 27 specimens. Of the ^remainder, 50 (including 13 “adults”) were females and 34 (eight “adults ) were males. In most the gonads were small to minute. However, six females in adult plumage and three in “first-winter” dress showed some signs of enlargement, with ovaries measuring 1-1.5 cm. along their longest axes and largest eggs 1-2 mm. in diameter. It is interesting to note that 60% of the sample were females and three possible explanations exist: (i) that there is a similar dispropor- tion in the sex ratio of the living population; (ii) that females were more susceptible to the destructive agent; or (lii) that the bulk of the males had already left on their northward journey when the malady struck. Cullen (1957) believed that males predominated on certain breeding grounds of the related Arctic Tern; and Lack (1954) has discussed the “general impression of the ornithologist . . . that male birds are rather commoner than females, which suggests that females have a heavier mortality”. Thus, on general grounds, the first possibility seems less likely than the second. However, Lack thought that heavier mortality was attributable to such factors as predation of hen birds while incubating, rather than to any inherent weakness associated with the fact that, amongst birds, females are the hetero- gametic sex. (d) Weight Among 15 “adult” specimens judged sufficiently fresh to give reliable results, weights ranged from 76 gm. to 118 gm. and averaged 97.8 gm ; one of the lightest birds (77.2 gm.) was a male found alive and weighed a few hours before it died. Fifty-one “first-winter” birds ranged from 79 am. to 1 15.5 gm. and averaged 100.2 gm.; seven of these which were taken alive had weights varying from 91.5 gm. to n4gm. Szczepski and Kozlowski (1953). who provide the only weights of normal Common Terns that 1 can trace in the literature, gave a range of 101-175 gm. for adult birds. If it is assumed that the mean lies about half-way between these figures, then the present series averaged about 25% lighter than normal breeding birds. 1 10 COMMON TERN MORTALITY IN SOUTH AFRICA (e) \nternai condition of afflicted birds The differences in weight between sick and healthy birds are rather smaller than might have been expected on the basis of post-mortem examinations, since all specimens in this series showed extreme emaciation. There was a marked wastage of the breast muscles and a complete absence of the subdermal fat deposits that are laid down by some long-distance migrants before their journey north. Lungs, liver, kidney, spleen and heart appeared normal, but most •specimens exhibited inflammation of the lower intestine. However, :the most striking abnormality was a marked clouding of the airsacs and visceral mesenteries with a film of greyish-yellow exudate. According to Brandly (1959), a similar lesion is frequently observed in infections with pneumotropic strains of Newcastle Disease. Further similarities between Newcastle Disease and the present epizootic were the signs of prostration exhibited by afflicted birds and the existence of a profuse fluid diarrhoea. Similar symptoms were also observed by Beretzk (1959) in an epidemic which destroyed many hundreds of 'Mallards ( Anas platyrbjnchos) near Szeged, Hungary, in 1957. (/) Viro logical findings These will form the subject of a separate publication, but I am indebted to Professor Kipps for permission to mention here that a virus similar to, but not identical with, that of Newcastle Disease was isolated from the specimens supplied to his laboratory. Endeavours to identify tiffs virus (which is lethal for domestic chicks) were at first unsuccess- ful, but it has recently been shown that it is neutralised by a serum prepared from a virus believed to have been responsible for an epidemic amongst Kittiwakes (Rissa tridactyld) in Scotland. Dr. Becker found that he could infect chicks experimentally by injection or, less success- fully, by placing the virus in their drinking water. There was, how- ever, no direct passage of the disease from infected birds to healthy companions; nor was it possible to induce illness in experimentally infected Swift Tern chicks. On the basis of these observations, it seems possible that the infec- tion may have been spread in nature as a result of the terns’ habit of • drinking and bathing at their roosting places, for which they usually seek out stretches of shallow stagnant water that rapidly become con- taminated with their own excreta. These same stretches of water are generally frequented by numbers of sand plovers, notablv the White- fronted ( Charadrius marginatus') ; a special watch was kept for signs of illness amongst these birds, therefore, but none was detected. DISCUSSION The malady which overtook lingering or overwintering Common 1 1 1 BRITISH BIRDS Terns on southern Cape coasts during 1961 had several interesting features. Firstly, there was its sudden and virtually simultaneous onset in the third week of April at all points along the considerable stretch of coastline (approximately 1,000 miles) covered by the observa- tions. Secondly, there was the equally abrupt cessation of mortality during the second week of May. From these two facts it would appear that the disease spread rapidly and ran a short course, killing or conferring immunity on all susceptible birds within a matter of days. Thirdly, the virus appears to have been curiously host-specific, pro- ducing illness in Common Terns and (probably) in the somewhat dis- tantly related Kittiwake, but not in Arctic Terns, Swift Terns or White-fronted Sandplovers or the scavenging Black-backed Gulls and Cape Ravens. Fourthly, the disaster was remarkable for its severity, which may be judged from the fact that at least 1,300 birds are known to have died in four small areas alone. Population studies indicate that, in normal circumstances, the average annual mortality among different bird species varies from about 20% to 60% (Lack 1954, Gibb 1961). However, despite the fact that such substantial numbers die, most do so unnoticed, as Captain le Gras remarked. Thus, although the full extent of the mortality in this disaster cannot be assessed, the number of dead birds counted suggests that it must have been very high indeed. A basic question remains: what precipitated this spectacular epi- zootic? Patently, no infection generates spontaneously, but must always be present amongst the population to a greater or lesser degree. It is known, for instance, that Newcastle Disease in a mild or sub- clinical form may persist unrecognised amongst poultry flocks i.or years at a time (Brandly 1959)' Because the clinical disease is most prevalent in autumn and winter it has been suggested (e.g. by F. R. Beaudette, see Brandly 1959) that obvious manifestations are pro- voked by cold or adverse weather. In the present case, there is a suggestion (the Kittiwake disaster) that the virus responsible is endemic on the breeding and feeding grounds of various Charadriiformes in the northern hemisphere. It is thus not impossible that terns suffering subclinical infections may bring the virus south with them on their autumn migration. There was, however, a long interval between the October arrival of these birds in “winter” quarters and the onset of the disease nearly six months later. In his discussion of the “pestes” or pandemic maladies which periodically overtake the guanays and other seafowl of the Humboldt current, Murphy (1936) pointed out that illness is most pronounced and mortality highest in years when abnormal oceanographic con- ditions prevail, more specifically when the warm equatorial current COMMON TERN MORTALITY IN SOUTH AFRICA “El Nino” displaces the colder waters normally washing the South American west coast. He suggested that, although various diseases, abnormal multiplication of endoparasites, etc., must play their part in these disasters, their ultimate source “lies in the change in the physical environment and a resultant malnutrition”. Lovat was inclined to j'place a similar interpretation upon the results of the classic study of strongylosis in grouse (summary in Lack 1954); and the idea implicit n the suggestion by Beaudette, quoted above, is not very different, it amounts to this: a minor infection, present in subclinical form, may iiissume epidemic proportions with high mortality if the host popula- t ion is under some form of stress. The same might occur if the causative agent itself underwent some mutation enhancing its virulence. However, it was with the first possibility in mind that enquiries were >jet afoot regarding local marine and meteorological conditions during March and April 1961. In the first of these months phenomenal ains amounting to as much as five times the normal fell over the mterior of the Cape, and the Weather Bureau (1961) stated that : as far as can be ascertained . . . such heavy precipitation simultaneously hwcr such a large area of the Karoo (60,000 square miles) has never oefore been recorded”. Good rains continued during April and : looded rivers carried large amounts of silt to the sea. I Regarding marine conditions, Messrs, de Jager and Rand of the Division of fisheries kindly informed me that officers of their research xssels operating off the west coast noted nothing unusual. However, or evidence that some abnormalities did exist in the south I am ndebted to E. Middlemiss, who left Cape Town on 21st April on a ea journey to Durban. On that date, between Cape Town and False Jay, he saw the most extensive areas of “red water” he has ever encountered. The patches were well-defined and, off Camps Bay to Uangkop, were hardly more than a few hundred yards apart. “Red water”, which appears intermittently off Cape coasts, is produced by le excessive multiplication of a dinoflagellate, which is normally >■ resent in small numbers in the plankton. The organisms contain a ighly poisonous alkaloid and various marine animals, such as fish ad crawfish, have occasionally been recorded as dying in some umbers during these “blooms”. The phenomenon is known from -veral parts of the world and its exact causation is not understood, ut it is often associated with atypical meteorological conditions, he possibility thus exists that the outbreak of “red water” may have sen directly associated with the illness in the terns, or it may have een the cause or result of other circumstances producing a food lortage and precipitating disease. Unfortunately, these suggestions cannot be advanced in any but ie most tentative form. They deal in phenomena which are little u3 BRITISH BIRDS understood and which have been hardly measured, if at all. Further- more, the epizootic itself began and ended so abruptly as to leave no time for the development of adequate investigations before the dis- appearance (on migration ?) of most of the surviving birds. REFERENCES Anon. (1956): “African recoveries of birds ringed in Europe”. Ostrich, 27: 185. (i960): “Recovery of tern ringed in Finland”. Ostrich, 31: 34- Austin, O. L. (1942): “The lifespan of the Common Tern {Sterna hirundo )”. Bird- Banding, 13: 159-176. Beretzk, P. (1959): “Observed cases of birds’ epidemies”. Aquila, 65 : 371-372. Brandly, C. A. (1959): “Newcastle Disease”. In Diseases of Poultry, edited by H. E. Bicster and L. H. Schwarte. Iowa State Univ. Press. Cullen, J. M. (1957): “Plumage, age and mortality in the Arctic Tern”. Bird Study, 4: 197-207. Gibb, J. A. (1961): “Bird populations”. In The Biology and Comparative Physiology of Birds, edited by A. J. Marshall. New York and London. Lack, D. (1954): The Natural Regulation of Animal Numbers. Oxford. McLachlan, G. R., and Liversidge, R. (1957) : Roberts’ Birds of South Africa. Cape Town. Murphy, R. C. (1936): Oceanic Birds of South America. New York. Nordstrom, G. (1961): “Der Vogelberingung in Finnland im Jahre 1959”. Mem. Soc. Flora Fauna Fennica, 36: 32-106. Peterson, R. T. (1947): A Field Guide to the Birds. Boston, Mass. Spencer, R. (1961): “Report on bird-ringing for i960”. Brit. Birds, 54: 449-495. Szczepski, J. B., and Kozlowski, P. (1953): Pomocnige Tabe/e Ornitologicgne. Warsaw. „ Weather Bureau, Dept, of Transport, S.A. (1961): “Monthly weather report . March 1961. Witherby, H. F., Jourdain, F. C. R., Ticehurst, N. F., and Tucker, B. W. (1941): The Flandbook of British Birds. London. Vol. 5 . Development of paddling and other movements in young Black-headed Gulls By Miriam Rothschild (Plate 19) Recently, in an interesting paper in this journal. Sparks (1961) discussed the relationship between foot-movements and feeding in shore birds. In view of his conclusions, it seems worth recording the age at which paddling and other movements were first performed by young Black-headed Gulls (Lams ridibundtts ) hatched in an incubator and reared in captivity (Rothschild 1936, 1940). Paddling takes the form of rapid “marking time”: the bird changes its weight quickly from one foot to the other and keeps up the dance for 30 to 1 20 seconds. It then ceases abruptly, steps backward a pace, and glances sharply at 114 DEVELOPMENT OF PADDLING IN YOUNG GULLS ts feet. Usually it does not look downwards until its feet are station- lry, but I have known cases where the bird has glanced down before t has actually stopped paddling. Sooner or later all the birds hatched in the incubator showed this saddling behaviour. In most cases it started when they were 21 days >ld, but precocious chicks began at the age of 1 2 days. It is not known what particular external stimulus, if any, initiates the paddling for the iirst time. My gulls often first executed the movement on the bare 1 ground. The behaviour appeared to arise spontaneously and I was quite unable to trigger it off in any bird which had not previously saddled — even, for example, by immersing its feet in cold or running water, or by giving it sight of water or worm-like objects. Once an ndividual had paddled, however, it could be stimulated to repeat the performance by the sensation of cold water round its feet or by the ;ight of a running stream. At about the age of three months, the saddling reaction was occasionally initiated by excitement at the ppearance of a feeding dish; rarely it was also performed if the bird was frustrated, although it was not a usual form of displacement activity. As time wore on, and possibly because the movement was lot rewarded by the finding of food, paddling gradually became less aid less frequent among the captive gulls until, by the age of ten or welve months, they were seen doing it only once or twice a month. A bird blind from hatching also developed the complete paddling reaction at the usual age of three weeks. Even the backward step ind downward jerk of the head at the cessation of the foot movement 00k place. The bird could see nothing, which showed that these ast two actions were part of the same series of innate movements and • vere not developed as a result of the bringing of prey to view from he muddy or sandy substrate. They placed the bird in a favourable position in which to take advantage of such an occurrence.* The sudden development from one day to another of innate pieces >!'f behaviour, some of which consisted of a series or sequence of Movements and were manifest en bloc , was a characteristic feature of hese gulls hatched in incubators. Thus the bathing movements were developed as a whole at an early gc, only one phase being added at a later period. Up to the sixth ay, the chicks merely stood still when placed in water. On the eventh day, a few reacted by defaecating and they also drank a few rops of the water. By the eighth day, almost all the chicks bathed * In this connection, however, it is perhaps worth noting that chicks two to three ■ ays old could not feed properly if their eyes were covered. They “peeped” ' ontinuously and did not open their beaks even when touched with the feeding ■ ipettc, nor did they take any food. The moment their sight was restored they ed normally. ”5 BRITISH BIRDS vigorously, going through all the typical movements (except the one) of the adults. This series of movements was also carried out by experi- enced birds if the bathing dish was empty. At the age of 27 days, a side-to-side “bathing roll” was added to the wing-flapping, head- ducking and up-and-down dipping of the body. Three different types of wing-stretching were developed at different ages. The first stretch, when the wings are raised and arched over the back (plate 19a), occurred from the seventh day onwards. The second movement, in which the outstretched wing is supported on the outstretched leg (plate 19b), was first noted at the age of 20 days. The type illustrated in plate 19c, which is much less frequent and often accompanied by aggressive manifestations, was first developed at 40 days. Adult sleeping attitudes were, on the contrary, gradually built up. As chicks, the gulls lay with their heads resting side to ground. After shedding their down and up to the age of four weeks, they still slept on the ground, lying on their breasts, but with their heads and beaks stretched out in front of them. At the age of four weeks, they began sleeping with their heads tucked under their wings, but still lying down. On the thirty-second day, a few started to sleep standing up and also began standing on one leg. A small number of chicks made attempts to feed themselves on the third day after hatching, but none did so freely until the ninth day. Independent feeding was largely the result of trial and error or random pecking, and was not developed suddenly. The chicks were stimula- ted to peck at dark objects on a white ground or at small objects float- ing on their bathing water before they developed foot-paddling. At the age of 30 days the young gulls combined both pieces of behaviour and, after paddling, stepping back and looking down, they would peck at any floating object in the dish — not necessarily anything edible — and even at dark marks on the enamel bottom. Preening was basically an innate ritual, the chicks performing quite elaborate toilets on the first day of hatching; when the down was replaced by feathers and the wings developed, the preening became more complicated or specialised. A worm-like object, such as a piece of string or bacon rind, the sudden appearance of a stream of running water from a tap or hose, of the sight of a newly-hatched chick, all released spontaneous and often frantic excitement in the young gulls. This was sufficient to override their normal behaviour and even temporarily obliterate the pecking order hierarchy or territorial inhibitions. A new experience, such as a flying insect in the vicinity or a large bird passing overhead, not only evoked intense interest but might trigger off an entirely “new” behaviour pattern which, up to then, had lain dormant. 1 16 JV .te i (). The deve- ncnt of wing- tches in young . :k-headed Gulls i nts ridibundus). u, the first stage hi wings raised arched over the kk; this started at . ^n days. Centre, second develop- nt with one out- ttchcd wing sup- f.ced by a leg; this noted first at nty days. Bottom, third in order, :n associated with .er; this was seen (forty days. The i : two wing- tchcs are used :n the bird has n resting or ing, but the third y if wide awake :ge 1 1 6) ( photos : dan/ Rothschild) Plate zob. Start- ing to roll an egg into the nest. This is an outsize model that has no connec- tion with the experi- ments described on pages 1 20-1 29, but the action is typical. Bending over the egg, it rolls it back with the under-side of its bill (page 121) ( photos : N. Tinbergen) Plate 20A. Black- headed Gull (L arm ridibimdus ) lifting egg-shell to remove it. It holds the thin edge in its bill and cither takes it away immediately or nibbles it for a while first. It has been shown that such] shells near the nest increase the risk of predation (page 120) Real shell (j) Smooth rim (k) Painted rim (1) Flanged egg ’late 2i. Model eggs and egg-shells used in experiments with Black-headed i'iulls {JLarus ridibundus), Cumberland, 1961 (pages 120-129 ) {photos: John Haywood) (“Notched rim” is not shown) Plate 22. Scarlet Grosbeak ( Carpoclacus erythrinus), Finland, lunc 1958. A regular autumn vagrant to Shetland, it is otherwise rare in Britain. Females and young males, of which this is one, look identical and show no red. Note the dumpy shape, uniform plumage, round head, beady black eye and heavy conical bill; the wing-bars are more striking in autumn (pages 130-131 )(photos: Eric Hosking) FOOT-PADDLING IN GULLS It is obvious, from these few notes, that it is in fact extremely difficult and time-consuming to attempt to sort out the innate or learned components of any complicated piece of behaviour, such as foot- paddling, by observations made on wild birds. REFERENCES Rothschii.d, M. (1936): “Rearing animals in captivity for the study of trematode life histories”. J. Marine Biol. Ass., 21 : 143-145. (1940): “Rearing animals in captivity for the study of trematode life histories, II”. J. Marine Biol. Ass., 24: 613-617. Sparks, J. H. (1961): “The relationship between foot-movements and feeding in shore birds”. Brit. Birds, 54: 337-340. Foot-paddling in gulls By N. Tinbergen I should like to supplement the interesting comments recently made by Sparks (1961) on the functions of foot-paddling in gulls, since more is known about it than is apparent from his article. In my book The Herring Gull's World (1953), where I referred to the excellent description given by Walker (1949), I reported that at least one population of Herring Gulls ( Tarns argentatus ) applies this move- ment on a large scale, and succeeds in making earthworms crawl out on to the surface where they are then eaten as they appear. Earth- worms are, in fact, a major item in the diet of the colony concerned. I also took issue with the opinion of Portielje (1928) who claimed that Herring Gulls paddle on the seashore and, in doing so, bring the marine worms Arenicola marina and Echiurus pallasii to the surface. I doubted the correctness of this, firstly because when I saw Herring Gulls paddle on the shore they did it in shallow pools and secondly because I believed that no worm of the inter-tidal zone reacts to mechanical disturbance of the soil by moving up; if anything, such worms withdraw. I argued that the peculiar response of at least some earth- worms* of rising to the surface when the ground is vibrated may be effective against their main predator, the Mole (Talpa europaea). I finally pointed out that Black-headed Gulls (E. ridibundus ) also select shallow pools when paddling on the seashore, and I suggested that the function in this context was the whirling up of small animals lying on or in the mud, thus making them visible. This was also the opinion I of my brother, L. Tinbergen, who described in detail (1951) how Black-headed Gulls apply paddling systematically in shallow water *Professor G. P. Wells informed me that, while earthworms of the genus Allolo- Ibopbora have this response, he believed that the common lawn-worms ( Lnmbricus ) do not. “7 BRITISH BIRDS on the tidal flats of the Frisian Sea in Holland; their foot movements whirl up the sand and mud, thus exposing Hydrobia, Corophium, small Nereis , Scoloplos and, above all, masses of “small tube-dwelling worms”. The sand settles a little in front of the bird’s feet, so that the paddling results in the formation of two V-shaped pits with a kind of delta in front of each V (such marks were illustrated by Swennen and van der Baan 1959, plate 7). While paddling, the gulls look down and now and then pick up small objects in front of their feet. Sparks’s observations seem to tally well with this account. A relevant case of this type of paddling by a Herring Gull was reported to me by J. Peterson. He saw an immature Herring Gull on the quay at Lerwick, Shetland, paddle in a pool which was entirely black and opaque from coal dust suspended in it. On the bottom of this puddle were numerous grains spilt during unloading, and as these appeared at the surface, whirled up by the bird’s trampling, they were neatly picked up. We have, therefore, direct evidence of two functions of foot-paddling. First, Herring Gulls, and also Common Gulls (L. cams'), practise it consistently on meadows, and actually catch earthworms in large masses with this method. Black-headed Gulls do not seem to apply paddling at all when catching earthworms (which, for instance, those at Ravenglass, Cumberland, eat by the thousand); as far as I have seen, they collect them when they are brought up by the plough. Second, Herring Gulls, Common Gulls and, to a much greater extent, Black- headed Gulls apply it in shallow water where it obviously serves to whirl up an invisible prey. It is worth adding that many other birds have this foot-paddling: Portielje (1927) mentioned it of adult Wood- cock ( Scolopax rnsticola ), Flamingo ( Pboenicopterns ruber), Shelduck (Tadorna tadorna), Bar-headed Goose (A user indicus), and several herons (Ardeidae); and Heinroth (1911) listed several species of duck and swan which do it in shallow water. Foot-paddling seems often to occur, even in adult birds, as a rather automatic and “stupid” response to a wet substrate; Heinroth men- tioned that one of his swans started to paddle in a film of water cover- ing the ice on one of the ponds of the Berlin Zoo. The ontogeny of paddling seems to be very much like that of many other species-specific behaviour patterns in birds. Miss Rothschild’s interesting observations elsewhere in this issue (pages 1 14-1 17), which show that it appears at a certain relatively constant age in entirely inexperienced Black-headed Gulls, correspond to those of Portielje (1927) on young Mallards {Anas platjrbynchos ) and of Heinroth on young Woodcock. Miss Rothschild’s report that a blind young gull began to perform the entire sequence of paddling and “looking down” demonstrates beautifully how independent of experience the movement is when it first appears. 1 18 FOOT-PADDLING IN GULLS All the writers mentioned agree that, in young birds, paddling can be elicited in a great variety of situations, though most observations ^concern wet substrates (the feel or even the sight of water) ; however, Portielje saw young Herring Gulls paddle on dry sand, and Miss Rothschild noted that her young Black-headed Gulls did it when they ^aw a worm. When we compare these aspects with the fact that Miss Rothschild’s gulls gradually reduced the amount of paddling as they grew up, and with the facts mentioned above about the dual function of paddling in adult birds, it seems very likely that, while the response is innate and, at first, spontaneous, it can soon be elicited by a wide array of -stimuli. It then becomes increasingly selective as the birds grow up and learn not to apply it where they have not been rewarded, and to restrict it to situations in which it does lead to the discovery of food, iln addition, experienced birds have learned to go to the habitats where ;they can apply the method successfully, whereas young birds seem to Mo it merely when they stumble upon wet spots. Why Black-headed Gulls do not hunt earthworms by paddling remains a puzzle; it is just possible that they are not heavy enough. Another unsolved question is to what extent, and with which . animals, gulls are successful by producing the “quicksand eflect” on a wet beach, discussed by Sparks. Two of my correspondents, R. ■ Stanier and Dr. J. Verwey, have told me that pressing or trampling on wet sand, which produces semi-liquid quicksand, makes animals such as young Cockles ( Cardium edule), which are lighter than this “liquid”, come to the surface passively. Mr. Stanier told me that in More- cambe Bay, Lancashire, fishermen occasionally collect Cocldes by trampling on one spot until a small pool is formed in which the Cockles float to the surface. It seems possible that this is a third context in which paddling might often be rewarding. REFERENCES Heinroth, O. (1911): “Beitrage zur Biologie, namentlich Ethologie und Psycholo- gic der Anatiden”. Proc. 5 tb In/. Orn. Congr., pp. 589-702. Portielje, A. F. J. (1927): “Ornitho-psychologische opmcrkingen”. Ardea, 16: 20-23. (1928): “Zur Ethologie bzw. Psychologic der Silbermowe, Partis a. argen/atus Pontopp.”. Ardea, 17: 112-149. Rothschild, M. (1962) : “Development of paddling and other movements in young Black-headed Gulls”. Brit. Birds, 55: 114-117. Sparks, J. H. (1961): “Relationship between foot-movements and feeding in shore birds”. Bril. Birds, 54: 337-340. Swennen, C., and van der Baan, G. ( t 9 5 9) : “Tracking birds on tidal flats and beaches”. Brit. Birds, 52: 15-18, plates 5-8. Tinbergen, L. (1951): “Trappclcnde Kokmeeuwen”. De Levende Natuur, 54: 218-219. 119 BRITISH BIRDS Tinbergen, N. (1953): The Herring Gull's World. London, pp. 32-35. (I955): “Zilvermeeuwennieuws”. De Levende Natuur, 5 8 : 21-30. Walker, A. B. (1949): “Herring Gull ‘paddling’ on grass field”. Brit. Birds, 42: 222-223. How do Black-headed Gulls distinguish between eggs and egg-shells? By N. Tinbergen, H. Kruuk , M. Paillette, and R. Stamm * (Plates 20-21) INTRODUCTION Black- headed Gulls (JLarus ridibtmdus ) remove the empty egg- shell shortly after the hatching of the chick. An investigation into the survival value of this response and of the stimuli eliciting it (Tin- bergen et at. 1962a) yielded the following results. An empty egg-shell at a distance of four inches from a single egg laid out in the dunes rendered such an egg more vulnerable to predation by Carrion Crows ( Corvus corone) and Herring Gulls (L. argentaius) ; this suggests that egg-shell removal may help to reduce predation. The response can be elicited throughout the incubation period by a variety of objects in the nest or on its rim, in fact by “any object which does not resemble an egg, a chick, or nest material”, although the egg-shell itself is optimal. In systematically conducted tests with dummies, it was found that colour, shape, size and distance between nest and shell affected the response. These results suggested, therefore, that this seemingly trivial res- ponse, which normally takes no more than twenty seconds of a bird’s time each year, contributes to the survival of the brood; and they showed that it is controlled by a complicated and well-adapted mechanism. This first study, while not allowing us to list all the characteristics of the situation which elicits egg-shell removal, showed that the birds distinguish between egg-shell and nest material by at least four characteristics: in fact, the egg-shell is distinguished by being three- dimensional, rounded, less oblong than nest material, and partly white. The present paper deals with the question of how gulls distinguish between egg-shells and eggs. Failure to do so would naturally *Dr. Tinbergen is from the Department of Zoology, Oxford University; Mr. Kruuk from the University of Utrecht, Netherlands; Miss Paillette from the Laboratoire de Physiologic Acoustique, Jouy-cn-Josas, France; and Dr. Stamm from the Zoologisches Institut dcr Universitiit, Basel, Switzerland. 120 GULLS DISTINGUISHING EGGS AND EGG-SHELLS j ^ Fig. i. 1 he first stages of egg-shell removal {left) and egg retrieving {right) ! in the Black-headed Gull {Larus ridibundtis) (see below) {sketches: N. Tinbergen) endanger the brood, and we have actually never observed a gull removing its eggs or chicks. Although an intact egg and an egg-shell as left after the chick has : latched have much in common, they elicit two entirely different sets I • )f responses. An egg in the nest is brooded and occasionally shifted. Hf an egg happens to lie on the nest’s rim or even a little outside the ( m rest, the bird often retrieves it. It may either sit down first or remain I standing in the nest, then may gently touch the egg’s upper or distal I S surface with the ventral side of its bill. This is then often followed by rolling in , which is done by bending over the egg and balancing it Uigainst the under surface of the lower mandible, then rolhng it back I I owards the breast, i.e. into the nest cup (plate 20b). A shell in or near the nest is taken in the bill (plate 20a). The bird I (gets bold of the thin edge and either walks or flies away with it at once, I >r nibbles it for a while before removing it. Nibbling may be inter- rupted when the bird drops the shell, but it ultimately leads to “carrv- I I ng”. Sometimes a gull pecks at the material which is left behind in he shell and it may eat some of it. 121 BRITISH BIRDS The situations eliciting the two responses in our experiments were the same except for the objects (egg and egg-shell) themselves. The differences we see between an egg and an egg-shell could be described in various ways, and the following descriptions guided us in our attempts to find out to which properties the gulls reacted: Egg (1) Smooth, oval outline (2) Closed; no opening (3) No thin edge or rim (4) Heavy (ut not Shell- with-lead’ ’ nor “Real shell”, four did the opposite, and ten treated the models similarly (p— .059). The number of birds which showed billing to “Filled shell” but to neither “Shell-with-lead” nor “Real shell” was 1 3 ; four did the opposite, and eight did not show this difference (p=.o2 5). Finally, the number of birds which showed billing to either “Filled shell” or “Empty egg” but to neither “Shell-with-lead” nor “Real shell” was 21 ; four did the opposite, and three did not distinguish clearly either way (pc.ooi). Table 3 summarises further information that can be extracted about the difference between “Real shell” and “Shell-with-lead”. The first *A11 p values in the remainder of this paper were computed according to the sign test. I2J BRITISH BIRDS Table 3— Comparison of responses of Black-headed Gulls {Larus ridibundus) to “Real shell” and “Shell-with-lead”, Cumberland, 1961 This shows the numbers of birds which responded with each of the reactions listed in the first column to “Real shell” but not to “Shell-with-lead” (+), which did the opposite ( — ), or which did not differentiate (o) (p values based on sign test) + — O Significance Carrying 7 0 5 p= .008 Lifting* O 5 2 P= -031 Rolling 2 O 3 not significant Nibbling I 15 4 p=< .001 Poking O 10 2 p= .001 *This category includes intention-carrying line allows us to say that “Real shell” elicited much more carrying, and the second shows that “Shell-with-lead” was more often merely lifted and then dropped. The fourth line shows that “Shell-with- lead” very often gave rise to mere nibbling, while the fifth says the same about poking. These data demonstrate that neither model elicited rolling, but that both elicited some or all of the removal sequence. This obviously consists of two parts, nibbling and carrying, and it is also obvious that the “Shell-with-lead”, while eliciting nibbling, stopped the real carrying which normally follows nibbling. In other words, the presence of the lead inhibited the action chain half-way. That this was due to the weight of the lead will become clear in the next experi- ment. Experiment C This experiment was designed to test four hypotheses which we had developed as the results of Experiment B took shape. First, we had gained the impression that the “Real shell” elicited removal mainly through having a thin edge, rather than through being hollow. We therefore offered an empty egg with a flange of shell glued on it at right angles to the surface. The flange measured 2 cm. x 1.5 cm. and could be considered flat. This model, which we called “Flanged egg” (plate 21I), was presented with the flange turned up and the longitudinal axis pointing radially. It thus offered a thin edge, but no hollow. Second, to see whether the fact of a shell’s being hollow had some effect, and also to have a control model in connection with “Shell- with-lead”, we filled a real shell with cottonwool so that it had very 126 GULLS DISTINGUISHING EGGS AND EGG-SHELLS much the same appearance as the plaster-filled egg or “Filled shell”. However, whereas the plaster neatly fitted the edge, the cottonwool (though concealing the hollowness) allowed the bird to see the thin edge as separate from it. This model we named “Cottonwool shell” (plate 2 if). Third, to see whether a serrated edge was more stimulating than a smooth one, we introduced two model eggs with similar sized holes 40 mm. from the blunt end. One had a smooth edge and the other was artificially serrated. These we called “Smooth rim” (plate 2 1 j) and “Notched rim” respectively (the latter is not illustrated here, but the notches were of the same size as the white patches on “Painted rim”, plate 21k). Fourth, we thought that a real egg-shell might owe part of its effec- tiveness to the amount of white it showed. A smooth-rim model (with a hole 40 mm. from the blunt end) was therefore given a series of white triangles along the outside of the rim, so as to fake a serrated edge to the khaki exterior. This was known as “Painted rim” (plate 21k). With the “Real shell” as a control, there were thus six models in this experiment. Each of these was presented 18, 19 or 20 times, the slight difference being due, as in the previous tests, to some of the series being prematurely ended bv nest-relief. The results are given in Table 4. Although the scores for rolling and intention-rolling in Table 4 are higher for “Flanged egg” and “Cottonwool shell” than for “Real Table 4 — Results of Experiment C with Black-headed Gulls (Laras ridibundus ), Cumberland, 1961 This shows the numbers of birds which responded to the various model eggs with each of the reactions listed. The first two columns give the ultimate responses, irrespective of the incomplete movements which may have preceded them. The names of the model eggs and the small letters with them correspond to those on plate 21 C/5 c Rolling* Carrying* Billing Nibbling Poking Ignoring Total presentatioi (1) Flanged egg 6 12 4 12 O I l9 (f) Cottonwool shell 6 *3 5 13 O I 20 GO Real shell I 14 6 II 5 2 20 (j) Smooth rim 15 2 5 5 2 I 18 Notched rim 9 9 7 6 I O l9 00 Painted rim 12 8 12 4 5 O 21 ♦These categories include intention-rolling and intention-carrying respectively 127 BRITISH BIRDS shell”, the differences are not significant. “Flanged egg” and “Cotton- wool shell” have not been compared in one series with “Empty egg” and “Filled shell” (Table 2), but neither of the latter models were carried even once; every single bird which responded to them did so by rolling. We must conclude, therefore, that “Empty egg” and “Filled shell” were treated like eggs (i.e. retrieved) and that “Flanged egg” and “Cottonwool shell” were treated like a real shell (i.e. re- moved), although we must leave open the question whether the birds distinguish to a slight extent between the different models within these groups. The main character to which the gulls respond by carrying must be one that is found in both “Flanged egg” and “Cottonwool shell” but absent from the other models. It follows that the thin rim is the important character and that neither hollowness nor broken outline, not their combination (as found in “Filled shell”), are sufficient to make the bird carry, although, as we have seen, “Filled shell” elicited rolling with a greater delay than an egg does. The high carrying score for “Cottonwool shell” also shows that the low carrying response to “ Shell- with-lead” (Table 2) was due to its weight and not to the sight of something inside the shell. Turning now to the characteristics of the shell’s rim (the figures in the three lower rows of Table 4), we find that these scores are not significant either. However, because the differences between these models are relatively simple and straightforward, it is worth extracting fuller information from our protocols and counting all responses shown in all tests instead of merely fisting (as in Table 4) whether or not a response occurred in any one test. Many birds responded more than once in a test; moreover, many birds showed in one and the same test elements of both rolling and carrying. By counting all these responses in every case, we can determine for each test an index which gives the ratio between the number of egg-rolling movements and the number of carrying responses — a “retrieving-over-carrying index”. By comparing these indices for the various models, we find that in ten cases the index was higher for “Smooth rim” than for “Notched rim”, in six the indices were equal for these two models, and one bird had a higher index for “Notched rim” than for “Smooth rim” (p= .006). Thus “Notched rim” elicited relatively more carrying than “Smooth rim”, which in turn elicited relatively more rolling. This same index was higher for “Smooth rim” than for “Painted rim” in eight cases, it was equal for both models in eight more, and one bird showed the reversed response. These differences are also significant (p=.o2). We can therefore conclude that both serrating the edge, as in “Notched rim”, and adding the white pattern of “Painted shell” increased carrying and reduced retrieving. 128 GULLS DISTINGUISHING EGGS AND EGG-SHELLS SUMMARY AND CONCLUSIONS Experiments were carried out at Ravenglass, Cumberland, in the summer of 1961, to determine how Black-headed Gulls (Laras ridi- bundus ) distinguish between eggs and egg-shells. These elicit entirely different sets of responses: eggs are rolled into the nest and brooded, while shells are picked up in the bill and removed. The following paragraphs summarise the conclusions reached. The egg-shell elicits removal because it differs from the intact egg in the following characteristics: it shows a thin edge; this edge is serrated; and it shows white. The “decision” to remove it is already t taken before the bird can have checked its weight. Neither the inter- ruption of its outline nor its hollowness could be shown to contribute t to removal, though both seem to exert an inhibiting influence on roll- ing. In addition, it was shown that egg-shell removal is a chain of acts: nibbling is elicited by visual stimuli; during nibbling the weight is (checked and, if it does not grossly exceed that of a real shell, the object is carried; if it equals the weight of an egg or a chick, the chain is broken off. This prevents chicks from being carried away when they have hatched but not yet left the shell; whether other safeguards t exist as well we cannot say. Most of the population in which these responses were studied must have had previous breeding experience. Very little can be said, therefore, about the extent to which the responses are innate or could be the consequence of conditioning. Three one-year-old birds, which were tested with eggs and shells when they had not yet laid at all, rolled in an egg and removed a shell in a way indistinguishable from experienced birds (Tinbergen, Kruuk and Paillette 1962). ACKNOWLEDGEMENTS (Our thanks are due to Sir William Pennington Ramsden, Bt, and the Cumberland County Council for permission to work in the Ravenglass gullery; and to the Nuffield Foundation and the Nature Conservancy for support. M. Paillette wishes to express her gratitude for financial assistance received from the British Council and the Zoological Society of London; R. A. Stamm was helped by a grant from the Janggen- Pohn Stiftung. REFERENCES Siegel, S. (1956): Non-parametric Statistics for the Behavioral Sciences. New York. Tinbergen, N., Broekhuysen, G. J., Feekes, F., Houghton, J. C. W., Kruuk, H., and Szulc, E. (1962a): “Egg shell removal by the Black-headed Gull, Icarus ridibundus L.: a behaviour component of camouflage”. Behaviour (in press). Tinbergen, N., Kruuk, H., and Paillette, M. (1962b): “Egg shell removal by the Black-headed Gull, Laris ridibundus I.. II. The effects of experience on the response to colour”. Bird Study (in press). 129 Studies of less familiar birds 1 17. Scarlet Grosbeak By Kenneth Williamson Photographs by Eric Blocking (Plate 22) The Scarlet Grosbeak ( Carpodacits erjtbrinus ) is a primarily Asiatic bird whose range extends into eastern Europe. It is a rare visitor to Britain, apart from Shetland (notably Fair Isle) where it is of annual occurrence in the autumn. It is a species which is in the process of expanding quite vigorously north and west in Finland and, particularly if it should spread into Scandinavia, it may eventually be seen with greater regularity in Britain. Plate 22 and the notes which follow are intended to assist identification of what is a rather undis- tinguished bird when not in adult male plumage. The photographs were taken near Oulu, Finland, which is almost the present north- western limit of its breeding range. The Handbook says “ Carmine head, breast and rump of adult male, with browner wings and tail and stout bill, unmistakable” — and indeed, if all vagrant Scarlet Grosbeaks in this country lived up to their name, then identification would set no problem. Practically all, however, are either females or young of the year in a relatively nondescript plumage similar to the bird shown in the plate. I do not know of any way of distinguishing between the adult female and first-winter plumages except that birds with fresh-looking remiges and rectrices are probably adults which have recently completed the post-nuptial moult, since the young do not renew these flight-feathers in autumn. Even the first-summer males are exactly like the females and the pair at the nest in the photograph were almost identical. Such birds might be overlooked as pale Corn Buntings (Emberi^a calandra ) or even hen House Sparrows ( Passer domesticus), but there are a number of minor but quite distinctive points which will serve to identify them. The plumage of the upper-parts is a yellowish- or greenish-brown, sometimes a little brighter on the rump, often a little browner or greyer on the crown. The feathers are not so prominently dark-centred as in the other two species and, indeed, the mantle looks almost uniform at a short distance. The under-parts vary from greyish- to huffish-white with fine brown streaks which terminate abruptly on the lower breast in some birds, but in others extend on to the belly and flanks. There are prominent buffish- white wing-bars at the tips of the greater and median coverts, and the latter group of 130 NOTES feathers is often a darker brown than the rest of the wing. The tertials and inner secondaries also are tipped with whitish. (It should be noted that these wing-markings are greatly reduced in the much- abraded plumage of the breeding bird depicted in the plate.) Besides the plumage differences, the Scarlet Grosbeak has quite a ^characteristic “jizz”. Birds often adopt a dumpy stance, head retracted, as noted by L. S. V. Venables in The Handbook , and the sweet, ttuneful call-note twee-eek is unmistakable. The beady black eye stands out prominently against the uniformly pale brown (sometimes inclining to rufous) cheeks, ear-coverts and lores; and the head itself .always appears nicely rounded, a sparrow’s being flatter by comparison. The heavy, conical bill, which continues the line of the forehead, is 'dark horn above and paler below, almost flesh-colour with a mauve or purplish tinge. The legs are dark flesh and the inside of the mouth is rose-red. At Fair Isle, though sometimes alone, the birds are often in company 'with House Sparrows or Twites ( Carduelis flavirostris ), and frequent oat- •stooks standing in the fields, or attack the seeding-heads of various weeds such as sowthistle (So neb us sp.), ragwort (Senecio aquations ) and autumnal hawkbit (Leontodon autumnale). The last week of August ind first fortnight of September is their best period, but there have been occasional records into November, and George Stout recorded three associating with sparrows on i ith January 1930 (Scot. Nat., 1930: 60). Though hardly an autumn passes without the occurrence of several birds, there is only one reliable spring record, for 2nd April 1926. Notes [Peregrine incubating Kestrel’s eggs.— On 13th May 1961, I was prospecting some crags in the Great Glen, Inverness-shire, in the lope of finding a pair of nesting Peregrines (Falco peregrinus). As I approached the most likely-looking face from below, a female Peregrine appeared in the air above and began to circle silently. She was still here half an hour later and her obvious reluctance to leave the place uggested an occupied nest, but her complete silence was abnormal or a bird with eggs or young. I worked my way to the crag top and, o my surprise, found a clutch of six Kestrel’s (F. tinnunculus ) eggs in he disused nest of a Raven (Corvus corax). I had not seen a Kestrel t all, although I had clapped repeatedly below. My surprise was all he greater because Kestrels very rarely nest close to Peregrines, at east on inland cliffs, and I was still expecting to find a Peregrine’s yrie there. 1 3 1 BRITISH BIRDS While I was making my way down a gully, the Peregrine suddenly stooped down and pitched on a shelf near the base of the crag. She sat there for a few minutes, then took wing, circled for a short while and finally swung into the now hidden upper part of the crag. The ledge where she had first alighted proved to be an empty eyrie; she had evidently been brooding there, for there were fresh flecks of down and traces of egg-shell which could have been recent. As the bird did not reappear, I returned to the top of the crag and, partly screened by vegetation, cautiously looked over at the Raven’s nest. The Peregrine was incubating the Kestrel’s eggs as though they were her own. I stayed there for several minutes only five yards from her, but she remained oblivious of my presence and was still sitting when I left. Evidently the Peregrine had either lost her own eggs or been un- able to lay, but still felt the urge to incubate. She had presumably dispossessed the Kestrels, which were nowhere to be seen, and adopted their eggs. I was not able to return later and so do not know how this peculiar situation ended, but the Peregrine was not behaving as a normal nesting bird and I thought it probable that she would eventually desert the eggs. D- A. Ratcliffe Water Rail killing Wren.— At about midday on 2nd January 1962, Mr. R. Roe, who was building a sluice in the marsh on the R.S.P.B. Reserve at Minsmere, Suffolk, saw a Water Rail ( Kalins aquaticus) run across a path, jab its bill into a Wren (' Troglodytes troglodytes ) and carry it off into the reeds. This incident, observed from four yards, occur- red in a cold spell when most of the land was snow-covered, the ground frozen hard and the meres iced over. During this weather, Water Rails had become bold and two to four were frequently seen together on ground newly disturbed by machinery. The Wren had earlier been noticed in a wheel rut and, from the fact that it did not fly but moved only to one side when the workmen passed, was obviously weak. Mr. Roe, in answer to my questions about an hour after the incident, said that when the Water Rail jabbed its bill into the Wren, its mandibles were opened to about a quarter of an inch at the tips. The victim was carried off clear of the ground and was not held by a wing or a leg. The Handbook has one record of a shrew ( Sorex sp.) being taken by a Water Rail, but none of a bird. However, some comparable observa- tions were published by Kenneth Williamson in 1949 (Scot. Nat., 61: 31). He described the finding of a Water Rail and three Twites (Carduelis flavirostris ) in the catching-box of a trap on Fair Isle on 2nd October 1948: one of the Twites had been partially eaten, another had recently been killed, “having a hole in the breast obviously made by a spear-thrust of the water-rail’s bill”, and the third was uninjured. 132 NOTES I He also mentioned an experience of G. T. Kay, who introduced a Water Rail into a large outdoor aviary: this bird killed and ate a waxbill (Estrildidae), a Greenfinch ( Chloris chloris ) and a Chinese Quail I(Excalfactoria chinensis'). What was clearly the same incident was quoted by R. M. Lockley in I Know an Island (1938, p. 182), but he gave the birds concerned as a Quail (Col nr nix coturnix ), a Greenfinch and a Snow Bunting ( Plectropbenax nivalis ), the rail “picking out the meat and leaving the skins and bones clean in a remarkable manner . . The Minsmere record seems to differ from these others in that both the Water Rail and its victim were fully at large. H. E. Axell 'Woodcock alighting on bird-table.— 1 have two bird-tables in my garden at Scunthorpe, Lincolnshire. One of these is about two feet tfrom a window and the other some five yards away. During the cold | -spell at the end of 1961 I kept both well supplied with “Swoop”. At 1.30 p.m. on 28th December, I was astonished to see a Woodcock | (Scolopax rusticola ) on the nearer table. It was probing in the food I and appeared to be eating. Unfortunately it soon saw me and flew 1 off before I was able to make any detailed observations, but it seems uquite remarkable that a wading species such as this should ever land on a bird-table at all, let alone try to feed there. The table is four feet high. The temperature at noon that day was 28°F and the .ground was frozen hard. Frank Norris ■ Distraction displays of Common Gulls.— I can add two comparable observations to the recent record of an apparent distraction display by a Common Gull (Lams canus ) (Bril. Birds, 54: 429), but these are the only instances I have witnessed in many hours of study of this species at its breeding colonies in Ireland. On 14th June 1944, at Lough Corrib, Co. Galway', Common Gulls had young on a rocky' islet from which I was just departing. The male left the islet in great agitation and flew low immediately in front of the boat. It half-settled on the water with wings beating violently, then rose, went a little further ahead and repeated the performance ; this it did over and over again, -giving the impression that it was trying to draw us away. Sometimes t was just above the surface with feet dabbling, at other times it ictually sank on to the water. It kept turning its head round as if to watch us and it stayed extraordinarily close to the boat. The other case was on Inishinny, near Bunbeg, Co. Donegal, on 13rd June 1948. A number of Common Gulls had nests and y'oung n sandhills amid marram grass. Some of the adults were seen to fly ow over a sandy slope, then run on tiptoe down it with half-spread vings. This was performed quite frequently and by several different ’itds. Robert F. Ruttledge 1 33 BRITISH BIRDS Feeding behaviour of Kingfishers. — The note by N. L. Hodson (Brit. Birds, 54: 430) prompts me to record some observations that 1 made on Kingfishers ( Alcedo atthis) between 3rd and 15th September 1961 at Estartit in Spain, by a small reed-fringed lagoon and at the mouth of a river. At the former locality, about a mile south of Estartit, one of these birds usually fed in the normal manner on small fish, but, in the absence of perches, used the sand-dunes as a vantage point. It also regularly hovered over the reed-beds, however, and on several occasions I watched it pick off one of the large numbers of dragonflies which were settled there. It would return to the sand- dunes to eat these, apparently devouring them whole. At the mouth of the river, about two miles from the lagoon, what was presumably a second bird similarly made use of the sand-dunes as a vantage point, even in preference to the branches of trees overhanging the water. As well as fishing, however, this bird also quite frequently hovered over the dunes at a height of only a few inches, apparently following some moving object. It would then settle and catch and eat whatever it had been following. I was unable to see exactly what it was catching, but a search of the area showed that there were only occasional lizards and numbers of fairly large spiders. These latter frequently emerged from burrows in the sand and ran across the dunes. Had the kingfisher been feeding on the lizards I should probably have been able to see them caught, and I decided that it was more likely that the spiders were its prey. In either case, I have been unable to trace any previous records of Kingfishers catching food on dry land in this manner. The behaviour described above appeared to be anything but un- usual with the birds concerned, both types of feeding being seen fairly regularly and on several dates. J. T. R. Sharrock House Martins building nest of cement. — During the dry weather in the early part of June 1961, at a site on the outskirts of Bishop’s Stortford, Hertfordshire, a pair of House Martins (Delichon urbica ) succeeded in constructing the greater part of their nest with wet cement in place of mud. The site itself is some forty feet above the ground on a private house. One or two pairs of House Martins have attempted to build there in several recent years, but the owner has invariably broken up the nests before the eggs have been laid. It was on 2nd June 1961 that I first noticed that material had been added to a crescent of mud left from the previous year and I was immediately interested in the peculiar tone of the fresh deposit, which appeared to be exceptionally yellow. About seventy yards awav, the foundations of a new house and concrete drive were then being laid. It was the practice of the workmen to put down wet cement in tire late afternoon. 134 NOTES and on yd and 4th June I was able to watch the birds gathering material. This they did in the evenings, after the workmen had gone and while the mixture was still wet. They appeared to take the cement only from the drive, where it contained a large proportion of sand, and to gather only the coarse, detached flakes between the worked surface and the wooden moulding along its edges. At no time did I observe any attempt to pick up material from the rammed, flattened face of the drive. In most years, mud is abundant in the immediate vicinity of the site, where the soil consists of heavy clay and there are four small ponds, each with a marginal cattle-wade. At this particular period, however, several weeks without significant rainfall had dried these out com- pletely. By 7th June, the lip of the nest-cup had made contact with the roof and the owner of the house prepared to destroy the structure. Hitherto, his custom had been to do so by hurling a tennis ball at the nest from the ground, but the cement had set so hard that this proved quite ineffectual; as a result, he was obliged to climb up by ladder and break the accumulated mass with a small hammer. Arnold Darlington Unusual death of House Martin. — On 29th July 1961, at Hornsea, Yorkshire, I noticed an adult House Martin (Delichon urbicd) suspended from its nest about sixty feet up under the eaves of a house. It was apparently dead, with its head held in a noose of grass or thread. Presumably it had become entangled in loose nesting material and, in struggling to get free, had eventually hanged itself. The other adult was busy feeding the young and continually brushed upwards past the corpse. The bird was still dangling there on 6th August, but had fallen down by the 13th. On this last date the remaining adult and four fully-fledged young were perched near-by. G. R. Bennett [There are many records of birds hanging themselves accidentally in loops of cotton or thread. Nestlings and juveniles are the most frequent victims, but experienced birds also occasionally come to grief this way. We have not previously heard of an instance involving an adult House Martin, however. — Eds.] Hooded Crow asleep on the ground.— A recent note {Brit. Birds, 54: 405) described a Blue Tit {Parus caeruleus ) and a Carrion Crow 'Corvus corotie) sleeping on the ground. On 20th July 1961, at about 5 p.m. and in bright sunshine, I noticed a Hooded Crow (C. coronc cor nix) standing quite still with its beak tucked under its scapulars— apparently asleep — some three feet from the edge of a thirty-foot cliff on the Isle of Ganna, Inner Hebrides. I approached quietly to within BRITISH BIRDS two feet of the bird, but hesitated momentarily before attempting to catch it. It suddenly woke up and jumped over the cliff, calling furiously. I was left with a tail feather in my hand! P. R. Evans Rook asleep on the ground. — On the afternoon of ioth July 1961, I came upon a Rook ( Corvus frugilegus) apparently asleep on grassland near Lanchester, Co. Durham. Its head was tucked into its feathers and my first impression was that it must be sick. I approached to within a few feet of it before it awoke and flew off to join a party of about twelve other Rooks in an adjacent field. Its flight was perhaps a little erratic for the first yard or so, but thereafter appeared normal. Sleeping on the ground in this way certainly seems a highly dangerous thing for an arboreal bird to do, but I do not believe that this Rook was either injured or diseased. If it had been, I should have expected it to stand out from the other Rooks in the party which it joined, but neither on the ground nor in flight was it possible to distinguish it. Probable inheritance of crossed mandibles in Robins.— During the winter of 1960-61 our garden at Oxford was frequented by a cock Robin ( Erithacus rubecula ) with a completely crossed bill. This dis- ability did not prevent his getting a good living, though he had a permanently tattered and bedraggled appearance, presumably through being unable to preen properly. He was very lively and aggressive and had found himself a mate by the end of February. Their first nest was not discovered, but the pair built again in June and five eggs were laid. All hatched and the young fledged safely, but one of the five had a crossed bill exactly like its father’s. Unfortunately I was unable to keep track of this one after it left the nest. V . M . C A 1 r d [The rather scanty evidence that is available on the inheritance of bill deformities was discussed by D. E. Pomeroy in his paper on “Birds with abnormal bills” which appeared in the February issue (see pages 60-61). — Eds.] J. C. 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Revolutionary ZEISS Binoculars Eric Hosking using his Zeiss binoculars Specially designed for spectacle wearers Mr. Eric Hosking, F.R.P.S., M.B.O.U., the celebrated ornithologist, says: “/ am more than pleased and delighted with my 8x30B Zeiss binoculars and have found them invaluable now that I have to wear spectacles all the time.’’' With these new Zeiss binoculars the user — even when wearing spectacles —has the advantage of a field of view many times larger than that normally obtained when using binoculars with 6 CAVENDISH SQUARE, LONDON spectacles. This has been achieved by the use of an entirely new eyepiece unit. Like all the latest Carl Zeiss binoculars, the new 8 x 30 B is also fitted with the unique Zeiss tele- objective system which gives im- proved performance with smaller size. Illustrated booklet and name of your nearest stockist on request from the sole British agents W.l. TELEPHONE: LANGHAM 6097 Printed in England by Dicmer & Reynolds Ltd., Eastcotts Road, Bedford Published by H. F. & G. Witherby Ltd., 5 Warwick Court, W.C.i British Birds River Warbler on Fair Isle : a bird new to Britain Peter Davis Radar evidence on migratory orientation David Lack Studies of less familiar birds: 118 — Rock Bunting and Rock Sparrow P. A. D. Hollom, Arthur Gilpin and others 'Principal Contents (with eight plates) Three British Birds AN ILLUSTRATED MONTHLY JOURNAL Edited by P. A. D. Hollom E. M. Nicholson I. J. Ferguson-Lees Stanley Cramp Photographic Editor: Eric Hosking Hon. Editors: W. B. Alexander N. F. Ticehurst Editorial Address: 30 St. Leonard’s Avenue, Bedford Contents of Volume 55, Number 4, April 1962 Page River Warbler on Fair Isle: a bird new to Britain. By Peter Davis (plate 23a) 137 Radar evidence on migratory orientation. By Dr. David Lack . . . . 139 Studies of less familiar birds: 1 18— Rock Bunting and Rock Sparrow. By P. A. D. Hollom. Photographs by K. J. Carlson, R. G. Carlson, Arthur Gilpin and H. R. Lowes (plates 24-31) U8 Notes: — Little Grebes attacking Moorhens (W. Edmund Harker) 164 Fulmar laying egg in Northamptonshire garden (L. S. Taylor) . . . . 164 Water Rail drowning small Passerines (Alfred R. Blundell) . . . . 165 Great Spotted Woodpecker taking thistle heads (Dr. Bruce Campbell) . . 163 Swallows feeding on froghoppers (N. L. Hodson) . . • • ■ • • • Blackbird recovering from collapsed eye (M. P. Harris) (plate 23c) . . 166 Radde’s Bush Warbler in Norfolk (R. A. Richardson, B. R. Spence, H. G. Alexander and Kenneth Williamson) (plate 23b) 166 Curious behaviour of Starlings (Colin Drage) 168 Annual subscription £ 2 (including postage and despatch) payable to H. F. & G. Withcrby Ltd., 3 Warwick Court, London, W.C.i A BINOCULAR WITH EXTRA POWER The WRAY £Xe A>e/>a A newly designed glass with a very wide aperture giving an unusually high light-gathering power, a desirable feature for the bird-watcher Retail price £38.17.10 including tax Send for comprehensive binocular brochure in hide case From all leading instrument dealers opticians and stores WRAY (Optical Works) LTD BROMLEY KENT Telephone: RAVensbourne 0112 Choose a lightweight glass Choose PFEIFER BINOCULARS First quality glasses, fully coated on all optics, they have a high light intake and by reason of their extremely light weight are ideally suited to the bird watcher. The following models are available from stock : 8x30 £25 10 0 8X40 £32 10 0 8X50 £42 10 0 Available on deferred terms SOLE AGENTS FOR THE U.K. A II prices include solid hide velvet lined case Trade enquiries invited COGSWELL i HARRISON LTD. MASTER GUNMAKERS SINCE 1770 DEPT. BB, 168 PICCADILLY, LONDON, W.l (opposite Bond Street) Phone: HYDe Park 4746/9809 The West Wales Naturalists’ Trust (the west wales field society) Membership is open to all who are interested in the study and conservation of wild life in Wales. By joining (subscription: £1 Is. Od. per annum), you will receive the quarterly journal Nature in Wales free. Your member- ship card entitles you to join in the field excursions, lectures and meetings in the several parts of Wales in which the Trust operates. It enables you to visit the Trust’s several island sanctuaries and nature reserves including St. Margaret’s, Cardigan Island, Grassholm (owned by the Royal Society for the Protection of Birds and wardened by the W.W.N.T.) and Skomer. In order to stay at Skokholm Bird Observatory visitors must be members of the W.W.N.T. The activities of the Trust include the co-operative study by marking (with rings, etc.) of animals, including birds and seals, and the record- ing of their distribution and habits in Wales. PUBLICATIONS (post free): Island of Skomer, ed. John Buxton and R. M. Lockley, 18s. (few copies left); The Birds of Carmarthenshire by G. C. S. Ingram and H. Morrey Salmon, 5s. (in stiff covers Is. extra) (4s. to members); A List of Pembrokeshire Plants by F. L. Rees, 3s.; The Plora oj St. David s Peninsula by C. L. Walton, 3s. ; Skokholm Bird Observatory Reports for the years up to 1960, 3s. each; Nature in Wales, back numbers, 3s. THE WEST WALES NATURALISTS’ TRUST 4 Victoria Place, Haverfordwest, Pembs The Popular Handbook of Rarer British Birds By P. A. D. HOLLOM 39 plates in colour 37/6 net PUBLISHED BY WITHERBY Plate 23A. River Warbler {Locustella fluviatilis). Fair Isle, September 1961. This shows the general shape, the blurred streaks on the under-parts, the stout bill and the indistinct supercilium (see opposite) {photo: Angela Davis) Plate 23B. Radde’s Bush Warbler {Phjlloscopus schwanj), Norfolk, October 1961. Note the short and stout bill, the long and narrow, buffish-white supercilium, and the dark eye-stripe and crown (page 166) {photo: P. R. Clarke) Plate 23c. Blackbird {Turdns merula) with eye punctured, per- haps by the bird itself in trying to remove the large tick fixed behind it (page 166) {photo: C. Stockton ) British Birds »cr PURCHAS iy's V\ Vol. 5 5 No. 4 April 1962 — River Warbler on Fair Isle: a bird new to Britain By Veter Davis (Plate 23 a) A first-winter River Warbler (Locus tella fluviatilis) was trapped at Fair Isle on 24th September 1961, and seen again on the following day. This is the first record of this east European species in the i British Isles, although it breeds as near to us as the Oder River in -north-east Germany, and has occurred in southern Norway, Heligo- and and Holland. The bird was found shortly after noon on the 24th, in the incom- parable “warbler-ditch” at Lower Leogh, by G. J. Barnes, R. M. Medderman, P. J. Slater and the writer. It was skulking in tussocky Drass in a shallow and open section of the drain; as we watched, it : lew up to the lowest wire of the adjacent fence, and gave us a brief i >ut unimpeded view from behind. It was obviously a Locusiella, but >ne we had not previously seen; it was larger than a Grasshopper 'Warbler (L. naevia ) and had dark olive-brown, unstreaked upper-parts. We were not able to see the underside, but noted an indistinct pale upercilium. Its fan-shaped tail appeared noticeably long and broad, ts legs and feet were seen to be pink, and seemed large and strong for tts size. A short single-panel mist-net was erected in the ditch, and within en minutes of its discovery the bird was in the hand. It was taken o the laboratory, and was now seen by some fifteen other observers, he following description was made: Entire upper-parts, wings and tail dark olive-brown, with a rather rufous tinge, especially on the scapulars, wing-coverts and upper tail-coverts; feathers of crown and forehead indistinctly tipped darker brown, otherwise no streaking or barring above. Lores, cheeks and car-coverts greyer brown; very indistinct *37 BRITISH BIRDS huffish supercilium. Under-parts whitish, washed yellowish-buff, with blurred and indistinct grey-brown streaking on chin, throat and upper breast; flan s and sides of breast washed grey-brown with yellowish overlay ; centre of lower breast and belly whiter than rest of under-parts, unstreaked; under tail-coverts grey-brown with broad whitish tips ; axillaries and under wing-coverts washe pale grey-brown, with pale yellow tinge on outermost coverts, near carpa joint. Outer web of 2nd primary dirty-white; shafts of tail feathers dark above, whitish below; flight-feathers in good condition, tail slightly chipped; twelve rectrices. Soft parts: upper mandible horn-coloured with slight flesh tinge, especially near cutting-edge, and lower mandible pale flesh tinged dark towards tip; gape pale yellow; legs and feet clear flesh-pink, paler behind and on the soles ; eye dark grey-brown. Measurements: wing 73 mm., bill 16.5 mm., tarsus 23 mm., tail 52 mm.; weight 17.1 gm. at 1255 GMT. Wing-formula: 1st primary 5 mm. less than primary coverts; 2nd longest, 3rd —2.5 mm., 4th — 3.5 mm., 5th —8 mm., 6th — 11 mm., 7th —13 mm., 8th —16.5 mm.; no emargination ; no notch on inner web of 2nd. No method of ageing River Warblers is given in K. Williamson’s Identification for Ringers: 1 (i960), but according to H. E. Dresser s A Manual of Palaearctic Birds (1902), p. 1 36, “the young bird has the upper parts more rusty in tinge, the under parts tinged with ochreous, and the throat is also indistinctly striped”. Our warbler showed these characters. In several other species of this genus the first-winter birds are said to be more rufous above, and in all they are more yellow below. The warbler was photographed in colour by several of the visitors, and in black-and-white by my wife. The monochrome reproduction on plate 23a shows the general appearance, the blurred streaking of the under-parts, the stout bill and the indistinct supercilium. Towards the end of the photography it escaped from my hand and flew away; but about ten minutes later it entered one of the observatory buildings and was recaught. It was then transported to more congenial sur- roundings at the Gilsetter Marsh. Here we had excellent views as it crept among the sedges; the streaked breast seemed a good field- character on the occasions when a front or side view was possible. None of the visitors nor I saw the River Warbler on the 25 th, but it spent the day creeping about the stone dykes at Lower Stonybreck, and the occupants of that croft pointed it out to our cook, Pat Adams, during the afternoon. She watched it at close range through a window and saw that it was the ringed bird. It had disappeared by the following day. We had to distinguish the Fair Isle bird from Gray’s Grasshopper Warbler (L. fasciolata ) and from Savi’s Warbler (L. luscinoides), particularly the less rufous form L. /. fusca. Neither of these species has streaked under-parts, however, so that field-identification would probably have been possible even if we had been unable to catch it. The differences of size, wing-formula and coloration were readily available to us in Williamson’s invaluable guide already mentioned. 138 Radar evidence on migratory orientation By David Lack Edward Grey Institute, Oxford INTRODUCTION Laboratory experiments on orientation in animals are proceed- ing so rapidly that this may be a useful time at which to review evidence on the orientation of bird migrants over the sea provided by radar. This evidence requires local knowledge for its interpretation and, since even with local knowledge I have made mistakes in the past, I have restricted this paper to my own analysis of the data from East Anglia. These data came mainly from personal visits to a Norfolk radar station in March, April and September. In addition, I am extremely grateful to Dr. M. T. Myres, J. L. F. Parslow and J. Wilcock of the Edward Grey Institute for their observations in the same area in October and November; to the Department of Scientific and Indus- trial Research for substantial grants to finance their work; and to H.Q. R.A.F. Fighter Command and the personnel of the Norfolk radar station for providing us with every facility on our visits. I am also much indebted to the Research Laboratories of Marconi’s Wireless Telegraphy Co., who kindly lent me for analvsis their outstanding films of a radar display in this area taken at intervals throughout the year. Finally, Dr. J. F. Monk, R. E. Moreau, J. L. F. Parslow and Dr. A. C. Perdeck very kindly criticised the manuscript before publica- tion, and Dr. Perdeck amplified the recent Dutch work on Chaffinch migration. The radar observations from which the ensuing findings are drawn are described in a series of papers in The Ibis { by Lack 1960a, 1962 and ffi press, and for the Alarconi films by Eastwood and Lack in press); if no further reference is given, the observation concerned is documen- ted in one or other of these papers. experiments on orientation in migrants Nearly all the experiments on bird orientation have been carried out on non-migratory domestic pigeons ( Columba Iivia var.), but there have been a few important exceptions. First, Ruppell (1944) caught many Hooded Crows ( Corvus corone cornix ) on passage through Rossitten in East Prussia and displaced them rather south of west to Flensburg in western Germany before release. The ringing recoveries of these birds showed that both their wintering area and especially their breed- ing area had been displaced to a corresponding extent to the west. *39 BRITISH BIRDS The same held for later displacements to the south-west in Germany. From this it was argued that Hooded Crows arrive in their winter quarters and return to their breeding grounds by travelling on a fixed bearing for a fixed distance; the factors determining this bearing and distance were unknown, but presumably had an innate basis. These results held for most adults as well as for the juveniles, but some individuals, mainly if not entirely adults, returned to their normal quarters. Perdeck (1958) carried out similar experiments on the Starling ( Sturnus vulgaris), another mainly diurnal migrant, which he caught in large numbers on passage in Holland, displacing them rather south of east before releasing them in Switzerland. He found that the dis- placed juvenile Starlings travelled in the same direction from their release-point as they would have taken from their place of capture to reach the normal wintering area in England; these birds returned to the same (displaced) wintering area in France in subsequent years, but the evidence was inconclusive as to whether or not there had been a corresponding shift in their northern breeding area. Displaced adults differed markedly from the juveniles in that they returned to their normal wintering area in England. Perdeck concluded that juvenile Starlings arrive in their winter quarters by travelling on a fixed bearing, whereas adults have true homing (or “goal”) orientation, based on previous experience of the area concerned. Kramer (1950, 195 2) made the critical break-through in showing that a caged Starling in a state of migratory restlessness oriented itself by the sun. The fact that it did not head in the true migratory direction needs further study, but does not affect the conclusion that it used a “sun-compass”. Shift of the apparent position of the sun by mirrors caused a corresponding shift in the orientation of the Starling. To use the sun to maintain a constant heading, it is necessary for the bird to allow for changes in the sun’s apparent position with the time of day, and Kramer’s pupil Hoffmann (195 3, 1954, 1960) demonstrated experi- mentally that the Starling possesses the necessary “internal clock” (see also Schmidt-Koenig i960). This suffices to explain how a juvenile bird can migrate on a fixed bearing by day. Later, Sauer (195 5> x957> 1958) showed similarly that juvenile warblers obtain their bearing at night from the stars; this he tested both under the natural sky and in a planetarium. The other factor enabling a juvenile bird to reach the wintering area normal for the population to which it belongs is that causing it to cease migration after a while. Possibly the bird might react to the time for which it has flown, but whether in that case it makes any allowance for the wind is not known. Another possibility is that it might depend on an innate astronomical clue for its latitude. Sauer (1957) 140 RADAR EVIDENCE ON ORIENTATION claimed that a Lesser Whitethroat ( Sylvia curruca) in a planetarium changed its orientation from SE to south when presented with the night-sky at the latitude of the Mediterranean, where it makes this change of heading in nature. He also had suggestive evidence that birds presented with the night-sky of their wintering area ceased their migratory restlessness. However, a Whitethroat (S. communis ) taken thus to South-West Africa, at the extreme southern limit of the winter range of this species, continued to head southward, though three Garden Warblers (L. borin') were nearly inactive. Hence further observations on this matter are needed, especially in view of the criticisms of Sauer’s work by Wallraff (i960). One would also like to know why it is that, in autumn, caged migrants used for physiological experiments cease their migratory restlessness after a while; this might possibly be because they had been active for the time normally needed to reach their wintering area, but the situation is so unnatural that other explanations are possible. In sPring> on the other hand, migratory restlessness is usually, though not always, maintained right through the summer until the moult (refer- ences in Lack 1960b). This might perhaps be because, in nature, migratory restlessness in spring is normally inhibited bv breeding behaviour; alternatively it might be because the caged birds have had previous experience of their breeding area and are aware in some way that they have not reached it. Critical experiments are greatly needed. The factors enabling an adult migrant to return to its home area after displacement on migration are also quite uncertain. This faculty is presumably the same as the “homing” of pigeons, and in this connec- tion Kramer (1952, 1957, 1959, 1961) made the important distinction between the “compass-sense” (which for the homing pigeon, as for the juvenile migrant, is based on sun or stars) and the “map-sense”, by which the bird is able, so to speak, to fix its position with respect to its goal so as to head in the correct direction after displacement. Matthews (195 5) postulated that the sun provides not only the compass but also the sense of position, through variations in the sun-arc. Kramer (Joe. cit.) and his school (Schmidt-Koenig i960, Wallraff i960) rejected this view on the grounds that the necessary discrimination of the sun-arc in the brief time available would make too great demands on a bird’s visual acuity, time-sense, and capacity to compare with past experience. Matthews (1961) replied that more time might be avail- able than previously supposed if the initial directions taken by homing pigeons on release were due to “nonsense-orientation” northward. Pennvcuick (1961) produced a modified theory of sun-navigation, based on sun-altitude and its rate of change, but it is as yet untested and Schmidt-Koenig (1961) considered it to be contrary to some of the experimental evidence. While Kramer and his school concluded BRITISH BIRDS that the sun is not concerned in the map-sense, they freely admitted their inability to suggest an alternative explanation. In one of his planetarium experiments, Sauer (1957) shifted the night- sky to that appropriate, at the time in question, to an area far to the east, and reported that a juvenile Lesser Whitethroat then headed back west, instead of orienting to the south-east. This suggests that it obtained not merely its compass-direction but its map-position from the star- pattern. But the latter conclusion was challenged by Wallraff (1961). This was partly because of the diversity of Sauer’s results. In addition, such a shift might be interpreted as a shift in time rather than space, since the star-pattern concerned would have reached the bird’s home area some hours later; hence its internal clock might have been affec- ted. Further a corresponding shift of the night-sky to the west pro- duced no corresponding eastward heading by the bird. Sauer (1961) replied vigorously, but this point also should, I think, be regarded as unsettled. This is not, of course, to doubt Sauer’s discovery that a night-migrant uses the stars for its compass-direction. Finally, Merkel and Fromme (1958) and Fromme (1961) placed Robins ( Eritbaci >ften set out in a strong cross-wind and in fairly disturbed weather, so t::hat drift is frequent and rather extensive. This difference is most rceadily explained on the supposition that juvenile birds, on their 1 irst migratory flight to winter quarters wrhere they have never been, .annot compensate for drift, so that if they are drifted a long way they 1° not reach the area to which their population is adapted and may emd in an area where they cannot survive. Juveniles probably com- prise about half the birds migrating in autumn. In spring, on the other hand, all migrants are returning to an area where they have been oefore and so they can presumably compensate for drift. This inter- pretation fits with the displacement experiments on a variety of wild )irds showing that they can home to their breeding area (summarised )y Schiiz 1952), and with Perdeck’s (1958) finding that displaced uvenile Starlings do not reach their normal wintering area. It does lot fit with part of Ruppell’s (1944) results with Hooded Crows, which ailed to reach their former breeding area after displacement, nor, for he opposite reason, with Sauer’s (1957, i960, 1961) claim that juvenile varblers can correct for longitudinal displacement by bico-ordinate ■ navigation based on the stars on their first autumn flight. It should Pe added that there seems to be more urgency about the spring than : le autumn migration, and this may be a further reason why birds Dmetimes set out in less good conditions in spring. A further interesting point is that, while autumn migrants do not sually set out in strong opposed or cross winds, they migrate freely l strong following winds. This might possibly mean that a juvenile figrant does not depend on the time for which it has flown for its ^termination of where to end its migratory journey, since it will avel much faster with a strong following wind than with a weak fllowing or weak opposed wind. This particular piece of evidence , however, far from conclusive. RESPONSES TO COAST adar shows that, at night, departing migrants coming to a coastline irmally proceed straight over it and out to sea without deviation in 145 BRITISH BIRDS their tracks. Rarely, with an opposed wind and a nearly full moon, a little coasting was seen, but only when the coastline was close to their normal heading. The idea that night- migrants use “coastal guiding lines” (Williamson 1955, pp. 181, 183) can be ruled out. In daylight, also, most migrants proceed straight over a coastline and out to sea without deviation, but with opposed winds or in dis- turbed weather a proportion of them not infrequently follow a coast- line close to their heading, and the coasting birds may later leave in a concentrated stream from a projecting headland or sharp turn in the coast. A visual observer on the coast may see a misleadingly high proportion of migrants coasting, not merely because the coasting birds fly past him instead of across (Van Dobben 1953, p. 216), but also because many of those crossing the coast may be altogether above visual range. The idea that day-migrants are effectively “guided” by coastlines to their winter quarters can also, I think, be excluded — except perhaps in the case of the Chaffinch (Yr ingill a coe/ebs), discussed later. (It may be noted in passing that the term “guiding-line” was not origi- nally used in this definitive sense, cf. Van Dobben 1953, Lack 1959c, p. 386). Radar shows that immigrant birds over the sea by day often alter course towards the coast when within some ten miles of it, presumably j because they have seen it, and this sometimes involves a temporary change in their direction of up to 45 degrees. It also means that a visual observer on the coast may obtain a misleading idea of the direct I tion of the main passage over the sea, as I earlier inferred from visual observations on arriving Starlings (Lack 1954, p. 3). After crossing the North Sea westward from Holland in autumn, diurnal migrants sometimes (but not by any means always) turn upwind along the Norfolk coast. With a northerly wind, the coasting stream in east Norfolk moves north, in north-east Norfolk NW, in north Norfolk west, and on the east side of the Wash south, so that, if an individual continues along the coast for the whole distance, it even- tually turns through 180 degrees. I have discussed elsewhere (Lack 1959c, p. 386) why migrants might continue coasting beyond a marked turn in the coast. The initial tendency to coast upwind after a sea- crossing needs further study. More complex changes in direction were sometimes detected by radar when migrants were within sight of land by day, such changes being particularly marked on Marconi films covering the Straits of Dover. Birds departing from Cap Gris Nez WSW often turned west in the Straits or the English Channel and eventually WNW. This was not a simple response to the sight of the Kent coast, because the place where, on average, the birds changed direction differed rather markedly on different days and also at different times on the same day, 146 RADAR EVIDENCE ON ORIENTATION while different individuals sometimes differed at the same time. Sometimes, moreover, the birds continued changing towards NW when already well over Kent. Similar changes were occasionally observed near North Foreland, in diurnal migrants that had come NNE through the Straits of Dover and later changed to NNW; and here also, the birds by no means always turned so as to reach land as quickly as possible. This suggests that a gradual shift in the standard direction of the migrants was involved; changes of this type with time of day have been demonstrated for the Chaffinch in .Holland in autumn (Van Dobben 1953, A. C. Perdeck in discussion). The most elaborate changes in direction correlated with a coast- line are those of the Norwegian Chaffinches, just mentioned, which pass through Holland in autumn. These birds leave southern Norway probably rather east of south, change to SSW in Denmark . and eventually to WSW as they move south down the east side of the ‘North Sea. After they reach northern Holland, some take off WSW •for eastern England, but others continue along the coast to Cap Gris Nez, from which many leave WNW (Van Dobben 1953, Perdeck 1961 and in Hit.). Others follow the coast south and west beyond Cap Gris Nez and presumably later turn north to reach England, as has : been shown for the Starling (Klomp and Perdeck ^1959). This ! movement brings the Norwegian Chaffinches to England by a short crossing of the North Sea. But the birds actually follow the coastline chiefly in adverse weather, particularly with a strong head-wind, and ! also in the latter part of the morning when the migratory urge is presumed to be waning, while adult males do so to a greater extent than females or juveniles (Van Dobben 1953, Perdeck T96i). In the | early mornings in good weather, the birds fly high and are not directly influenced by the coastline, but their direction of flight still varies progressively round the North Sea in the way described. This sug- gests that, though their direction can be modified by sight of the coast, !.he\ are not directly “guided’ by it, and that the primary factor 1 nvolved is a progressive change in the standard direction or innate leading. In this connection a Marconi radar film showed that, on a arge westward arrival, presumably of Chaffinches, in early October, ! ome of the birds far out in the southern North Sea off Suffolk had already turned NW, whereas others flew west or WSW here and : flanged to NW only after crossing the English coast. If the succes- ive changes in direction have an innate basis, thev presumably depend n some way on distance flown, but, once again, it is not known how he birds estimate this. LONG-DISTANCE CHANGES IN DIRECTION I Tie Norwegian Chaffinches just discussed seem exceptional in the M7 BRITISH BIRDS extent to which they change their heading in the course of their migra- tory journey, some of them eventually through 180 degrees, from SE to NW. Smaller changes in heading occur in two groups of European Passerine night-migrants that winter in tropical Africa. First, the Lesser Whitethroat, Red-backed Shrike (Lanius cristatus collurio) and Lesser Grey Shrike (L. minor) leave western Europe about SE and change to south somewhere around the eastern Mediterranean; secondly, the great stream of warblers and flycatchers migrating SW and SSW in autumn through western Europe to Iberia must there change to east of south in order to reach any point in tropical Africa, where they winter (Moreau 1961). These changes presumably have an innate basis, and they are presumably made either after the migrants have flown for a given time or distance, or when they have reached a given latitude, as discussed earlier. ^ Radar has revealed two further “dog-legged” migrations. First, the vast majority of Passerine night-migrants that breed in Britain leave in late August and September just east of south, not SSW; but, since ringing recoveries show that they later reach western Iberia with the main European stream, they evidently change their heading from a little east of south to well west of south somewhere near the southern border of France. The same birds must change again to east of south in order to reach their tropical wintering areas, as already mentioned. Hence they make two changes in heading in the course of their journey, and both presumably have an innate basis. Secondly, many Knot ( Calidris canutus ) reach Norfolk in August and early September on days when the wader migration tracked by radar comes SSW. As Knot do not breed in appreciable numbers west of the Taimyr peninsula, they presumably change from nearly due west to SSW before leaving Scandinavia. Similar considerations apply to a smaller extent to various other arctic waders. REVERSED MIGRATION The two main migratory movements over East Anglia in spring are of winter residents departing eastward and of summer residents arriving from the south and heading NNW. But not infrequently with a cold easterly wind there is a westward arrival from the east, and occasionally with a cold northerly wind there is a southerly departure. Such “reversed migrations” occur by both day and night and, though their existence was known earlier, they have proved to be much commoner in East Anglia than was formerly supposed. Their survival value is obvious. But their occurrence presents a complex problem in orientation, as pointed out by Sauer (1961, p. 234), since night-migrants in spring respond to the spring star-pattern by travelling in the direc- tion appropriate to the autumn. This phenomenon presents no 148 RADAR EVIDENCE ON ORIENTATION particular difficulty, however, if the birds use the stars or sun purely as a compass. Similarly, small movements of Passerines occur eastward from East Anglia with westerly winds at intervals throughout the autumn and, at least in October, these probably include reversed migrations, as the echoes resemble those from thrushes. Three ringing recoveries also demonstrate such reversed movements in this group. A Blackbird (Tardus merula ) ringed at Spurn Point, Yorkshire, on 6th November 1954 was recovered four days later in Germany (Brit. Birds, 48: 492); another ringed on Fair Isle on 21st November 1958 was recovered in Norway ten days later (Brit. Birds, 5 2 : 474) ; and a third ringed on Fair Isle on 14th October 1959 was recovered in Norway two days later (Brit. Birds, 53: 492). Also, a Redwing (Tardus musicus ) ringed on :Bardsey, Caernarvonshire, on nth October 1959 was recovered in .Belgium a month later (Brit. Birds, 53: 491), again an eastern movement, but not a reversed migration for this species. Another curious autumn movement, a small one restricted to nights in late August and ■ September with a wind between NE and SE, is that of small Passerine night-migrants heading west from Holland to East Anglia. Accom- panying “falls” at the east coast observatories indicate that typical ' Continental night-migrants, notably Redstarts (Phoenicurus phoenicurus ) and Pied Flycatchers (Muscicapa hjpoleuca), participate. As these species normally migrate SSW towards Iberia, this is not a true reversed movement, nor is it directly down-wind, and its significance is quite obscure. More typical reversed movements occur northward in autumn with southerly winds, but they are extremely sparse and rare in East Anglia. They are commoner elsewhere in England (J. L. F. iParslow in press), while much bigger northward movements with ^southerly winds in autumn have been demonstrated by radar in eastern U.S.A. (Drury, Nisbet and Richardson 1961). REDETERMINED MOVEMENTS — EVIDENCE FROM RINGING Radar has provided no evidence for the existence of “down-wind .directed drift , by which Williamson (1952, 1955, 1959) supposed that migrants disoriented over the sea in full overcast descend low, re- orient by the waves, and fly down- wind; but the negative is not 1 inclusive, since if such flights occur they would probably be below ■radar range. Williamson considered this type of “drift” a valuable idaptation enabling the birds to escape from full overcast, and it is an issential part of this theory that the drifted birds (many of which would oe juveniles) should afterwards be able to correct for their displace- nent by a “redetermined” movement. In this connection, William- :on (x95 5) stated: “it is already clear from a preliminary examination of a number of bird observatory records that drifted birds quite 149 BRITISH BIRDS obviously have a faculty for accurate re-orientation and are not ‘disoriented waifs’, as some students of migration have cla • This view accords with Sauer’s (1957, 1961) claim that juvenile warblers can correct for displacement by bico-ordinate navigation based on the Trs but not withPerdeck’s (19,8) finding that juvenile Starlings do not correct for displacement; however, the Starling usua y migra ^ The "point is so important that I decided to examine the records published annually in the “Reports on bird-ringing in Bnttsb Birds of probable Scandinavian night-migrants ringed at the British east coast observatories in autumn and later recovered outside Brita n. The most spectacular was a juvenile Red-backed Shrike ringed ^ Northum- berland in late August and recovered in Sicily a month later (Bri/. Birds, 48- 496). This species normally migrates SE, however, and ther^ no evidence that the bearing of Sicily from Northumberland differs from the normal heading in autumn of the population to which this bird belonged. On present evidence, therefore, this bird might v eil have headed in the same direction as before it drifted to England, without any correction for displacement. . Better evidence comes from the many Robins ringed after the great “fall” on the English east coast in early October 1951. Of six then rino-ed at Spurn Point in Yorkshire or Cley in Norfolk and later recovered abroad, one in the Gironde and two in Charente Maritime, France, were nearly due south of where ringed, but two in M^°rca were SSE and one in Italy was SE; another ringed on the Isle of May, Fife, was recovered SSW in Portugal. One might perhaps conclude from this that the first three and the last were juveniles, and the others adults, and that the three adults corrected for displacement by head- ing south-eastward to their normal wintering grounds, while the four juveniles failed to correct and continued on their normal south or SSW heading, thus reaching a different wintering area. But other explanations are possible, for instance that two different Robin popula- tions with different wintering areas were involved in the “fall”, so the •evidence is quite inconclusive. After another Robin arrival in early October 1959, chiefly in south- eastern England, six recoveries were SSW of where ringed, in Iberia (Williamson and Spencer i960). This might suggest that no change in heading occurred, but these birds may not have been drifted | appreciably off-course to the west in the first place. A seventh Robin ringed on Fair Isle in the same period must have been drifted west, but, as it was later recovered SSW in Portugal, it may not have changed its heading on leaving Fair Isle. The other Scandinavian chats, warblers and flycatchers, which between them comprise the bulk of the September “falls” at the east 150 RADAR EVIDENCE ON ORIENTATION coast observatories, have provided very few ringing recoveries abroad. Of the species which normally migrate south-westward (i.e. omitting the Lesser Whitethroat), none of those ringed on the British east coast in autumn have been recovered in the same autumn appreciably east of where ringed. The most typical Scandinavian migrant is the Pied Flycatcher and, of the seven recoveries abroad in the same autumn, six were SSW of where ringed, five in Portugal and one at Cadiz, while one was south of where ringed, in Charente Maritime, France. Hence all seven were in areas regularly frequented by Scandinavian migrants on passage. But it is not know whether these ringed individuals were adults or juveniles. Nor is it clear whether they appreciably changed their heading after leaving England or whether they con- tinued on the same SSW heading as before, while the one individual recovered south of where ringed might, presumably, have been drifted eastward in the Bay of Biscay by the prevailing westerly winds. Similar doubts attend the few recoveries of other drifted species. Clearer evidence for redetermined movements is provided by the Continental Redwings (7 . m. musicus ) ringed in autumn on Fair Isle. These birds normally head south-westward, so they were evidently drifted oft-course to Fair Isle and several have later been recovered in Continental Europe between south and SSE of where ringed (Goodacre i960), presumably having corrected for this displacement. Similarly, Continental Song Thrushes (T. p. pbilomelos ) ringed at British east coast observatories after presumed westward drift on autumn passage have been recovered on the Continent between south and SSW of where ringed (Goodacre i960), though the changes in direction have been less marked than in the Redwings. In both species, however, the proportion of recoveries is so small that all may have been either adults returning to wintering grounds known from a previous year, or juveniles accidentally drifted back east by the prevailing westerly winds later in their journey. Hence the possibility remains open that : the bulk of the juveniles did not correct for drift, but continued south- westward into the Atlantic and so did not provide any ringing re- coveries. There is, therefore, no convincing, or even suggestive, evidence from the ringing recoveries that drifted juvenile migrants in their first autumn can redetermine their direction towards the normal wintering area for their population. This is, of course, a negative statement, ■and the possibility that juvenile migrants have this capacity is not ^excluded. If they have it, however, it would seem to require an extremely complex behavioural mechanism. The juvenile migrant must be able not merely to respond to a succession of star patterns, but by their means to compensate for lateral displacement away from an area of which it has no prior experience, all on an innate basis. One BRITISH BIRDS must beware of rejecting a hypothesis because it seems to ask too much of a biological mechanism, but it is legitimate in cases of this sort to ask that the evidence in favour of the hypothesis be strong, and as yet it is weak or non-existent. . , It may be added that if juvenile birds in their first autumn do not have the capacity to correct for drift, this might help to explain why nearly all “rarities” (i.e. birds far beyond their normal range) are juveniles in their first autumn. Failure to correct for drift could not, however, provide the whole explanation of this phenomenon, as some of the rarities have come such immense distances that one must suppose that either their innate headings or their star-compasses were astray. redetermined movements— evidence from radar I earlier claimed (Lack 1959c, P- 394) that radar evidence supported the idea that drifted migrants later redetermine their course This was particularly because, after big “falls” of Scandinavian night-migrants in Norfolk with SE winds from 2nd to 4th September 1958, 1 detected by radar, on subsequent nights with westerly winds, eastward depar- tures of small (Passerine-type) echoes, which I postulated were the drifted birds returning to the Continent. Later experience has shown, however, that such eastward departures occur regularly from Norto in autumn with westerly winds and are unrelated to previous tal s , so they are not, or at least are not mainly, redetermined movements. Unfortunately radar has not revealed the direction later adopted y the Scandinavian chats, warblers and flycatchers after autumn tal s in Norfolk, probably because they comprise so small a fraction ot the migrants on any one September evening that their echoes are swamped by those from departing summer residents. I also (Lack 1959a, b, c) thought that I detected redetermined movements heading SSE in early April 1958, after big tails o Continental migrants on the British east coast with SE winds in late March. Moreover, the echoes heading SSE stopped at the Norfolk coast, where typical Continental species or subspecies were seen think there is no doubt, in this case, that the movements heading SSE were indeed of returning Continental birds. It was later suggested to me that it might be more correct to interpret them as reversed, rather than redetermined, movements, since the birds’ heading was nearly due south. However, the main direction of Continental night- migrants in spring is probably NNE, and so, if this held for the migrants in question, a movement SSE was not directly in reverse. 1 therefore think that these were true redetermined movements. As such, they present no particular theoretical difficulty in spring, as the birds are returning to a known goal. A more curious movement was often seen over the North Sea north >■ ! jjzGsr M , * y wJfl . W. M ' 'late 24. Rock Bunting {Emberi^a rid) at nest, Spain, May 1961. The breast I nd head arc grey with black bands over, through and below the eye; the under-parts re buffish-orangc, and the back is chestnut streaked with black. The females are nly slightly less well marked than the males (pages 158-162) (photo: Arthur Gilpin) Plates 25 and 26. Habitat and nest of Rock Bunting {Ember^a da), Spain Alay-Junc 1961. Habitats vary from steep rocky ground in mountains to more gentle slopes with scattered bushes, and from several thousand feet down almost to sea-level m some places (page i59) ( photos : H. R. Lours, /eft, and Arthur Gilpin ) Pi AXES 27 and 28. Rock Buntings ( Emberi?a da ) at another nest, Spain, June 1061 Note the unstreaked chestnut rump. This nest was at a height of three or four feet, but many are among stones on the ground (page 160). Onh the female incubates, but both feed the young {photos: K. J. Carlson, below , and R. G. Carlson) Plate 29. Rock Sparrow ( 1‘e/ronia petronia), Spain, May 1961. It resembles8 female House Sparrow, but note the whitish spots at the end of the tail and to striped head-pattern: the broad pale superciliary is set off by the dark side t( the crown and the dark patch behind the eye (pages 162-163) {photo: Arthur Gi'pll,l •E 30. Rock Sparrow ( Petronia pelronia), Spain, May 1961. This head-on 1 shows the streaked under-parts and the boldly barred under tail-coverts. The I pattern is completed by an equally distinctive pale stripe running the length I : crown from forehead to nape. 'I he sexes are identical ( photo : H. R. Lowes) . ; • <2 - Plate 31. Nest-sitc of Rock Sparrow ( Pe/ronia petronia), Spain, May 1961. 'Phis colonial species usually breeds in holes in broken rocky country or deserted buildings, but some nest in hollow trees and here the birds were sharing a river bank with Bee-eaters in pleasant fertile country (page 162) {photo: Arthur Gilpin) RADAR EVIDENCE ON ORIENTATION of Norfolk on October mornings, by Myres in 1959 and by Parslow in i960, though we did not appreciate its significance until Bourne I and Myres (in prep.) saw similar movements off northern Scotland. With SE winds over the North Sea during the night and morning’ the radar display often showed around sunrise a moderate or large immigration heading SSW towards Norfolk, the echoes being typical in size and speed of those from thrushes. These echoes later decreased in density, while others became common which were of similar size and moved at similar speed, but which headed about SSE, and these usually reached their highest density around 10 a.m. A similar I phenomenon was also seen with NE winds over the North Sea, except ithat on two such occasions there was already a large immigration head- ing SSE at sunrise. On one of these last occasions, and on several : mornings with a SE wind when both SSW and SSE movements were detected, there was an arrival of Continental Redwings, Fieldfares (1 urdus pilaris ) and Continental Robins (E. r. rubecula) at the English east coast observatories. These were presumably the species detected by radar and, to judge from the size and speed of the echoes, thrushes .greatly predominated. On none of these occasions were any echoes ^detected moving SSE over the land, but on quite a number of them, including those when the whole movement over the sea was SSE i similar echoes moved SSW over the land. These observations indicate that, with easterly winds in October E Scandinavian thrushes heading SSW during the night change their heading to SSE in the first part of the morning while in flight over the North Sea. The direction of the change, through about 45 degrees rowards the east, suggests compensation for drift by easterly winds. such, however, it was not entirely effective, since with a fairly trong easterly wind, the resultant tracks were on some occasions due outh and rarely west of south. Usually, all migrants travelling over he sea eventually changed to a SSE heading, and since it seems un- ikely that all the birds on all these movements were adults, the behaviour in question presumably occurs both in adults and in juveniles 1 11grat^ng for the first time. Similar behaviour was not recorded : unng the frequent SSW immigrations towards Norfolk of Scan- • inavian chats, warblers and flycatchers with easterly winds in late uigust and September. . thrush behaviour might be explained in one of several ways. Tie possibility that the birds are compensating for westward drift by lco-ordinate navigation after sunrise, though not excluded, seems nlikely. Pointing against it, the change always seemed to be from a eading of SSW to about SSE, irrespective of the strength of the wind id hence of the amount of drift, while over the land the birds changed ick to a heading of SSW. As a second possibility, Tinbergen (1956) U3 BRITISH BIRDS showed .ha. Chaffinches WSw” to SSW thejr heaf"| d"“Et*sC behaviour is restricted to days with easterly and eventuaUy SE «h.s ^ contrast, however^ the winds (A. C. ler Scanclinavian thrushes over the North alteration in directio during; the period of change Sea did not appear to be gradual, s“a • d J eith'r SSW or SSE, changed !«W to SSE But as such a change was not observed on the SS°W arrivals” with a westerly wind in the North Sea this response is !viInTethed only if the birds are aware, in addition, that they ^ey'lght're^le westward drift either by reference to objects onffie s”a or by the later rising of the sun. On one occasion when there were SE winds throughout the North Sea during t e mg , resultin'* in extensive westward drift, the wind was light SW off xwfr, Ilf next morning: vet the birds evidently changed direction to SSE though reference to the surface of the sea at dawn wou ave fnfficaSd eastward, no, westward, drift. C-ver.ly.^two -ca- sions with westerly winds during the nig t in rlv wind I Sea so that there was no westward drift, there was a light easterl) wi off Norfolk next morning; ye, the birds did not change direc t Perhans therefore, they react to the later rising of the sun, but the I relationship is not quantitative, i.e. they do not vary their heading in I relation to the extent of their drift. Clearly, further study of remarkable behaviour is greatly needed, and all the conclusions m SC?hTSt^ystaTlehb=haviour here postulated, namely a fixed change in compass heading in response to sigh, of the sea at dawn together with awareness of westward drift, might well be a valuab and effective adaptation for birds liable to drift seaward into he Atlantic, or to overshoot their wintering grounds in Irel • curious, however, that the Scandinavian chats, warUers and flyca cher in September do not show similar behaviour off Norfolk But th y have much further to travel, for whereas many of the Scandin. thrushes spend the winter in Britain, the chats warblers a y catchers are on their way to tropical Africa. Possibly, tlieref , smaller species show a similar response further south in then jour } , g\Vith easterly winds off northern Scotland in October, Bourne and Myres (in prep.) found, similarly, that Scandinavian thrushes often 1 < A RADAR EVIDENCE ON ORIENTATION .came in south-westward during the night, flew low over the sea after midnight, rose high at dawn, and then flew either SSW or south- eastward, and sometimes eastward or north-eastward. Evidently a similar phenomenon occurs here — indeed, this was where it was first 'recognised — and it appears to be more complex than oft' Norfolk, but the details have not yet been worked out. There are also corresponding movements in autumn off eastern USA, where night-migrants may be drifted eastward into the Atlantic ioy north-westerly winds. Visual observations on the mornings after -such movements show that many birds return westward to land .'Baird and Nisbet i960), but, since British migrants in sight of the cioast head directly towards it, visual observations may not show the t:rue change in direction over the sea out of sight of land. The return .movement has now been confirmed by radar (Drury, Nisbet and .Richardson 1961), but such details as the precise westward headings if the birds over the sea, and whether any of them continue south- eastward by day, have not yet been published. CONCLUSION The radar observations reviewed here provide no decisive answers to‘ :he questions raised by the conflicting experiments discussed at the itart of this paper. Ultimately, the answers must come from critical experiments, but meanwhile the tentative conclusions suggested by cadar may be summarised. In general, the radar observations fit best with the view that migrants in flight orient solely by a sun-compass or ;tar-compass, since they do not, so far as can be determined, allow for ateral displacement by the wind (unless flying very low). On this dew, a drifted adult migrant re-orients by its postulated map-sense inly after it has alighted. Hence the occurrence of disorientation in fill overcast might mean merely that the compass-sense is then in- iperative, and it does not necessarily follow that the map-sense depends in sun or stars ; it does follow, however, if the map-sense depends on ion-visual means, that this is not used, and presumably cannot be ised, in flight. The existence of reversed movements in spring and utumn may also be held to favour the view that the birds use sun or tars primarily as a directional compass, since otherwise they must ometimes use the star-pattern appropriate to one season of the year to .avigate in the direction appropriate to the opposite season. Radar observations also fit best with the view that juveniles in their rst autumn do not use bico-ordinate navigation, since it is otherwise ard to see why the wind conditions in which migrants set out are uch as to minimise drift in autumn (when many juveniles are travel- ng), tmt not in spring (when all are returning to an area where they ave been before). If, however, the juveniles travel on an innate D5 BRITISH BIRDS heading, some other (innately based) factor is needed to determine when they stop, and, since they set out freely with strong or light following winds, or with light opposed winds this factor is no perhaps dependent on the time and distance for which they have flow through the air. It is also necessary to postulate for various species thirie innate heading is changed during the course of migration. Indeed various British night-migrants evidently change their heading twice on their way to Africa, while Scandinavian Chaffinches have a progressive change in heading through perhaps 180 degrees between Lrway and southern England or Ireland. Finally, Scanffinavian thrushes drifted westward by easterly winds in autumn change the heading from SSW to about SSE when in flight over the North Sea bv day but apparently return to a SSW heading after making the land. On present effidence this can be explained as a relatively slmPle re^n^ to the sight of the sea, and bico-ordinate navigation need not be m Finally I would stress again that the above conclusions are highly tentative and that the problems raised can be solved only by experi- ment. SUMMARY ( \ Tn rlsvlieht and at night, migrants over the sea normally travel on straight tricks with L> alteration in direction at the change from daylight (sumcompass) to for lateral drift, suggesting that in flight Z ^mXured, ho, this noght he merely because their '^“idy normally for ,he iuvc“‘? migrating to an unknown area. In spring they often set oot in a strong cross-wmd, £ that drift ma, he extensive, bu, *VST “Sions of (5) Night-migrants do not normally follow the coas . dir^t&tfZrdi— Sants change their heading during their • ( } me of them twice and Chaffinches (Fringilla coelebs) in a complex way. ’TrR ^sefmii^tas occur both spring and autumn initiated oyer the land with winds opposed ,0 the normal direction of migratton for the season 7 T“ 1" Response to sight of the sea combined with awareness of westward drift. references Bamo 1 and Nishet, I. C. T, (i960): “Northward fall migration on the Atlantic coast and its relation to offshore drift”. Auk, 77: H9-I49- It6 RADAR EVIDENCE ON ORIENTATION Drury, W. H., Nisbet, I. C. T., and Richardson, R. E. (1961): “The migration of 'angels’”. Natural History (New York), 50 (8): 10-17. Fromme, H. G. (1961): “Untersuchungen iiber das Orientierungsvermogen nacht- lich ziehender Kleinvogel ( Eriihacus rubecula, Sylvia communis)”. Zeits. Tierpsychol. 18: 205-220. Goodacre, M. J. (i960): “The origin of winter visitors to the British Isles. 5. Redwing ( Turdus musicus). 6. Song Thrush ( Turdus philomelos)” . Bird Study, 7: 102-110. Hoffman, K. (1953): “Die Einrechnung der Sonnenwanderung hei der Richtung- sweisung des sonnenlos aufgezogenen Stares”. Naturwiss., 40: 148. -(i9J4)‘ “Versuche zu der im Richtungsfinden der Vogel enthaltenen Zeitschatzung”. Zeits. Tierpsychol., 11: 453-475. — (i960): “Experimental manipulation of the orientational clock in birds”. Cold Spring Harbor Symposia on Quantitative Biology, 25 : 379-387. I-Klomp, H., and Perdeck, A. C. (1959): “De veldwaarnemingen. Jaarvcrslag van het Vogcltrekstation over 1958”. Limosa, 32: 96-106. IKramer, G. (1950): “Orientierte Zugaktivitat gekafigtcr Singvogel. Weitere Analyse der Faktoren, welchc die Zugaktivitat des gekahgten Vogels orientieren”. Naturwiss., 37: 188, 377-8. (J952): “Experiments on bird orientation”. Ibis, 94: 265-285. (I957) : “Experiments on bird orientation and their interpretation”. Ibis, 99: 196-227. ( 1 9 5 9) : “Recent experiments on bird orientation”. Ibis, 101: 399-416. ; (I9(^I): “Long-distance orientation”. Chap. XXII (vol. 2, pp. 341-371) in Marshall, A. J., Biology and Comparative Physiology of Birds. New York and London. Lack, D. (1954): “Visible migration in S.E. England, 1952”. Brit. Birds, 47 : 1-15. (T 95 7) : “The Chaffinch migration in North Devon”. Brit. Birds, 50: 10-19. (I959a): “Migration across the North Sea studied by radar. Part 1. Survey through the year”. Ibis, 101: 209-234. (x 95 9b) : “Watching migration by radar”. Brit. Birds, 52: 258-267. ( 1 9 5 9C) : “Migration across the sea”. Ibis, 101: 374-399. (1960a): “Migration across the North Sea studied by radar. Part 2. The spring departure 1956-59”. Ibis, 102: 26-57. (1960b): “The influence of weather on Passerine migration. A review”. Auk , 77: 171-209. Matthews, G. V. T. (1955): Bird Navigation. Cambridge. —(1961): “‘Nonsense’ orientation in Mallard Anas platyrhynchos and its relation to experiments on bird navigation”. Ibis, 103 : 21 1-230. Merkel, F. W., and Fromme, H. G. (1958): “Untersuchungen iiber das Orien- tierungsvermogen nachtlich ziehender Rotkehlchen ( Erithacus rubecula)”. Nalur- wiss., 45: 20: 499-500. Moreau, R. E. (1961): “Problems of Mediterranean-Saharan migration”. Ibis, 103: 373-427,580-623. ’ennycuick, C. J. (i960): “The physical basis of astro-navigation in birds: theoretical considerations”. J. Exp. Biol., if. 573-593. ’erdeck, A. C. (1958): “T wo types of orientation in migrating Starlings, Sturnus vulgaris L., and Chaffinches, Fringi/la coelebs L., as revealed by displacement experiments”. Ardea, 46: 1-37. C1 96 1) : “Jaarvcrslag van het Vogeltrekstation over i960”. Limosa, 34: 169-185. 'recht, H. (1961): “Uber das Heimfindevermogen von Vogeln”. Psychol Beitr 6: 241-263. BRITISH BIRDS Precht, H., et al. (1956) : “Einige Versuchezum Heimfindevermogen von Vogeln. r/ppell'; w! (^^'“Versuche uber Heimfinden ziehender Nebelkrahen nach Verfrachtung”. J. Orn., 92: 106-132. , , Saint Paul, U. von (1953): “Nachweis der Sonnenonentierung bci nachtlich ziehenden Vogeln”. Behaviour, 6: 1-7. . . , ~ , Sauer, E. G. F. (1957): “Die Sternenorientierung nachtlich ziehender Grasmucien (Sylvia atricapilla, horin und curruca)”. Zeits. Tierpsychol., 14: 29-70. ' (1961) : “Further studies on the stellar orientation of nocturnally migrating birds”. Psychol. For schung, 24: 224-244. . . Sauer, E. G. F. and E. M. (1955): “Zur Frage der niichtlichen Zugonentierung von Grasmiicken”. Rev. Suisse Zool., 62: 250-259. _ , „ ~ ,, c . (i960): “Star navigation of nocturnal migrating birds . C old Spring Harbor Symposia on Quantitative Biolog)', 25 : 463-473. _ . , Schmidt-Koenig, K. (i960): “Internal clocks and homing . Cold Spring Harbor Symposia on Quantitative Biology, 25 : 389-393. (1961): “Sun navigation in birds?” Nature, 190: 1025-1026. ScHiiz, E. (1952): VomVogelwg. Frankfurt a.M. f Tinbergen, L. (1956): “Field observations of migration and their significance lor the problems of navigation”. Ardea, 44: 231-235. Van Dobben, W. H. (1953): “Bird migration in the Netherlands . Ibis, 95 '• Wallraff, H. G. (i960): “Does celestial navigation exist in animals?” Cold Spring Harbor Symposia on Quantitative Bio/oey, 25 : 451-461. ^ Williamson, K. (1952): “Migrational drift in Britain in autumn 195 1 . Scot. Nat., 1 (1955): “Migrational drift”. Act. Congr. Int. Orn., 11: 179-186.^ (1959): “The September drift-movements of 1956 and 1958 . Brit. Birds, 52: 334'377- , , ^ . r and Spencer, R. (i960): “Ringing recoveries and the interpretation ot bird-movements”. Bird Migration, 1 (4): 176-181. Studies of less familiar birds 1 18. Rock Bunting and Rock Sparrow Bj P. A. D. Hollom Photographs by K. J. Carlson , R. G. Carlson, Arthur Gilpin and H. R. Cowes (Plates 24-31) The Rock Bunting (Emberi^a da) is an extreme rarity in this country. The earliest record is of two netted by bird-catchers in late October 1902 near Shoreham, Sussex, and these were followed by one seen at Faversham, Kent, in mid-February 1905; then, after an ROCK BUNTING AND ROCK SPARROW STUDIES interval of over fifty years without any report which can now be considered acceptable, one was recorded at Dale Fort, Pembrokeshire, on 15th August 1958. The species has also occurred as a vagrant in north France, Belgium, Holland and Fleligoland, but the nearest breeding places are south and ceast France, Switzerland and south and west Germany. In the last 1 country its range extends north down the Rhine valley to the neigh- bourhood of Bonn, as well as in a few tributary valleys, especially that of the Moselle. It is also found throughout the Iberian peninsula, most of Italy, Greece, the Balkans and in the Carpathian mountains where it extends west into Czechoslovakia and north Hungary; in north Africa from Morocco to Tunisia; and across Asia from Turkey through the Himalayas to eastern China and Mongolia. Vaurie (1959) lists ten races, and describes the bird as not migratory but to some extent a wanderer. In Germany, however, it is regarded by Niethammer (1937) as both a resident and a migrant with winter- iquarters in north Africa; most of the German breeding birds leave in (October or November and return in March or April. Similarly, in the Geneva area Geroudet (1954) finds that most are migratory, .arriving in early or mid-March and probablv continuing to do so into April; in autumn, after the second broods are on the wing in August, they tend to collect into parties but remain on the breeding grounds until the middle or end of October. Voous (1960) lists the species as both sedentary and migratory; the birds which inhabit mountains usually descend in winter to lower levels, while the most northerly populations winter in the southern parts of the breeding range. In west China the species extends above 17,500 feet in the >ubalpine shrub zone; in Europe, however, lower levels are certain y avoured, in Greece from 5,000 to 6,000 feet, in the Alps seldom ex- reeding 5,000 feet, and in Spain sometimes up to about 8,000 feet but or the most part appreciably lower and at times down almost to sea :evel. As its distribution in the Mediterranean area and south Europe in general would suggest, the Rock Bunting requires warmth and sun- hine as well as rocks and bushes in its breeding localities, and at least n the northern part of its European range it seeks out warm dry outhern or south-western slopes, with oak scrub or other bushy over, hedges, or patches of young conifers. The slopes are often teep, with rocky outcrops, stony gullies or quarries, and the terrain nust be relatively open with a certain amount of bare earth and low egetation, though preferably a few scattered small trees. Such ultivation as small vineyards, terraced or with drystone walls and stony oil in hilly country, is also accepted. These conditions are best satis- ed on the lower mountain slopes. In Spain, where so much of the D9 BRITISH BIRDS countryside is denuded and impoverished, the bird is often found in such bare surroundings as on plate 25a where the nest on plates 24-26 was sited at about 5,000 feet among broom and rosemary (plate 26b). Geroudet, in the article already referred to, gives an excellent des- cription of the country occupied in the French Alps by this attractive but unobtrusive bird, and his account of its breeding habits adds a good deal to the information recorded in The Handbook. In mid-May the area is shared with such birds as Bonelli’s Warbler (Thylloscopm bonelli). Garden Warbler ( Sylvia borin' ), Blackcap (S. atricapilla ), Black- bird (Turdus merula ), Robin ( Eriihacus rubecula). Cuckoo ( Cuculus canorus) and Linnet ( Carduelis cannabina), with Black Kite (Milvus migrans) and Alpine Swift {Apus melba) overhead. Amongst so many calls and songs, it is not always easy to pick out those of the Rock Bunting at once. Finally, a thin and sharp tsi comes from somewhere in the bushes not far away but out of sight. From time to time the discreet call is repeated, but the bird itself remains invisible until the observer eventually locates it, motionless and watchful, on the topmost shoot of a hazel. After another sharp call it flies off, showing clearly the white outer tail-feathers, to disappear in a quarry. This is a typical experience. Even where relatively numerous, the Rock Bunting appears only intermittently. Its cries confuse the watcher, and its unexpected departures, frequently to a considerable distance, mislead him. The only way to get on terms is to be as patient and discreet as the bird itself, keeping quiet and still for long periods. The following is a summary of the results of Geroudet s observa- tions at eight nests. The female alone builds (the male was never seen with nesting material) and she also undertakes the whole of the incuba- tion. When flushed from the eggs or young she often indulges in an injury-feigning display; in this she runs from the nest, spreading her wings occasionally, and appears to somersault over small rocks in her path. Incubation lasts 12-13 days. Both parents feed the brood, seeking food to a distance of about 150 yards, mainly in brushwood. They fly back fairly high and direct with the food, which includes caterpillars and small butterflies, but settle several yards from the nest and complete the journey on foot, climbing slowly over the stones. When leaving again, they fly direct from the nest. The young leave the nest when 10-1 3 days old, but are still unable to fly for another few days and during this time they hide on the ground, creeping and hopping among the stones and grass. At least sometimes, and perhaps generally, the species is double-brooded. Some of Geroudet s nests were hidden in dry vegetation or sheltered by an earth bank or a stone, and others were very open, placed on the ground, hardly screened y thin grasses and sometimes in the full glare of the sun; none was in thick undergrowth. 160 ROCK BUNTING AND ROCK SPARROW STUDIES On the other hand, the Spanish nest illustrated on plates 27 and 28 was one of two found at heights of three or four feet against the centre [trunks of small evergreens five or six feet high. As is rather better 'ihown on plate 24, the nest itself is fairly substantial, the exterior rather oosely built of large stalks of dry grasses, with an inner section of iner pieces more closely arranged, and the cup often lined with horse- lair or fine rootlets. In this case the nest was practically on the ground at the base of a clump of rosemary. The song has been likened by many observers, including Jakobs 1 9 5 9)» *-° °f the Dunnock ( Prunella modular} s'). It is typically uttered from a bare spike at the top of an oak or other exposed tree- op perch, but also from a vineyard stake or a commanding wire. Geroudet gives the period as from early April to July or just into August, with some revival in October. Dandl (1959) in Hungary near Budapest has heard quiet winter song during mild, still weather in an rrea where breeding does not occur. In such winter quarters the species occupies habitats frequented by 'Other buntings and finches, Pricam (1957) in the Geneva area mention- ig Reed Buntings (E. schoeniclus ) in particular and an occasional Cirl •unting (E. cirlus ), also Chaffinches ( Friugilla coelebs ) and Bramblings T montifringilld). Voous recalls that in north Africa it is often found i large Hocks with Cirl Buntings. European wintering flocks seldom ppear to exceed a dozen or so birds; although they may feed with ther Passerines, the Rock Buntings maintain contact with each other nd separate as a group on taking flight. At this season the habitat lay be a less wild one, of hedgerows, fields, copses, bushes and way- de trees, but the birds remain unobtrusive and elusive. As both ncam and Dandl have noted, they feed on the ground, always within .ach of trees or bushes, and if undisturbed they remain quietly for ours in one place. As soon as something unusual occurs, however, ne will fly to settle well up in a bush or tree and others will join it’ .illing their sharp tyi-ty note. Perched thus, their warm orange- cown plumage renders them relatively inconspicuous if a few dead aves of, for example, oak, beech or chestnut remain on the branches, further alarmed, they may suddenly swing up vertically into the air id fly a few hundred yards to disappear into cover, or may slip away vanish more furtively but equally effectively through the branches. The Rock Bunting is one of the easiest European buntings to entify. The clean, clear-cut grey and black pattern of the head is ell brought out in plates 24-28, but black-and-white photographs nnot convey the full contrast between the cold grey of the head and ’per breast and the warmth of the rest of the plumage, which is iffish-orange below and black-streaked chestnut-brown above. ie rump, showing on plate 27, is chestnut without streaks and the 161 BRITISH BIRDS dark tail has a white outer edge which is often conspicuous. The narrow whitish wing-bar shows well in plate 24. The Atwc . sexes are normally substantially similar, having the same basic head patter "he female is slightly' duller with some dark spots breast and flanks; these can be seen in plates 24-26. Ha t on (,9S7) has drawn attention to the fact that in addition to this male- J plumage there is a quite distinct and predominantly brown form of femTle Young birds closely resemble young Yellowhammers IE. cimnelk), but have distinctive orange-buft under-parts. 1 The illustrations this month also include two photograph the Rock Sparrow (?,trom„ petroma), on plates 29 and 5°. w“e f 3 shows a breeding area in central Spain. The birds in this instance were nesting in company with Bee-eaters (Merops apuster) in holes in a river bank in pleasant fertile country, which is an unusual ype of «e and habitat. Colonies are generally found in warm, aria, y - the birds usually nesting in broken, rocky terrain or n rums ancient buildings, castles, high bridges, but also in towns, oh i ho low treed olive groves and in wells in semi-desert. The colonies in the old fortifications of Carcassonne in south-west France and in the ruins Baalbek in Lebanon may be quoted as notewort y examp e . The world range is similar .0 that of the Rock Bunting, extending from Madeira to Manchuria, but the Rock Sparrow does not breed in Germany Switzerland or Austria (although formerly doing so when The summers were warmer and dryer), nor in the Ca^atluan It is relatively sedentary, but in winter may wander away from the vicinity of the nesting colony. The birds gather into flocks by late August and in winter sometimes feed in company with finches Dresser (.87-1881), who recorded much information about dj species stated that during the autumn and winter its foo cons o| cereals 'of several sorts, seeds of wild plants and grasses . and foerr.es [ various kinds. During the spring and summer « feed ^o‘h « and its young on insects, including caterpillars and small gr«shopp«; later turning to garden fruit and especially cherries, fo 1 “movements on the ground than other sparrow-s, N.e.hamm« ", 7) adding that it does not hop like a House Sparrow P<« SL) or8a Tree Sparrow (P- — ) but runs like a p.pin J general habits it much resembles the House Spat , j as bold as that bird and is less addicted to human habitations ""They^low throat patch is a very poor recognition feature a. med- range being often invisible even when looked for carefully und g ightfog conditions. The large whitish spots a, the end of the mther short tail on the inner webs of the feathers, are much more help u They are not alwavs as evident on a perched bird as might appear tron ; t ibz ROCK. BUNTING AND ROCK SPARROW STUDIES late 29, but they can show well enough on one which is flying away > w, especially if its tail is fanned, and they are seen to advantage in ; ie which is clinging at the entrance hole to its nest with its tail spread )• give support. The head, however, provides what is probably the nst visual guide to the bird’s identity, with its broad pale superciliary Tripe extending from the eye to the side of the nape. This super- liary is set oft by the dark side of the crown, but if the top of the r.:ad is visible an equally distinctive, broad, pale, central band can be :een running the length of the crown from forehead to nape, as in a ;male Brambling or a Lapland Bunting (Calcarim lapponicus) in winter, ie pattern on the side of the head shows well in the photographs, bere the edge of the pale crown-stripe can also just be detected! te general coloration of the bird is otherwise rather like that of a 1 male House Sparrow, but the under-parts (including the flanks) are till streaked and the under tail-coverts are boldly barred with dull .own and whitish. This streaking and barring can be seen on plate The sexes are indistinguishable; the young birds resemble their 'rents, but lack the yellow throat spot. Apart from plumage distinctions, the calls are diagnostic, the birds ■ a breeding colony persistently uttering a plaintive wee-eep or mel-eep , communal chirping which is abruptly ended for intervals of silence! can seem a more sibilant wee^-ee^ or wee^-we when the wheeziness the sound is intensified by echoing out from a rock face. In flight uave rendered it chee-leep , more musical than anv call of the House narrow. LOebru (195 8)> who observed the Carcassonne colonv in two seasons ords that pairs were formed and hunting for suitable nesting cavities \ the second half April. Display flights included gliding, climbing I parachute descents something after the manner of a Serin {S trims arms): Nest building was in progress in mid-May, and the young the first broods flew between 25 th June and 5 th July. Second )ods were reared in the same nests and flew in August, 40 days "f t e edging of the first brood in two cases and 45 days in a third th parents fed the young. Dresner described the nest as a somewhat bulkv and carelessly con- lcted affair of straw, grass bents, fine roots, wool, hair and bits of , lined with an abundance of feathers. It is built like that of a use Sparrow in holes in rocks, masonry, hollow trees or earth banks. -n abandoned House Martins’ {Deli chon urhica) nests are recorded laving been used. The eggs number four to seven, and cannot be inguished with certainty from those of the House Sparrow. REFERENCES D.L; J.' (,I,959)! “Breeding of the Rock Bunting in Hungary and surrounding rntorics . Aquila, 65 : 184-188. g i63 BRITISH BIRDS Debru, H. (1958): “Remarques sur la biologie du Moineau soulcie Petronia p. hetronia (L Y\ Oiseau, 28: 1 12-122. Dresser, H. E. (1871-1881): .4 , ,f ,t,B, rJs f do„ _ rpnr.nr.FT P (iosa): “Le Bruant fou au Saleve . Nor Uiseaux, 22. 145 Sarrison,’ J. M. (1951): “Exhibition of and remarks upon dimop dusm n he female of the Rock Bunting, Ember, Za cm cm Linnaeus .... Bull. d. U. 71. Takobs B (1959): “Zum Brutvorkommen und zur Brutbiologie der Zippammer tZberi-aciacia L.) im Moscital”. Orn. Mitt., 1 1 : «M25 • . Niethammer, G. (1937): Deulscben Vogt 'Ikmk. „ J Pricam, R. (1957): “Hivernage de Bruants fous dans le pays de G Oiseaux, 24: 160-163. . T j Vaur.e, C. (195 9) •• The Birds of the Palearcltc Fauna. London. Voous, K. H. (i960): Atlas oj European Birds. London. Notes Little Grebes attacking Moorhens. — With regard to the recent note by ] B and S. Bottomley on Little Grebes (Podiceps ruficollts ) attac king Coots CFulica am) and domestic ducks (Anas sp.) (Bnt Birds, 54 • 4*7), k seems worth repotting that I saw several such attacks on Moorhens (Gallinula chloropm) on a lake at Alderwasley, Derby, m June .195 5- • ° one occaston two Moorhens were fighttng when one of a pa* of Ln.le Grebes shot across the surface straight towards them a, a distance of about five yards Eoth Moorhen et^ted n j shower of water and fled for the shore as the head of the Little Gr appeared between them. Several other attacks on single Moorhens were also noted. Sometimes the Little Grebe remained under water To th what one saw was the Moorhen suddenly rear up and M while a swirl in the water mdtca.ed a -ond attac before the lattle Grebe showed itself. Fulmar laying egg in Northamptonshire garden.— On 27th May “-ftoli by my aunt that a “sea-gull” had laM an egg m her garden at Northampton and that the bird was still there Vj* dubiously I investigated and to my astonishment I ™ £ at a Fulmar (Fulmarus glacialis). I captured the r < tdVd on the h Pitsford Reservoir, Northamptonshire, that evening. . j I i rfo p een and bathe before flying off in a southerly direction. p“ ^ SS ^ so far inland during the nesting season, but this ha k TaylJP breeding record for Northamptonshire! ^ | 164 NOTES Water Rail drowning small Passerines.— At about i.o p.m. on 4th January 1962, when there were four inches of snow on the ground but it was not actually snowing, my wife called me to look out of the window of our cottage at Cavenham Mill, near Bury St. Edmunds, Suffolk, at the way a Water Rail (Kallus aquations) was behaving. A few moments before I had cast out half a pint of crushed oats and crumbs and the Water Rail was making threatening rushes at the House Sparrows (Passer domesticus ), Great Tits (Par us major). Blue Tits (P. 1 caeruleus) and other birds which were feeding there. I thought at first that it was just trying to scare them away so that it could have the food to itself, but suddenly it seized what I think was a Dunnock (Prunella modularis) in its beak and carried it swiftly down to the edge j ■ of the mill-pool some twenty feet from our front door. There the Water Rail stepped into shallow water and held its captive right under 1 until it was dead, whereupon it started to peck at it. Later the same day, at about 3.0 p.m., I happened to glance out of the window again and saw the Water Rail drowning another bird. This time it seemed to be a hen Chaffinch (Fringilla coelebs). The 'Water Rail was also seen to pick to bits a dead Song Thrush (Turdus Philomelas) which had been killed by the frost and which we had thrown 'down on the edge of the pool. Alfred R. Blundell [We recently published another note on Water Rails killing small birds (Brit. Birds, 55: 13 2- 13 3) and it seems that such predatory activi- ties are probably less unusual than might have been supposed. Since : the earlier note went to press, we have heard from Mr. G. T. Kay whose ^experience with a Water Rail in his aviary was quoted in the note in 'slightly different versions from R. M. Lockley’s I Know an Island (1938, p. 182) and The Scottish Naturalist (61: 31). What actually happened was that he came across his Water Rail eating a Chinese (Quail (Excalf actoria chinensis) and saw it kill a Greenfinch (Chloris chloris) with a blow on the skull. An Orange-cheeked Waxbill jEstnlda melpoda) and a Snow Bunting (Plectrophenax nivalis) were also found dead, but there was no proof in their cases that the Water Rail was involved. — Eds.] Great Spotted Woodpecker taking thistle heads. — At about 11 a.m. GMT on 28th January 1962, near Woodstock, Oxfordshire, I saw a emale Great Spotted Woodpecker (Dendrocopos major), which I had oreviously watched working along a fine of trees, drop to the ground n a grass field where there were a number of dead spear thistles Cirsium vulgare) and then fly into an adjacent hedge with a thistle- lead in its bill. It wedged the head into a cavity on the trunk of an dder bush and proceeded to hammer at it, fragments flying off as it 165 BRITISH BIRDS did so. I walked up and collected the thistle-head, which was fixed by its base. The woodpecker almost at once picked up another head and wedged it in a field maple a few yards further along the hedge. I sent both heads, and a third which I picked off the ground, to C. S. Elton, Director of the Bureau of Animal Population, who writes: “The two attacked spear thistle heads had remains of gall structures in but no larvae. The unattacked small head had no gall. G. C. Varley tells me that the Trypetid flv galling flower heads of the spear thistle is Urophora sty lata. At this time of year galls should have fairly fat fly larvae in, but of course they have parasites.” It therefore seems possible that the woodpecker was looking for gall-fly larvae rather than taking the seeds of the thistle. In both cases the head was taken off the ground, not from a standing plant. Bruce Campbell Swallows feeding on froghoppers.— Recent notes by Bryan L. Sage and H. Dickinson (Brit. Birds, 54: 246-247 and 43°) have recorded various Passerines feeding on sandhoppers (Talitrus locustra). On] nth May 1961, at Eye Brook Reservoir, Leicestershire, my attention was attracted by the antics of five Swallows ( Hirundo rustica) which were making rapid sorties from the boundary fence and hovering a few inches above the road. They were pecking at something on the metalled surface and were so engrossed that I was able to approach close enough to see that they were, in fact, feeding on froghoppers (Cercopis spurn aria). N- L- Hod son Blackbird recovering from collapsed eye.— Plate 23c shows the head of a first-winter male Blackbird (Tardus merula ) at Swansea, Glamorgan, on 19th September 1961. It had a large tick on the left - side of its head and its left eye had collapsed in such a way that it occupied a region at the rear of the orbital cavity which was otherwise empty. It seemed that the eye had been punctured, perhaps by the bird itself in its efforts to remove the tick. The bird was in goo condition and the state of its eye suggested that the accident had occurred in the previous day or so. It was capable of flight, but kept colliding with obstacles on its blind side. We removed the tick and kept the bird for two days, by which time its eye had healed and its sight returned to normal. Harris Radde’s Bush Warbler in Norfolk.— On the evening of 3rd October 1961, while working through the Suaeda bushes at The Hood, Blakeney Point, Norfolk, B.R.S. and R. Harris discovered a large, dark olive warbler, about the size of an Icterine (Hippolais ictenna). The bir was easily captured in a mist-net and proved to be quite unfamiliar. 166 NOTES | The failing light made an accurate appraisal impossible and so it was decided to take it back to Cley where, after being weighed, it was put to roost in a dark box. The following morning it was minutely c examined by R.A.R., B.R.S., H.G.A. and P. R. Clarke and found to be a first-winter male Radde’s Bush Warbler ( Phylloscopus sckwarvj). This identification was later confirmed by K.W. The following "is a sum- mary of the detailed descriptions taken : Upper-parts: forehead and crown dusky olive; mantle, scapulars and rump olive-greenish-brown tinged oily yellow (shade varying according to light); upper tail-coverts possibly browner; outer webs of tail and wing feathers similar but rather more strongly tinged yellowish-brown, especially the secondaries; carpal joint pale primrose yellow. Sides of head: a very broad and heavy dark stripe from lores through eye topped by a long and narrow but clear-cut supercilium of buffish-whitc tapering to nape; a light crescentic mark below eye served to enhance this striking face pattern; ear-coverts mottled olive and pale yellowish. Under-parts: chin and throat pale yellowish-white; sides of breast strongly sullied with olive-grey; flanks similar but tinged buff- belly creamy-white beautifully suffused with primrose; under tail-coverts warm creamy-buff or pale yellow-ochre. Soft parts: irides dark brown; bill short, stout and broad at base, upper mandible dark horn with orange-horn cutting edges and lower mandible orange-horn with dusky tip; inside mouth bright chrome-yellow; strong rictal bristles; tarsi, toes and claws yellowish- straw tinged pink. Measurements: wing 66 mm., bill (from skull) 12.5 mm., bill width (at gape) 10 mm., tarsus 23 mm., tail (from preen gland) 54 mm’ (tips of rectriccs pointed and outer ones 4.5 mm. shorter than longest, giving slightly rounded effect); weight (at dusk after transport to Cley) 1*3.5 gm. Wing-formula: 4th primary longest, 3rd -0.5 mm., 3th - 1.5 mm., 6th -4 mm., 7th —6.5 mm., 2nd (=9th) —9 mm., 1st 11.5 mm. longer than primary- coverts; 3rd to 6th emarginated. We were particularly struck by the strength of the claws and they had a clinging quality which reminded us of a young Swallow ( Hirundo rustica ) irn the hand. To enable as many interested people as possible to see the bird, it was released in R.A.R.’s planted garden aviary till the afternoon. 1 t was then ringed, returned to Blakeney Point and watched among trree-lupins in the sand dunes. It was last seen there at dusk on the 1 olio wing day, 5 th October. In the field it appeared a large, dark, oily-olive leaf-warbler with father short rounded wings, a longish tail, a dark crown and a heavy dackish line through the eye contrasting markedly with a very con- picuous, long, narrow supercilium of huffish-white which tapered o the nape. This and the short, stout bill gave the head a bold and 1 Imost shrike-like appearance. The under-parts showed as pale ellowish, clouded on the breast and flanks with olive, and the vent was a quite distinctive shade of warm buff. The straw-yellow legs 7oked fairly long. When feeding, it adopted a rather Sylvia- like ' 'Osture, keeping low in the bushes or marram grass and frequently .opping on the sand; it persistently flicked its wings and dipped its 167 BRITISH BIRDS tail in typical Vhylloscopus manner. In the aviary it took earwigs offered in a china dish and minute flies which it caught in flight or picked from the wire netting, from the perches and from a plate-glass window, but it ignored mealworms and elderberries. It drank freely from an earthenware flower-pot saucer and bathed once. The only note heard at any time was a single or double chat-like chik of alarm. There is only one previous British record of this central and east Siberian species and that was a bird killed at North Coates, Lincolnshire, on ist October 1898. R. A. Richardson, B. R. Spence, H. G. Alexander and Kenneth Williamson [A series of photographs of Radde’s Bush Warbler on its Siberian breeding grounds, by Dr. Irene Neufeldt of the Academy of Sciences in Leningrad, appeared in British Birds with an accompanying articie in March i960 (5 3 : 1 17-122 and plates 13-18). — Eds.] Curious behaviour of Starlings. — At about 2.30 p.m. on 17th September 1961, at Abbots Ripton, Huntingdonshire, I saw a flock of a hundred or more Starlings (Sturnus vulgaris ) performing in a way which I have never seen before. They were flying at a height of 1 00-150 feet over a twenty-acre field and going round and round in a clockwise circle about thirty yards in diameter. Individual birds , would regularly stop flapping their wings, let their legs hang down and then reach under their bodies with their heads to peck in the direction of their dangling feet. This pecking action would last about four seconds and then the bird concerned would resume normal flight, though still in the circle. It seemed that any one bird indulged in the pecking action about three times each circuit. The behaviour lasted for about twenty minutes and throughout this time the whole flock was silent apart from occasional scolding notes ; these were rather like the sounds Starlings make when a cat or other predator is near the nest- hole. Eventually, nearly all the birds returned to the ground and began feeding, though one or two remained in the air and continued this impressive display. I had a good view of them all the time and there was no question of their hawking for flies or any other aerial food. The temperature was 54°F and the day was calm and cloudy with intermittent rain. Colin Dr age [Mr. Derek Goodwin points out that this behaviour is not unlike that of Black-headed Gulls (Barits ridibundus ) above a foraging Stoat ( Mustela erminea). We should be most interested to hear from any- body who has seen Starlings doing this. — Eds.] f{S8 PU^CHASE.3 Irish Naturalists’ Journal A quarterly magazine de- voted exclusively to the botany, geology and zoology of Ireland and publishing bird records as a regular feature Edited by Miss M. P. H. Kertland Department of Botany Queen’s University Belfast 7 Annual subscription io /- post paid BOOKS ON BIBOS Catalogue on request WVHELDON & WESLEY LTD Lytton Lodge Codicote, Hitchin, Herts The Isle of May A Scottish Nature Reserve W. J. EGGELING The Isle of May, lying in the Firth of Forth, has been renowned for over a century as outstandingly interesting to naturalists, especially as a station for the study of bird migration. Dr. Eggeling of the Nature Conservancy has known the Isle since boyhood, and was concerned with the building of the Bird Observatory there. He is now secretary of the committee in charge of it. 35 half-tone plates, 30s. OLIVER & BOYD Read! Hark! Learn! Witherby’s Sound-Guide to British Birds By MYLES NORTH and ERIC SIMMS Introduced by J A M ES FISHER “An imaginative enterprise. . . . For many years British bird- watchers have looked on Witherby’s ‘Handbook of British Birds’ as their bible. Now they have a bible to listen to as well.” — Observer “A fine work which can justly claim to be indispensable to anyone who wishes to learn the songs and calls of British birds the easy way.” — Country Life “The recordings themselves are technically brilliant.” — Scotsman In two parts, each £ 5 5s. Part 1, Non-Passerines; Part 2, Passerines Zoological Record Section Aves 1960 The Aves section of the Zoological Record, the only annually pub- lished and comprehensive bibliography of ornithological literature, is an indispensable work of reference for those who need to know of recent research and developments in the study of birds in all parts of the world. Compiled by Lt.-Col. W. P. C. 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Of revolutionary design, this is undoubtedly the best lightweight portable telescope yet produced. Bush- ed for fitting to a photo tripod or can be hand-held. £39 . 8 . ° TRY IT ENTIRELY WITHOUT OBLIGATION Printed in England by Dicmer & Reynolds Ltd,, Eastcotts Road, Bedford Published by H. F. & G. Witherby Ltd., 5 Warwick Court, W.C.i British Birds Principal Contents Slender-billed Gull in Sussex : a bird new to Britain D. D. Harber Recent changes in the habits of the Kittiwake J. C. Coulson and A. Macdonald Mortality and weights of Fieldfares in Anglesey in January 1962 P. Hope Jones Obituary: Alfred Hazelwood (1913-1961) More examples of the best recent work by British bird-photographers Letters 3 1 MAY 1962 British Birds AN ILLUSTRATED MONTHLY JOURNAL Edited by P. A. D. Hollom E. M. Nicholson I. J. Ferguson-Lees Stanley Cramp Photographic Editor: Eric Hosking Hon. Editors: W. B. Alexander N. F. Ticehurst Editorial Address: 30 St. Leonard’s Avenue, Bedford Contents of Volume 55, Number 5, May 1962 Page Slender-billed Gull in Sussex: a bird new to Britain. By D. D. Harber .. 169 Recent changes in the habits of the Kittiwake. By Dr. J. C. Coulson and A. Macdonald . . . . . . • • • • • - • • • • I7I Mortality and weights of Fieldfares in Anglesey in January 1962. By P. Hope Jones . . . . • • • • • ■ • • • • • • *78 More examples of the best recent work by British bird-photographers. Photographs by Mr. and Mrs. J. B. Bottomley, S. C. Porter, Morley Hedley, C. Stockton, C. C. Doncaster, D. M. Turner-Ettlinger, R. Jones, E. K. Thompson and Guy B. Farrar (plates 32-40) 181 Obituary: Alfred Hazelwood (1913-1961) 182 Notes : — Wilson’s Phalarope in Cornwall (Rev. J. E. Beckerlegge, Dr. W. R. P. Bourne and J. L. F. Parslow) •• •• i83 Wilson’s Phalarope in Nottinghamshire (E. T. Lamb and W. Priestley) . . 185 Wilson’s Phalarope in Co. Wexford (O. J. Merne) 186 Food of tits (Dr. E. A. R. Ennion) 187 Blackbirds rearing five broods in one season (H. Mayer-Gross and C. M. Perrins) l89 Dusky Warbler on Fair Isle (Peter Davis) O0 Nest sanitation by unfledged Pied Flycatchers (W. S. Medlicott) . . . . 192 Siskins breeding in Devon (P. J. Dare) x93 Reviews : — Deaths of Birds and Mammals from Toxic Chemicals. January-June 1961. Reviewed by R. K. Cornwallis .. .. .. •• •• •• *95 Studies on the Behaviour of the Black-tailed Godivit [Limosa limosa (L.)]. By Hans Lind. Reviewed by R. G. B. Brown i$>6 Letters : — Ringed birds in snow (Miss Eileen A. Soper; Robert Spencer) .. .. 197 Snow Bunting recovered in Newfoundland (S. L. B. Lee) 198 Destruction of Flouse Martins’ nests (Douglas Carr) 199 A possible explanation of “reverse migration” (M. J. Rogers) . . . . 199 Requests for information: — Wreck of Fulmars in February and March 1962 (John Cudworth and B. S. Pashby) 200 Wreck of Shags in March 1962 (I. J. Ferguson-Lees and Robert Spencer) 200 Annual subscription £2 (including postage and despatch) payable to H. F. & G. Witherby Ltd., 5 Warwick Court, London, W.C.i Eleanor Pettingill, an ornitholo- gist’s wife, lived on the Falkland Islands during one summer when her husband was filming penguins for Walt Disney. Her amusing book provides one of the most delightful records of penguin life ever written. With 32 pages of charming photographs 25/- Bv ELEANOR RICE PETTINGILL CASSELL Choose a lightweight glass Choose PFEIFER BINOCULARS First quality glasses, fully coated on all optics, they have a high light intake and by reason of their extremely light weight are ideally suited to the bird watcher. The following models are available from stock : 8x30 £25 10 0 8x40 £32 10 0 8X50 £42 10 0 Available on deferred terms ■SOLE AGENTS FOR THE U.K. DEPT. 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Kertland Department of Botany Queen’s University Belfast 7 Annual subscription io /- post paid Zoological Record Section Aves 1960 The Aves section of the Zoological Record, the only annually pub- lished and comprehensive bibliography of ornithological literature, is an indispensable work of reference for those who need to know of recent research and developments in the study of birds in all parts of the world. Compiled by Lt.-Col. W. P. C. Tenison, D.S.O., the current issue documents references to over 2,500 articles and books that appeared mainly in 1960. Obtainable from the Zoological Society of London, Regent’s Park, London, N.W.l. Price 12/5d (including postage). Plate 32. Long-tailed Tit ( Aegithalos caudatus ), Lancashire, winter 1961 (page 182) (J. B. and S. Bottomley) British Birds Vol. 5 j No. 5 May 1962 Slender-billed Gull in Sussex: a bird new to Britain By D. D. Harder On i9th June i960, at the sewage outlet in the sea off Langney Point, Sussex, I saw among Black-headed Gulls ( Lams ridibundus) an immature gull of about the same size as these but with a markedly longer bill. On this occasion the bird was seen only quite briefly land no other details were recorded, my attention being focused on the remarkable bill. On 22nd June i960, however, I saw the bird again, in the same place, and pointed it out to R. H. Charlwood who was equally struck by its unusual appearance. On this occasion it was present during the whole of the afternoon, feeding off the sewage out- let, and was watched by us at ranges down to thirty feet, on and off for two to three hours. The description which follows was recorded by us jointly at the time. The plumage differed little, if at all, from that of a Black-headed Gull noulting from first summer to second winter, except that the browns vere paler than in any individual of that species present; there were ilso greyish markings on the side of the head behind the eve and on the tape. But structurally the bird differed so noticeably that it could at >nce be picked out at any reasonable range from the first-summer Black-headed Gulls which were with it. The bill was about one third onger than that of a Black-headed Gull and certainly no thinner; in act, if anything, it was slightly thicker. It had a definite downward :urve at the end before coming to a sharp point (this is, of course, the ypical shape of a gull’s bill, but it was more noticeable in this bird han in the Black-headed Gulls). In colour it was obscurely reddish mh a black tip. The neck was distinctly longer and slightly slimmer han that of a Black-headed Gull. The tail also appeared longer, the xtra length being approximately that of the (narrow) dark bar at its 169 BRITISH BIRDS end. The bird spent most of the time we watched it feeding or looking for food on the surface of the water at the sewage outlet, and the extra length of neck and tail gave it a different outline from that of the Black-headed Gulls which were doing the same thing; in particular, it appeared to have both ends more depressed. The legs were dark with the under-sides of the feet greenish-yellow. The structural differences were such that the possibility at once occurred to us that this might be a Slender-billed Gull ( Earns genei), a species with which neither of us was familiar. But, on reference to the Field Guide to the Birds of Britain and Europe, we found it stated that the bill is ‘‘‘'noticeably more slender ” than that of the Black-headed Gull. Nevertheless, I at once wrote to P. A. D. Hollom describing the bird. A correspondence then ensued, as a result of which I learned that the Field Guide was incorrect in this respect, and I began to realise that our bird could indeed be of this species. Meanwhile I had found it twice more, at the same place and under similar conditions, on 6th and ioth July i960. On the first of these dates I saw it only quite briefly, but on the second I again had long, close views during at least two hours, and was once more struck by the way it stood out among the Black-headed Gulls, still more of which were now present. I also observed that the flight was slightly more buoyant than in the other species. As on previous occasions, the bird was seen only in flight, but for as long and as near as could be wished. I then visited the British Museum (Natural History) in London and examined six skins of Slender-billed Gulls and also some of Black- headed Gulls. The bills of the former seemed to me to correspond very closely with that of the Langney Point bird in shape and size. The same applied to the length of the neck, allowing for the fact that this is very much affected by the way a skin is prepared. I did not observe any extra length of tail, however. A couple of the skins of immature genei had greyish markings on the head in the same places as in the Langney Point bird, though these were distinctly more obscure. On the other hand, there was no skin of a Slender-billed Gull in precisely the same stage of plumage, first-summer, as the Langney Point bird. By now I was convinced that our bird was a first-summer Slender- billed Gull, but in view of the paucity of available field descriptions, particularly of immatures, I wrote to H. P. Medhurst who has seen many of this species at Aden. In his reply he gave the features by which he distinguishes them in the field. In brief, these consist of the bill “longer and not slimmer than in ridibundus” , with a “downward curve” at the end; the “head protruding further than in ridibundus when in flight”; and the tail “appearing longer than in ridibundus ”, although it is uncertain “whether it is the tail-feathers which are longer 170 CHANGES IN KITTIWAKE HABITS or whether it is the actual hind portion of the body which is longer” He also described the tail as “distinctly wedge-shaped, far more than in ri ibundus . This last feature we did not notice, perhaps because the contrast with the shape of the tails of the Black-headed Gulls was obscured by some of these being in moult. Otherwise, of course the structural features identifying the Slender-billed Gull in the field are precisely those which we noted in the Langney Point bird. Medhurst also mentioned the paleness of the markings of immature genet (com- pared with those of ridibmdus) and added that the dark patch behind the eye varies greatly, being absent in some and prominent in others. In fact, every feature by which the Langney Point bird differed in plumage and structure from Black-headed Gulls is an identification feature of the Slender-billed Gull. The identification was rendered aH the more conclusive by the fact that neither Charlwood nor I had jany idea of this at the time when we recorded these features, some of ’■which, so far as I am aware, have never appeared in print before. I : have since learned that I. C. T. Nisbet has seen a Slender-billed Gull 'Similar to ours in Greece in August, and that every detail of a first- year bird which I. J. Ferguson-Lees saw in Rumania at the end of May 1961 corresponded with the description which we have given of ours including the colour of the soft parts. [Recent changes in the habits of the Kittiwake By J. C. Coulson Department of Zoology, Durham University and A. Macdonald INTRODUCTION wiTTi wakes (Rissa tridactyla) are relatively specialised gulls- not mly are they adapted to nesting on small rock ledges on precipitous 1 faces (see Cullen 1957), but they are probably the most oceanic >f the gulls outside the breeding season, the majority spending the winter over a large area of the North Atlantic and North Pacific Oceans without ever coming to land. Because of these habits, the pecies does not often come into contact with man. Apart from ceding on the waste from sea-going ships and particularly fishing essels, it has not, until recently, been associated with civilisation 1 *he way that man7 other species of gulls will follow the plough ieed on refuse dumps and take food from the hand. In the last sixty years, however, the Kittiwake has increased con- derably as a breeding bird in the British Isles, particularly in England BRITISH BIRDS and Wales, and with this increase there has been a marked change in the type of cliff used for nesting. Recently formed colonies are noticeably lower than the old-established ones and this trend has resulted in the use of cliff's only a few feet high, as well as of window ledges on buildings and even of flat ground (Coulson in press). This has tended to bring the Kittiwake into closer contact with human habitation. Some of the more recent colonies — for example, at Dun- bar in East Lothian and at Lowestoft in Suffolk — are very close to, or even actually in, harbours. In recent years, we have noticed several other changes in the habits of the Kittiwake on the east coast of Great Britain and this paper presents a summary of these observations. PENETRATION UP THE RIVER TYNE The River Tyne is tidal for about twenty miles of its length (the upper part only at spring tides and therefore only slightly brackish). Its banks are industrialised and include a wide belt of dense population (Fig. i). Since it is permissible to put untreated sewage direct into tidal waters, the tidal reaches, particularly from Newcastle upon Tyne to the mouth of the river, are heavily polluted. This part therefore supports a very limited animal population and, in particular, very few fish. Pollution is usually stated to be the sole reason for the decline of the river as a breeding area for Sea Trout (Saltno trutta) and Salmon (.S', salar). The Kittiwake was not recorded on the Tyne at Newcastle until a single bird was noted in 1951 (Temperley 1952). In the last ten years, however, the position has changed considerably and by 1961 the species could be seen almost daily between February and June within sight of the Tyne Bridge. A.M. has made counts since 1952, usually once a week, of the gulls present on a stretch of almost a mile below the Tyne Bridge, while J.C.C. has independently recorded Kittiwakes since 195 8 on the same part of the river. Table 1 shows the seasonal distribution of records between 1952 and i960. The first Kittiwakes appear at Newcastle at about the same time as they return to the breeding colonies near the river mouth, namely early February. The peak numbers occur just before the majority of the breeding birds start laying (mid-May) and there is then a marked decline during the time most of them are incubating eggs or taking care of young. The last are seen at Newcastle in the middle of July, although many remain at the colonies until the end of September. The average number of Kittiwakes recorded at each visit between 15th February and 6th June is shown in Table 2 for each year from 1952 to i960. These particular dates select the season when the birds occur most frequently on the river. While there is no evidence of a 172 CHANGES IN KITTIWAKE HABITS .NORTH -shields' H TYNE s SOUTH' SHIELDS NEWCASTLE GATESHEAD' NORTH SEA ,IG’ The tidal reaches of the Tyne, showing the local breeding colonies of , Kl“,wakc (&'•"* tndactyla) (■*) and the known resting places of this species -along the river : (•). Alternate one-mile lengths of the river arc shown dark to .give a scale and the major built-up areas arc shaded. The Tyne Bridge is marked under the s of Newcastle 'Smooth, progressive increase each year, there has been a marked tendency for more to be present in recent years and this is clearly seen from the three-year averages. As already mentioned, it is now .uncommon to visit the river between February and early June without seeing at least one Kittiwake. From 1952 to 1956 only adults were seen (137 in all), but in 1957 ttwo out of 63 were immatures, in 1958 one out of 79, in 1959 seven out of 83 and in i960 ten out of 96. The percentages of what are rmainly one-year-old birds has thus risen from 3% in 1957 to as high is 12% in 1959 and 10% in i960. There is thus some evidence that ..in increasing number of immature Kittiwakes are also penetrating far Jpstream, although the habit apparently originated amongst adults. On two occasions, J.C.C. also made a survey of the distribution of Kittiwakes upstream from Newcastle. A single bird was seen at the t idal limits near Wylam, and groups of 15 and at least 20 at the mouth )f the River Derwent, a tributary of the Tyne (Fig. 1). r 7ood Jndoubtedly the majority of Kittiwakes seen in the river are searching or food. Both at Newcastle and at South Shields (about two miles rom the river mouth), they take very small particles from the water’s 03 Table i— Seasonal numbers of Kittiwakes (R/'bh /ri/» on the River Tyne at Newcastle, 1952-60 All counts were made on a 0.9 mile stretch below the Tyne Bridge (Fig. 1) and are summarised here in fortnightly periods. Note that no Kittiwakes were seen before 1st February or after 18th July, in spite of a total of 59 visits at other times of the year 8ny z luoaj 8ny i-jnf 61 M 8Iinf^ ]nf b-unf lz unf oz-unf L unf 9-Aejy bz £z-Abj^ 01 Abjaj 6-ady 9 z jdy iz-idy zi idy 1 i-JBjy 6z jepi £1 JBjy bi-JEj,\[ 1 qaj bi-qyj 1 ub{ ii oj dn o 6 o o o N 4 o 4 vq rT\ N > Vw O o Z u IS <-W o o c: c d V C 1/5 g d A a ■m . VO _ o o 2 o «-* n C a ^ d v a *h U co w o n u £ 03 o *1 w a o u o 4-) Vd O a C n3 0 C 1 o ?E b c t'S > U3 PI OJ 50 cl v-< 6 .S2 *-< co G z < 1 C F-* 0 J8 S J Vm 0 d C > C H S a 0 ' 0 > u * a N z 2 v° O' W D T> t-3 « s .s < t? 0 Vd H « « CHANGES IN KITTIWAKE HABITS surface without alighting; some also swim buoyantly and pick up tiny floating morsels after the manner of phalaropes. The river is so heavily polluted that there is little possibility that they are collecting living animal food, and it seems more likely that they are feeding on •sewage. This is also suggested by their tendency to accumulate at i sewer outfalls and by their habit of following the North Shields- >South Shields ferries to feed on materials forced to the surface by the i (turbulence produced by the twin propellers. It seems significant that (this latter type of feeding occurs almost exclusively when the tide is .low or on the ebb, for that is when most of the sewage passes down- sstream. In the last few hundred yards of the Derwent, which is fresh water, Kittiwakes were feeding almost exclusively on fish taken from just lelow the surface. We have not been able to identify these, but it was absented that several were over six inches long. Although Common dulls (Lams cams ) were as numerous there as the Kittiwakes and were (ilso trying to obtain the same food, it was noticeable that the latter uad much greater success. Westing sites Kittiwakes have been found resting at two riverside sites near New- ■astle (Fig. i). One is a building about a mile downstream from the hyne Bridge; we have no evidence of breeding attempts, but more >irds occur each year and the site would appear to be suitable for nest- rig. The other is a wooden quay near the mouth of the Derwent; : aere is no possibility of nesting taking place there. It is assumed that the Kittiwakes which occur on the Tyne are mostly rcom the colonies near the mouth of the river (Fig. i). All the sixty iairs which breed on the riverside warehouse at North Shields are ' olour-ringed, however, and since only two colour-ringed Kittiwakes iave been seen on the river at Newcastle, it is clear that these are not ne birds involved. The colony beside the north pier at Tynemouth insists of only about twenty breeding pairs, but that at Marsden hree miles to the south) contains some 3,000 pairs and probably most : : the birds entering the river come from there. However, two Kitti- akes ringed on the Fame Islands have been recovered in the Tyne id so it is likely that some other colonies are involved. TAKING BREAD ittiwakes have for many years had the opportunity of taking bread ■ ad probably have done so) from the waste thrown overboard from ips crossing the Atlantic. In recent years, J.C.C. has observed ittiwakes regularly taking bread at Dunbar, East Lothian, and at >uth Shields, Co. Durham. At Dunbar, where there is a colony 175 BRITISH BIRDS nesting on a low cliff on the harbour side, they readily leave their ledges to pick up bread thrown into the harbour or on to the quay-side. This may have developed from the habit of scavenging on the fishing boats lying in the harbour and taking fish from boxes on the boats or the quay. These Kittiwakes will also take small fish (“sprats”) which are caught by children in the harbour and thrown down on the quay below the colony. At South Shields, Kittiwakes can be seen on a freshwater lake, in a park just behind the beach. Originally they came to this lake solely to bathe, but within the last five years some have started to take bread thrown to other birds such as Black-headed Gulls (Icarus ridibundus ), Mute Swans ( Cygnus olor') and Moorhens ( Gallinula chloropus). It seems likely that the habit has developed from copying the Black-headed Gulls, but as yet only a minority of the Kittiwakes visiting the lake appear to do it. OCCURRING IN TOWNS Kittiwakes normally avoid flying over land except when going to bathe in fresh water or, in the high Arctic, when travelling to and from inland breeding cliffs. These birds now regularly fly over the centre of North Shields to a small reservoir in the middle of the town about a mile and a half from the coast. This reservoir has steep banks, the tops of which are covered with long grass and bushes, and, apart from a small projection in the water, there is no suitable place for them to stand after bathing. They therefore fly to a church near-by and alight on the tower parapet to preen. Thus, during the spring and summer, it is possible from one of the main streets in North Shields to see Kittiwakes standing on a church tower. DISCUSSION Although the Kittiwake can be considered a specialised gull, this has not resulted in a lack of adaptability. In recent years it has started to nest on flat ground (Salomonsen 1941) and has shown a change in the type of cliff used for colonies (Coulson in press), while the present paper has demonstrated that the species is now penetrating inland and also exploiting new food materials. It may be valuable to consider some of the possible effects of these changes in habits. During the last hundred years there has been a considerable increase in the occurrences of several species of gull inland in this country. It is possible that the Kittiwake may be beginning to show the same trend. While this bird probably depends more on fish for its food than the other gulls, there is now a tendency for it to feed with greater frequency on such materials as sewage and bread. In addition, it is probably for the first time feeding regularly 176 CHANGES IN KITTIWAKE HABITS on fish caught in freshwater. These changes may spread during the next few years and the Kittiwake may occur more commonly on fresh water during the breeding season. Linked with these developments is the possibility that the Kitti- wake may start to breed inland. There has been a colony on the River Tyne at North Shields, some two miles from the sea, since 1949. The formation of a new colony is usually heralded by a number of indivi- duals using the site for some years as a resting place. Resting sites are already in use at Newcastle, some ten miles from the river mouth, and in the centre of North Shields. Kittiwakes have nested on window ;ledges of buildings in Great Britain since 1935 and they have recently parted to breed on sloping roofs in the Lofoten Islands off the coast of 'Norway (Wagner 1958); such habits must greatly increase the number > of possible nesting sites available for the species. This discussion is obviously speculative, but it is considered import- ant to draw attention to these changes so that, if they extend to other areas, the spread can be recorded in detail. SUMMARY Gince 1951, Kittiwakes (Rissa tridactyla) have occurred regularly on the River Tyne mt Newcastle, ten miles from the river mouth. They are present from February until mid-July and systematic counts have shown that the numbers are increasing, '"ood appears to be the cause of this new habit and the birds tend to congregate at ■eewer outfalls or where ferries make the water turbulent. Further upstream from Newcastle, Kittiwakes have been seen to take fish from fresh water in the River Jerwent, a tributary of the Tyne. Kittiwakes have also been recorded taking bread irom human beings at Dunbar and South Shields, and standing on the top of a r hurch tower in the centre of North Shields well away from the sea. It is suggested 7 . these new habits could produce a marked change in the ecology and breeding ; istribution of the species. ACKNOWLEDGEMENTS We should like to thank Dr. L. Davies for critically reading the lanuscript and making several helpful suggestions. Ibis, 99 ; REFERENCES - OULSON, J. C. (in press): “The Kittiwake enquiry, 1959”. Bird Study. ullen, E. (1957): “Adaptations in the Kittiwake to cliff-nesting” 275-302. fuLOMONSEN, F. (1941): “The Kittiwake [Rissa t. tridactyla (L.)l breeding in Den- mark”. Dansk Orn. Foren. Tidsskr., 35: 159-179. emperley G. W. (1952): “Ornithological report for Northumberland and Durham for 1951”. Naturalist, 1952: 109-129. 'agner, G. (1958): “Die Brutvogel von Rost (Lofoten)”. Sterna, 3: 59-72. l77 Mortality and weights of Fieldfares in Anglesey in January 1962 By P. Hope Jones The Nature Conservancy Fieldfares ( Turdus pilaris ) are regular winter visitors to Anglesey as a whole, and in mid-October 1961 large numbers of these and other thrushes arrived in the county. Sightings of Fieldfares on New- borough Warren National Nature Reserve and in the adjacent Newborough Forest, both in the south of the island, are relatively in- frequent, however, and, apart from a few flocks in October, only three individuals were noted in those areasinthe 1961-62 winter until the very cold spell in early January. The relatively heavy snowfall of 3oth/3ist December had been pre- ceded by several days and nights of very hard frost, and conditions were particularly severe for most land birds; there were several local reports of dying thrushes — Redwings (T. musicus) in particular — and finches. On 2nd January numerous thrushes were seen on the edge of the Cefni Estuary salt marsh, which lies between Malltraeth and Newborough Warren, and the following morning an attempt was made to catch some. It was found that a flock of about 150 Field- fares, accompanied by a few Redwings, Song Thrushes (T. philomelos ) and Mistle Thrushes (T. viscivorus ), was feeding on the berries of sea buckthorn (Hippophae rhamnoides). These buckthorn bushes had been cut down in late November, and the birds were having to feed on or very near the ground. As a result, they were relatively easy to trap in mist-nets, and twenty-nine were soon weighed, ringed and released. Several were apparently so weak that they were unable to fly and these were caught by hand, weighed and released without being ringed. Only a few freshly-dead individuals could be found, but small patches of feathers in the snow told their own story. Doubt- less many dead and dying Fieldfares were eaten by the attendant Carrion Crows ( Corvus corone ), and possibly some were taken by other predators — it was known, for example, that a Merlin ( Falco columbarius ) and a Flen Harrier ( Circus cjaneus ) frequented that locality. From the warmed patches and droppings, it was evident that many Fieldfares had been roosting under clumps of marram grass ( Ammophila arenaria ) in the adjacent sand dunes, and here too were the familiar patches of feathers showing the activity of predators. Many more birds could have been caught, but netting was discontinued to minimise distur- bance. FIELDFARE WEIGHTS IN ANGLESEY IN JANUARY 1962 A thaw began on 4th January, and was well under way by the follow- ing day when another short session with the nets produced a further eleven birds. By this time they were able to feed over much of the salt marsh and the flock had dispersed to a large extent. Again a few weak individuals were found; five of these apparentlv starving birds were picked up, warmed and fed, but all except one died within three days. The site was visited again on 7th January, but by this time all the Fieldfares had disappeared from the area. A pointer to the amount of subcutaneous fat on a Passerine can be obtained by inspection of the bird’s tracheal pit. In none of the dead Fieldfares, and in only one of the weakened ones, was any fat visible at all. Of those trapped, roughly half were without any trace of sub- cutaneous fat in the tracheal pit and all were very emaciated. From unpublished observations I made in the Camargue, southern France, it seems that in the presence of a good food supply the weights of wintering Reed Buntings ( Emberi^a scboeniclus ) tend to rise with falls in temperature; similarly, from North American data, Helms and Drury (i960) concluded that winter weight changes in American Tree Sparrows ( Spi^ella arborea ) and Slate-coloured Juncos ( Junco hyemalis ) were temperature dependent. This tendency appeared to hold good in the Blue Tits {Pams caeruleus) and Robins (Erithacus rubecula ) which frequented the houses at Malltraeth during the cold spell: six Robins and sixteen Blue Tits trapped between 1st and 7th January all showed thick deposits of fat in the tracheal pit and around the belly, and were relatively heavy. The average weights of the Fieldfares might also have been expected to rise during the cold spell, but the weight change was, in fact, reversed because of the great ■scarcity of food. From the corpses and feather patches counted, it is thought that the actual mortality in this particular flock was between 10% and 20%, and there is every reason to believe that, had the cold weather and snow cover continued, many more would have died. The series of fifty-eight weights of birds in this flock showed an interesting picture. Four groups were readily distinguishable and the average for each is shown in Table 1. Table i Weights of dead, weak and more vigorous Fieldfares {Tardus pilaris), Anglesey, January 1962 Number Average weight Freshly dead 4 58.2 gm.* Too weak tody 14 63.4 gm! Stronger (3rd January) 29 78.0 gm. Stronger (5th January) 11 84.5 gm. *ln the light of the picture presented by all the other weights, it is considered that 3nc dead bird which scaled 82.7 gm. probably died from causes other than starva- ' 10,1 anci thls record has therefore been omitted from this calculation. BRITISH BIRDS There seems to be very little information available on normal weights of Fieldfares in Britain, but the average of five autumn birds on Great Saltee (Co. Wexford) was 96.24 gm. and a longer series from Fair Isle gives some idea of the range which can be expected. In the latter case, the distribution of weights of thirty-seven birds identified as mates did not differ significantly from that of thirty-two identified as females (p > o . 1 o) and the combined mean was 98.26 gm. (5=9.97). It would seem, therefore, that an average of between 90 gm. and no gm. might reasonably be expected for autumn migrant Fieldfares. The mean weights of the Anglesey birds compare very unfavourably with these figures: those trapped were in general about one-fifth less, and the weak and dying as much as a third. One very interesting Fair Isle record (not included in the above calculations) was that of an adult male noted as “dying of starvation” at 58.7 gm.— very near the Mall- traeth average of dying birds. The weights given by Ash (1957) for eleven Fieldfares found dead in the cold spells of 1954 an<^ 05° averaged 5j.9gm. and more recently, during this same January, Harris (1962) found that twenty-five corpses on Skomer Island, Pembrokeshire, averaged 58.4 gm. When these figures are taken in conjunction with the Malltraeth average of 58.2 gm. and the single Fair Isle weight of 58.7 gm., it seems probable that the minimal weight for this species may be just under 60 gm. The increase in the mean weights of the Malltraeth birds from 78.0 gm. on 3rd January to 84.5 gm. on 5th January is significant (pCo.oi) and was almost certainly a result of the amelioration in the weather, which allowed the birds to feed over a much bigger area and on a wider variety of foods on 4th and 5 th January. Of four Fieldfare corpses examined for endoparasites, only one was found to be infected and that by a single Nematode, probably Ascaridia galli. ACKNOWLEDGEMENTS I am indebted to Peter Davis and Kenneth Williamson for providing weight data from Fair Isle and Great Saltee respectively, and to I. Herbert and W. Threlfall for their examination of the Fieldfare corpses. SUMMARY (1) Observations were made on a flock of 150 Fieldfares ( Turdus pilaris) near Malltraeth, Anglesey, during hard weather in early January 1962. (2) All the birds handled were very emaciated, and there was a mortality of between 10% and 20%. (3) The weights of the trapped birds averaged about one-fifth, and the weak and dying about one-third, lighter than the average of sixty-nine autumn migrant Fieldfares at Fair Isle. (4) A significant increase in the average weight of trapped birds was noted after the thaw had made more food available. 180 RECENT WORK BY BRITISH BIRD-PHOTOGRAPHERS REFERENCES Ash, J. S. (1957): “Post-mortem examinations of birds found dead during the cold spells of 1954 and 1956”. Bird Study, 4: 159-166. Harris, M. P. (1962): “Weights from five hundred birds found dead on Skomer island in January 1962”. Brit. Birds, 55 : 97-103. Helms, C. W., and Drury, W. H. (i960): “Winter and migratory weight and fat field studies on some North American Buntings”. Bird Banding, 31 : 1-40. More examples of the best recent work by British bird-photographers (Plates 32-40) In this issue we are publishing our third annual selection of the est contemporary work by British bird-photographers (cf. Brit. Birds, 53. plates 25-32; and 54: plates 27-34), the main object being to keep a permanent record in one place as a yardstick for the future. It must be remembered, however, that a number of the best recent photographs, particularly of less common species, appear in this journal in the normal course of events. Some of those which have been published in our “Studies of less familiar birds” in the last year, or which are scheduled to come out in that series quite soon, would certainly otherwise have been included here. In this connection we should particularly mention the Bonelli’s Warblers ( Phylloscopus bonelli) by M. D. England (Brit. Birds, 54: plates 62-64) and the Rock Buntings ( Ewbert\a cia ) by K. J. and R. G. Carlson, Arthur Gilpin and H. R. Lowes (Brit. Birds, 5 5 : plates 24-28). The main selection was made at the Autumn Nature Exhibition of the Royal Photographic Society, but we have also kept a careful watch on photographs circulating in the folios of the Zoological Photo- graphic Club and the Nature Photographic Society, as well as those published in various books and magazines, and we do appeal to all photographers to send in prints which they consider might have a chance of inclusion. We wish to encourage the newcomer while not overlooking the work of the long-practised photographer to whom the novice owes so much, and we like to vary the species as much as possible. Some birds are far more difficult to photograph than others not because they are rare but because of their general temperament’ their shyness at approaching the nest or their suspiciousness at coming down to bait. A prize example of this is the Magpie (Pica pica ) which had probably not been successfully photographed at the nest on more than half a dozen occasions before Morley Hedley achieved it in April 1961 (plate 35). 181 BRITISH BIRDS This is the first occasion in these annual selections that we have published two photographs by one photographer or, in this particu ar case, bv one pair of photographers-Mr. and Mrs. J. B. Bottomley. Husband and wife do their photography jointly, taking turns in the hide and sharing the dark-room work. Their Long-tailed Tit (Aegithalos caudatus) (plate 3-) and Great Spotted Woodpecker (Dendrocopos major) (plate 34) were both taken at feeding places in their woodland garden, thus emphasising that there is no need to travel great distances to secure successful photographs. EricHosking Obituary Alfred Hazelwood (1913-1961) Alfred Hazelwood died on 7th December 1961 at Bradshaw, near Bolton, Lancashire. He had returned home on 23rd November after spending five weeks at the Manchester Royal Infirmary, where his condition had been found to be inoperable. Born at Doncaster on 30th April 1913, he matriculated at Doncaster Grammar School, held a Studentship for two years at the Bird Room of the British Museum (Natural History), and in the early thirties be- came Assistant at the Doncaster Museum and Art Gallery. He relinquished this post in 1935 to be Assistant Curator at the Chadwick Museum, Bolton. Appointed Curator to the Bolton Museums and Art Gallery in 1957 by unanimous vote, without the vacancy having been advertised, he was subsequently responsible for considerable improvements such as the complete reorganisation of the Art Gallery, the establishment of a Cotton Machinery Museum at Tonge Moor and the taking over of Smithshills Hall. In 1939 he married Ellen Gallwev, who was then Assistant Curator of the Tolson Memorial Museum at Huddersfield. She being a herpetologist and generally interested in all branches of natural history, their interests were so much intertwined that it proved to be a perfect partnership. He saw service with the Royal Navy in the Second World War, attaining the rank of Lieutenant R.N.V.R. During a commission in the Northern Isles he met the late Samuel Bruce of Lerwick, with whom he struck up a mutual friendship. As he never forgot a kindness, it was a measure of his appreciation that after hostilities had ceased he coaxed “Sammy” out of his native Shetland tor the first time and set about showing him as much as possible of English and Scottish bird life. It was also during his period of service with the navy that he and 1 A day out from Scapa with an arctic convoy, I was handing over 182 met. NOTES the watch to him and casually remarked (without knowing of his interest in birds) that the Fulmars were getting darker. He replied, with a quick look, “Yes, we shall see more of them as we get further north”. Thereafter, until things became too “busy”, he would leave me a perfect near-life-size pencil drawing whenever he handed over the watch. The first time it was of a Fulmar and there followed a Par- tridge, a Peregrine and so on. Thus began a friendship which grew ever stronger with the years. Hazelwood joined the Yorkshire Naturalists’ Union in 1940 and was President in 1958. He became a member of the British Ornitholo- gists’ Union in 1935, and in June 1959 he was invited to join the Rarity Records Committee of British Birds. In 1961 he was elected President of the North Western Museums, and for years he was on the Lancashire and Cheshire Fauna Committee. Flis chosen sports were few, but he had a deep love of wildfowling and would give a good account of himself after a long spell of abstinence. Lately he derived much pleasure from village cricket, being Chairman (and a pitch-roller) of the Bradshaw Cricket Club from 1959. Although birds were his chief love, he took an untiring interest in natural history as a whole. In the field he was a wonderful companion and if, as can so often happen, the intended bird did not turn up, the day was never dull, interest being unobtrusively switched to Natter- jack Toads, Edible Snails, dragonflies, ferns, the flora of the limestone pavement, or anything else that offered. He was dedicated to his work and yet would always gladly find time to give a helping hand to anyone from the very young upwards if they showed an honest desire to learn. Fools he suffered none too gladly, albeit quietly and without outward flurry. If a speaker clashed with him, he would cast a penetrating look, more of surprise and pity than of annoyance, and then the other would be passed by and forgotten astern. His opinions he voiced forthrightly in the face of all opposition. Above all, however, he was essentially a kindly man, unobtrusive with his wide knowledge and with an abounding sense of humour of a deliciously dry type. His passing leaves a gap which can never be filled. His most devoted wife survives him, as do their daughter, Margaret, and their three sons, John, Philip and Anthony, to all of’ whom the deepest sympathy is extended. A.L.W.M Notes Wilson’s Phalarope in Cornwall. — Early on the morning of 15 th June 1961 J.E.B. came across an unfamiliar medium-sized wader with plain brown upper-parts and a dull white rump and tail, on Marazion Marsh, Cornwall. He contacted Dr. G. Allsop and between them they 183 BRITISH BIRDS watched the bird for about five hours. N. R. Phillips was then told and he and R. Khan saw it that evening. Two days later it was found independently by W.R.P.B. and J.L.F.P., and subsequently a number of other observers went to see it. It was last recorded with certainty on 4th July. It was recognised as a species of phalarope by its charac- teristic position when swimming and by the delicate proportions o its head, neck and bill, while its relatively large size, comparatively drab coloration and distinctive face-pattern together proclaimed it a male Wilson’s Phalarope ( Phalaropus tricolor). The detailed descrip- tion which follows is based mainly on that obtained by W.R.P.B. and J.F.L.P. on 17th June, but the notes made by J.E.B. and others agree well with it : An unusually large, long-legged, long-billed phalarope, perhaps approximatmg in size to a small Reeve (. Philomachus pugnax ) or a Wood Sandpiper (Tringa glareol a), and behaving rather like those species, fcedmg mainly by wading along the shore rather than swimming, and having a loose, erratic, wavering flight. Forehead, crown and hind-neck ash-grey with an inconspicuous paler longitudinal patch on the nape. Rest of upper-parts except rump and tail grey-brown, appearing uniform in flight, but showing darker feather centres (especially on the scapulars) on the ground. Rump and tail off-white in flight, the tail actually slightly more brownish-grey but without any well-defined dark tip. Supercilium white, broadest over and just behind the eye, where it ceased abruptly, with a fairly broad, blackish stripe running from the bill through the eye and curving down to merge with the markings on the side of the neck. Chin white, contrasting markedly with warm-buff sides of neck, vinous-buff fore-neck and upper breast, pinkish-buff sides of lower breast and buff flanks the last faintly marked with brownish streaks. Central under-parts white, and under-wing whitish or pale grey. Eye dark. Bill black, straight and very slender, considerably longer than head, markedly longer than in other phala- ropes. Legs rather long, dark, but upper tibia paler, possibly yellowish. Feet black, protruding beyond tail in flight, the toes apparently slightly lobed. Although tamer than many waders, it was not quite so confiding as most Grey or Red-necked Phalaropes ( Phalaropus fulicarius and lobatus ) frequently are. When approached to within 25-30 feet it normally flew off quietly to another part of the same pool and sat there, later returning to the original area to feed in muddy water less than six inches deep. On the 15th it frequently associated with a Ruff and was then comparatively unapproachable, flying up at the same time as the Ruff, but not always accompanying it; it would then even fly high and circle. It usually waded up to its belly, but swam freely in deeper water, holding its head and neck well up and its tail depressed, the tips of the closed wings extending just beyond the tail. It fed by picking small objects from the surface all round, and also by sweeping the bill from side to side with the tip submerged, but apart from a couple of half-hearted turns it was not seen to spin. In general its behaviour was rather subdued and it did not call. While it presented no particular difficulties of identification, the 184 ate 3 5 . Magpie (Pica pica ) at nest, Yorkshire. April 1961 (page 181) (Mor/ej Medley) 3 4- Female Great Spotted Woodpecker (Dendrocopos major), Lancashire, April 1961 ( J • B. and S. Bottomley) Plate 36. Blackbird (' Turdus meruld) and Starling ( SUtrnus vulgaris), Glamorgan, December i960 (C. Stockton). Below, Knot ( Calidris canutus) and Redshank (Tringa tot anus), Denmark, August 1957 (C. C. Doncaster) r* 14^ % * Plate 37. Immature Ringed Plover (Charadrius hi at icula), Cheshire, August 1961 (D. At. Turner-Ett linger) p ■B m k • J jrs ifjj k \ 7 m %4 ▼ 'a Pi. ate 38. Female Kestrel {Fa/co tinnuncu/us), Norfolk, June 1959 (R. Jones) Plate 39. Female Pintail {Anas acuta) y Hebrides, June 1961 {A.. W'inspear-CunontX Female Red-breasted Merganser ( Merges serrator), Cumberland, June >9*1 (E. K. Thompson 40. Barn Owls (Ty/o alba), Ayrshire, October 1961 Little Gull ( Lams minutus ) at nest, Denmark, June 1 NOTES combination of a long, needle-like bill and contrasting face pattern at rest and the presence of a plain wing and dull white rump in flight being very distinctive, it did differ in several respects from the illus- tration of a male Wilson’s Phalarope in P. A. D. Hollom’s The Popular Handbook of Rarer British Birds (i960). In particular, the bill seemed longer, the upper-parts paler and more uniform brown, and the neck less chestnut, while the paler pa,tch on the nape, at the time thought to be a plumage aberration rather than a normal character, was much less distinct than in the illustration. The generally drab coloration and the presence of streaks on the flanks suggest that it may have been a first-summer bird. J. E. Beckerlegge, W. R. P. Bourne and J. F. L. Parslow Wilson’s Phalarope in Nottinghamshire. — On 16th July 1961, at about 9.0 a.m., P. Hope and W.P. saw an unusual wader on the Burton Meadows area of Nottingham Sewage Farm. Later in the morning they met E.T.L., A. W. Preston and Richard Preston and took them to see the bird which was then swimming on open water in the manner of a phalarope ( Phalaropus sp.). They all made notes, and returned home to compare them with descriptions in The Popular Handbook of Rarer British Birds (i960). In the afternoon E.T.L. and W.P. with D. J. Young and P. Carr found the bird again, and obtained sufficient details to confirm it as a Wilson’s Phalarope ( Ph . tricolor). Early the following morning it was seen by Mr. and Mrs. A. Dobbs and C. A. Johnson, and during the next ten days by a total of about thirty people. It was last recorded on 28th July. The descriptive notes below have been summarised from the observations of all those mentioned above. In general appearance the whole bird was very white, this being striking even at a distance and making it stand out from all other waders. Its under-parts were gleaming white, but above it was actually very pale grey with the primaries perhaps a litde darker; the forehead, crown and nape were paler grey than the mantle, back and wings; the rump was white and the tail was also very pale; a dark smudge extended behind the eye. It had a slender neck, smallish head, fairly long and very thin bill, and slender legs ; both bill and legs were black. It was a typical phalarope in shape and action, but larger than either Red-necked or Grey (Ph. lobatus and fulicarius ), being only a little smaller than a Redshank ( Tringa totanus). When standing on the mud or in shallow water, it seemed very tall in comparison with, say, the Dunlins ( Calidris alpina ). It spent much of its time swimming and held its head very upright as it did so; this made it look longer- necked than other phalaropes and it had something of the appearance 185 BRITISH BIRDS of an immature Little Gull (JLarus minutus). As it swam about, it would move its head from side to side, or twirl its body in a semi- circle, and snap at insects on the surface of the water. It actually seemed to prefer the water to the land, but it was sometimes seen on the mud of the sewage tanks or on adjacent plough or grassland with such waders as Redshanks, Dunlins, Ruffs ( Philomachus pugnax ) and Lapwings ( Vanellus vanellus) ; Green and Wood Sandpipers (T. ochropus and glareola) were also in the area for comparison. It was never heard to make a sound and was always fairly shy compared with Red-necked and Grey Phalaropes, flying off when the Redshanks did. In flight it had a plumpish torpedo-shaped body and the square white rump was very prominent, particularly as the plain grey wings (no wing-bar) seemed darker than when it was at rest; the wings looked rather rounded. E. T. Lamb and W. Priestley Wilson’s Phalarope in Co. Wexford. — A Wilson’s Phalarope ( Pbala - ropus tricolor ) in almost complete winter plumage was identified at Lady’s Island Lake, Co. Wexford, on 12th and 13th August 1961. It was first seen by me on the 1 2th and, as a result of a telephone call, B. D. Cooper, S. Holohan and Major R. F. Ruttledge joined me on the following day. Together we had the bird under observation for one and a half hours. At the end of that time, for no apparent reason, the Dunlin ( Calidris alpina) with which it had been feeding began to leave the lake in small parties; and with one such group the Wilson’s Phalarope departed and did not return. The following description was made under excellent conditions of light and weather, at various distances down to about thirty yards: Noticeably larger than Dunlin and smaller than Black-tailed Godwits ( L.imosa limosa), both of which were seen near-by ; about the size of, or a little smaller than, a Redshank ( Tritiga totanus). Bill black, straight and thin — quite needle- like— and between if and 12 times the length of the head; legs and feet looked black, though once R.F.R. thought he detected a greenish-yellow tinge on the front of the tarsus; eye dark. Head small and dainty, neck rather long and noticeably slender; body slender (but in certain attitudes rather “full- breasted”) and tapering towards tail. Forehead white; crown and nape very light grey-brown; fairly noticeable white superciliary above a short, dark and not broad line running backwards for a quarter to half an inch behind the eye. Cheeks, chin, throat, sides of neck, breast, flanks, belly and under tail-coverts all an unmarked and delicate off-white, appearing very white at any distance at all. Back of neck light greyish-brown, contrasting with the white sides of the neck and giving a “maned” effect; mantle and back a soft, unmarked, pale greyish-brown; rump, upper tail-coverts and tail (except tip which had irregular brown marks) pure white. Primaries dark grey-brown in marked contrast to body colour; scapulars, wing-coverts and secondaries light greyish- brown, at some angles looking almost pure grey. 186 NOTES In flight, the neat white rump and upper tail-coverts produced a pattern recalling a Wood Sandpiper (T. glareola), while at certain angles the mantle and upper wings looked quite brown (there was no wing- bar whatever); the under-wings were white; the feet projected be- yond the tail, and we thought that just the bases of the tarsi did so as well. In general, it was a strikingly white wader that, even at two hundred yards or more with the naked eye, stood out from the Dunlin like a Sanderling ( Crocetbia alba ) in winter plumage. It fed ashore nearly all the time (no “spinning” was seen) and was very active, ^constantly rushing about in a darting fashion and rapidly picking food from the surface of the shallow water or mud. It had a strangely crouched posture with its body at about 30° to the ground, its neck and head more nearly horizontal and its tail rather raised. No call was heard. It should be noted that, though the bird was apparently well into winter plumage, its leg colour had not yet reached the pale -.state of that season. O. J. Merne [These are the sixth, seventh and eighth records of this North American wader in Britain and Ireland, which seems remarkable when one remembers that the species was only added to our list as recently •as 1954 (Brit. Birds, 48: 15-17). In the eight years since then it has occurred once in May, twice in June, once in July, twice in August and ttwice in September, in widely scattered places in all four countries. The lack of any overlap in the dates of the three 1961 records raises the possibility of a single bird wandering from Cornwall to Nottingham and thence to Wexford, changing from summer to winter plumage in rthe course of the eight weeks concerned. However, a comparison of the descriptions, especially of notes on size and behaviour, suggests that at least two different individuals were involved. — Eds.J Food of tits.— A recent note by Bryan L. Sage on the food of the Marsh Tit {Par us palustris ) (Brit. Birds, 55: 89) reminds me that, where tits and the seeds of Compositae are concerned, things are not always what they seem. In August 1947, at Flatford Mill, Suffolk, during a bird course organised by me, several Goldfinches (Cardue/is carduelis ) were being watched one afternoon at a range of about 25 feet as thev fed on the seeds of greater burdock (Arctium lappa ) growing along a rough hedgerow; two Marsh Tits joined them and all were busily attacking the heads and scattering the down. It was noticed that, when the Goldfinches extracted beakfuls of pappus, thev rolled it between their mandibles for a few seconds before discarding it; whereas, when the Marsh Tits plucked out pappus, they dropped it 187 BRITISH BIRDS immediately. One of the exercises of the course was to collect (after careful observation) the remains of any food material on which a bird had actually been working. In this instance bundles of pappus seen to have been discarded by (a) Goldfinches and (b) Marsh Tits were collected separately. It was found that the former had been severed immediately above the seeds as neatly as by a pair of scissors, while those thrown away by the Marsh Tits had their full complement of seeds untouched. Further investigation showed the heads to be infested with small orange-pink larvae about three millimetres long; there were up to twenty in a head, living at the base of the pappus among the seeds, and it was noted that the heads partially stripped by the Goldfinches appeared still to contain their full quota. While it could not be claimed that the Marsh Tits were actually seen to be extracting and eating the larvae, clearly they were not interested in the Arctium seeds. Small larvae (? Cynipidae) can be found similarly in the heads of thistles (e.g. Cirsium palustre and vulgare ) and, indeed, in many other plants. A parallel observation concerned a Great Tit {Varus major ) and a turkey 02k(jQuercus cerris ). The Great Tit was watched working along the twigs of the tree and gently tapping the acorns. Now and then it would concentrate its attention on a particular acorn, evict it from its capsule and immediately follow it down to the ground; there the acorn was broken up and its contents devoured piecemeal. One might have assumed that the bird was eating the kernels, but when the actual remains were collected (including one nearly intact acorn from which the tit had been suddenly frightened away) it was found that the acorns were full, not of kernel, but of five to seven weevil larvae, each in its own round cell and between them filling to capacity the entire space within the shell — a good meal. One further incident can be added, involving a Blue Tit (P. caeruleus) which profited from the exertions of a Lesser Spotted Woodpecker ( Dendrocopos minor). The latter, a resident male, was often to be seen opening up the long swollen stem-galls on willows ( Sa/ix ). As it passed from branch to branch, it would frequently be followed, at first or second remove, by what was probably the same individual Blue Tit which then took its turn in searching and pecking at the broken gall. These galls were found to contain larvae of various sizes from less than one to over four millimetres in length (whether different ages of one species of gall wasp or of different inquilines is not known). It seems likely that the very small larvae might be too minute to interest the woodpecker, but a profitable investment for the tit. E. A. R. Ennion i 88 NOTES Blackbirds rearing five broods in one season.— A pair of Black- birds ( T urdus meritin') nesting in Queen’s College, Oxford, in 1961 laid their first clutch in January and went on to raise five successful broods totalling at least fifteen, and almost certainly sixteen, young. The first brood was reported by Mr. A. C. Larke of Queen’s College to Dr. Bruce Campbell and it is believed the nestlings hatched on 7th February. The first four broods were all reared in one nest and the fifth in a -second, both being old ones remaining from the previous year and situated some five yards apart on sheltered ledges of the college build- ing. Details of each brood are summarised below (when events were not observed, data were estimated and are shown in brackets) : lFirs/ brood- (Ist CSS 23M January): (clutch 3 eggs): (hatched 7th February): 3 young (8 days old) 15th February: ist young left 23rd February: other 2 young left 24th February. •Second brood, (ist egg 4th March): 3 eggs 8th March: 2 eggs and 1 very small young 19th March: 1 egg and 1 young 28th March: (young left 3rd April): young near empty nest 4th April. Third brood, ist egg nth April: 5 eggs 19th April: 3 eggs and 2 young 27th April. 4 young 6th May: (young left nth May): 4 young near nest 12th May. fourth brood, (ist egg 18th May): 5 eggs 24th May: (hatched 2nd June): 5 young (4 days old) 6th June: 2 young in nest and 3 young near-by 18th June: nest empty 119th June. ■ Fifth brood in different nest. Lining about 26th June: ist egg 28th June: 4 eggs -2nd July: 3 eggs and 1 young 12th July: 1 egg (chipping) and 3 young 13th July: .4 young 25th July: 1 or 2 young left 26th July: 1 young dead in nest and 2 young near-by 28th July. There is no reason to doubt that all five broods were raised by the s;ame pair. The hen was exceptionally tame and in the later part of t.he season would fly to the nest on seeing anyone approach; she then bad to be lifted off and would sit on the back of one’s hand and peck t while the contents of the nest were examined. The winter of 1960-61 was unusually mild and damp, and several tests of Song Thrushes iff urdus pbilomelos) were reported in December. 1 During the five days prior to 23 rd January (when the Blackbirds’ irst egg was probably laid) the minimum grass temperature never fell ts low as freezing point. The -weather throughout February and Vlarch was exceptionally mild, with only two days wflth frost in "ebruarv; however, there were two short spells of cold in March and hese could have resulted in the poor success from the second brood. 961 was a year of early breeding for a variety of species. The Blackbirds fed largely on a college laum near the nest. The act that the lawn was kept watered undoubtedly helped them to find vorms, but even so it became hard in warm weather and they then oraged elsewhere, possibly having to go considerable distances. 189 BRITISH BIRDS Between 4th May and the second week oi July Oxford had virtually no rain, except for one inch which fell on 12th June; during this time many young Blackbirds starved in other nests under observation and comparatively few new clutches were begun. That the college birds had difficulty in finding food is suggested by the long fledging periods. Although the last brood took less time than the earlier ones, the hen was noted as being vert thin on 21st July, feeding visits were rather infrequent and the cock (already moulting his tail-feathers) fed the fledged young on bread. One young in this brood died when fully- feathered and a second, known to have reached flying age, was un- accounted for. We know of no other certain case of five broods being successfully reared in one season. However, four appear to be raised not in- frequently. A record in The Countryman (5 5 : 46) tells of a pair which lost their first brood late in the nestling period and went on success- fully to rear four further broods, each of three young. Two nest record cards received by the British Trust for Ornithology for i960 give instances of Blackbirds producing four broods : in one case a fifth brood may have been reared but the evidence was not con- clusive; the other pair made seven nesting attempts, from four of which young were fledged. Finally, there are at least two records of four broods in this journal (Brit. Birds, 40 : 85 and 48: 93): the second of these pairs reared seventeen young, one more than the Oxford birds produced. H. Mayer-Gross and C. M. Perrins Dusky Warbler on Fair Isle. — The second British Dusky V arbler {Phjlloscopus j uscatus) was trapped on Fair Isle on 14th October 1961. The first was obtained by W. Eagle Clarke at Auskerry, Orkney, on 3rd October 1913 {Scot. Nat., 1913: 271-273). The only other west European record (apart from the now suppressed Sussex occurrence of 1916) was claimed by H. Gatke, who believed he saw one at Heligoland on 24th October 1876, though his description in Heligoland as an Ornithological Observatory (1895), pp. 284-285, is not entirely convincing. The species breeds in central Asia from about 8 3°E to the Pacific, and winters from north-east India to south China. The Fair Isle bird was found bv Charles Hodgkinson beside the stream in the upper part of Vaadal, at about 1000 hours GMT. He recognised it as a small, extremely dark leaf-warbler which lacked any green or yellow, and recorded that it uttered a curious hard chak. It was a skulker, and he soon lost it downstream in the irregularities of the valley. Whilst trying to relocate it, he was joined by Rex Clive; together they searched the area for over an hour, until Clive spotted it inside the Vaadal trap and drove it into the box. The warbler was seen in the laboratory by G. K. Brown, M. Jones, 190 NOTES S. L. White and myself, and photographed by my wife. The follow- ing details were recorded: [entire upper-par/s from forehead to upper tail-covcrts dark earth-brown, perhaps slightly paler on rump. Wings dark drab-brown with paler buff-brown edgings on flight-feathers and similar but slightly darker edgings on greater coverts; tail uniform dark drab-brown; remiges in good condition, but tail slightly abraded. Narrow but distinct buff-white supercilium extending well back above car-coverts and slightly down-curved behind, palest immediately above eye and matched by a narrow pale mark below eye; lores and line behind eye as crown; checks and ear-coverts fairly warm buff, tipped grey-brown. Under-parts: chin buff-white, throat and upper breast deeper buff with greyish wash on tips; lower breast clear buff, almost yellowish; centre of belly off- white; sides of breast and flanks washed grey-brown with warm buff tinge superimposed; under tail-covcrts and sides of ventral area clear buff; axillaries and under wing-coverts clear buff. Soft parts: upper mandible dark horn, lower similar for distal half and pale yellowish-flesh at base; gape yellow; legs and feet medium reddish-brown at front, yellowish-brown behind and on soles, generally slightly darker than those of most typical Willow Warblers (P/j. trochilus ); eye dark brown. Bill slender, narrow at base; three rictal bristles, rather short; numerous short nasal hairs. Measurements: wing 54 mm., bill 13 mm., tarsus 21 mm., tail 45 mm. (outermost feathers c. 5 mm. shorter than penultimate ones); weight 8.1 gm. at 1145 GMT. Wing-formula: 1st primary 10 mm. longer than longest primary covert; 4th and 5th longest, 2nd -7 mm., 3rd —1.5 mm., 6th -1 mm., 7th —3 mm., 8th -4.5 mm., 9th — 6 mm.; 3rd to 6th emarginated. The yellowish tinge of the lower breast and the condition of the flight- feathers suggest that the bird was in its first winter. After release at North Haven, it flew up to the rockv outcrop above the observatory and then on to the open moorland. Here it was watched from close range as it fed from the short turf of sheep tracks among the ling. In general shape and carriage it was very like a small ChifFchaft (P b. collybita ), though quite unlike our commoner leaf- warblers in coloration, appearing dark brown above and pale greyish- buff below. There was nothing in the colour to remind one of an autumn Reed Warbler (A croce phalus scirpaceus), though this was the comparison made by Gatke and repeated in The Handbook. Autumn Reed Warblers are much redder, both above and below, than the bird we were watching. The long, narrow, buff-white supercilium was fairly conspicuous at close range, but not particularly noticeable at twenty yards or so; Giitke’s bird seems to have had “very prominent” ■eyebrows of a rustier colour. Our bird flicked its wings and tail repeatedly, but this may have been because it had been handled, for Hodgkinson stated that it had not done so when first observed. It moved very restlessly along the sheep and rabbit tracks; here it fed exclusively from the ground, though on the steeper slope it had made one or two aerial sallies after flying insects. It was still ground- 191 BRITISH BIRDS feeding when we left it after about fifteen minutes. It was not seen again. This warbler had to be distinguished from Radde’s Bush Warbler (Ph. schwarff), and it was fortunate that we had C. B. Ticehurst’s A Systematic Review of the Genus Phylloscopus (1938) at the observatory, as well as a typescript of K. Williamson’s forthcoming Identification for Ringers: 2. Radde’s Bush Warbler has a more or less olive tinge on the upper-parts, often some yellow on the belly, a broad and con- spicuous supercilium, a stouter and broader bill, and averages some- what larger and heavier than the Dusky Warbler. The wing and tail measurements of the Fair Isle bird were near the lower limits gi\en for the Dusky, and therefore outside or at the lowest figures for the Radde’s. The weight was well within the range shown by Ticehurst for passage Dusky Warblers, but half a gramme below the minimum for Radde’s. Ticehurst states that the Dusky has three rather short rictal bristles, whereas Radde’s has five or six long ones. The wing- formulae of the two species are very similar. This Dusky Warbler was present at Fair Isle at the same time as two other Siberian birds, a Lanceolated Warbler ( Rocustella lanceolata ) and what was considered a Siberian Stonechat ( Saxicola torquata maura'), and within four days of two others, a Dusky Thrush (Turdus eunomus ) and a Richard’s Pipit ( Anthus novaeseelandiae ). Some of these will be described in separate notes. Charles Hodgkinson drew my attention to the curious coincidence that the previous records of Dusky Warbler and Siberian Stonechat in Britain also came within one week, the Dusky Warbler on 3rd October 1913 at Auskerry and the Stonechat on 10th October 1913 on the Isle of May {Scot. Nat., 19 O' 273'274)- Peter Davis Nest sanitation by unfledged Pied Flycatchers. — On 23rd June 1958, at Hawick, Roxburghshire, I was watching a pair of Pied Flycatchers ( Muscicapa hypoleuca) feeding their brood in a nest-box. The young, which were about ten days old, were coming to the entrance for the food in the normal way. I was struck by the fact that each of the parents would afterwards sit quite still outside the box for five seconds or more, just looking into the hole. They seldom actually went inside, vet on every third or fourth visit the parent concerned would take away a large white dropping about the size of a threepenny bit and I could not make out how they were obtaining these without going in. Eventually, however, I saw a young bird come to the entrance with a dropping in its bill and pass it to the adult. I could hardly believe what I had seen, but subsequently I was able to confirm it quite clearly several times. The male removed the droppings less 192 NOTES frequently than the female did, though he waited at the entrance hole just as much. On 2nd July, after the young had flown, I took the box down to examine it. The distance from the bottom of the hole to the floor was four and a half inches. The nest was in one corner, the material being three inches deep on three sides and two on the fourth. Inciden- tally, buried in it I found three small corpses, pressed down quite flat, and a single broken egg. These young, which had been about one week old when they died, had presumably been squashed and suffocated by the two or three stronger nestlings which fledged. W. S. Medlicott [At first sight this record seems quite incredible, but at least two similar reports concerning \X rens ( / roglodytes troglodytes ) are to be found in the literature. These observations, which were described by the Rev. E. A. Armstrong and Dr. W. H. Thorpe in a paper on “ ‘Casting’ by Shetland Wren nestlings” (Brit. Birds , 45: 98-101) and also men- tioned by the former in his book l he II ren (195 5, p. 204), were made by Mrs- G. A. Morris and Mrs. T. Silva in Hertfordshire and Kent respectively. Each reported that they and friends had clearly and repeatedly seen a brood of young \\ rens pass faecal sacs to their parents with their bills. We showed Mr. Medlicott’s note to the Rev. E. A. Armstrong who commented as follows: “This observation is strong confirmation of the accuracy of those on \\ rens. It now seems proved that, in some circumstances, nestlings of species breeding in covered or ca\ ity nests will pass faecal sacs to their parents after picking them up in their bills. It seems relevant to add that young Crowned Hornbills (lockus alboterwinatus ) will pick up dung and drop it from the aperture of the nest(R. E. and W. M. Moreau, Ibis, 1940: 639-656); also that the adult Chough (Pjrrhocorax pyrrhocorax) will sometimes lay a chick s faecal sac on the edge of the nest and carry it off later after brooding (A. Schifferli and E. M. Lang, 1940, J. Onu, 88: 550-575). Such alternative forms of behaviour suggest that it is not quite out of the question that cuckoos may occasionally place their eggs in other birds’ nests with their bills.” — Eds.] Siskins breeding in Devon.— According to both The Handbook and D. A. Bannerman’s The Birds of the British Isles (vol. I, p. 108), the Siskin ( Carduelis spinas ) has exceptionally been recorded breeding in some southern counties of England. Such birds are usually regarded as probably of captive origin, however, and so the following records of obviously wild Siskins breeding in Devon seem of particular interest. During each of the last five breeding seasons, 1957-1961, small *93 BRITISH BIRDS numbers of Siskins have frequented areas of Forestry Commission coniferous woodland, between i,oooft. and 1,400 ft. above sea level, on central Dartmoor. The first birds were noticed in the East Dart valley at Believer on 15th April 1957 and two pairs were subsequently identified there. In May and June the males indulged in frequent song flights over an extensive plantation of well-grown Sitka spruce ( Picta sitchensis ) admixed with smaller stands of other conifers. Breed- ing was established on 18th June, when P. F. Goodfellow located a pair feeding five fledglings. This family was seen by myself later the same day and on several occasions up to mid- July. There was no indication, however, that the second pair had succeeded in rearing a brood. In late April 1958 Siskins reappeared at Believer after being absent during the previous autumn and winter. In May and June at least two, and possibly four, pairs were present. They were very restless and ranged freely for food over a wide area between Believer and the village of Postbridge, a mile further up the East Dart valley. In addition to feeding in the tops of plantation conifers they foraged in pastures and hedgerows, on rough hillsides among gorse ( U/ex europaeus ) and hawthorns ( Crataegus monogyna), as well as in beeches (Fagus sylvatica) and willows ( Salix spp.) and in gardens at Postbridge. Successful breeding was again established when, on 25 th June, I found a female Siskin feeding two fledglings which appeared to have been out of the nest nearly a week. In 1959, when I was unable to visit the area, three pairs of Siskins were reported at Believer by a number of observers, but no young were seen (Report of the Devon Bird-Watching and Preservation Society for 19 jf). In i960 I first saw Siskins again at Believer on 18th April. About two pairs frequented the area, but breeding was not determined. During 1961 two males were repeatedly observed and one of these was definitely mated. No fledglings were seen clearly, but on 5 th July I heard and glimpsed several Siskins which, from their calls, I considered to be juveniles. I have additional records of Siskins in the breeding season at four other localities, all between one and four miles from Believer: (i) Fern- worthy Plantation, several on 18th May 1957, one on 19th July 1958 (R. M. Curber), one on 22nd June i960 and one on 24th June 1961; (ii) Soussons Down Plantation, one on 16th June 1957, a male singing on 10th July 1958 and two males singing and chasing two days later (this is a young conifer plantation about a mile from the breeding area, which it is believed the Believer birds visited occasionally) ; (iii) 1 wo Bridges, one on 17th April 1957 ; and (iv) Princetown, one on 28th May i960 in mixed woodland. These observations suggest that, since 1957, wild Siskins have begun 194 REVIEWS to colonise certain coniferous woodlands on central Dartmoor. In at least one locality the species is now a regular summer resident. It is interesting to add that there has been a parallel colonisation of these same woodlands by Redpolls {Carduelis flammea). The Siskin is known to have bred only once before in Devon, on the island of Lundy in 1952 (P. Davis, 1954 , A List of the Birds of Lundy). P. J. Dare Reviews Deaths of birds and mammals from toxic chemicals, January-June 1961. The second report of the Joint Committee of the British Trust for Ornithology and the Royal Society for the Protection of Birds on Toxic Chemicals, in collaboration with the Game Research Association. Published, 1962, by the R.S.P.B., The Lodge, Sandy, Bedfordshire. 24 pages. Murder will out. For several years many people, some of them officials who ought to have known better, have denied that the in- creasing use of a growing variety of chemicals in agriculture is the cause of need for concern about its effect on wild life. This report should remove any traces of complacency that may still linger in their minds. With a dispassionate matter-of-factness that is more telling than any emotional outburst, it leaves no shadow of doubt that in the spring of 1961 many thousands of birds were killed by these substances. Details of 324 incidents are given (four times as many as in the spring of i960), in which the deaths of fifty species of birds and twelve of mammals were recorded. Of these incidents, 292 were caused by dressed seeds. The W'oodpigeon was the species most commonly found dead (in 193 of the 292 incidents) followed by the Pheasant (80), House Sparrow (64) and Greenfinch (48). A map and table show that most deaths occurred in the mainly arable counties, my own county of Lincolnshire easily holding the unenviable position at the top of the league table. The species involved, the scale of two of the major incidents, the duration of incidents (deaths often occur over many weeks), the importance of sprays and dressings other than those used for seeds, the efiect on fertility of sub-lethal doses and the effects already visible on the status of such birds as the Sparrowhawk and Kestrel are discussed, and the details set out in clear tables. In a most important section the results of chemical analyses of 79 corpses are described. All but three of these (a Hare, a Snipe and a Wigeon) showed varying amounts of mercury and organo-chlorine. The flesh of four of the corpses was analysed and found to contain mercury. Included in the 79 were one Sparrowhawk, two Kestrels and four owls, the first direct evidence of the secondary poisoning that had previously been suspected but not proved. J95 BRITISH BIRDS In a soberly worded conclusion the authors welcome the recom- mendation of the Sanders Committee ( Report of the Research Study Group on Toxic Chemicals in Agriculture ancl Food Storage, H.M.S.O., 1961, 4s. 6d.) that research, both fundamental and applied, should be extended. For, though the case is proved, there are still many queries. Will the “voluntary ban” on the spring use of dieldrin, aldrin and heptachlor be effective ? How harmful is B.H.C. ? Are wet seed-dressings more dangerous than dry ones? What will be the long-term effect on the vegetation of the continuous use of weed- killers (themselves not usually harmful to birds) and the effect, in turn, of that on insect populations? These chemicals have become an accepted part of modern agricultural practice and their use or disuse touches the farmer in the most sensitive part of his anatomy, his pocket. If he is to make wise use of the scientists’ cleverness, he needs to be told authoritatively much more about the ultimate effects of these new and powerful aids to husbandry. The amateur naturalist has already made an invaluable contribution in convincing the powers-that-be that this is a matter of great gravity; but there is still much to be done and his unremitting vigilance is needed. R. K. Cornwallis Studies on the Behaviour of the Black-tailecl Godwit [Limosa limosa (L.)]. By Hans Lind. Meddelelse fra Naturfrednings- radets Reservatudvalg No. 66. Munksgaard, Copenhagen, 1961. 157 pages; 51 text-figures. 24.00 D.Kr. (about 24s.). The waders form one of the largest sub-orders of birds, and yet their breeding biology has been very little studied ; even when their nesting grounds are accessible, the concentration of birds is often too small for detailed work. Dr. Lind’s study of the Black-tailed Godwit, based on four years’ systematic observation at the Tipperne sanctuary in west Jutland, is therefore a welcome and important contribution to our knowledge. This publication opens with detailed descriptions of the breeding godwit’s inter- and intraspecific hostile behaviour, of courtship and other inter-pair displays, and of nest-building and egg-laying. Terri- toriality is next discussed; the birds tend to nest close together in “sub-colonies”, often including Lapwings, Redshanks and other birds, and the members of these groups seem to provide a communal defence against predators. But Dr. Lind’s most detailed work deals with incubation behaviour. Lie shows how this varies with the time after laying, the number of eggs in the nest, and the weather. I was particularly interested in his work on the little-studied subject of the behaviour of the hatching chick ; he shows that the last chick hatches more quickly than the first, and points out that simultaneous hatching 196 LETTERS of the young in a clutch cannot always be used to show that brooding began with the laying of the last egg. However, I find his conclusions on the motivation of godwit behaviour too sweeping and so less convincing. For instance, his diagrams of the inter-relationships between the predator-situation calls (fig. 2) and of the hostile ground displays (fig. 5) seem to me too detailed, considering the amount of observation on which they are based, and I can see no justification at all for his fig. 7, purporting to show how the various displays are dependent on locomotory ten- dencies. Further, some of the criteria used in the analysis seem to be ambiguous; for example, the distance between the opponents in a fight (table 4) could be a measure, not only of the absolute intensity of the underlying tendencies, but of the degree of conflict between them— Dr. Lind does not appear to distinguish between the two. Again, in the ceremonial flight a sequence of movements found in other contexts seems to have been ritualised; in his analysis, Dr. Lind takes no account of the possibility that the underlying motivation may also have changed in the course of ritualisation. I could wish, too, for a more detailed discussion of the positions of the bill and back feathers in the hostile displays; why shotdd the bill be lowered and the feathers ruffled with postulated increased dominance of attack in the Upright posture, but the opposite be true of Forward, Crouching and Tail-up? But, if I disagree with many of Dr. Lind’s conclusions, I feel that his attempt at an analysis of the motivation of godwit behaviour will form a starting point for further work on the waders. Anyone interested in the group should not overlook this publication. R. G. B. Brown Letters Ringed birds in snow Sits, During the snowy period of early January 1962, in my garden sanctuary near Welwyn, Hertfordshire, I saw two ringed birds, a Blue Tit {Par us caeruleus) and a Long-tailed Tit (. Aegithalos caudatus), with their rings thickly coated with frozen snow. They came to the freeding trays in this condition on a number of occasions. The additional weight of this cold “bracelet” must surely be detrimental to a small bird struggling to maintain life in difficult circumstances. The knowledge gained by ringing is great, but my observation raises the question whether it is advisable to ring such small birds. Some thought might be given to the possibility of designing a ring on which frozen snow is less likely to collect. Eileen A. Soper [We showed this letter to Mr. Robert Spencer, Ringing Officer of the British Trust for Ornithology; his comments appear overleaf. Eds.] 07 BRITISH BIRDS Sirs,— From time to time the Bird Ringing Committee has received reports of snow accumulating on rings, but they have been so in- frequent as to suggest that it is quite exceptional. However, following the severe weather in early January 1962, four people, including Miss Soper, reported this phenomenon and I therefore spent a day watching in my garden, where the majority of the birds are ringed. The snow was about i| inches deep; the temperature about 28° F in the morning, rising to 320 F in the middle of the afternoon. I found that many birds acquired temporary snow accumulations on their rings, although it happened most frequently with Song Thrushes (T urdus pbilomelos ) and Blackbirds ( Tardus merula ) which spent much of the time foraging through the snow. Snow-balls also gathered on the legs and plumage of several unringed birds. Some snow-coated rings achieved diameters about that of a cigarette, but the majority were smaller. On the few birds I was able to catch and examine, the snow was confined to the outside of the ring and crumbled away on being touched. On both the day of observation and on subsequent days I could find no evidence of leg damage on the small number of retraps I was able to handle. Robins (Erithacus rubecula ), Dunnocks ( Prunella modnlaris), Blue Tits ( Par us caeruleus ), Song Thrushes and Blackbirds were all seen to remove snow from their rings by pecking. A female Blackbird which was carrying a large accumulation of snow on the ring, and a small one on the unringed leg, was seen to fly to an adjacent fence where it perched for some five minutes with its feathers fluffed out so that the legs and feet were invisible. When it left the snow had melted away, but this thawing process may have been unintentional. It thus seems likely that although snow may accumulate on rings, and indeed on the bodies of birds, it is easily and frequently removed. If it were a definite hazard, the problem would have come to light long ago in the many countries which experience winters more severe than ours. Robert Spencer Snow Bunting recovered in Newfoundland Sirs, — I was very interested in the recovery in Newfoundland of a Snow Bunting ( Vlectrophenax nivalis ) ringed on Fair Isle, in the “Report on bird-ringing for i960” (Brit. Birds, 54: 493), but I did not feel satisfied by the interpretation that this bird had probably wintered on different sides of the Atlantic in successive years. I therefore examined the charts of the Daily Weather Report for the period immediately preceding the occurrence in Newfoundland on 1st May i960. These showed that on the previous day, 30th April, when there was a low pressure centre some 500 miles SSE of Cape Farewell, a north-easterly airstream extended from Iceland right over southern Greenland to 198 LETTERS Newfoundland, reaching 30 knots at sea-level between Greenland and Newfoundland. In addition, fronts near Iceland and southern Green- land were giving overcast conditions and rain in both these areas. In other words, the conditions were exceptionally suitable for pro- longed drift of a bird migrating from Europe to Greenland, which might easily have brought it to Newfoundland by 1st May. It may be noted also that the original occurrence of this bird on Fair Isle on 7th April 1959 corresponded with a period of fresh (1 5-30 knot) north to north-west winds from the area of Iceland, with a depression off Shetland. The five recoveries in northern Russia of Snow Buntings ringed in north-east Greenland (Dansk Qrti. Foren. Tidsskr., 55: 207) sugg^st that this species regularly migrates from Greenland over northern Scandinavia; so this is perhaps more likely to have been a Russian wintering bird drifted south to Fair Isle on spring migration than one of the comparatively few wintering on the North Sea coasts. South-westward drift at a later stage of the migration in the following spring would then account satisfactorily for the occurrence in Newfoundland. S. L. B. Lee Destruction of House Martins’ nests Sirs,— Apropos of the interesting note on House Martins ( Delichon urbica) building a nest of cement (Brit. Birds, 55:1 34-135), I wonder if you would consider drawing the attention of your readers to Section i(b) of the Protection of Birds Act, 1954, where it is stated: “If any person . . . takes, damages or destroys the nest of any wild bird wdile that nest is in use ... he shall be guilty of an offence against the Act.” One can understand some people objecting to the droppings below ' the nests of blouse Martins, but the inconvenience can be obviated by placing a board underneath. This has the further advantage of giving a chance to the nestlings if the nest falls down for any reason. Douglas Carr A possible explanation of “reverse migration” S*rs> “I was interested in Dr. I. C. T. Nisbet’s recent paper on “South- ceastern Rarities at Fair Isle” (Brit. Birds, 5 5 : 74-86) and should like to suggest an improbable, but possible, explanation of “reverse migra- tion . This I think could be the result of a mere error in the direction- finding mechanism in the individual bird. If it is accepted as a valid hypothesis that birds on long distance migration (as opposed to homing) instinctively develop a sense of the appropriate direction by reception of the light of sun, moon or stars from a certain angle, a purely mathematical error could surely occur in the brain mechanism responsible for receiving this information and translating it into nervous action. This might result in the adoption of the reciprocal 199 BRITISH BIRDS instead of the “intended” bearing, a mistake familiar to all of us who use maps and compasses, though in this case the “error” should not be regarded as anything other than instinctive. The fact that “reverse migration” vagrants are usually juveniles suggests that the immaturity of the direction-finding mechanism may be responsible for an error of this nature. Furthermore, the aberration of only a very small proportion of the migrating population makes me wonder whether it may result from some individual factor rather than from the effect of such a major diversionary influence as wind or temperature. I do not pretend to explain the coincidence of high temperatures in the area of origin, which Dr. Nisbet’s data show. M. J. Rogers Requests for information Wreck of Fulmars In February and March 1962. — Unusual numbers of Fulmars (Fn/marns g/acia/is) were noted close inshore on various parts of the east coast during February. In some areas a high proportion were of dark or intermediate phases. During the next few weeks many dead Fulmars were washed up on beaches from at least Aberdeen to Kent and odd ones were reported inland. Fulmars are generally regarded as particularly hardy birds and a wreck of this kind seems almost un- precedented. An analysis is therefore being prepared and we ask that all records be sent either to B. S. Pashby, 3 Ann’s Place, Napier Terrace, Norfolk Street, Hull, Yorkshire, or to John Cudworth, 17a Prospect Road, Ossett, Yorkshire. Data required include numbers of Fulmars seen offshore (with, if possible, proportions of dark and light individuals), whether or not such birds were feeding, and numbers and colour phases of ones found dead (with any information on other species seen dead at the same period). Even though it is now three months after the event, it is still worth looking out for remains of Fulmars on beaches. Wreck of Shags in March 1962. — Exceptional numbers of Shags ( Pbalacrocorax aristotelis ) appeared in southern England from the end of the first week of March and many were recorded inland. The wreck seems to have been on a much larger scale than the one in February and March 1958 {Brit. Birds, 51: 131), though the general pattern was similar in that mostly first-year birds were involved and the area concerned was the south-east coast and a broad fan of inland counties between west and SSW of the Wash; ringing recoveries so far suggest that most, if not all, again came from colonies in north-cast England and south-east Scotland. Robert Spencer and I. J. Ferguson-Lees are preparing an analysis of this wreck and would be glad of any inland records which have not already been sent to them, as well as details of unusual concentrations on the coast. Notes on local weather conditions (especially visibility) at time of arrival and observations on roosting, feeding and other behaviour would also be welcome. All information should be sent to I. J. Ferguson-Lees, 30 St. Leonard’s Avenue, Bedford. We regret the absence of the “Recent reports and news” from this and the previous three issues. It is hoped to resume this as a regular feature very shortly. M2 zoo A NEW AID FOR ORNITHOLOGISTS Photo by Eric Hoiking attracts all garden birds Swoop wild bird food is an excellent aid to bird study. Its balanced formula of ten different foods — each carefully tested tor acceptance by granivorous, insectivorous and omnivorous birds— has been shown to attract a remarkable variety of species, including migrants. Apart from its obvious use on the bird table. Swoop will be found in- valuable as bait for bird photography. Recommended by the r.s.p.b., Swoop is available at all grocers and pet shops. Price 1/11 per pack WILD BIRD FOOD Retail price Send for comprehensive binocular brochure £38.17.1 including tax in hide case HII.GBK & W A ITS From all leading instrument dealers opticians and stores WRAY (Optical Works) LTD BROMLEY KENT Telephone: RAVensbourne 0112 A BINOCULAR WITH EXTRA RAWER The WRAY A newly designed glass with a very wide aperture giving an unusually high light-gathering power, a desirable feature for the bird-watcher SMALL ADVERTISEMENTS 12/- for 3 lines (minimum); 4f for each extra line or part thereof. For the use of a Box Number there is an extra charge of If. “CRAIGELLACHIE” GUEST HOUSE, Aviemore. An ornithologists’ mecca in the Spey Valley. Crested Tit, Eagle, Greenshank, etc. Own grounds of \2\ acres. The services of a resident guide can be had at reasonable cost if required. Brochure. BOOKS REQUIRED. The Food of Some British Wild Birds by Collinge, 2nd edition. Also volumes 1, 2 & 3 of The Handbook of British Birds by Witherby. Quote each. Box MY313. 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Except for records of rarities, papers and notes are normally accepted only on condition that the material is not being offered to any other journal. Photographs (glossy prints showing good contrast) and sketches are welcomed. Proofs of all contributions accepted are sent to authors before publica- tion. After publication 25 separates of papers are sent free to authors (two or more authors of one paper receive 15 copies each); additional copies, for which a charge is made, can be provided if ordered when the proofs are returned. Contributors arc asked to observe the following points, attention to which saves the waste of much editorial time on trivial alterations: 1 . Papers should be typewritten with double spacing, and on one side of the sheet only. Shorter contributions, if not typed, must be clearly written and with similar spacing. 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English names are mose used in / )e Handbook of Brt/isb Birds, with the exception of the changes listed in British Birds in January 1953 (46: 2-3). The scientific name of each species should be given (in brackets and underlined) immediately after the first mention of the English name. Subspecific names should not be used except where they are relevant to the discussion. It is sometimes more convenient to list scientific names in an appendix. Dates should take the form “1st January 1962” and no other, ^except in tables where they may be abbreviated to “1st Jan.”, “(an. 1st”, or even “Jan. 1”, whichever most suits the layout of the table concerned. It is particularly requested that authors should pay attention to reference lists which otherwise cause much unnecessary work. These should take the following form: Iucker, B W. (1949): “Species and subspecies: a review for general ornitholo- gists . Brit. Birds. 42: 129-134. Witherby, H. F. (1894): Forest Birds: Their Haunts and Habits. London, p. 34. Various other conventions concerning references, including their use in the text should be noted by consulting examples in this issue. 4. Tables should be numbered with arabic numerals, and the title typed above in the style used in this issue. The title and any headings within the table should not be underlined, because this sometimes makes it difficult for the editor to indicate the type to be used. It is most important that the layout of each table should be carefully planned with an eye to its final appearance; above all, it should be borne mlnd that tables must cither fit into the width of a page, or be designed to fit a whole page lengthways. All tables should be self-explanatory'. 5. Figures should be numbered with arabic numerals, and the captions typed on a separate sheet. All line-drawings should be in indian ink on good quality drawing paper (not of an absorbent nature) or, where necessary, on graph paper, but this must be light blue or very pale grey. It is best if maps, graphs, etc., are drawn twice the size ot the final reproduction (ideally, therefore, for the normal 4" width the original should be 8" wide); sketches of birds, however, should be only slightly larger than the size at which it is intended they should appear. It is always most important to consider how each drawing will fit into the page. The neat insertion ot lettering numbers, arrows, etc., is perhaps the most difficult part of indian ink drawing and unless he has had considerable experience of this kind of work an author should seek the aid of a skilled draughtsman. BimtyuiiiLiiiiiiHiflum>>iniiHntit>||u>|M||||||||||||t|1>> THE PICK OF THE WORLD’S GREAT BINOCULARS ON 14 DAYS’ FREE TRIAL II x 60 WRAY (as illustrated) A remarkable, new, fully coated binoc- ular, which combines good magnifica- tion with high light transmission. 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Bush- ed for fitting to a photo tripod or can be hand-held. £39 .8.6 try it entirely without OBLIGATION Ex- Admiralty 7x50 CANADIAN & U.S. NAVAL BINOCULARS " Ideally suited to bird-watching requirements, this in- strument has many outstanding characteristics which combine to make it one of the world’s greatest binoculars. The advanced optical system produces an extraordinarily high light transmission, giving maximum performance even under the dullest conditions. Another feature is the wide field of approximately 660 yards at 3 miles, plus an excellent stereo- scopic or 3D effect. These binoculars are in perfect con- dition and are supplied complete with leather case and straps. Current value estimated at £60. Offered under our 5 years’ free maintenance service at Printed in England by Diemer & Reynolds Ltd., Eastcotts Road Bedford Published by H. F. & G. Witherby Ltd., , Warwick Court, W.C.i British Birds Principal Contents Albinism and melanism in birds Bryan L. Sage (with seven plates) Robin recaptures on Fair Isle Peter Davis Post-fledging behaviour of Choughs on Bardsey Island Susan Cowdy ,3 JUL 19 62 PURCHASED June 1962 British Birds AN ILLUSTRATED MONTHLY JOURNAL Edited by P. A. D. Hollom E. M. Nicholson I. J. Ferguson-Lees Stanley Cramp Photographic Editor: Eric Hosking Hon. Editors: W. B. Alexander N. F. Ticehurst Editorial Address: 30 St. Leonard’s Avenue, Bedford Contents of Volume 55, Number 6, June 1962 Page Albinism and melanism in birds. By Bryan L. Sage. Photographs by K. F. W. Doughty, Walter Higham, Eric Hosking, A. Schifferli, C. W. Teager and others (plates 41-47) . . . • • • • • • • • • 201 Robin recaptures on Fair Isle. By Peter Davis . . . . . . • • 225 Post-fledging behaviour of Choughs on Bardsey Island. By Mrs. J. B. Cowdy 229 Notes : — Red-legged Partridge paddling in the sea (C. A. E. Kirtland) .. .. 23} Sociable Plover in Dorset (J. W. Riley and Dr. K. B. Rooke) . . . . 233 Sociable Plover in Hertfordshire (T. R. E. Devlin, A. R. Jenkins and Dr. L. Lloyd-Evans) . . . . . . • . • • • • • • 2?6 Herring Gull with abnormal bill (M. P. Harris) (plate 48b) . . . . 236 Short-toed Lark with abnormal bill (George E. Watson) (plate 48a) . . 237 Barn Owls catching sparrows at roost (Bryan L. Sage) . . . . . . 237 Budgerigars clinging to intruding Barn Owl (Mrs. P. V. Upton) . . 238 Kingfisher trapped by frost (D. Massey) .. .. .. .. .. 238 Song Thrush floating on the sea (D. C. Mole and R. Chainey) . . . . 238 Willow Warbler attacking posturing Robins (P. D. R. Lomas) . . . . 239 House Sparrow feeding young on cuckoo-spits (F. Fincher) . . . . 239 Letters : — Black-headed Gulls eating acorns (C. J. Stevens) . . . . . . . . 239 “Kingfisher ducking Kingfisher” (B. Shepard) . . . . . . . . 240 Foot-trembling in plovers, herons and a passerine (J. N. Hobbs) . . 240 Annual subscription £2 (including postage and despatch) payable to H. F. & G. 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OJs- ODHAMS I British Birds Vol. 55 No. 6 J une 1962 Albinism and melanism in birds i lj By Bryan L. Sage ilRCHA 3tD (Hates 41-47) INTRODUCTION The study of heterochrosis or colour variations in the plumage of birds is a subject that the majority of field ornithologists either ignore ; entirely or regard with only mild curiosity. In the early years of the present century and before that, however, interest was more wide- spread and a number of very fine skin collections of abnormally (coloured birds were built up. Among the most notable were those of 'C. J. Carroll in Ireland and Joseph Whitaker in Nottinghamshire, and 'the very large collection of international scope formed by Lord Walter Rothschild at Tring Museum. One of the more recent workers in ’this country with a deep interest in the subject was the late W. E. Glegg who published a detailed study (Glegg 1931) relating to Essex speci- mens. Since then there have been few British publications apart from a scattering of isolated records, though a forthcoming paper by IHarrison and Harrison (in press) will deal with the possible evolu- tionary implications of albinism and melanism in birds. On the other hand, a good deal has been published in America, including such valuable papers as those of Lee and Keeler (1951) and Nero (1954). Colour variations in birds fall into four main groups — albinism, xanthism, erythrism and melanism. The present paper deals only *uth the first and last of these, though examples of xanthism in Wood Warblers are shown on plates 44 and 45. As a result of appeals for nformation on albinism and melanism published in British Birds, Bird Study and various local journals several years ago, and broadcast by fames Fisher and Dr. Bruce Campbell, I have received communications rom over one thousand correspondents in the British Isles, Canada, ■he United States, South Africa, British Somaliland and Australia (so 201 BRITISH BIRDS that interest in the subject is by no means lacking). Several thousand records of albinism and melanism in a wide variety of species have been card-indexed, and it is proposed eventually to analyse them in a manner that will show which families, genera and species are most liable to these conditions. Meanwhile, the present paper is confined to a dis- cussion of causes and effects. From the aesthetic point of view the beauty of many of these aber- rant birds is quite remarkable, but there are also a number of practical ways in which the field ornithologist may be affected. An obvious one is the matter of mis-identification. There are many instances of inexperienced observers reporting partially white Chaffinches* and House Sparrows as Snow Buntings, or male Blackbirds with white on the breast as Ring Ouzels. Less common have been cases of albinistic Black-headed and Common Gulls being identified as Ivory Guffs. The persistence with which individual birds return year after year to the same area can be easily observed if abnormally marked individuals are involved. Two such cases have concerned Oystercatchers. A pure white one was seen in Morayshire, Scotland, almost annually from 1937 to 1956 (Scot. Nat., 61: 185-187; and 68: 115-116) and I am informed by F. R. Smith that another white individual appeared on the Exe Estuary, Devonshire, every year from 1940 to 1955. These records throw interesting light on the apparent longevity of the Oyster- catcher. Another way in which such aberrant birds are useful is in tracing the movements of flocks. At one time or another it has been possible to do this with geese, waders and various Passerines. Finally, one may mention the subject of behaviour, a field that has hardly been touched so far as abnormally coloured individuals are concerned. In numerous species the sexual functions of display and ceremonial behaviour, and threat displays, are focused so largely round colour patterns that the study of albinos might be very rewarding. It is clear from correspondence and conversations with numerous ornithologists and naturalists that a considerable amount of misunder- standing exists regarding the causes of abnormal colorations. The most frequent misconception is that these conditions are purely due to mutation and always hereditary, but this is not so. The study of albinism and melanism leads one into many fields of science from endocrinology and genetics to physiology and biochemistry. The purpose of this paper is to set forth in a reasonably non-technical manner the diverse factors which may give rise to these conditions, and I propose to discuss each separately. *Scientific names of all the birds mentioned in the text will be found in Appen- dices A, B or C, the first two of which are lists of the species in which albinism and melanism have been recorded in the British Isles. 202 ALBINISM AND MELANISM IN BIRDS Before proceeding further I should point out that it is possible for albinism and melanism to occur in the same individual. This is admittedly a somewhat rare occurrence, but two examples may be quoted. The late J. Whitaker had in his collection a Curlew obtained in Caithness in 1906; this bird had the back and part of the head pure white spotted with black, and the remainder of the plumage was dark . chocolate in colour. Similarly, Canon G. A. K. Plervey informs me that in Westmorland in April 1957 he saw a Blue Tit that was entirely sooty black interspersed with white. In addition, as pointed out by Harrison and Harrison (in press), white primaries occur constantly in the first definitive plumage of the chicks of the melanistic mutant of i the Pheasant (i.e. var. tenebrosus). In later stages of development these mutants lose the white feathers entirely. Another general aspect is the resistance of red and orange carotenoid pigments to change. I have a number of records of albinistic or melanistic Robins and Bullfinches in which these colours remained i unaltered, and Dr. J. M. Winterbottom has kindly drawn my attention ito a male Red-crowned Bishop in the British Museum (Natural History), which was collected in Northern Rhodesia in 1937; this bird has the usual black parts of the plumage replaced by white, but 'the red areas are unaffected. A Green Woodpecker seen by R. H. C. Brackenbury in Warwickshire in i960 was pure white with the excep- tion of the red crown. A number of white examples of the Grey Parrot have been reported from time to time, but the red tail has generally remained unaffected. However, odd individuals of such species as these are occasionally found to have the red or orange pigments missing or much reduced. Mechanism of melanogenesis Before proceeding further it will not be out of place to describe briefly ■ the process by which melanin pigments are formed in the avian body. As stated by Fox and Vevers (i960), the lack of coloured pigments in albinos is due to the absence of an enzyme known as tyrosinase. This enzyme, which is produced within the body cells by the genes respon- sible for normal colour, causes the formation of melanin by oxidisation of amino acids in the body cells. In other words tyrosinase is an organic catalyst produced by the living cells. There is experimental evidence that hormones and vitamins can influence melanogenesis. In connection with the former, Woronzowa (1929) described how the grafting of pituitary gland into albino axolotls ( Amblystoma sp.) — salamander-like reptiles found in Mexico — caused the development of melanin. An interesting correlation between dietary vitamin D and melanisation of feathers was demonstrated by Decker and McGinnis (1947). They found that males, females and 203 BRITISH BIRDS castrated cocks of various breeds of poultry deposit abnormal quantities of black pigmentation in the feathers when maintained on a diet defi- cient in this vitamin. Even Buff Orpington chicks, a breed which normally has no black pigment in the plumage, showed intense black pigmentation after six weeks’ feeding on a diet deficient in vitamin D. The experiments carried out by Decker and McGinnis suggest that vitamin D exercises some influence over the degree of oxidisation of melanin compounds in the developing feather. ALBINISM Albinism in its various forms may be defined as the complete or partial absence or suppression of the normal coloured pigments. A pure albino in the strictest sense is an individual in which there are no coloured pigments in any part of the plumage or soft parts. The feet, legs and bill generally appear yellowish-white or pinkish, and the eye appears pink due to the absence of the ocular melanin pigment which permits the blood in the capillaries to be seen through the retina. In partial albinos the normal coloration is present to a varying degree and the soft parts may or may not be affected, but the irides are always normally pigmented. Partial or incomplete albinism may be symmetri- cal or asymmetrical, the latter being the most frequent. A particularly interesting case of symmetrical albinism in a Blackbird is shown on plate 42b. According to Hachisuka (1928), albinism is always of a hereditary character, but this is true only of albinism in the strictest sense as defined above. In the present paper the terms “albino” and “albinism” are used in the widest sense to refer to any individuals that are com- pletely or partially white, irrespective of the colour of the soft parts or whether the condition is genetically based; it is most important that this be borne in mind. Individuals in which the normal pattern and colour of the plumage is discernible but very pale or washed out in appearance are said to be leucistic or dilute. An example of this is the Oystercatcher on plate 46b. This condition is a form of imperfect or partial albinism and is due to a general reduction of pigmentation over the entire plumage (see Hutt 1949). Other synonymous terms for this condition are ghosting or schizochroism. Hutt, when dealing with dilution in the fowl, considered it apart from albinism largely on the basis that dilution affects all pigments, whereas in albinism carotenoid pigments are very often unaffected. Experimental evidence (e.g. Mueller and Hutt 1941) has shown that in some species a sex-linked recessive factor is responsible for the diluted plumage effect. A very fully investi- gated case of plumage dilution in a Blue Jay was described by Whitaker (i960). The blue of this and many other species is due to scattering of 204 ALBINISM AND MELANISM IN BIRDS light through a modified layer of transparent cells in the barbs; these are gas-filled vacuoles which lie above cells containing a brown melanin pigment. Microscopical examination showed that the pigment in the cells of the pale bird was greatly reduced as compared with a normal bird. Feathers in which the natural oils are absent or reduced are prone to bleaching as there is a loss of protection against chemical or light action; some instances of dilute plumage may be attributable to this cause. Hereditary albinism Hereditary albinism in birds is generally' of a recessive character. That is to say that in individuals possessing genes for normal colour and also for albinism, the former may be expected to be dominant over the latter. The experimental evidence for such a statement has been carried out primarily on Pheasants, but it is supported by field observations on various other species, notably the Blackbird. The nature of simple Mendelian recessiveness is best demonstrated dia- gramatically (see Fig. i on page 206). As a matter of interest I have compiled Table 1 from data on Pheasants presented by Bruckner (1941), and this should be examined in conjunction with Fig. 1. Bruckner’s results agree closely with those obtained byr Morgan (1958) in a similar series of breeding experi- ments, also with Pheasants. Both these workers proved conclusively that the albinistic plumage was due to a single, autosomal (i.e. not sex- linked), recessive gene. It will be noticed that in the backcross matings in Table 1 there is a deficiency of white birds compared with the expected ratio. Statistical checking showed that this was not significant, and it was believed to be due to a higher embryronic mor- tality rate in the white birds. Table 1 — Breeding experiments with albino Pheasants (■ V hast anus colcbicus) (from Bruckner 1941) Generation Parents Actual White progeny Normal Expected ratio White Normal Fi Fe Backcross f3 One normal, one white Both Fj normal One F, normal, one white Both white segregates from backcross mating 0 48 117 75 i°3 149 145 0 0 103 49-25 147-75 131 131 75 0 The data given in Table 1 are, of course, applicable only to controlled experimental conditions. In wild populations the spread of albinism is controlled by various external factors. These include an inevitably higher mortality rate from predators, possible difficulty in obtaining a 205 BRITISH BIRDS BACK CROSSES heterozygote homozygote homozygote heterozygote heterozygous Homozygous (normal) (albino) |homozy^ous heterozygous) \r normal Fig. i. Diagram to demonstrate simple Mcndclian reccssivencss (see explanation opposite) 206 ALBINISM AND MELANISM IN BIRDS mate when colour patterns essential to sexual display are absent, and post-breeding dispersal over wide areas reducing the probability of suitable matings. Other reasons are discussed in the section on the EFFECTS OF ALBINISM AND MELANISM (pages 217-220). EXPLANATION OF FIG. I This explanation is intended primarily for those who profess no knowledge of genetics. When following the figure it is helpful to bear in mind the fundamental principles that each parent provides the new body cells with an equal number of chromosomes (the structures on which the genes are located) and that the number of chromosomes in any species remains constant (through a process of reduction which need not be discussed here). In the diagram, for the sake of simplicity, it is assumed that plumage colour is controlled by a pair of genes which are situated at the same locus on the chromo- somes: that responsible for the normal is designated A and that for albinism a. It is also assumed that the gene for albinism is recessive in the presence of that for normal colour. Where the genes in a pair arc similar (i.e. A A or aa) the indivi- dual is a homozygote; where they are dissimilar (i.e. Aa) it is a hetcrozygote. The parental generation consists of a normal homozygote and an albino homozv- gote. It follows that two types of reproductive cells will be produced by these parents (i.e. A and a) and the first filial generation (F^ must all be heterozygotes of the same kind (i.e. Aa). As the albinism is recessive they are normal in colour. The second step shows an inter se mating between the heterozygotes of the F, generation to produce the second filial generation (F2). The expectation now is normal homozygotes, hctcrozygotes and albino homozygotes in the ratio 1 : 2 : 1. As a is recessive to A, it follows that the heterozygotes will be normal in appearance, even though they differ genetically from the normal homozygotes. The albino homozygotes will be pure white like the original albino parent. As a final stage, the lower part of the diagram illustrates two backcrosses (the . crossing of the progeny with their parental stocks). On the left is the backcross of the Fx hetcrozygote to the albino homozygote; the expectation here, as in any back- cross to a recessive form, is of normal heterozygotes and albino homozygotes in the ratio 1:1. On the right is the backcross of the normal homozygotc to the hetcrozygote; the expectation now is of normal homozygotes and heterozygotes in the same ratio 1:1, the recessive gene being concealed (as in the Fx generation) because it occurs onlyr in the heterozygous phase. The diagram thus illustrates some of the combinations of matings that are theoretically possible in a population where an albino homozygote is present. The mathematical probability of the heterozygotes breeding together depends upon the frequency of the albino gene in the population. If the frequency of the • 1 T recessive gene is — then the frequency of the double recessive will be — P p 2' _ t^ese various principles in mind, this figure should be studied in conjunction with Table 1 which shows the results of actual breeding experiments with normal and white Pheasants. In cases of mating between albino homozy-gotes there arises a state of recessive dominance in which all the progeny are pure albinos. This is an extremely rare event in nature, particularly so far as birds are concerned, but a perfect example of the persistence of recessive dominance in an isolated population of animals was cited y Boyd (1946): some albino Water Snails ( Planorbis corneas ) were introduced into a Cheshire pond in 1927 and a pure albino population was still nourishing in 1934. 207 BRITISH BIRDS The breeding experiments with Pheasants described above provided evidence which suggests that partial albinism may sometimes be genetically based. Bruckner found that the dominance of the gene for normal colour was not always complete, since some heterozygous individuals had occasional white feathers in the plumage and, con- verselv, homozygous recessive birds sometimes had an odd coloured feather in the plumage. Rollin (1962) described the case of a feral “blue rock” pigeon which had an odd white feather on the lower neck and two smaller white feathers behind the eye throughout its life, these being moulted annually. Breeding experiments showed that the bird was heterozygous for white and that the condition was, in fact, hereditary. Although hereditary albinism in birds is nearly always recessive, there is evidence to suggest that some cases of partial albinism may be dominant. It has been known for a very considerable time that dominant piebald types occur in mice, the Rabbit ( Orjctolagus cmiculus) and in various breeds of the domestic fowl; and a lengthy discussion of this subject will be found in Bateson (1909). Whilst I am not aware of any conclusive data relating to wild birds, it is not impossible that the persistent occurrence of partially white birds in the population of a given area may be due to (a) incomplete dominance of the genes for normal colour, as in Bruckner’s Pheasants, or (b) the existence of a dominant piebald phenotype within the population. Without con- trolled experiments, however, it would be virtually impossible to prove which. It is more or less self evident that in a very isolated population a recessive gene may gain a much higher frequency of expression than in a population where there is gene flow over a wide area. This theory was proposed by Edson (1928) to explain the high numbers (about 40%) of white-spotted individuals in a flock of Brewer’s Blackbirds. Hanson (1949) put forward the same theory to explain the high frequency of white-spotted birds in flocks of Canada Geese migrating through Illinois. So far as the British Isles is con- cerned there is a considerable amount of suggestive evidence relating to the Blackbird. For instance, Mrs. W. M. Martineau wrote to me that when she came to live at Lymington, Hampshire, in 1935 there was a Blackbird with white head and neck in the area, and that through- out the following 22 years there was always at least one individual with some white on the head; and all were males. Again, B. Keeley, writing in March 1957, stated that there had been partly white Black- birds in the vicinity of his home at Chipstead, Surrey, for the previous twenty years or so, the white being mainly on the wings and body. An interesting example of partial albinism evolving in isolation is provided by the Ravens of the Faeroes, which were named Corvus \ varius by Briinnich in 1 764. This name was given to a white-speckled 208 ALBINISM AND MELANISM IN BIRDS mutant which had been known there since at least the Middle Ages and which at one time formed a considerable proportion of the population. A rapid decline in the numbers of this mutant began about 1850, however, and K. Williamson informs me that it was last seen in 1902. The same mutation also occurred occasionally in Iceland, but it was always very rare there. The inheritance of this mutant was studied by Dr. Finn Salomonsen who found that the distribution of black and white was approximately the same in all individuals, and that the responsible factor was recessive. Some authorities still recognise the Faeroe Ravens as a distinct subspecies (C. c. varius) on the basis of pale tips to some feathers of the hind neck. Some examples of incomplete or partial albinism produce a barred eilect in the plumage and it may be that, in some instances at least, there is an analogy with the “barring” occurring in the domestic fowl. Here Hutt (1949) showed that a sex-linked gene inhibits the deposition of melanin within the individual feather, causing a white bar on a feather that would otherwise be all black. It will be noted that in 1 this paper frequent mention is made of work done on the various breeds of domestic fowl; this is a matter of necessity as, with the .exception of Pheasants, little or no work of a similar nature has been (carried out on wild birds under controlled conditions. The genetical (experiments with poultry have shown that at least four different types of white plumage may be recognised, each having its own special properties. In one of these types the pure white acts as a dominant, a condition not so far known to occur in wild birds. However, these '.white types of plumage in the fowl are not albinos in the strictest sense, as the eyes and often the soft parts also are pigmented. So far as I am aware, pure albinism (still in the strictest sense) has never been found acting as a dominant to colour in any animal species. Under the present heading we have also to discuss the question of albinism arising as a result of inbreeding. I have come across several references to this subject. Hewitt (1862, 1863) described how he ttook eggs from wild Mallard and hatched them under bantams. The young were reared and were allowed to breed only among themselves, with the result that each succeeding generation became larger, with the white collar broader and less regular, and some of the primary wing- feathers turned white. I have previously described (Sage 1955) the population of aberrant Mallard on Roath Park Lake, Cardiff, Glamor- ganshire. These birds are largely sedentary and considerable inbreed- ing certainly occurs; most individuals show varying amounts of white on the wings and some also have the lower neck and breast white. In the case of a wild population we have the evidence quoted by Delacour (1956) who stated that when Dr. Alexander Wetmore visited the island of Laysan in 1923 he found a population of twenty 209 BRITISH BIRDS Laysan Duck (the local race of the Mallard, A. p. laysanensis ) of which most showed traces of albinism in the plumage. This state of affairs had obviously been brought about by continuous inbreeding. Turning to groups other than ducks, it is well known that the dove popularly known as the “White Java” is merely an albino form of the Collared Dove which can be produced by close inbreeding from the normal type. Similarly, there is the white variety of the Java Sparrow which the Chinese probably evolved originally by selected inbreeding of pied birds. Albinism due to diet It has been known for many years, particularly among aviculturists, that incorrect or unbalanced feeding can affect the plumages of birds, ^ causing both deficiency and excess of pigment (some examples of melanism will be discussed under that subject). Data on this aspect have been acquired almost entirely by experiments with captive birds, and it is impossible to say just how far the results have any analogy in wild populations. In the wild it would be extremely difficult to prove that complete or partial loss of pigmentation was due to a defective diet. There is no doubt, however, that many (if not all) species of birds are able to convert common alimentary carotenoids to coloured compounds of different constitution. Two Continental workers (Brockmann and Volker 1934) maintained Canaries on a carotenoid- free diet. As a result, after moulting or experimental plucking, the new feathers appeared white. Conversely, it is also an established fact that if Canaries or white varieties of domestic fowl are fed on paprika (Hungarian red pepper) or cayenne pepper in an oily medium, such as olive oil, the plumage assumes an orange or crimson colour. It is also now known that the loss of red or pink colour in captive birds of species such as the Flamingo and Scarlet Ibis is caused by a lack of certain carotenoids in the diet. So far as I am aware, the only intensive study done in this country on the effect of diet on the plumage of wild birds is that of Rollin (195 3, 195 9) with Blackbirds and Song Thrushes taken from the nest and reared in temporary captivity. His experiments showed that white or greyish feathers, particularly in the tail, could be produced by vary- ing the percentage of earthworms in the diet. He also found that an insect diet superseded by one of dog biscuits, or a diet consisting exclusively of the latter, produced white feathering. I am, however, quite unable to agree with his final conclusion that an unbalanced diet is the main cause of partially white plumage in wild populations of the Blackbird and other species. I know of no evidence that wild birds ever encounter conditions which compel them to exist on an un- 210 ALBINISM AND MELANISM IN BIRDS balanced diet for any length of time. Rollin quoted the high incidence of partly white Blackbirds in the wholly urban area of Jesmond Dene, Newcastle, compared with the complete absence of such birds in an entirely rural district of north Northumberland farmland, as evidence in support of his hypothesis. However, assuming that the partly white condition in the Jesmond Dene population, which is wholly sur- rounded by built-up areas, is genetically based, then we should expect it to persist. In a relatively isolated population of this nature the mating of two individuals heterozygous for albinism would be far more probable than in a rural population. The discussion under the section on Hereditary albinism is applicable to this case. Then, again, the Blackbird certainly feeds less on domestic scraps and artificial foods than the House Sparrow or Starling, so that if an abnormal diet were the cause of partial albinism to any great degree we should expect to find a higher incidence of this condition in these two fairly sedentary and social species. According to the records in my possession, however, this is not the case. In this connection it is worth drawing attention to the work of Piechocki (1954) who examined a total of 20,93! blouse Sparrows which had been killed by poisoning: there were no pure white birds, and the incidence of partial albinism was less than one per cent. A. Ibinism due to senility There is a considerable amount of evidence to suggest that albinism, primarily partial, may gain expression as a result of increasing age, a condition that is perhaps comparable with the greying of the hair in human beings. C. W. Teager’s Blackbird on plate 41 seems to have been such a case. One of the earliest observers to draw attention to this subject was Johnson (1852), who kept a male Blackbird in captivity. This ' individual became whiter with each succeeding moult and finally died at the age of four. As this was a captive bird, however, the condition may have been caused by diet or other factors. Butler (1902) mentioned a Chaffinch which was pied when it was trapped and became much whiter at two succeeding moults. More recently, various instances have been mentioned in this journal. Rankin (1954) recorded that an adult male Blackbird ringed on 6th February 1952 had the head and neck mainly white, and that when it was re- trapped in February 1953 the white extended to the breast, mantle, wing-coverts and tail; he has since informed me that the bird was caught once more in 1954 when it was even whiter. Band (1956) trapped a male Blackbird annually from 1950 to 1952 and again in 1954 and 1955; on all occasions except the last the plumage was quite normal, but in 1955, when the bird was at least five years old, there 21 1 BRITISH BIRDS were patches of white over most of the plumage. Finally, I am in- formed by J. Laurie that a female Blackbird at Leigh-on-Sea, Essex, became progressively whiter from 1954 until by April 1957 it was pure white except for one or two normal feathers. Albinism due to shock I have come across only two references suggesting albinism from shock and both concern Blackbirds kept in captivity. J. H. Fennell (1844) described how a male, severely frightened by a cat, moulted and became pure white. A. C. Smith (1852) recorded a similar case, in which the bird assumed a piebald plumage. These records are very old, however, and there appear to be no more recent ones. J. J. Yealland of the London Zoo informs me that he has never come across such a case in his long experience of aviculture. It seems wiser, therefore, to be cautious about shock as a possible cause of albinism until such time as we have a properly authenticated observa- tion. If cases do occur, they may be analogous with instances of the hair of human beings turning white within a very short space of time after a severe shock to the nervous system. Albinism due to disease and injury There appears to be a paucity of information on albinism and disease or injury, at least so far as wild birds are concerned, although Hutt (1949) stated that in domestic fowls the spontaneous development of white feathers after injury is not uncommon. Gunn (1876) obtained a pure white female Blackbird near Norwich, Norfolk, and associated the colour of the plumage with the diseased state of the bird’s liver, which was black in colour. A case of partial albinism in a Goldfinch was similarly attributed by Macpherson and Duckworth (1886) to the diseased liver which was found when the bird was dissected. Another instance of this kind, involving a buff- coloured Red Grouse in the possession of the Hon. C. H. Wynn, was recorded by Forrest (1907). However, I have discussed this subject with Dr. James M. Harrison who informs me that he does not know of any liver disorder which would be likely to affect the colour of the plumage in this way. Until further evidence comes to hand, there- fore, these three cases must be considered not proven. On injury there is a little more information. Writing in America, Brimley (1944) referred to a male Red-winged Blackbird which was partially albinistic, including a large white patch on one side of the breast. Under this white patch was an old wound where a shot had ploughed through and left a furrow, on each side of which the flesh was discoloured and almost gangrened in appearance. In his opinion 212 ALBINISM AND MELANISM IN BIRDS this was the cause of the partial albinism. He also put forward the theory that birds which are seized by a predator and manage to escape with the loss of some feathers may develop partial whiteness in the affected areas. Then there is a case described by Phillips (1954)- A Great-tailed Grackle collected in Mexico was white on one side of the face. It was subsequently ascertained that a large yellow cyst was present beneath the skin at this point, and that this had formed round a sliver of some kind which was imbedded in the jaw muscles. Similarly, Hachisuka (1928) mentioned a hen Capercaillie which was bitten by a Stoat {Mustek ermine a) ; after the wound had healed, white feathers grew on the affected part. More recently, Dr. Bruce Campbell has passed on details of an interesting observation by G. R. A. Wright. For two or three years a Blackbird, identifiable by a deformed foot, had frequented the latter’s garden. In the summer of 1961 this bird was found hanging by the neck from the mesh of some fish netting protecting raspberry canes. The bird was released and was not seen again until the winter, but when it reappeared it had a ring of white feathers round the neck. There is a considerable amount of experimental evidence relating to traumatic causes of partial albinism. Dealing with mammals, both Duerst (1926) and Schultz (1918) have discussed the experimental infliction of wounds which, on healing, have grown white hairs. Similar work has been done on various breeds of the domestic fowl; for instance, Pearl and Boring (1914) and Krizenecky (1930) have shown that albinism can occur as a result of plucking. We should also note the statement of Fox and Vevers (i960) that “As a final instance of loss of melanin it may be noted that injury can be respon- sible for the disappearance of melanocytes”. The occurrence of isolated white feathers can also follow damage to or blocking of the gland by which the pigment passes into the feather. A similar explanation may be applied to parti-coloured feathers. Where pigmentation proceeds normally at first and ceases later, the feather will be normally coloured from the apex to the point where pigmentation ceased, and white from then on. Alternatively the gland may be non-functional at first and start operating later, in which case the distribution of the pigmented and white areas will be reversed. A simple experimental lesion of the pulp of a growing feather will cause it to develop white. Summary Before going on to discuss melanism it may be useful briefly to sum- marise some of the points considered in the preceding pages: (1) Pure albinism in the strictest sense is congenital and, so far as is 213 BRITISH BIRDS known, always acts as a Mendelian recessive. There is no proven evidence that such individuals ever revert to normality. (2) It is impossible for pure albinism to be developed from a state of normality, i.e., it must show in the first definitive plumage. (3) Some forms of partial albinism are hereditary and probably mainly recessive, but it is known that dominant piebald varieties occur in some animals including the domestic fowl and, therefore, possibly also in other species of birds. Partial albinos always have pigmented irides. (4) Individuals of normal coloration may develop partial or com- plete albinism (but not pure albinism in the strictest sense) from diet, senility, injury and possibly disease and shock. As this type of albinism is not congenital, the affected individual may later revert to normality. (5) Hereditary partial albinism may occasionally revert to nor- mality, as for instance the white primaries which occur only in the first definitive plumage of Pheasant chicks of the mutant variety tenebrosus. (6) Experimental work with Pheasants indicates that albinism is not a sex-linked condition and this is supported by observations on numerous species in the wild. However, Mueller and Hutt (1941) reported sex-linked imperfect albinism in the domestic fowl and analogous cases may occur in wild species. MELANISM Melanism is the exact opposite of albinism in that it is caused by the excessive deposition of melanin pigments. This results in an abnor- mally dark appearance and melanistic individuals are generally blackish or dark brown in colour. The condition is certainly of much less frequent occurrence than albinism, even taking into account the fact that it may often be overlooked because it is far less noticeable, particularly in species where the normal colour of the plumage is dark. Another major difference between albinism and melanism is that the latter is generally a Mendelian dominant, that is to say that it can gain expression in the heterozygous phase in the Fx generation. Cases of recessive melanism have been found in some organisms (e.g. moths), but they are generally rare mutants and do not spread. The dominant nature of melanism often results in populations where the melanistic phase is very numerous and distributed over a wide area. A good example can be found in the spread of the melanistic variety of the Grey Squirrel ( Sciurus carolinensis ) in Hertfordshire, where it has been known for a great many years (see Fordham 195^ who quotes a number of references, and Shorten 1954)* Before the arrival of myxomatosis I was aware of several Hertfordshire colonies 214 ALBINISM AND MELANISM IN BIRDS of Rabbits where blackish individuals wTere common. At one of these colonies approximately 46% of the population were melanics, and blackish Rabbits had been known there for at least twenty years. Melanistic Rabbits are also of common occurrence in Australia and, according to Barber (1954) this type may comprise 35% of the total population in the forested interior of Tasmania. A similar state of affairs, though on a more restricted scale, existed in the Partridge population of the Tring area of Hertfordshire. In January 1915 the late Lord Walter Rothschild exhibited to the British Ornithologists’ Club two melanistic Partridges which were representative of a type that had been shot at Tring for ten successive years. Norma/ and abnormal melanism Under this heading I propose to discuss two types of melanism. The first, which can conveniently be designated normal melanism, refers to those dimorphic or polymorphic species in which a melanistic plumage phase is of regular occurrence. The second, abnormal melanism, covers individual species not normally producing a melanis- tic phase. There are a considerable number of birds in the world which are known to have a normal melanistic phase. Among British species one immediately calls to mind the dark brown or blackish varieties of the Snipe, Pheasant, Red Grouse, Partridge, Buzzard and Montagu’s Harrier. In several cases, such as the Snipe and Montagu’s Harrier, these melanistic varieties were described as separate species before their correct identity was known. In addition to the Buzzard and Montagu’s Harrier, a number of other birds of prey have a melanistic phase. Examples are Eleanora’s Falcon in the Mediterranean, the Gabar Goshawk in Eastern Africa, and the Rough-legged Buzzard and Short-tailed Hawk in America. In the majority of these cases the melanistic type is of random distribution. In all the species mentioned so far, the normal plumage is fairly dark, but melanistic phases also occur in birds which are normally mainly white. In Africa, for example, the Little Egret has various colour phases ranging from the normal white through pale grey and sooty-grey to blackish-slate. Under certain ecological conditions natural selection may favour a melanistic type. A good example is found in the blackish forms of the Desert Lark which occur on black lava terrain in various parts of the range of that species. The race of the Partridge in north-west Germany (P. p. spbagnatorum ) is another case of a melanistic form adapted to a particular habitat, in this case black peaty soils. An interesting example of an occasional melanistic form becoming established and replacing the normal form in comparatively recent times is that of the West Indian Bananaquit. Attention was first 215 BRITISH BIRDS drawn to this species by Lowe (1912), and now most of the birds on the islands of St. Vincent and Granada are black. Analagous instances are known among such mammals as the Hamster ( Cricetus cricetus') and the Brush Opossum ( Trichosurus vulpecula). Industrial melanism among moths is now a well established fact. What may well have been the beginning of an identical situation in the House Sparrow was suggested by Hardy (1937)* who stated that a slight but definite darkening of the plumage had taken place in the population of this species in the Liverpool area. In recent corres- pondence Mr. Hardy informs me that his studies were terminated by the outbreak of war in 1939, and that he has since been unable to follow the matter further. Confirmation of this possibility is provided by Noble Rollin who tells me that before 1930 he also found evidence of industrial melanism in House Sparrows whose plumage could not be made lighter by washing. Data on the present situation in Liver- pool or other industrial areas would be of great interest. One of the most remarkable cases of partial melanism so far recorded is that seen in the specimen of the Gabar Goshawk figured by Hachisuka (1928). This bird is quite normal on one side and entirely melanistic on the other. In the British Isles most records of melanism in species other than those normally having a melanistic phase involve isolated instances only. During the period 1954-1959, however, melanistic Great Tits were reported from Ashtead, Esher, Hersham, Long Ditton, Oxshott, Surbiton and Woking, all in Surrey, and there can be little doubt that most of these records are related. In at least one case (that at Oxshott) the young of a melanistic parent all apparently had normal plumage, but, as recorded by Perrins (1959), eight out of nine young Great Tits in a brood at Hersham were melanistic (plate 47). There the female parent was normal, but the male was unfortunately not seen. Some instances of melanism in gulls are worth mentioning. The most interesting concerns Black-headed Gulls. During December 1961 and January 1962 at least four individuals (two entirely blackish and two piebald) were seen in the vicinity of Seahouses, Northumber- land (Evans 1962). On 3rd January one of the blackish birds was trapped and examined, and it was established that the condition was due to pigmentation and not oiling. The great interest of this record lies in its possible connection with an entirely blackish bird of this species seen at Elton, Co. Durham, by Dr. J. D. Summers-Smith in December 1956. It is difficult to resist the conclusion that there is somewhere a breeding colony where this melanistic type has been perpetuated. If such a colony could be located and the aberrant birds colour-ringed, valuable information on the inheritance of this condition might be obtained. 216 ALBINISM AND MELANISM IN BIRDS It is worth noting that melanism has been reported in two other guHs m the British Isles. Stokoe (1954) photographed a black Herring Gull at St. Bees Head, Cumberland, in July 1952 and a similar observation was made by Canon G. A. K. Hervey in the same area in August 1957. Meanwhile, another Herring Gull which was almost entirely dark brown was seen by Dr. Summers-Smith at Seaton Carew Co Durham, in December 1954. A juvenile Lesser Black- rc -n GU 1 WJth dark brown uncler-parts was identified on the Isles of Scilly in July 1925 (Robinson 1926); and another, dark brown with the exception of the head and wings, was seen at Morecambe, Lanca- shire, in August 1957 by Canon Hervey. Melanism due to diet It is an established fact that the plumage of birds can be made black or dark brown by selective feeding. The example that is generally quoted is that of the Bullfinch, which will turn quite black if fed on a diet of hempseed with a high oil content. However, other species can be equally affected. Stevenson (1866) mentioned a Goldfinch which became black as a result of being fed freely on such a diet, and Newman (1855) described a similar experience with a Hawfinch, -hnsty (1890) quoted a case of a Redwing which was caught in January and became pure black when it moulted in August; he did not state the cause, but it also may well have been connected with the diet in captivity. It is hardly necessary to add that when the hemp- seed is removed from the diet an affected bird will gradually return to its normal colour. The chemical and physiological processes in- volved were discussed in detail by Staples (1948). Goodwin (1957) recorded a somewhat different example of tem- porary melanism in the Spotted Dove. He suggested that the con- dition might have been brought about by adverse factors operating during the growth and pigmentation of the first adult plumage, in particular an over-fat condition induced by insufficient exercise and a diet rather rich in fats ; here food alone could not have been entirely responsible. Bannerman (1953) mentioned that one of a brood of five Goldfinches reared by Col. R. F. M. Meiklejohn in Estonia was coal black, and remained so until the first moult when it became normal. is temporary melanism presumably had no connection with food owever, as the other four birds were not affected. EFFECTS OF ALBINISM AND MELANISM Such information as is available on the effects of albinism and melanism consists mainly of scattered and random observations, and there appears to be a great lack of detailed work on the subject. Two points regarding albinos which immediately come to mind 2I7 BRITISH BIRDS are vulnerability to predators and persecution by other birds. So far as the first is concerned, it is obvious that a white or nearly white bird will, in all but a few specialised habitats, be far more conspicuous to predators than one that is normally coloured, and there is little doubt that mortality from predation is higher. Persecution by birds of the same or other species is a variable factor. In some instances albinos are attacked, and in other cases they are accepted. There are numerous references to both types of behaviour in the literature and it does not seem necessary to quote them. In the introduction to this paper I mentioned the subject of display. Sexual display and other forms of behaviour that involve the use of special plumage patterns and striking colours may well be affected if these are absent or reduced. Close study of abnormally coloured individuals may show that unusual behaviour patterns are acquired in the course of time. Physiologically speaking there is little doubt that most pure albinos are pathological to a greater or lesser degree, and have a poor expec- tation of life. Experimental work has produced much interesting evidence of this. For example, Dunn (1923) reported a lethal gene linked with recessive white in the White Wyandotte fowl. Hunter (1939) described a light-feathered generally recessive mutation of the Mallard which was produced after 18 years in captivity; his breeding experiments with this strain showed that a semi-lethal weakness of embryo and duckling was associated with the light gene. Similarly, in his experiments with Pheasants, Bruckner (1941) found evidence which suggested that embryonic mortality was higher in the homozy- gous albinos. Defective eyesight may also often be correlated with albinism. One of the best examples of this in wild birds is provided by the work of Mcllhenny (1940) on the Mockingbird. A total of twelve nests were studied, all belonging to one male and his two successive mates. The male and the first female were evidently heterozygous for albinism, for 18 of the 43 young they hatched were albinos. These were deficient in sight, weak in voice and far less active on the wing; none lived long, whereas all but two of the normal young survived. Keeler, Hoffman and Shearer (1949) studied a faded feather mutation in the Turkey; such mutants were found to have defective vision, broken or missing feathers, weak bones and small bodies. Keeler also found that a pair of albino Collared Doves had defective vision. Lincoln (1958) described how an albino Purple Martin died as a result of colliding in flight with the branch of a tree; post-mortem examination showed that it was apparently suffering from starvation, and it was assumed that poor eyesight had also prevented the bird from catching an adequate supply of insects. Similar instances have been found in 218 ALBINISM AND MELANISM IN BIRDS mammals. For example, the manner of the death of a pure albino Otter (L»/ra lutra ) in broad daylight suggested that it had defective vision (McDonald 1959). The case of the albino Mockingbirds that were less active on the wing has already been mentioned. Keeler noted exactly the same thing in his albino Collared Doves. Dr. Alexander Wetmore found the albinistic Laysan Duck to be so lacking in the power of flight that that they could be run down and captured by hand (see Delacour 1956). We have already seen that in pure albinos the soft parts are always depigmented, with the result that the irides usually appear pink or reddish and the legs and bill pale yellowish or whitish. However, it should be added that some pure albinos have blue eyes. It is generally supposed that this phenomenon is peculiar to the Pheasant, but I also have records of a pure white Dunnock and a pure white House Sparrow with .blue eyes. The genetics of this character evidently require further study. I have already pointed out (Sage 1958) that in some birds a lack of pigment in the soft parts is not necessarily correlated with any plumage abnormality, as in the case of the Moorhen which may have yellow legs and bill and normal plumage. Structural modifications of the feathers may sometimes be associated with albinism, and this aspect was dealt with by Chandler (1916). The best known example is the “hairy” variety of the Moorhen in which albescent plumage is accompanied by a lack of interlocking barbules on the feathers. A similar condition has been recorded in some other species, however— for example, the Jay— and Nero (1954) referred to Red-winged Blackbirds with individual white feathers of this hair-like texture. It may be pointed out that in fowls and pigeons there is a condition known as silkiness, in which the barbules fail to interlock owing to some structural deficiency (see Hutt 1949). Mrs. J. Gladwin has given me details of a male Blackbird trapped at Rye Meads, Hertfordshire, in November 1961, which had a single white primary feather. This was coarser than the other primaries in texture and the shaft was thicker; in addition, it did not he in fine with the other feathers but was twisted. As the shaft was straight the twisting evidently originated from the sheath. A further instance of structural variation associated with partial albinism was recorded by Finnis (1959). A juvenile male Blackbird found dead in Kent in May 1959 had a considerable amount of grey in the plumage including most of the wing feathers. On examination it was found that the feathers were unusually fragile and that the tips of the rectrices exhibited an abnormal amount of abrasion. A remarkable association of a physical defect with albinism was described to me by C. J. Beese. A pied Blackbird in his garden was apparently quite deaf as on several occasions he approached it closely 219 BRITISH BIRDS from behind without being detected, sometimes even making a con- siderable noise. He added that he had also known of albinistic House Sparrows and Rabbits, as well as rats and mice, which were apparently quite deaf. So far as melanism is concerned there appears to be very little on record regarding correlated conditions. In quite a few instances melanistic mutants of the Pheasant are larger and more robust than normal individuals. Legendre (1941) wrote of the dark mutant Pheasant — “The bird is large and robust. As a game bird, the dark Pheasant presents itself as flying high and fast. Its weight is greater than that of ordinary Pheasants.” This should not be taken as an invariable rule, however, as some melanistic individuals are no heavier or larger than normal birds, though a melanistic Buzzard that was taken from a nest in Caernarvonshire and hand-reared was stated to be of above average size (Niall i960). I have been unable to trace any records of lethal conditions associated with melanism. acknowledgements In the course of this study I have been assisted by a great many people in diverse ways, and in particular by the hundreds of correspondents who have given me information. In this connection I am especially grateful to Dr. Bruce Campbell, James Fisher and R. S. R. Fitter for passing on many records sent to them and also for much encourage- ment in other directions. I. J. Ferguson-Lees has likewise helped me considerably in ways unconnected with his editorial work. On the more technical side, I am indebted to Drs. James M. and Jeffery G. Harrison whose brains I have picked on countless occasions and who generously gave me a preview of their forthcoming paper. I. C. J. Galbraith of the British Museum (Natural History) kindly discussed a number of genetical points with me and I must also thank Kenneth Williamson for providing a history of the pied variety of the Raven in Iceland and the Faeroes. Finally, I am most grateful to F. Metcalf who prepared the final drawing of the figure on page 206. REFERENCES Band, R. M. (1956): “Albinism related to age”. Bri/. Birds, 29: 153-154. Bannerman, D. A. (1953): The Birds of the British Isles. Edinburgh and London. Vol. 1. Barber, H. N. (1954): “Genetic polymorphism in the rabbit in Tasmania”. Nature, 173: 1227. Bateson, W. (1909): Mendel’s Principles of Heredity. Cambridge. Bolam, G. (1912): Birds of Northumberland and the Eastern Borders. Alnwick. Boyd, A. W. (1946): The Country Diary of a Cheshire Man. London. Brimley, C. S. (1944): “Albinism sometimes due to injuries”. Chat, 8: 11. Brockmann, H., and Volker, O. (1934): “Dcr gelbe FederfarbstofT des Kanaricn- vogels ( Serinus canaria canaria ) und das Vorkommen von Carotinoiden bel Vogeln”. Hoppe-Seyl. Z., 224: 193-215. 220 Plate 41. Partial albino male Blackbird (Ti/rdns merula), Essex, January i960. The next autumn this bird became much whiter— its head and back pure white and its tail and wings broken white; only its under-parts stayed largely black. This and other cases of progressive albinism suggest that white plumage sometimes develops as a result ot increasing age (pages 201-225, especially 211) {photo: C. IF. Teager) m Plate 42. Above, partial albino Red-necked Grebe (Pod/ceps griseigena), Switzer- land, October 1955 {photo: A. Schifferli ). Such albinism is often unequal in distribution (page 204), but an interesting case of almost perfect symmetry in a Blackbird (T Urdus merula) is shown below {photo by permission of G. W. Temper ley) Plate 43. Mounted specimens of nearly pure white Corncrake ( Crex crex), Derbyshire 1892, and Curlew (Ntmenius arqua/a), Northumberland 1 8 5 6 {photos from If hillock 1 89 3 and Bo/am 1912). Albinism has been recorded in a great variety of birds: Appendix A (pages 223-224) lists 160 species of 104 genera in Britain alone Plates 44 and 45. Xanthistic Wood Warblers (Phy/loscopus sibilatrix ), Wales, )une 1954. Xanthism is due to excess retention of yellow and loss of dark pigment. Here the male (above) was normal except for a straw-coloured cap, but the female (1 opposite ) had a primrose head and back, darker yellow shoulders and tail-coverts, white under-parts and white outer-tail; her bill and legs were the colour of dead bracken, but note that her eyes were dark brown (page 204) ( photos : Erie Hashing) l Plate 46. Above, partial albino Lapwing (1 anellus vanellus ), Yorkshire, April 1930 {photo: Walter Highatn). Below, dilute Oystercatcher ( Ehaematopus ostralegus), Cheshire, October 1954; this is an imperfect form of albinism in which there is an even reduction in pigment over the entire plumage (page 204) {photo: Er/c Hoskitig ) Plate 47. Four views of a mclanistic young Great Tit (Pants major), Surrey, May 1957 • This bird was from a brood of nine, all but one of which were similarly black and grey-black all over — even to the parts that are usually yellow and white. The mother was normal and the father not seen (page 216 ) (photos: K. F. IV. Doughty) Plate 48. Deformed bills of Short-toed Lark {Calandrella cinerea) {above) and Herring Gull {Larus argentatus). The lark (upper mandible elongated and twisted) was 30% underweight; the gull (upper mandible broken, lower elongated) was a good weight and healthy (pages 236-237) ( photos : George E. Watson and C. Stockton ) ALBINISM AND MELANISM IN BIRDS Bruckner, J. H. (1939): “The inheritance of melanism in pheasants” J Hered „ ‘inheritance of white plumage in Phasianus" . Auk, 58: 536-542 Butler, A. G. (1902) : Agricultural experiences during about twenty years study of birds in captivity . Zoologist, 1902: 252 Christy, R. M. (1890): The Birds 0/ Essex. ' London. Chandler, A. C. (1916): “A study of the structure of feathers with reference to their taxonomic significance”. Univ. California Pub/, in Zool., 1 3 : 242-446. OmlnU ’’ a"d McGinnis, J. (1947): “Black pigmentation in feathers of Buff Orpington chicks caused by vitamin D deficiency”. Pror. Soc. Exp Bio! N Y 06: 224-228. ' " Delacour, J. (1956): The Waterfowl of the World. London. Vol. 2. uerst, U. (1926): Stang-Wirt' s Tierbeilkunde und Tiervucht. Vol 1 n 127 Donn, L C “A lethal gene m fouls". A, dr. N.,„ f'JT Edson, J. M. (1928): An epidemic of albinism”. Auk, Ay. 277-278. iVANs, P. R. (1962): “Mclanistic Black-headed Gulls in Northumberland”. Brit Birds, 55: in press. Frr* J'1H' 4' L44f '• °n thc Sudden chan8c of colour in the plumage of birds produced by fright ’. Zoologist, 1844: 566. FlRN//S’if -,Gn(l9^9/): “Abcrrant iuvenilc Blackbird T Urdus menda mcrula Linnaeus”. Dull. lint. Urn. C/.y 79: 152. F— W’f H‘ “Advancc of Grey Squirrels (Sciurus caro/inensis ) and 170 °f mean'Sm ln north Hertfordshire”. Proc. Zool. Soc. Lond., 126: Forrest, H. E. (1907): The Fauna of North Wales. London Fox, H. and Vevers, G. (i960): The Nature of Animal Colours. London. tlegg, W. E. (1931): “Hetcrochrosis in Essex birds and in their eggs”. Essex lya/., 23 : 171-202. 0 Goodwin, D. (1957): “Temporary melanism in a Spotted Dove”. Bull. Brit. Orn. Ci., 77 : 3"5- IL» E'7(l/7^: “N;0teS °n the occurrence of rare birds in Norfolk and Suffolk . Zoologist, 1876: 4787-4789. Hachisuka, M. (1928): Variations Among Birds. Tokyo. H' C, (l949); “Notes on white spotting and other plumage variations in geese . siufc, 66: 164-171. Hardy, E. (1937): “Polluted wild life”. Country Life, 81 : 676. ™S°*’ J; G‘/in PrCSS): “Albinism and melanism in birds as illus- ted by the Mallard and their possible significance”. Bull. Brit. Orn. Cl. 82 Hewitt, E. (1862, 1865): “Wild ducks reared with tame”. J. Hortic , 1862- 772 • Hunter, J. R. (1939): “A light mutant of thc Mallard duck”. J. Hered 20- Hutt, F. B. (1949): Genetics of the Fowl. New York. Johnson J. (1852): “Inquiry respecting the Blackbird supposed to have become white through fright”. Zoologist. 1852:3632. Keeler, C. E., Hoffman, E„ and Shearer, R. (1949): “Faded bronze plumage: an autosomal mutant in the turkey”. Poultry Science, 28: 633-635. K~U*i3?:4;'S"r,,mMischm Albinism,'s bdm Gca“8d” L w,S"C',2lK6?:To:8c!'.E' "Pigm",t v"ia,io'“ «• ,hdr ta LE™i’iM; (iI94I): 5 226 ROBIN RECAPTURES ON FAIR ISLE (range 12.3 to 18.8) and for the 33 which were later retrapped it was also 15.3 (range 12.3 to 17.2). In autumn the average for all Robins was 14.9 gm. (11.7 to 18.8), and for the 36 later recaught it was also 14-9 (I2-5 to 18.0). Thus there is no reason to suppose that the retraps were in worse shape than the rest. Since the recapture data were insufficient for a day-by-day analysis of recapture weights, the figures were grouped in periods of several days. On the few occasions when an individual was caught more than once within each group of days, the mean of its recapture weights was used. Even after grouping, the samples are too small and the conclusions are therefore tentative and exploratory. They are logical, however, and accord with what one would expect to happen, so that it is likely that larger samples would confirm the results. The ideal would be a long series of birds retrapped at frequent intervals through- out their stay, but experience has shown that this would take manv years to accumulate. A few individuals which were retrapped several times are discussed below. The data for both spring and autumn are summarised in Table 1. Table i Weight increases of migrant Robins (Erithacus rubecula) on Fair Isle in spring and autumn ' ° 1S th.C