HARVARD UNIVERSITY LIBRARY OF THE Museum of Comparative Zoology Tfie WIson Bulletin PUBLISHED BY THE WILSON ORNITHOLOGICAL SOCIETY WEST VIRGINIA U. • MORGANTOWN, W. VA. VOL. 79, No. 1, MARCH 1967 PAGES Lt128 IVJJS. COIviP. -O'. library IvIAh 1 3 1967 In f-\ K V M I \ ij UNIVERSITY The Wilson Ornithological Society Founded December 3, 1888 Named after ALEXANDER WILSON, the first American Ornithologist. President — Aaron M. Bagg, Farm Street, Dover, Massachusetts. First Vice-President — H. Lewis Batts, Jr., Dept, of Biology, Kalamazoo College, Kalamazoo, Michigan. Second Vice-President — William W. H. Gunn, 455 Meadow Wood Road, Clarkson, Ontario. Secretary — Pershing B. Hofslund, Dept, of Biology, Duluth Branch, University of Minne- sota, Duluth, Minnesota. Treasurer — C. Chandler Ross, Academy of Natural Sciences, 19th and Parkway, Philadelphia, Pennsylvania. Elected Council Members — Stephen W. Eaton (term expires 1%7) ; Jeff Swinebroad (term expires 1968) ; Kenneth C. Parkes (term expires 1969). Membership dues per calendar year are: Sustaining, $10.00; Active, $5.00. The Wilson Bulletin is sent to all members not in arrears for dues. The Josselyn Van Tyne Memorial Library The Josselyn Van Tyne Memorial Library of the Wilson Ornithological Society, housed in the University of Michigan Museum of Zoology, was established in concurrence with the University of Michigan in 1930. Until 1947 the Library was maintained entirely by gifts and bequests of books, reprints, and ornithological magazines from members and friends of the Society. Now two members have generously established a fund for the purchase of new books; members and friends are invited to maintain the fund by regular contribution, thus making available to all Society members the more important new books on ornithology and related subjects. The fund will be administered by the Library Committee, which will be happy to receive suggestions on the choice of new books to be added to the Library. William A. Lunk, University Museums, University of Michi- gan, is Chairman of the Committee. The Library currently receives 104 periodicals as gifts and in exchange for The Wilson Bulletin. With the usual exception of rare books, any item in the Library may be borrowed by members of the Society and will be sent prepaid (by the University of Michigan) to any address in the United States, its possessions, or Canada. Return postage is paid by the borrower. Inquiries and requests by borrowers, as well as gifts of books, pamphlets, reprints, and magazines, should be addressed to “The Josselyn Van Tyne Memorial Library, University of Michigan Museum of Zoology. Ann Arbor, Michigan.” Contributions to the New Book Fund should be sent to the Treasurer (small sums in stamps are acceptable). A complete index of the Library’s holdings was printed in the September 1952 issue of The Wilson Bulletin and newly acquired books are listed periodically. The Wilson Bulletin The official organ of the Wilson Ornithological Society, published quarterly, in March, June, September, and December, at Morgantown, West Virginia. The subscription price, both in the United States and elsewhere, is $5.00 per year, effective in 1965. Single copies, $1.25. Subscriptions, changes of address and claims for undelivered copies should be sent to the Treasurer. Most back issues of the Bulletin are available (at $1.25 each) and may be ordered from the Treasurer. Special prices will be quoted for quantity orders. All articles and communications for publications, books and publications for reviews should be addressed to the Editor. Exchanges should be addressed to The Josselyn Van Tyne Memorial Library, Museum of Zoology, Ann Arbor, Michigan. Second class postage paid at Lawrence, Kansas, U.S.A. Allen Press Inc., Lawrence, Kansas THE WILSON BULLETIN A Quarterly Magazine of Ornithology George A. Hall Editor Editorial Advisory Board Tom J. Cade William C. Dilger William W. H. Gunn William A. Lunk Andrew J. Meyerreicks Robert W. Nero Kenneth C. Parkes Raymond A. Paynter, Jr, Ornithological Literature Editor Olin Sewall Pettingill, Jr. Volume 79 1967 Published by THE WILSON ORNITHOLOGICAL SOCIETY THE WILSON BULLETIN A QUARTERLY MAGAZINE OF ORNITHOLOGY Published by The Wilson Ornithological Society Vol. 79, No. 1 March 1967 Pages 1- CONTENTS Variation in Central American Flickers Lester L. Short, Jr. The Double-scratch as a Taxonomic Character in the Holarctic Emberizinae C. I. O. Harrison Movements of Female Ruffed Grouse during the Mating Season Robert B. Brander Weights of Birds from Alabama and North Carolina Paul A. Stewart and Robert W. Skinner Foods of the Black-bellied Tree Duck in South Texas Eric G. Bolen and Billy J. Forsyth Wind Drift, Leading Lines, and Diurnal Migration Helmut C. Mueller and Daniel D. Berger The Contexts of Songs in Black-throated Green and Blackburnian Warblers Douglass H. Morse Damage by Golden-Fronted and Ladder-Backed Woodpeckers to Fence Posts and Utility Poles in South Texas John V . Dennis Agonistic Behavior in the American Goldfinch .... Ellen L. Coutlee General Notes CAVITY “excavation” BY CLIFF SWALLOWS Abbot S. Gaunt and Sandra L. Gaunt AN INSTANCE OF “W'llITE VVI NG-B AHKINc” IN THE COMMON CHOW Lester 7. Short, Jr. and Roxie G. Laybourne 128 5 22 28 37 43 50 64 75 89 no 113 COMPARATIVE FORAGING REIIAVIOR OF MYIOZETETES SIMILIS AND M, GHANA- DENSIS IN COSTA RICA Joel Cracraft 115 ATTACK BEHAVIOR OF A LOGGERHEAD SHRIKE Larry D. Caldwell 116 UNUSUAL BEHAVIOR OF THE YELLOW-HEADED BLACKBIRD Jerry R. LongCOre 117 AN AGGRESSIVE DISPLAY BY A TUFTED TITMOUSE Gary 0. Wallace 118 CAPE MAY WARBLER IN COSTA RICA Alexander F. Skutch 118 FEEDING REACTIONS OF MYRTLE WARBLERS TOWARD WAX-MOTH LARVAE DYED VARIOUS COLORS Janet S. Chappell and Robert W. Ficken 119 TONGUE DEFORMITY IN IMMATURE ROBIN Sally Hoyt Spofford 119 ABNORMAL TONGUE IN A ROBIN Ralph M. Edeburn 120 The President’s Page Aaron M. Bagg 121 Ornithological News 122 Ornithological Literature 123 Dean Amadon, Birds around the World: A Geographical Look at Evolution and Birds, reviewed by Harold Mayfield; Maurice Brooks, The Appalachians, reviewed by Ernest P. Edwards; A. W. Johnson, The Birds of Chile and Adjacent Regions of Argentina, Bolivia, and Peru, reviewed by Claes Chr. Olrog; Harold C. Hanson, The Giant Canada Goose, reviewed by Charles D. Macinnes; Arthur S. Einarsen, The Black Brant: Sea Goose of the Pacific Coast, reviewed by Karl W. Kenyon; Henry Hill Collins, Jr. and Ned R. Boyajian, Familiar Garden Birds of America, reviewed by W. J. Breckenridge. tViUi.. COMP, ZOOL, LIBRARY MA8 1 3 1967 hiMfX V ArviJ UNIVERSITY VARIATION IN CENTRAL AMERICAN FLICKERS Lester L. Short, Jr. \ W j HILE investigating hybridization and its effects on flicker populations, W I undertook a general study of variation in the two North and Middle American species, Colaptes auratus and C. (Nesoceleus) fernandinae. For reasons presented elsewhere (Short, 1965a) the five major groups of C. auratus, namely the auratus, cafer, chrysoides, chrysocaulosus, and mexi- canoides groups, are considered conspecific. (A vernacular name for this assemblage is difficult to arrive at; perhaps “Black-breasted Flicker” best describes and distinguishes C. auratus.) The present paper deals with varia- tion in the allopatric Central American mexicanoides subspecies group of Colaptes auratus. This group is currently comprised ( Peters, 1948) of the races mexicanoides and pinicolus, which are usually regarded (Peters, 1948; Blake, 1953; Eisenmann, 1955; Miller, et ah, 1957) as part of the “species” Colaptes cafer. I have elsewhere dealt with variation in the allopatric. West Indian chrysocaulosus subspecies group of C. auratus (Short, 19656), and variation in the mexicanoides group will be treated similarly. Mensural and plumage features of this widespread species of flicker are highly variable, and their plumage patterns lend themselves to study because they are com- posed of discrete elements such as bars, spots, and patches. MATERIALS AND METHODS The study of Central American flickers was hampered by lack of specimens from various areas within this region of diverse terrain and habitats. For the sake of comparison with other populations of flickers, attention was focused primarily on late winter, spring and early summer specimens, i.e., those taken roughly during the breeding season. Seasonal variation was considered, and specimens collected at other times of the year were also included in the analysis when no seasonal variation was noted. Only adult flickers are considered here, as variation in the juvenal plumage of Colaptes auratus will be discussed elsewhere. The total number of adult specimens from which data in the report were gathered is 160. These include 90 males and 70 females from Mexico (Chiapas), Guatemala, El Salvador, Honduras, and Nicaragua. Sample sizes were insufficient to make locality by locality comparisons. Available specimens were therefore grouped into five composite samples, although this procedure is admittedly less desirable. Figure 1 depicts locali- ties represented by specimens used in this study, and also shows the segrega- tion of composite samples. These will hereafter he designated the Chiapas. Guatemala, El Salvador, Honduras, and Nicaragua sam})les. 5 6 THE WILSON BULLETIN March 1967 Vol. 79, No. 1 S c ° .t; 5 <3J c« £ '5->
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Lester L.
Short, Jr.
CENTRAL AMERICAN ELICKERS
7
The composite Nicaraguan sample was secured in the mountains of northern Nicaragua,
with specimens principally from San Rafael del Norte (total Nicaraguan sample = 8 $,
5 $ $ ) . The Honduran sample mainly represents east-central Honduras, and includes
moderate-sized samples from Subirana, Rancho Quemado, Cantoral, El Hatillo, and the
vicinity of Tegucigalpa ( total sample = 25 ^ ^ , 20 $ $ ) . The El Salvador sample comes
principally from Los Esesmiles, Department of Chalatenango (total sample — 1$ 5,6$ $ ) .
This composite sample, representing the small highland area of El Salvador, includes the
only flickers available from central Honduras to east-central Guatemala; it is effectively a
“West Honduran” sample.
The Guatemalan composite sample ( 33 5 5 , 33 $ $ ) is principally derived from central
and west-central Guatemala, with the following major localities: Lake Atitlan area,
Momostenango, Nebaj, and San Mateo. It also includes the eastern-most Chiapan locali-
ties Comitan, 25 miles SE Comitan, and Volcan de Tacana. The Chiapas sample (7 5 5,
6 $ $ ) comes from three areas in the central Chiapas highlands ( Ocosingo, Pueblo
Nuevo, San Cristobal de las Casas). The diversity within samples, particularly the
Guatemalan sample, somewhat restricts comparisons. The statistics presented below for
the composite samples reflect their variability, and are valid for the specimens being
analyzed.
Standard taxonomic procedures were used in the investigation. Measure-
ments taken were: wing length (chord), tail length, bill length (from nostril,
except as noted) and tarsal length. Data concerning some 30 quantitative
and qualitative characters were utilized in this study. Information derived
from study of some 5,000 specimens of flickers and their relatives (both
sexes and all age groups) provided a broad basis for considering variation
in Central American flickers.
ECOLOGY AND BEHAVIOR
Little is known of the ecology and behavior of the mexicanoides group of
flickers. The birds occur primarily in open pine forest and pine-oak wood-
land at various altitudes. Although generally found at elevations over 5,000
feet in Guatemala (Griscom, 1932; Land, 1962), they at least occasionally
descend to much lower altitudes. Dickey and van Rossem ( 1938) reported
flickers occurring in El Salvador down to 2,400 feet, and a female specimen
in the American Museum of Natural History (No. 326633 1 was taken at
2,050 feet in Honduras. These flickers are similar to other North American
flickers iCoIaptes auratus) in habits and behavior. They sufficiently resemble
the cafer subspecies group that most workers (see citations above) consider
them as part of Colaptes ^^cafer.’’’’ Dickey and van Rossem (1938:309) write
of mexicanoides as follows: “There appears to be little or no difference, in
the ecological niche occupied, between these El Salvador flickers and their
northern congeners. In call notes, habits, choice of nesting sites, and appear-
ance in life, they are scarcely, if at all, to be distinguished from Colaptes
cajer.^’’ Wetmore (1941:547) found Guatemalan mexicanoides like “typical
flickers in appearance,” hut considered their calls “quite different from the
8
THE WILSON BULLETIN
March 1967
Vol. 79, No. 1
CH I APAS
10
GUATEMALA
I I
EL SALVADOR
7
HONDURAS
I 6
NICARAGUA
6
ALL
5 1
-■4^
N “10
N • I I
N - 7
N “ 16
N = 7
N -53
165
WING LENGTH
-1 1 I
160 155 150
BILL LENGTH
-I 1 1 ^ ^ 1 I I I I I
145 140 M M 33 32 31 30 29 28 27 26 25
Fig. 2. Analysis of wing length and bill length in male Central American flickers.
The dark vertical lines indicate the means, and the horizontal lines the ranges of variation
in the samples. The white rectangle includes two standard errors around the mean, and
each black rectangle includes one standard deviation on both sides of the mean.
notes of the northern species.” Further observations of the behavior and
ecology of Central American flickers, comprising the southernmost ( and an
allopatric) population of Colaptes auratus, should be encouraged.
CHARACTER ANALYSIS
Wing Length
Variation in wing length is considerable, individual variation being pronounced to
the extent that female sample means are in several instances greater than those of males.
The geographical variation is clinal, with northwestern birds (Chiapas) having wings
averaging 9-12 millimeters longer than those of southeasternmost flickers (Nicaragua).
The dine for males (Fig. 2) has its steepest gradient between Guatemala and El Salva-
dor, while that for females is steepest from El Salvador to Honduras. The longest-
winged male is from Chiapas and the shortest-winged male from Nicaragua; the female
with the longest wings is from Guatemala and that with the shortest wings from Honduras.
Nicaraguan and Honduran birds do not overlap Chiapas specimens in wing length, but
do overlap measurements of Guatemalan birds. El Salvador flickers are intermediate
between those from Honduras and Guatemala, and their variation is sufficient to overlap
extreme samples from Nicaragua and Chiapas. Females have wings averaging but
slightly shorter than those of males.
Tail Length and Tail: Wing Ratios
There is a general dine of decreasing tail length from northwest to southeast, with
the tails of Chiapas birds averaging only 5-8 millimeters longer than those of Nicaraguan
flickers (Fig. 3). The dine is less marked than that for wing length. El Salvador birds
(both sexes) average closer to Chiapan flickers than do those from Guatemala. Despite
the small size of the Nicaraguan samples, both male and female ranges overlap those of
Lester L.
Short, Jr.
CENTRAL AMERICAN ELICKERS
9
CHIAPAS
0
_ 1
' f
GUATE MALA
I
-■rh-i
-■li-
1 0
EL SALVADOR
-i|:t
7
HONDURAS
1 0
NICARAGUA
6
ALL
43
TAIL LENGTH
_i 1 1 i_
m\m
TARSAL LENGTH
i —1 1 1 1 1 1
120 115 no 105 MM 30 29 28 27 26 25 24
Fig. 3. Analysis of tail length and tarsal length in male Central American flickers.
The dark vertical lines indicate the means, and the horizontal lines the ranges of varia-
tion about the means. The white rectangle includes two standard errors around the
mean, and each black rectangle includes one standard deviation on both sides of the mean.
the Chiapas samples. The southeastern flickers tend to have proportionally longer tails
than those from Chiapas and Guatemala, as the Honduran-Nicaraguan birds show tail
length 4.5-6% and wing length about 7% shorter than those of Chiapan flickers. Fe-
males’ tails average less than 1% shorter than those of males.
Bill Length
This feature is variable in flickers, and the Central American birds are no exception.
The more southeastern flickers have slightly shorter bills, but the average difference
in samples of both sexes is only a little over one millimeter (Fig. 2). The small Chiapan
and Nicaraguan female samples are virtually alike in bill length. Particular attention
was devoted to this character, for a chief characteristic of Dickey and van Rossem’s
(1928) race pinicolus is its shorter bill. Their measurements of the culmen from its
base (op. cit., p. 131) are:
pinicolus — 7 5 (5 (El Salvador) — 38.9-41.6 mm, mean 40.1 mm
mexicanoides — 4 $ $ (Chiapas) — 42.4-44.6 mm, mean 44.0 mm
I obtained the following measurements of the culmen (from the base):
Chiapas — 6 $ $ — 41.7-43.3 mm, mean = 42.73 mm
Guatemala — 6 $ $ — 42.8-44.4 mm, mean =: 43.35 mm
El Salvador — 5 $ $ — 38.8-41.9 mm, mean = 40.78 mm
Honduras — 7 $ $ -39.4-42.5 mm, mean = 41.31 mm
Nicaragua — 7 $ $ — 38.6-43.4 mm, mean z= 40.63 mm
El Salvador birds, from data for both kinds of measurements, do indeed appear to have
shorter bills than those from Guatemala and Chiapas. However, the sample from El
Salvador is small, and flickers from farther southeast are variable enough to overlap
considerably with northwestern birds. In fact, the Nicaraguan sample for the bill length
10
THE WILSON BULLETIN
March 1967
Vol. 79, No. 1
from nostril measurement (Fig. 2 for males; females also show this) and for culmen
length from the base of the bill, completely overlaps measurements of the Chiapan birds.
Considering the great variability of hill length in flickers, the difference between El
Salvador and Guatemalan-Chiapan flickers is minor. Individual variation dependent
upon psychological and or food availability factors results in variation in hill wear.
An example of such effects
is shown by
comparison of
two flickers for
various hill
measurements:
Specimen
a.
bill length
(from
nostril)
b.
bill length
(exposed
culmen)
c.
bill length
(culmen from
base)
c.
minus
a
$ Univ. Calif.
30.8 mm
37.7 mm
41.9 mm
11.1 mm
Los Angeles 18375
(El Salvador)
3 L^niv. Calif. Mus.
28.8 mm
37.0 mm
43.3 mm
14.5 mm
Vert. Zool. 115400
( Chiapas)
Thus, the “shorter billed” Chiapas flicker ( taken April 7 ) has a much longer bill base
and a worn bill, while the “longer-billed” El Salvador bird (taken Eebruary 19) ex-
hibits a shorter bill base and longer bill tip. Because of the effects of wear, minor bill
length differences are hence rendered unsatisfactory for defining populations of flickers.
Bills of females average 3-4% shorter than those of males.
Tarsal Length and Ratios
Considerable individual variation in tarsal length was evident, and means for the
Chiapan to Honduran samples are within a millimeter or so of each other (Eig. 3) with
great overlap. Despite a significant difference between Honduran and Nicaraguan
samples, overlap of both with other samples lessens its importance. Tarsal length thus
shows no apparent geographic variation in the northwestern four samples, but appears
to diminish between Honduras and Nicaragua. The tarsi of females average 1-2%
shorter than those of males. Due to the greater variation in bill length, and considerable
variation in tarsal length, ratios of tarsal length : bill length are highly variable. The
total range for 110 adults is 0.79-1.08, the same as the range for the single Guatemalan
sample.
Wing Shape and Length of 10th Primary
The non-migratory Central American flickers have relatively shorter, more rounded
wings than their relatives to the north, including C. a. mexicanus. In fact, their wings
are shaped very like those of the chrysocaulosus subspecies group (also non-migratory)
of the West Indies (Short, 1965Z>). The more rounded shape of the wings in mexicanoides
is caused by its generally short central primaries (P5-P81, and its fairly long outer
( P9, PIO) and inner (P1-P4) primaries. The fourth primary is almost as long as P8
in this form, not considerably shorter as in more northern races of C. auratus. The third
primary is considerably longer than P9, P2 is as long as or ( usually ) longer than P9,
and PI may be as long as P9.
The tenth primary is closely similar in length among individuals of the various samples.
El Salvador and Honduran birds have this primary the same size or longer than those
of Guatemalan and Chiapan birds, while the tenth primaries of Nicaraguan flickers are
Lester L.
Short, Jr.
CENTRAL AMERICAN ELICKERS
11
barely shorter.
Mean PlO
lengths and
sample sizes are
as follows
(measurements in
millimeters) :
Chiapas
Guatemala
El Salvador
Honduras
Nicaragua
41.80 (5)
40.56 (9)
42.60 (5)
41.33 (9)
39.14 (7)
9
-
39.11 (18)
42.60 (5)
40.38 (8)
39.60 (5)
Lack of a dine in PlO length renders this primary proportionally longer in the shorter-
winged southeastern populations.
Mean measurements of the ninth primary follow ( these measurements are taken from
the tip of the feather to the skin around the base of the feather) :
Chiapas Guatemala El Salvador Honduras Nicaragua
$ 96.60 (5) 93.83 (6) 95.60 (5) 90.63 (8) 90.14 (7)
$ - 94.07 (14) 96.3 (4) 88.63 (8) 90.40 (5)
Birds from El Salvador have longer ninth primaries, like Chiapan and Guatemalan
birds. However, the longer tenth primary in El Salvador flickers renders that sample
more like birds from Honduras than those from Nicaragua in the PlO : P9 ratio. A “t”
test of the differenee in the length of P9 between Guatemalan-Chiapan and Honduran-
Nicaraguan flickers gave “f” values indicating a highly significant difference (P = 0.001
or less) for both sexes.
Breast Spotting
As noted by Lafresnaye (1844) in describing mexicanoides, this form has more trans-
verse, bar-like spots than northern flickers. Only one of 91 adults had spots deeper
than broad. Depth and width of a “normal” central breast spot were measured in each
specimen. Averages for the five samples ranged as follows:
Range of average breast Range of average breast
spot depth spot width
$ S — 3. 7-4.3 mm 5.4— 6.1 mm
$ $ — 3.7-4.4 mm 5.4-7.5 mm
Chiapan flickers have rounder spots than those of the other samples (mean difference
between spot depth and spot width = 1.37 mm in 15 Chiapan adults, and 2.15 mm for
79 adults from southern Chiapas to Nicaragua). Females tend to have broader spots than
do males. More breast spots are visible per unit area in mexicanoides than any other
subspecies group except chrysocaulosus.
The strong tendency toward barring in this form is also indicated by the fact that the
lower abdomen was barred in all hut two of 77 adults checked for this feature. The
other two birds showed chordate bars, and none exhibited spots. As in other flickers
the females tend to he more strongly barred than males.
Breast Patch
Like the chrysoides and chrysocaulosus subspecies groups, mexicanoides has a deep
round, rather than narrow, crescentic breast patch. The depth of the patch is variable,
and the northwestern samples ( Chiapas-Guatemala) in particular show very deep breast
patches. A statistical treatment of the data is presented in Figure 4 ( males only ) . The
difference between the northwestern two and southeastern three samples is considerable,
of the order of 12-18%, compared with only a 6-7% wing length difference between the
extreme samples. Besides this geographic variation, mexicanoides exhibits a rather
considerable sexual difference in breast patch deptb.
12
THE WILSON BULLETIN
March 1967
Vol. 79, No. 1
CH I A PAS
17
GUAT EMALA
26
EL SALVADOR
7
HONDURAS
20
NICARAGUA
8
ALL
86
I I ^ I I
M M 30 25 20 15 10
Fig. 4. Analysis of breast patch depth in male Central American flickers. The
measurement is of the maximum depth of the breast patch. Vertical lines denote means,
horizontal lines indicate the ranges of variation within the samples. Each white rec-
tangle includes two standard errors around the mean, and each black rectangle includes
one standard deviation on both sides of the mean.
Malar Patch
The male malar patch in mexicanoides is variable in color, from red mixed with con-
siderable black, to red. An anterior area before the red-black portion is colored cinnamon-
rufous, and averages 11% (sample means 9-13%) of the total malar region. Utilizing
malar color scores fully described elsewhere (Short, l%5a), the specimens were as-
signed scores of “2”-“4” (briefly, “2” = 25-75% red, rest black; “3” = about 1-24%
black; and “4” =: all red). Considerable individual variation was encountered, es-
pecially in the northwestern samples. The following scores were attained by 87 males:
“2” =:: 12, “3” = 73, “4” = 2.
Females generally have cinnamon-rufous malar patches, with black or red visible on
the surface in 18 of 39 adults (46%). Shafts of the females’ malar feathers are black
at their bases. Gray color is lacking in malars of 79% (29 of 39) of the females, and
when present is found only in traces ( up to 15% of malar area in one Honduran fe-
male). Eight of the ten birds showing gray color are from the southeastern three
samples. Only one of 36 males showed gray color amid the cinnamon in the anterior
part of its malar patch, and that male is from Honduras. The southeastern flickers thus
show less black in the male malar patches and more gray traces in those of females.
Back Barring
Perhaps the most striking feature of mexicanoides is its much broader back barring.
Statistical treatment of data for back bar depth of all adults follows:
N X ± 2 SE SD Range Coeff. Var.
$ $ 88 3.65 ± 0.10 mm 0.45 mm 2.3-4.8 mm 12.33%
$ $ 68 3.65 ± 0.10 mm 0.41 mm 2.6-4.6 mm 11.23%
There is no sexual difference in mexicanoides, though females of other subspecies groups
of Colaptes auratus have broader bars than males. Back bar depth is much greater than
Lester L.
Short, Jr.
CENTRAL AMERICAN FLICKERS
13
in all other forms of C. auratus, including the chrysocaulosus group. There is no appar-
ent geographic variation in this character.
Test (1940) showed that mexicanoides has broader dark back bars than other North
American flickers, and pointed out that the light brown interspaces between the dark
back bars of mexicanoides are of the same width or narrower than the dark bars (in
contrast to the situation in other forms of Colaptes auratus, which have interspaces
always broader than the bars). He also noted that the interspaces are often two shades
of brown, being duskier near the black bars and more cinnamon-rufous away from them.
This imparts a tri-colored effect to the back color, an effect not noted in other North
American flickers. Bars on the upper wing coverts of mexicanoides are also broader
than in other North American flickers.
The number of dark bars on the back feathers is also greater in mexicanoides. The
number of complete and incomplete (bars noted as %, Vj, % complete or incomplete)
bars was counted on an upper back feather of 76 adults. No sexual difference was
evident, the male mean being 2.51 and that for the females 2.46 (means for more
northern flickers vary between 1.4 and 2.1). Sample means clustered around 2.5, and
no geographic variation was noted. The dark bar at the tip of each back feather was
not counted. These bars are small, but of sufficient depth so that some breeding birds
with worn feathers still possess them (in contrast, flickers from farther north have
narrower black tips, nearly always worn off by the breeding season).
Back Color
The backs of these flickers are rich, cinnamon brown to rufous brown, marked with
dark bars which are often (especially in southeastern populations) buff-bordered.
Chiapan birds average darker than the others, and show less variability. Guatemalan
flickers are highly variable, and exhibit the light and dark extremes of mexicanoides.
Samples from El Salvador, Honduras, and Nicaragua contain mostly lighter colored birds,
but a few Honduran individuals match the darkest Chiapan flickers. Females do not
differ from males in back color. Seasonal variation is considerable, the back color
being much darker in fall birds than in those taken during the breeding season.
Rump Markings
North American flickers generally exhibit a white rump patch. This patch is, however,
partly obscured by spots or bars in occasional individuals of the auratus, cafer, and
chrysoides subspecies groups, while the chrysocaulosus and mexicanoides groups gen-
erally have spotted and/or barred rumps. Scores were assigned as follows:
Score Condition of rump markings
0 White, no markings
1 1-6 spots or bars
2 More than 6 bars or spots, but rump largely white
3 Many markings, but one or several areas of white with no marks
4 Barred and/or spotted throughout
Central American flickers generally have rump patches scoring “2” or “3,” but scores
range from “1” to “4.” Females consistently show higher scores, as in all populations
of Colaptes auratus. Geographic variation is slight, and principally involves reduction
of markings in the southeastern populations. Nicaraguan flickers especially exhil)it less
barring or spotting in their rumps, and seven of the ten individuals scoring “1” come
from Nicaragua and Honduras. The lowest number of marks found was two, in a
Nicaraguan flicker. The average score for all Central American males was 2.63 (.V=:
14
THE WILSON BULLETIN
March 1967
Vol. 79, No. 1
87, SE = 0.03, sd=z0.84), and for all females 2.92 (.^'^ = 68, se z= 0.11, so = 0.87).
These compare with scores of 3.48-3.95 for samples of Cuban and Grand Cayman popu-
lations representing the chrysocaulosus group. Part of this difference is due to the
rather smaller markings in mexicanoides compared with chrysocaulosus, but the latter
obviously has a more heavily marked rump (only 19% of all mexicanoides score “4,”
while 84% of chrysocaulosus do so). Higher scoring individuals tend to have more
barring and less spotting on their rumps. About half the specimens of mexicanoides
examined showed markings predominantly bar-like, while the others exhibited spots only.
Upper Tail Covert Pattern
Variation in upper tail covert pattern in Colaptes auratus has been figured by Chap-
man (1891) and Short (19656). Although considerable variation exists in the cajer and
auratus subspecies groups, there is less variation in the chrysoides, chrysocaulosus, and
mexicanoides groups. The patterns exhibited have been categorized as all black, V-
striped, horseshoe-tipped, and barred ( 20 examples of these patterns are figured in
Short, 19656). The patterns grade into each other, and innumerable intermediate condi-
tions are possible. Altbough many individuals of the northern populations (auratus and
cater subspecies groups) show black, V-striped, and horseshoe-tipped patterns, these are
uncommon and barred patterns nearly universal in the other subspecies groups. Con-
sidering only the large, central upper tail coverts and their patterns in mexicanoides,
93% of the 115 individuals examined for this feature showed various barred patterns,
and fully 67% exhibited a single pattern (simple, barred pattern). Six additional
barred patterns were noted, while five different horseshoe-tipped, six V-striped, and one
all black patterns were also observed. Although enough patterns were evident to indicate
that mexicanoides has the potential for development of all major types, the number of
individuals actually showing patterns other than of the barred type was small. Only four
individuals showed no trace of the barred type of pattern. Nine birds exhibited two pat-
terns of the same or different types, either by having the central coverts bi-patterned
(feathers with one pattern basally, and another distally), or by showing asymmetry (one
covert with one pattern, the other with another pattern). No geographical variation was
noted, nor was there an indication of a sexual difference in patterns in these flickers.
Amount of Black in Tail
The extent of the black color at the tip of the tail was determined by use of three
measurements: 1) the length of the black area from the tail tip toward the tail base;
2) the length of the black area on one central rectrix from its tip toward its base; and,
3) the extent of black along the shaft of the outer rectrix (rectrix 5) from its tip toward
its base. Mean values for these in males are: 1) total extent — 39.29 mm, 2) R1 — 43.12
mm, and, 3) R5 — 9.87 mm. There is considerable individual variation, but geographic
variation is not marked. The latter is suggested by the data, and confirmed by statistical
treatment of data for black in the outer rectrix ( the measurement showing greatest
variation among the five samples). Applying an analysis of variance test to the data
from the four largest samples (all but El Salvador), an F value of 3.09 was attained,
yielding P — 0.05-0.10. The difference is not highly significant, for the chances are
one in ten to one in 20 that all four samples are drawn from the same population. Com-
parable results were obtained from data for females which showed about 2% less black
than males. Since this is nearly equivalent to the size difference between the sexes,
there appears to be no sexual difference in tbe extent of black in the tails of these
flickers.
Lester L.
Short, Jr.
CENTRAL AMERICAN FLICKERS
15
Tail Barring
Barring in the tail of mexicanoides tends to be less prominent than in more northern
populations of Colaptes auratus, and much less than in the chrysocaulosus group (Short,
19656). An exception is the inner (central) rectrix, which is as heavily barred as in
chrysocaulosus, and more strongly barred than in the other groups. Thus, rectrix one
has an average of 3-5 bars in mexicanoides (mean 4.10 for 42 males and 4.53 for 43
females from all samples), compared with 4-5 bars in chrysocaulosus and (usually)
1-2 bars in populations of the other groups. The outer rectrices, however, average 2.25
bars in 71 male mexicanoides, and 3.04 in 51 females (compared with 7-8 bars in
chrysocaulosus and 3-5 bars in the auratus and cafer groups). Females tend to be more
barred than males, both on rectrix 1 and 5. Rectrices 2-4 are unbarred, or with the
barest traces of a bar on number 2. No geographic variation was evident in this character.
Nuchal Patch
The auratus and chrysocaulosus subspecies groups possess a red nuchal patch gen-
erally lacking in the other groups. Some individuals of the mexicanoides group show a
partial nuchal patch, and Test (1940) noted the presence of a patch in three of 31
mexicanoides he examined. Individuals were scored for the nuchal patch character as
previously described (Short, 1965«). Briefly, a full nuchal patch is scored “0,” a
restricted, but unbroken one — “1,” a broken patch with several areas of red — “2,” a
trace or traces of red in one or several feathers — “3,” and the nuchal patch entirely
absent — “4.” All 64 females examined lacked red in the nuchal area, thus scoring “4.”
One-quarter of the males (20 of 80) showed some indication of red nuchal coloring, with
four individuals scoring “2” and 16 scoring “3.” The mean score for all males was 3.71
(se = 0.06). As might be expected with a feature found in only a small part of the
population, sample sizes are not adequate to demonstrate geographic variation, or the
lack of it, in the nuchal patch character for males. The number of males scoring “2”
and “3” in each sample is as follows: Chiapas — 6/17, Guatemala — 3/27, El Salvador —
2/7, Honduras — 5/21, and Nicaragua — 4/8.
Throat Color
The throat of mexicanoides is gray, about as in the cafer group, but slightly darker.
Signs of brown or tan color were observed on the throats of 25 of 112 adults taken from
late winter to early summer. This approach to the mixed tan and gray throats of most
juvenile flickers was not noted in the other subspecies groups. More females than males
showed tan or brown coloring (17 of 55 females, 8 of 57 males — a Cbi-square test shows
this difference to be significant at the P = 0.01 level), and the only two individuals
showing nearly as much brown and tan as gray were females. Tbe tendency for brown
or tan color to develop appears more pronounced in the southeastern populations. All
eight males showing such color came from the southeastern three samples, while 12 of
the 17 females do so. All four Nicaraguan females show brown or tan coloring, and two
of these are the birds with the most extensive development of these colors. Chiapan and
Guatemalan samples include no males and but five females with such tan or brown
coloring. It is likely that the mixed colors of the throats of these southernmost flickers,
and those of juvenile birds as well, reflect a past condition when both gray and tan
colors had developed, but before stabilization of one or tbe other had taken place. Fall
birds show still more brown and tan present. Seasonal variation involves wear and
fading, causing tbe throat to become grayer through tlu* fall, winter, and spring.
16
THE WILSON BULLETIN
March 1967
Vol. 79, No. 1
Color of Ear Coverts
The ear covert area includes the auricular feathers and feathers of the subocular
region (forward to the bill). This entire area is generally colored like the throat in
all forms of Colaptes auratus, and is thus gray in mexicanoides. Apparently genetic
control of the coloring of this area is relatively independent of that involved with throat
color, as indicated by studies of hybridization (Short, 1965aK Although tan color is
present in the otherwise gray ear coverts of some mexicanoides, it never approaches
comprising 50% of the ear-covert area. Unlike the case of throat color, more males than
females (17 of 80 ^ 5 , 10 of 63 $ $ ) show tan or brown color, although the difference
is not significant. Geographical variation is not evident, for Honduran and Chiapan
samples contain greater numbers of individuals with tan or brown traces, while only one
Nicaraguan (of 12), two Salvadoran (of 13), and eight Guatemalan (of 55) individuals
exhibit such traces. Southeastern samples thus contain proportionally as many birds
with brown and tan traces as do the northwestern samples.
Color of Under Wings and Tail ( — “Shaft” Color)
Shaft color in mexicanoides varies from orange to (rarely) salmon-pink. As in other
populations of C. auratus, there is no sexual difference in this character. Shaft color was
scored as in studies of hybridization in flickers (Short, l%5a). The scores attained
were “3,” “3.5,” and “4.” A score of “4” denotes the salmon-pink color normally found
in the cafer subspecies group. A score of “3” indicates orange shaft color, as found in
some hybrids between the auratus and cafer subspecies groups. The intermediate orange-
salmon color was scored “3.5.” The mean score for 159 adults taken from late winter
to summer was “3.26,” with two standard errors = 0.06 and one standard deviation =
0.37. Means for the two sexes considered separately were: $ $ (90) =r “3.29,” $ 9
(69) =i “3.26.”
Four birds showed yellowish in certain feathers. Three of these have very pale shaft
color overall, and one (Mus. Comp. Zool. No. 121036) has yellowish-orange in rec-
trices 3-5 on the right side, while the same feathers are orange-pink on the left side.
This yellow tendency is probably related to dietary factors and effects of fading as
discusssed elsewhere (Short, 1965a). No individual of mexicanoides exhibited a sym-
metrical pattern of bright yellow-orange shaft color in one, several or all remiges and
rectrices, as typically found in hybrids between the auratus and cafer groups. Mean shaft
color scores ranged from “3.06” for Honduras to “3.46” for Nicaragua. No clinal varia-
tion is evident, but Honduran flickers seem to be more uniformly orange-shafted than
those from elsewhere. In the other four samples, from 40 to 70% of the individuals
scored “3.5” and “4,” and, overall, 50% (51 of 102) of the birds in all four samples
exhibited such scores. However, only 7% (3 of 41) of Honduran birds scored “3.5” or
“4.” The Honduran sample is thus significantly different in this respect from the
others, including the Nicaraguan sample ( in which nine of 13 birds scored “3.5” or “4”) .
The meaning of this difference in unclear.
Crown Color
There is some variation in crown color in mexicanoides, with southeastern birds tend-
ing to have paler, more cinnamon-rufous crowns and northwestern flickers exhibiting
more rufous-chestnut coloring. There is overlap even between individuals of the ex-
treme (Nicaraguan and Chiapan) samples. Variation in color of the crown with respect
to hybridization between the cafer and auratus subspecies groups has been discussed
elsewhere (Short, 1965a). There is no evidence of gray traces in the crowns of speci-
mens of mexicanoides', all thus score “4” (typical non-gray, usually brown, crown of
Lester L.
Short, Jr.
CENTRAL AMERICAN FLICKERS
17
cafer subspecies group). However, mexicanoides has a rufous, rather than the brown,
crown of the cafer group (an approach toward mexicanoides is evident in some mexicanus
individuals, and in rufipileus of the cafer subspecies group, as well as in all races, es-
pecially tenebrosus, of the chrysoides group). Traces of red coloring were evident in
the crowns of four Honduran, one Chiapan, and one El Salvador males (traces in six of
48 males, or 13% of all males). Test (1940) reported red in the crowns of three of 17
mexicanoides males. The red, when present, appears primarily in the lores and sec-
ondarily in the feathers of the forehead. The crown feathers become lighter in color
over the course of the year, following the annual molt. There are no apparent sexual
differences in this feature.
Character Index Analysis
In order that all forms of Colaptes auratus be treated in a standard man-
ner for comparison of character (or hybrid) index values, the same scoring
system utilized in the study of hybridization between the cafer and auratus
subspecies groups (Short, 1965a) was applied to mexicanoides. The six
index characters are: crown color, throat color, ear covert color, extent of
nuchal patch, malar color (males ) and shaft color. Scores for each character
ranged from “0” for the extreme auratus group condition, to “4” for the
condition found in the cafer subspecies group ( races collaris, cafer) . Possible
character index values thus range in males (six characters) from 0 for an
individual registering the auratus condition in all characters to 24 for a bird
having a ca/er-like condition of each character. The corresponding values for
females (five characters) range from 0 to 20.
Character index values ranged from 19-23 in 87 males of mexicanoides and
from 17-20 in 63 females. The means with two standard errors are: males —
21.46 ± 0.20, and females — 18.79 ± 0.18. Of course, variation in index
values is dependent upon variation in the separate characters making up the
index. Thus, males vary considerably due to variation in nuchal, malar, and
shaft color. Females exhibit less variation in index values because they
lack one feature variable in males (malar character), and because they show
no nuchal variation. Crown color is non-variable in both sexes, as far as
hybrid index scoring is concerned (crown color varies in other ways, as
noted above). Crown color of mexicanoides is assigned a score of “4,” as
in the cafer group, because the rufous-chestnut color exhibited is closer to
the browns of that group than to the grays of the auratus group. Sample
means varied from 21.22 to 21.81 for males, and from 18.25 to 18.94 for
females. In terms of those characters important in describing effects of
hybridization between the cafer and auratus groups, mexicanoides indexes
near the former.
DISCUSSION
The variation encountered within the mexicanoides group of populations,
as indicated by available specimens, is largely clinal. For most characters
18
THE WILSON BULLETIN
March 1967
Vol. 79. No. 1
major clinal "steps'* are not evident. The El Salvador sample, representing
the area intermediate between the extreme Chiapan and Nicaraguan popula-
tions. is variously intermediate between them in most features. In some
characters, such as tail length. PlO : P9 ratio and breast spotting, the El
Salvador sample is closest to the adjacent Guatemalan birds, while in others
( e.g.. depth of breast patch and bill length i it is closer to those from Hon-
duras. Nicaraguan flickers are not represented by an adequate sample, but
certainly appear to differ in average features from birds farther to the north.
If no flickers occurred in the intervening area between Chiapas and
Nicaragua, the differences between birds in these extreme regions would
merit separate subspecific treatment for them. However, these extreme popu-
lations are connected by intermediate populations. Furthermore, for most
features, variants in the Guatemalan, and even the Chiapan samples, overlap
with one or more birds in the small Nicaraguan sample.* This fact, plus the
clinal nature of variation for many characters, and the considerable variation
encompassed within each of the larger samples (Honduras, Guatemala I .
militate against subspecific recognition of the Nicaraguan population.
Dickev and van Rossem (1928) described the race pinicoliis from El
Salvador. Those authors were unable to appreciate the variation and dines
in mexicanoides, for they saw no Nicaraguan and Honduran specimens ( op.
cit.. p. 131). As noted above, the El Salvador population is variously inter-
mediate between those of Honduras and Guatemala l and hence between
Nicaraguan and Chiapan populations), and this intermediate population does
not merit a trinomial name. Stone (1932:316) was unable to distinguish
pinicoliis from mexicanoides and I follow Stone in considering pinicolus a
synonym of mexicanoides. The subspecies group mexicanoides is thus com-
prised of the single subspecies mexicanoides.
The diagnostic features of this subspecies group are:
1) wings more rounded than in other subspecies groups (except chrysocaulosus group)
2) breast markings generally broad, bar-like
3> breast patch deeper, less crescentic tas in chrysocaulosus and chrysoides subspecies
groups)
4) malar patch mixed red and black in males and cinnamon-rufous in females
5) back bars deeper, more numerous than in other groups of Colaptes auratus (similar
to pattern found in the South American flicker subgenus Soroplex)
6) back tends to be tricolored < buff, brown, and black), especially in the southeastern
populations
7) rump patch moderately obscured by spots and/or bars, nearly to the extent found
in the chrysocaulosus group
* Additional 11?9) Nicaraguan specimens recently examined in the British Museum
enhance this overlap.
Lester L.
Short, Jr.
CENTRAL AMERICAN ELICKERS
19
8) “shaft” color generally orange to orange-salmon, less pink than in the cafer sub-
species group
9) crown deep rufous-chestnut in color, approached but not attained by certain popu-
lations of the cafer group
Characteristics of the subspecies mexicaiwides are those of the mexicanoides
subspecies group.
The Central American flickers, although distinctive, show certain color
pattern resemblances to the cafer and chrysoides subspecies groups. These
include:
1) all have a basically “brown” crown
2) all have a gray throat
3) all have a predominantly red malar patch in males
Additionally, mexicanoides shares with the cafer group the generally reddish
color of the “shafts.” In certain respects noted above, mexicanoides resembles
the chrysoides and chrysocaulosus groups more than it does the cafer group.
In still other features it shows resemblances to the chrysocaulosus group, but
not to the cafer and chrysoides groups. Mexicanoides is least similar to the
auratus group. The significance of these resemblances and differences in
terms of the past history of flickers will be discussed elsewhere. It is appar-
ent, however, that the distinctive features of the mexicanoides group preclude
the inclusion of the subspecies mexicanoides in the subspecies group cafer,
with which it is generally associated. The subspecies of the cafer group
{cafer, collaris, nanus, mexicanus, and rufipileus) generally exhibit clinal
variation, and not even the well-differentiated race rufipileus approaches the
level of morphological distinctiveness evident in mexicanoides. The Central
American flickers show the effects of long isolation from other North Ameri-
can flickers. While mexicanoides appears not to have differentiated to the
species level, its features warrant its equal status within Colaptes auratus as
a subspecies group along with the auratus, chrysocaulosus, cafer, and
chrysoides subspecies groups.
SUMMARY
The North American flicker, Colaptes auratus, is represented in Central America by
a population exhibiting distinctive morphological features. Variation within the Central
American population, occupying the highlands of Chiapas, Guatemala, El Salvador,
Honduras, and northern Nicaragua, is mainly clinal. Clines for the various characters
appear to he concordant, from northwest to southeast; however, the number of specimens
available was inadequate to show variation, or lack of it within major areas with diverse
topography, such as Honduras. The northwestern birds (Chiapas) tend to he larger,
darker, and less barred below than those from the southeastern populations. The clinal
nature of the variation, overlap among individuals of the extreme populations, and intra-
sample variation do not permit recognition of a second subspecies in the mexicanoides
group of flickers. The race pinicohis Dickey and van Kossem is held invalid, for the
20
THE WILSON BULLETIN
March 1967
Vol. 79, No. 1
El Salvador population is intermediate between those of Chiapas and Nicaragua.
Characteristics of the mexicanoides subspecies groups of Colaptes auratus are pre-
sented. This group shows similarities with each of these subspecies groups: chryso-
caulosus, cafer, and chrysoides. It differs in a number of important ways from the
cafer group, and merits equal status with the four other subspecies groups iauratus,
cafer, chrysocaidosus, and chrysoides) of C. auratus.
ACKNOWLEDGMENT
The opportunity to continue my investigations of flickers, including the present one,
was provided by a fellowship award from the Chapman Memorial Fund Committee of
the American Museum of Natural History, where much of the work was done. Drs.
Dean Amadon and Wesley E. Lanyon and the staff of the museum were most helpful.
Dr. Charles G. Sibley provided assistance and encouragement during early phases of
my flicker investigations. The Karl P. Schmidt Committee of the Chicago Natural
History Museum in 1961 gave me a travel grant, and the Louis Agassiz Fuertes Research
Grant Committee of the Wilson Ornithological Society in 1956 provided me with a
Fuertes award, for both of which I am grateful. Dr. Kenneth C. Parkes was especially
helpful with suggestions benefiting the manuscript.
I wish to thank the following individuals and institutions for the loan of specimens
essential to this investigation, and for assistance rendered during visits to certain of the
institutions: American Museum of Natural History (Dr. Dean Amadon), Dickey Col-
lection of the University of California at Los Angeles (Dr. Thomas R. Howell), Museum
of Vertebrate Zoology of the University of California at Berkeley (Dr. Alden H. Miller),
Carnegie Museum (Dr. Kenneth C. Parkes), Chicago Natural History Museum (Mr.
Emmet R. Blake) Florida State Museum of the University of Florida (Dr. Oliver L.
Austin, Jr.), Moore Laboratory of Zoology of Occidental College (Dr. J. W. Hardy),
Museum of Comparative Zoology of Harvard University (Dr. Raymond A. Paynter, Jr.),
Philadelphia Academy of Sciences (Mr. James Bond), and the U.S. National Museum
(Mr. Herbert G. Deignan).
LITERATURE CITED
Blake, E. R.
1953 Birds of Mexico. Univ. of Chicago Press, Chicago, 111.
Chapman, F. M.
1891 On the color-pattern of the upper tail-coverts in Colaptes auratus. Bull. Amer.
Mus. Nat. Hist., 3:311-314.
Dickey, D. R., and A. J. van Rossem
1928 Further descriptions of new birds from El Salvador. Proc. Biol. Soc. Wash-
ington, 41:129-131.
1938 The Birds of El Salvador. Field Mus. Nat. Hist., Zool. Ser., 23, No. 406.
Eisenmann, E.
1955 The species of Middle American birds. Trans. Linnaean. Soc. New York,
7:1-128.
Griscom, L.
1932 The Distribution of the Bird-life in Guatemala. Bull. Amer. Mus. Nat. Hist.,
64:1-439.
Lafresnaye, F. de
1844 Oiseaux neuveaux du Mexique. Rev. Zool., 7:41-43.
Lester L.
Short, Jr.
CENTRAL AMERICAN FLICKERS
21
Land, H. C.
1962 A collection of birds from the Sierra de las Minas, Guatemala. W''ilson Bull.,
74:267-283.
Miller, A. H., H. Friedmann, L. Griscom, and R. T. Moore
1957 Distributional Check-list of the Birds of Mexico. Part II. Pacific Coast Avi-
fauna, 33.
Peters, J. L.
1948 Check-list of Birds of the World. Vol. 6. Harvard Univ. Press, Cambridge,
Mass.
Short, L. L., Jr.
1965<7 Hybridization in the flickers (Colaptes) of North America. Bull. Amer. Mus.
Nat. Hist., 129:307-428.
19656 Variation in West Indian flickers (Aves, Colaptes). Bull. Florida State Mus.,
10:1-42.
Stone, W.
1932 The birds of Honduras with special reference to a collection made in 1930
by John T. Emlen, Jr., and C. Brooke Worth. Proc. Acad. Nat. Sci. Phila-
delphia, 34:291-342.
Test, F. H.
1940 Analysis of plumage coloration in the flickers, avian genus Colaptes. Ph.D.
thesis (unpubl.), Univ. California, Berkeley.
Wetmore, a.
1941 Notes on the birds of the Guatemalan highlands. Proc. U.S. Natl. Mus.,
89:523-581.
AMERICAN MUSEUM OF NATURAL HISTORY, NEW YORK, NEW YORK {FORMERLY,
BUREAU OF SPORT FISHERIES AND WILDLIFE, WASHINGTON, D.C. ) , 3 AUGUST
1965
THE DOUBLE-SCRATCH AS A TAXONOMIC CHARACTER
IN THE HOLARCTIC EMBERIZINAE
C. J. 0. Harrison
The Holarctic buntings of the sub-family Emberizinae are a relatively
uniform group of species, mainly birds of scrub or open plains, with a
bill adapted for seed-eating, mostly with a streaked brown plumage and bright
specific colouring which is often confined to the head and breast. Morpho-
logically they show little differentiation and it is therefore of interest that
they appear to be divisible into two groups by a behavioural character, the
presence or absence of which does not appear to be determined by, or cor-
related with, their immediate needs or surroundings. This is the use of the
double-scratch in feeding, shown by many of the North and Central American
species.
The double-scratch is a rapid backward kick performed simultaneously
with both feet which are scraped along the surface of the ground, scratching
back the superficial layer and exposing what is beneath. If the movement is
watched closely in a relatively long-legged species it will be seen that at the
commencement the bird is standing with bill pointing down, apparently
looking for food on the ground immediately below the head. Without moving
from the spot it then gives a small hop in which both feet are brought for-
ward, apparently almost to the spot that it was previously looking at. This
movement also tilts the body axis upwards so that the head is raised a little.
Immediately after the first hop brings the feet forward a second hop occurs
in which the feet are hardly raised hut are brought smartly back to their
former position, the claws scratching the surface and throwing back some of
the superficial material. This restores the body axis to its original position
so that at the end of the movement the bill is pointing down at the place
where the scratching occurred. This will presumably enable the bird to
observe immediately anything which has been exposed.
If no edible items are exposed the movement may be repeated in a rapid
series, the bird remaining in the one place. If the substrate is not too hard
or compressed the bird may rapidly excavate a sizable hollow. This be-
haviour is of obvious advantage to a species feeding in the fallen litter under
trees or shrubs or on bare ground, particularly in the winter months when
relatively little plant or animal food may be visible at the surface.
Among the Emberizinae this scratching movement appears to be confined
to American species. It was observed in the Song Sparrow {Melospiza
rnelodia), Swamp Sparrow (M. georgiana) , Tree Sparrow {Spizella arhorea) ,
Fox Sparrow {Passerella iliaca) ^ Rufous-naped Sparrow {Zonotrichia capen-
sis) ^ juncos (Junco spp.), and towhees (Pipilo spp.). Records of scratching
22
C J. o TAXONOMIC CHARACTER IN HOLARCTIC EMBERIZINAE 23
Harrison
in literature are rather sparse and appear more often as casual comments in
popular accounts, but it is also recorded in the following species, Black-
throated Sparrow ( Amphispiza bilineata) , Olive Sparrow {Arremonops
rufivirgata } , and Green-tailed Towhee (Chlorura chlorura) , (Wetmore et ah,
1964) and for the White-throated Sparrow [Zonotrichia alhicollis) (Peters
and Burleigh, 1951). The scratching habits are so marked in this group of
species that Vaurie {in Thomson, 1964) refers to “large feet for scratching”
as a typical character of the Emberizinae.
This ability to scratch in feeding appears to offer an isolating character
for a group of species within the Emberizinae which roughly comprises those
species sometimes referred to as New World sparrows. In addition to the
double-scratch the general characters of the group are a streaked brown
plumage with relatively subdued specific signal characters, usually consisting
of stripes or patches of varying colour on head and breast; sexual mono-
morphism; no eclipse nonbreeding plumage; hopping locomotion; and song
usually a repetitive phrase delivered from a perch. It certainly includes the
following genera — Spizella, Melospiza, Passer ella, Zonotrichia, Amphispiza,
and Arremonops — and is expected to include Passerculus, Ammodramus,
Passerherhulus, Ammospiza, Pooecetes, Chondestes, and Aimophila. Related
but slightly divergent genera are Junco, with more uniform and sober
coloured plumage; and Pipilo and Chlorura, consisting of larger birds,
mostly with more uniform colouring, though with conspicuously coloured
markings in some species.
Of the remaining Holarctic species there are two groups. One is the
longspurs of the genera Calcarius and Rhynchophanes. These are birds of
open country or tundra. They are terrestrial and normally walk or run, but
may hop occasionally. The long hind claw is associated with terrestrialism
and a walking gait. As far as is known they do not double-scratch. They
show marked sexual dimorphism, the males being boldly patterned and
coloured on the head and breast, the females dull in colour with a brown-
streaked plumage. The male has a winter eclipse plumage like that of the
female. Song is usually delivered in flight. There are four Nearctic species,
one of which, the Lapland Longspur (Calcarius lapponicus) also occurs in
the Palearctic.
The Snow Bunting iPlectrophenax nivalis) an arctic species with a
Holarctic distribution, may be a specialised offshoot of this longspur group.
It is sexually dimorphic, the female being browner and more streaked, the
male having a striking black and white breeding plumage and an eclipse-
type nonbreeding plumage. It is terrestrial, usually running or walking,
and does not use the double-scratch. Its relative lack of heavy pigmentation
24
THE WILSON BULLETIN
March 1967
Vol. 79. No. 1
and denser plumage would appear to be the result of adaptation to arctic
conditions.
Another odd species that might belong in this group, or else shows similar
hut parallel divergence, is the Lark Bunting i Calamospiza melanocorys ) ,
which shows marked sexual dimorphism, the breeding male being black with
a white wing patch while the female is brown-streaked. The male has a non-
hreeding eclipse plumage. Like the longspurs it is a mainly terrestrial species
of open country but would appear to be much more prone to perch than these.
There appears to be no useful information on gait and double-scratching.
The other main group of species is that of the typical Old World buntings
of the genus Emberiza. These species share with the longspurs the sexual
dimorphism, with a brightly patterned head and breast in the male, and an
inconspicuous brown-streaked plumage in the female. The male has an
eclipse nonbreeding plumage. As a group they differ in being much more
arboreal, occupying a similar range of habitats to those occupied by the
New World sparrows. They do not use the double-scratch in feeding.
Witherby et al. (1938) state that the normal locomotion of these birds is a
hop, hut a subsequent series of observations (Woods, 1946; Alexander, 1946,
1947, 1948; Ellis, Rayner, and Williams, 1948; Macpherson, 1949; Wallace,
1957) showed that in at least eight of these species walking or running
occurred as well as hopping when the birds were on bare ground. The song
is a repetitive phrase delivered from a perch or rock.
There is also a monotypic genus in Asia. The Crested Bunting ( Melophus
lathami) differs from species of the genus Emberiza in that the male has a
distinct crest ( although an incipient crest is present in the Rustic Bunting
{E. rustica ) , and a black plumage with brown wings. It is much more ter-
restrial in its behaviour and the very inadequate comments in literature
appear to infer that it normally walks. It mounts to a low perch to sing. It
would appear to be a specialised offshoot of Emberiza, and in some respects
forms a parallel to the Lark Bunting of North America.
DISCUSSION
It is customary to regard the Emberizinae as a group originating within
the complex radiation of nine-primaried oscines in the New World. The
longspurs must therefore be considered as a specialised group derived from
these, while the Old World genera are usually regarded as forms arising
from an invasion of New World forms.
In view of the probable phylogeny of these groups it is difficult to under-
stand the distribution of the double-scratch as a character of behaviour in
these species. As a form of feeding behaviour it is obviously of value to a
ground-feeding species and might be expected to be of greatest use to a
R J. o TAXONOMIC CHARACTER IN HOLARCTIC EMBERIZINAE 25
Harrison
terrestrial bird. It is, however, apparently absent in the more terrestrial
species and present in more arboreal birds. In addition it is present in one
large group of species on one continent and absent from a related group
apparently occupying similar niches on another. We cannot therefore dismiss
the pattern of presence and absence of this character as evidence of adapta-
tion to environment. Since the character is common to a large group of
closely related species, the New World sparrows, which show ecological and
morphological diversity to a limited degree only, it can be suggested that
it may be inherited through a common ancestor. It is, however, absent from
the related longspurs and Old World buntings which might have been ex-
pected to have also arisen from this ancestral stock. It seems improbable
that it should be lost in derived groups which would have equal need of it,
and that its present distribution is purely accidental.
Another possible explanation would involve reversing the general view on
evolutionary spread and suggesting that the New World forms might repre-
sent an adaptive radiation from an invasion of Old World bunting stock, and
that the ability to use the double-scratch represented a new and further evo-
lutionary development lacking in an earlier group.
There is a third explanation which would fit both the present view on the
evolution of these groups and at the same time explain the distribution of
the double-scratch as a behaviour character. Double-scratch is absent from
the longspurs although these are a mainly North American group obviously
related to the New World sparrows. The major behavioural difference be-
tween these two groups, and the one which appears relevant, is that of loco-
motion. The sparrows usually hop and the longspurs usually walk or run.
There appears to be a direct correlation between hopping and the use of
double-scratch in feeding. The description of this scratching already given
shows clearly that it is directly derived from hopping. It seems possible that
this is true of the scratching methods of feeding when these occur in any of
the Passeriformes. Double-scratching occurs in the wydahs (Viduinae), in
some of the thrushes (Turdinae ), and babblers ( Timaliidae) , and probably
in other groups. In each case it is associated with species in which hopping
is the usual mode of locomotion. There is no evidence of this type of scratch-
ing in species which normally walk such as the larks ( Alaudidae), wagtails
(Motacillidae ) , starlings (Sturnidae), and crows [Corvus spp.). There is
not an absolute correlation. The Blackbird iTurdus merula) is a species
which both hops and runs. Gibbs and Hartley (1957) refer to one digging
first with one foot then the other. One may, however, assume that there is a
direct morphological adaptation enabling a bird that hops to scratch in this
fashion, and that a change from hopping to walking as the normal mode of
progress involves structural changes that result in the loss of the ability to
26
THE WILSON BULLETIN
March 1967
Vol. 79, No. 1
use the double-scratch in feeding. It can therefore be supposed that the
evolution of the longspur group in bare open country involved the develop-
ment of walking and loss of hopping as the normal mode of locomotion and
this in turn involved the loss of the double-scratch associated with hopping.
The Old World buntings are similar to the New World sparrows but they
also show very close links with the longspurs in plumage. Their dual mode
of locomotion, which might be inferred to indicate partial adaptation by an
arboreal group to terrestrialism, could also be interpreted as indicating the
relics of terrestrialism in a group which has secondarily evolved a more
arboreal mode of life. It can therefore be proposed as a hypothesis that the
Old World buntings in their evolution from the New World sparrow stock
have passed through a phase similar to that shown by the longspurs, or share
a common ancestry with them; and that during this phase they have lost
the ability to use the double-scratch in feeding and have not re-evolved it.
Such a derivation would be a reasonable conclusion since the spread of
Nearctic Emberizidae into Eurasia would be most likely to have occurred
via a northern land-bridge or short sea crossing and would have occurred
most easily if the invading stock was adapted to tundra-like conditions and
able to exist near the ice-cap. The notion of a common ancestry of longspurs
and Old World buntings could be further argued with reference to the close
similarity between the Lapland Longspur as the present Eurasian longspur,
and the buntings of the Little Bunting {E. pusilla) — Reed Bunting {E.
schoenidus) — Rustic Bunting {E. rustica) subgroup.
SUMMARY
The Holarctic buntings of the subfamily Eml)erizinae can be divided into two groups
by the presence or absence of a behavioural character, the use of the double-scratch in
feeding. The double-scratch is a rapid backward kick of both feet by which the super-
ficial layer of the substrate is scraped hack. It may be repeated in one place until a
hollow is made. Within this group this scratching movement is confined to New World
sparrows, juncos, and towhees, being known for nine genera and suspected for another
seven. These species also show certain common characters of morphology and behaviour
as do those of the other groups subsequently mentioned. There are two main groups
within the remaining species. The terrestrial Longspurs, with a Holarctic distribution,
have a walking locomotion and lack the double-scratch. The Snow Bunting may he
related to these, and the Lark Bunting shows similar characters. The other main group
is that of the Eurasian Old World buntings, and the monotypic Crested Bunting. These
birds usually hop but may walk, and do not use the double-scratch in feeding although
occupying similar niches to the New World sparrows. The Old World species are
usually regarded as derivatives of New World stock. It is suggested that the double-
scratch is associated with hopping locomotion and may be lost by birds that walk;
and that the Old World buntings have evolved via a terrestrial walking form similar
to the longspurs, and in the process have lost, and failed to re-evolve, the double-
scratch mode of feeding.
c J. o TAXONOMIC CHARACTER IN HOLARCTIC EMBERIZINAE 27
Harrison ^ •
LITERATURE CITED
Alexander, W. B.
1946 Gait of Corn Bunting. Brit. Birds, 39:53.
1947 Gait of Yellow Bunting. Brit. Birds, 40:256.
1948 The gait of buntings. Brit. Birds,
Ellis, J. C. S., G. W. Rayner, and E. M. Williams
1948 The gait of buntings. Brit. Birds, ^\:2^6-2Kl .
Gibb, J., and P. H. T. Hartley
1957 Bird foods and feeding habits as subjects for amateur research. Brit. Birds,
50:278-291.
Macpiierson, a.
1949 Gait of buntings. Brit. Birds, 42:32.
Peters, H. S., and T. D. Burleigh
1951 The birds of Newfoundland. Houghton Mifflin, Boston.
Thomson, A. L.
1964 A new dictionary of birds. Nelson, London.
Wallace, D. I. M.
1957 Little Buntings in Middlesex. Brit. Birds, 50:208-209.
Wetmore, a. et al.
1964 Song and garden birds of North America. Nat. Geogr. Soc. Washington,
WiTiiERBY, H. F. et al.
1938 The handbook of British birds. Vol. 1. Witherhy; London.
Woods, H. E.
1946 Gait of Corn Bunting. Brit. Birds, 39:348.
BRITISH MUSEUM (NATURAL HISTORY) CROMWELL ROAD, LONDON, ENGLAND,
8 OCTOBER 1965
MOVEMENTS OE EEMALE RUFEED GROUSE
DURING THE MATING SEASON'
Robert B. Brander
Knowledge of sexual relationships in the Ruffed Grouse [Bonasa umbel-
liis) is inchoate. Displays related to mating have been described ( Allen,
1934; Bump et ah, 1947), but two basic questions remain unanswered in
the literature. Is the hen attracted to the site of the cock’s drumming per-
formance, and do the cock and hen form a pair-bond that is more than
transitory?
Hens, and cocks to a lesser degree, are seldom observed because of their
cryptic behavior within dense vegetation. For this reason, reports on mating
behavior have been deductions supported either by general observation in
the field or by extrapolation of observations on captive birds.
Bent (1932, p. 146 ) did not comment on pair-bonding, but he did speculate
that the cock leaves its drumming log and seeks out the hen. Roberts ( 1932,
p. 380) apparently favored the “opinion” that the Ruffed Grouse is polygy-
nous. Leopold (1933, p. 104 ) considered the mating behavior to be similar
to that of the Ring-necked Pheasant { Pliasianus colchicus) . in which each
male has its own separate group of hens. Grange (1948, p. 192 ) did not
know whether Ruffed Grouse pair or are polygamous, but he “guessed”
that they pair for the season, while Edminster (1954, p. 231) stated that
the Ruffed Grouse is promiscuous in its breeding habits. Lack (1940) de-
veloped a classification for pair-formation in birds and placed the Ruffed
Grouse among those species in which the sexes meet solely for copulation
and in which the female goes to the solitary male at its display site.
Allen (op. cit. ), after 15 years of study of captive Ruffed Grouse, pre-
sented evidence which allows interpretation of the duration of the pair-bond.
To complete the sequence of events described by Allen — synchronization of
mating cycles, dominance, copulation — would require, it seems to me, at
least a few days. Pair-bonding would not be a transitory affair and polygyny
is indicated.
Bump et al. (op. cit.), after a long-term study of captive birds, observed
the reactions on which Allen’s conclusions were based. They did not believe
that a synchronizational period is necessary to ensure fertilization of eggs.
It seemed probable to them that the female in the wild would seek out the
male in his territory; if they were both in the proper stage, copulation would
take place; if not, the hen would retire to return later or to move on to
another drumming male. Because of a postulated evenness of the sex ratio
^ Paper No. 5842, Scientific Journal Series, Minnesota Agricultural Experiment Station, St.
Paul, Minnesota 55101.
28
Robert B.
Brander
MOVEMENTS OF FEMALE RUFFED GROUSE
29
and the dispersed nature of the mating birds, the likelihood of a hen moving
on to another male would be slight, and this, they reason, would be tan-
tamount to “enforced monogamy.”
These observations and studies have yielded valuable information but as
Lack noted many years ago (1940), studies on the mating behavior of
captive Ruffed Grouse do not necessarily apply to wild birds. However, only
recently (see Marshall and Kupa, 1963) was the technique of radio-telemetry
adapted for use on Ruffed Grouse and thereby made possible the study of
that bird’s behavior under field conditions. I have used the telemetric method
to obtain data on the basic question of pair-bonding in Ruffed Grouse.
These are, I believe, the first field data on this behavior.
This study was done during the spring of 1963 at the Gloquet Forest Research
Genter, University of Minnesota. Gullion et al. (1962) have described briefly
the soils, topography, and vegetation of the Station. In general, peat soils
supporting black spruce iPicea mariana), balsam fir (Abies balsamea), and
larch (Larix laricina) are found in the lowlands; the aspens (Populus spp.),
white birch (Betula papyrifera), white spruce (Picea glauca), and jack
and red pines (Pinus banksiana and P. resinosa) predominate on the loamy-
sand uplands.
METHODS
Because cocks seldom left their drumming-activity centers (the immediate
area around a drumming log according to Gullion et al., 1962 ) , the problem
of pair-bonding was best attacked through a study of the movements of hens.
Radio-tracking was initiated in February so that home range boundaries
were well defined before the breeding season began. I succeeded in radio-track-
ing three hens (all immatures) through their mating activities and onto their
nests. An additional hen (an adult) was tracked but I failed to find her
nest.
The birds were taken in “lily-pad” traps and leg bands were affixed as
detailed by Gullion (1965). A radio-transmitter package modified from that
of Marshall and Kupa (1963 ) as described by Brander (1965 ) was then
attached. Both the performance of the female birds in flight and their
participation in social behavior indicated that the movements to be described
are not significantly different from those of unmarked birds.
As a rule, three precise locations were determined daily for each bird.
Precision was of an order which allowed placement of a bird within a
quadrat 33 feet square (0.025 acres). Locations were taken at mid-morning,
mid-afternoon, and during the night-roost period. Transmitter signals were
also monitored several times during the day so that the general location of
a bird was under rather constant surveillance.
The locations of all drumming-activity centers were also known. At least
30
THE WILSON BULLETIN
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Vol. 79, No. 1
Calculated Dates of
Table 1
First Egg and Oestrus for Three Hens
Bird number
Date on nest
Number eggs
First egg
Oestrus
1826
23 May
9
9 May
3- 6 May
1944
19 May
6
11 May
5— 8 May
1828
24 May
8
13 May
7-10 May
two cocks within
the study
area were
associated with
drumming-activity
centers but did not engage regularly in drumming performances.
For purposes of evaluation, I used information in the literature to cal-
culate the probable dates on which certain responses by the hens might
occur. On the average, Ruffed Grouse lay two eggs each three days until
the clutch of 9 to 14 eggs is complete (Bump et al., 1947). Knowing the
number of eggs laid by a certain date, one may derive the date of first
egg. Bump et al. ( op. cit.) also determined that captive hens were in oestrus
three to seven days prior to the laying of the first egg, the shorter period
being more frequent. The onset of oestrus was abrupt and if the hen were
mated promptly, oestrus ceased almost at once, but otherwise it lasted for
three to five days. [Oestrus is a term usually reserved for the class Mammalia
(Bullough, 1961) but Allen (1934) and Bump et al. (1947) apply it to the
Ruffed Grouse and I follow their usage.]
Using this information, I calculated the date of first egg for the three hens
and the dates that each hen might have been in oestrus. The results are
presented in Table 1.
Location and movement maps for the theoretical oestrous period were
constructed. These maps and interpretations are now considered for each
bird in turn.
RESULTS
Hen No. 1826. — The movement pattern of this bird from the morning of 1 May to
the morning of 10 May is given in Figure 1. Actually, the mating season for this hen
was adumbrated by her response to drumming activity, first on 25 April then on 27 and
28 April. On each of these dates she moved a short distance in the direction of a
drumming-activity center hut returned to her established winter range, a well defined
area of 26 acres. The drumming of DRl (Fig. 1) and another male in that area were,
apparently, the stimuli involved. Nothing more than movement response was indicated.
Then, on 1 May, she made a long northerly movement toward an activity center but
returned to her winter range that same evening. She did not approach the drummer
(DR2) which, probably, elicited her movement response. On 3 May she again made a
move to the north, and this time approached the drumming log of DR2. After spending
the night in a larch stand 500 feet west of his log, she returned to her winter range.
This was followed the next day (5 May) by a shorter northerly probe and retreat.
The next move, on 6 May, was unalterably to the north. Supposedly, 6 May was the
Robert B. MOVEMENTS OF FEMALE RUFFED GROUSE 31
Fig. 1. Immature female, No. 1826. Movements and locations during oestrus, 1-11
May. The 1 May location is in the southwestern part of the figure. DR and black
rectangle indicates a drumming male. Circles, squares, and triangles represent mid-
morning, mid-afternoon, and night-roost locations respectively.
last day of oestrus (Table 1). Open symbols are employed in Figure 1 for locations
thereafter (7, 8, 9, and 10 May).
She had already visited the activity center of one drummer (DR2) and then begi n
another series of visits. On 7 May she visited the center of DR3. This northeasterly
movement with return on 8 May was especially interesting since there were no active
drummers in that area but a tree planting crew using a tractor was there. I think
that her movement to within a few feet of this operation represented a response to a
false stimulus, the tractor, which was roughly analogous to that of a response to drumming.
Bump et al. (1947, p. 263-264) report several instances where grouse, of unspecified
sex, responded to tractor and wood chopping sounds. A final overt response to
drumming activity occurred the following day (9 May) when she moved eastward
and remained overnight within the activity center of DR4. On 10 May she returned
to the habitat in which she was to nest. Indications are that the first egg was laid
on that date.
Also, indications are that oestrus began seven days prior (3 May) to the first egg
and ended the day before. Calculated oestrous dates and egg laying rates as described
in Bump et al. (op. cit.) seem reasonably valid when applied to hen number 1826.
According to Bump et al. (op. cit., p. 267) oestrus in captives ceases almost im-
32
THE WILSON BULLETIN
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Vol. 79, No. 1
Fig. 2. Immature female, No. 1828. Movements and locations during oestrus, 4-11
May. The 4 May movement is from the north (arrow). DR and black rectangle indicate
a drumming male while NDR indicates a less persistent drummer. Other symbols are
as in Fig. 1.
mediately after copulation. Assuming that wild grouse react similarly, I interpret the
mating behavior of hen No. 1826 as follows: (1) oestrus, per se, commenced on
6 May; she responded to a drumming male on that date but did not copulate; (2) she
responded to another male on 7 May and again did not copulate; (3) she responded
to a false stimulus on 8 May; (4) successful copulation occurred on 9 May after she
had responded to the third male within her range. This hen, without question, was
attracted to the activity centers of drumming cocks, and sounds produced by the cocks
were the proximate stimuli which elicited her response. The pair-bond was transitory,
probably of a duration no longer than a few hours. Because the cocks continued to
drum after the hen had left their respective activity centers and, I presume, continued
to attract hens, this mating behavior is properly termed promiscuous. Even if the as-
sumption of a single copulation were not warranted, the behavior remains promiscuous.
Hen \o. 1828. — Tlie mating season for this bird was foreshadowed on the morning
of 25 April when she moved toward the sound of drumming activity. However she
remained within her tightly defined winter range (7 acres) until 4 May. Figure 2
shows her movements from that date through the oestrous season.
She moved into a drumming activity center on 6 May and it seems certain that
oestrus commenced on that date. Her movements indicated a responsiveness to drumming
at least through 10 May. The persistent drumming of an adult cock (DR, Fig. 2)
probably signaled the hen’s departure from the winter range, but a much less per-
sistent drummer (NDR) along her path of movement may have seeured her attention
also.
Robert B.
Braiulcr
MOVEMENTS OE FEMALE RUFFED GROUSE
33
Fig. 3. Immature female, No. 1944. Movements and locations during oestrus, 4-11
May. The 4 May location is in the southwestern part of the figure. See Fig. 1 for
explanation of symbols.
I interpret her mating behavior as follows: <1) oestrus, per se, commenced on 6
May; (2) copulation probably occurred on 9 or 10 May. This hen, as with number
1826, was unquestionably attracted by the sound of a drumming cock. While the map
of her movements and locations during the oestrous period may suggest a pair-bond
of some duration, particularly with NDR, observations during that period indicated that
lengthy juxtaposition of the sexes was circumstantial. Because the cocks continued to
drum after the hen had established her nest, this behavior was promiscuous.
Hen No. 1944. — Hen number 1944 was radio-marked on 26 April. An overt response
to drumming was noted on 29 April when she moved toward an activity center which
included two males. Another precursory response was noted on 1 May. Figure 3 shows
her movements from 4 May through the oestrous period.
The long movement to the northeast and into the range of a drumming male ( DR
in Fig. 3) probably marked the first day of oestrus; which was identical with the
postulated onset date for hens 1826 and 1828 — 6 May. After spending two days within
audible range of the drummer, she returned to his activity center on 9 May and then
into her nesting habitat on 10 May. A “non-drumming"’ male (NDR, Fig. 3) might
have influenced the hen's movements, hut I was reasonably sure that this did not occur.
The mating behavior of hen No. 1944 is interpreted as follows: (1) oestrus, per
se, commenced on 6 May; (2) copulation probably occurred on 9 or 10 May.
As with the other hens. No. 1944 was attracted by the sound of drumming to the
activity center of a cock. No more than a transitory pair-bond developed and the
behavior of both cock and hen indicated promiscuous mating.
DISCUSSION
A Basic question on the behavior of Ruffed Grouse was answered when
hens were observed responding: positively to drumming; cocks. The (juestion
of the duration of the pair-bond was not answered conclusively, hut the
34
THE WILSON BULLETIN
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Vol. 79, No. 1
Table
2
Patterns of Mating
Behavior in
Females as Related
TO Time
Behavior pattern
Bird
number
Pre-oestrus
Oestrus
Adumbration
Prelude
Mating
Copulation
1826
25 April
1 May
6 May
9 May
1828
25 April
4 May
6 May
9 or 10 May
1944
9
24 April
6 May
9 or 10 May
evidence is highly suggestive that the sexes meet solely for copulation and
that the mode of sexuality is promiscuous.
Promiscuity is a generic term which does not adequately depict the intricate
pattern made manifest in the movements of the three hens. Actuallv, four
levels of response are apparent in the pattern and these I term: adumbration:
passive restlessness to drumming: prelude: overt restlessness to drumming;
mating: proximal movement; copulation: nidification. Mating and cop-
ulatory phases comprise oestrus per se.
Onset dates for each of the phases are given in Table 2. The patterns
of responsiveness for the hens are strikingly similar and suggest that stimuli,
internal and external, are also arranged in a precise pattern. There is other
evidence that this is so. Data provided by Gullion ( unpublished MS. I from
a four-year study, also at Cloquet, Minnesota, indicate that the period of
most intensive drumming activity is precisely fixed in time. In his study,
males exposed to extremely variable annual meteorological and phyto-
phenological conditions still reached a peak in their drumming activity
within 3 days of 29 April. The peak was on 26 April in 1963, which coincides
with the adumbration phase of the behavior that I describe.
An inflexible pattern of mating has adaptive significance for birds faced
with extremes in wintering conditions. The periods of net loss in energy
storage must be balanced in the animal by periods of net gain. For northern
species these periods are rather rigidly fixed. The stress of winter begins
in early November, ends in early April, and is followed in quick order by
the stresses of mating, egg-laying, incubation, and care of young. Except
for a brief respite in April, these all may be periods of net losses in energy.
A scant two to three months remain for the hen to recoup her losses. There-
fore, a prolonged mating season becomes a luxury ill-afforded to endemic
northern species, and an inflexible breeding season which results from rigid
behavioral patterns should not be unexpected in the Ruffed Grouse of north-
ern Minnesota.
Robert B.
Krander
MOVEMENTS OF FEMALE RUFFED GROUSE
35
SUMMARY
A radio-telemetric system was used to obtain data on sexual relationships in the
Ruffed Grouse. The hen was attracted to the site of the cock’s drumming performance
but no more than a transitory pair-bond developed. A promiscuous mating habit was in-
dicated.
The movements of hens suggested varying levels of response to the stimuli of mating,
and responses were precisely fixed among hens and in time. Such an inflexible pattern
of mating has adaptive significance for Ruffed Grouse which winter in the rigorous
climate of northern Minnesota.
ACKNOWLEDGMENT
This paper is a contribution from a project supported by National Science Foundation
Grant No. GB-1345. The data from the current research on Ruffed Grouse at the
Cloquet Forest Research Center and the technicjues developed therein were essential
to this project. William H. Marshall and Gordon W. Gullion provided these data and
participated in many ways during the field work. Phillip Schladweiler, James Forbes,
and David Peterson were able field assistants. Frederick Greeley and David K. Wetherhee
offered valuable criticism of the manuscript.
LITERATURE CITED
Allen, A. A.
1934 Sex rhythm in the Ruffed Grouse (Bonasa umbellus Linn.) and other birds.
Auk, 51:180-199.
Bent, A. C.
1932 Life histories of North American gallinaceous birds. U.S. Natl. Mus. Bull. 162.
Brander, R. B.
1965 Factors affecting dispersion of Ruffed Grouse during late winter and spring
on the Cloquet Forest Research Center, Minnesota. Ph.D. Thesis, Univ. of
Minnesota,
Bullougii, W. S.
1961 Vertebrate reproductive cycles. John Wiley and Sons, Inc., New York.
Bump, G., R. W, Darrow, F. C. Edminster, and W. F. Crissey
1947 The Ruffed Grouse. New York State Conserv. Dept., Albany.
Edminster, E. C.
1954 American game birds of field and forest. Chas. Scribner’s Sons, New York.
Grange, W. B.
1948 Wisconsin grouse problems. Wisconsin Conserv. Dept., Madison.
Gullion, G. W.
1965 Improvements in methods for trapping and marking Ruffed Grouse. /. W’ildl.
L/gmC, 29:109-116.
Gullion, G. W., R. T. King, and W. H. Marshall
1962 Male Ruffed Grouse and thirty years of forest management on the Chupiet
Forest Research Center, Minnesota. /. Forestry, 60:617-622.
Lack, D.
1940 Pair-formation in birds. Condor, 42:269-286,
Leopold, A.
1933 Game management. (Jias. .Scribner's .Sons, New t Ork.
36
THE WILSON BULLETIN
March 1967
Vol. 79, No. 1
Marshall, W. H., AND J. J. Klpa , for Ruffed Grouse studies. Trans.
1%3 Development of radio-telemetry techniques tor nut
North Amer. Wildl. Coni., 28:443-456.
Roberts, T. S. . ^ Minnesota Press, Minneapolis.
1936 The birds of Minnesota. \ ol. 1. Lniv.
SACHUSETTS. AMHERST, MASSACHUSETTS, -*
new life member
Dr. Donald J. Borror, of Columbus Ohio
a ne« Life Member of The Wilson
Ornithological Society. Dr. Borror holds
decrrees from Otterbein College, and The
Ohio State L'niversity, and is current y
Professor of Zoology and Entomology^ at
Ohio State. Ornithologists know Dr. Bor-
ror as one of the pioneers in the recording
of bird songs and the analysis of these
recordings bv audiospectrographic means.
He is the author of numerous papers on
bio-acoustics, and has also published sev-
eral phonograph records of bird songs.
He has also co-authored a popular text-
book in entomology, and has publishe
many papers on that subject. He is a
member of the .\OU, the Entomological
Society of America, Society of Systematic
Zoology, and the American Association for
the Advancement of Science. Dr. Borror
is married, and has one son, who following
in his father's footsteps, is a professor of
zoology.
WEIGHTS OF BIRDS FROM ALABAMA
AND NORTH CAROLINA
Paul A. Stewart and Robert W. Skinner
IN Alabama and North Carolina from 1958 to 1963 we weighed 363 birds
of 102 species and 2 hybrids. Some of the birds were collected in
pesticide-bird studies of the U.S. Fish and Wildlife Service; others were col-
lected in a program of the Alabama Department of Conservation to build up
an educational collection of bird skins; the remainder were banded and
released. In Alabama, most of the birds were collected in Montgomery County,
but some were taken at locations scattered over the State. All of the North
Carolina collections were made at the Hydrologic Experiment Station near
Asheville. Our list of birds for which weights were obtained contains 63
species and 2 hybrids not weighed by Norris and Johnston (1958. Wilson
Bull. 70:114-129) who collected in Georgia and South Carolina. It seems
desirable, therefore, to publish these additional data on bird weights from
the southeastern United States. Because of the smallness of the sample in
individual categories, no deductions are attempted.
METHODS
The birds collected in Alabama by the senior author were taken in bait traps
and were immediately either killed or weighed and released; those taken in
North Carolina were mist-netted and immediately killed. The specimens taken
by the junior author were shot. All birds killed by both authors were placed
in plastic bags and in refrigeration soon after collection. Weights were taken
when the birds were removed from refrigeration 2-60 days later. Presumably
it might have been desirable to have weighed the birds immediately after
capture. Based chiefly on studies with mammals. Banks ( 1965. /. Mammal.
46:110), however, concluded that, with specimens kept in refrigeration up to
three months, “the change in weight caused by freezing is negligible.” The
hours when the birds were captured varied but were not recorded. The smaller
birds were weighed on a Chatillon spring balance provided by the U.S. Fish
and Wildlife Service; larger birds were weighed on a double-beam balance.
In most cases individual weights were taken only to the nearest 0.5 g.
The birds collected for skins were aged by checking the degree of ossifica-
tion of the skull or by plumage characters. They were sexed by examination of
the gonads. Because it was difficult to avoid cross-contamination, the birds
collected for chemical analysis of jiesticide residues were not dissected for
aging and sexing, but. like the birds handed and released, were aged and
sexed by external characters when possible. Sex or age were not obtained
for some birds. Detailed data are presented in Table 1.
37
38
THE WILSON BULLETIN
March l')67
Vol. 79, No. 1
Table 1
Weights (Grams) of Birds with Species, Age, Sex, Date and State of Collection
Common Loon iGavia immer) — Female, adult, 28 April, Alabama: 2,891.6.
Horned Grebe iPodiceps auritiis) — Male, immature, 15 February, Alabama: 515.0. Fe-
male, immature, 17 March, Alabama: 384.0.
Gannet i Morns bassanus) — Male, immature, 17 March, Alabama: 2,948.3. Female, adult,
17 March, Alabama: 3,061.7.
Canada Goose (Bronta canadensis) — Female, adult, 21 December, Alabama: 3,855.5. Fe-
male, adult, 29 December, Alabama: 3,628.7.
Lesser Snow Goose {Chen hyperborea) — Male, adult, 16 October, Alabama: 1,814.4.
Mallard (Anas platyrhynchos) — Male, adult, 8 December, Alabama: 1,170.0; 1,345.0;
1.372.0. Female, adult, 8 December, Alabama: 1,180.0; 1,393.0.
Black Duck (Anas rubripes) — Male, adult, 6 December, Alabama: 1,200.0.
Mallard X Black Duck — Unsexed, adult, 8 December, Alabama: 1,370.0.
Pintail (Anas acuta) — Male, adult, 28 December, Alabama: 802.0.
American Widgeon (Mareca americana) — Male, adult, 1 December, Alabama: 558.0.
Male, adult, 27 December, Alabama: 789.0. Male, adult, 29 December, Alabama: 713.0.
Female, adult, 6 December, Alabama: 696.0.
Wood Duck {Aix sponsa) — Male, adult, 26 December, Alabama: 587.0.
Canvasback (Aythya valisineria) — Male, adult, 29 December, Alabama: 1,086.0.
Lesser Scaup (Aythya af finis) — Female, adult, 29 December, x\labama: 499.0.
Bufflehead ( Encephala albeola) — Female, adult, 12 December, Alabama: 389.0.
Hooded Merganser (Lophodytes cucuUatus) — Male, adult, 26 December, Alabama: 748.5.
Female, adult, 26 December, Alabama: 518.0.
Mississippi Kite (Ictinia misisippiensis) — Male, adult, 7 May, Alabama: 260.0. Female,
adult, 24 August, Alabama: 297.7.
Cooper’s Hawk ( Accipiter cooperii) — Female, adult, 30 January, Alabama: 609.5.
Red-tailed Hawk (Buteo jamaicensis) — Male, immature, 27 August, Alabama: 963.9.
Male, immature, 14 December, Alabama: 878.8. Male, immature, 27 January, Alabama:
949.9. Female, immature, 2 November, Alabama: 1,190.7. Female, immature, 19 Novem-
ber, Alabama: 1,190.7. Female, immature, 9 December, Alabama: 1,105.6. Female, im-
mature, 16 December, Alabama: 1,389.1. Female, immature, 20 January, Alabama:
1,190.7. Female, immature, 26 February, Alabama: 907.2. Female, immature, 7 March,
Alabama: 1,048.9. Female, immature, 9 March, Alabama: 1,162.3.
Red-shouldered Hawk (Bnteo lineatns) — Male, adult, 1 December, Alabama: 491.6. Male,
immature, 19 October, Alabama: 680.4. Female, immature, 23 November, Alabama:
878.8. Female, adult, 14 December, Alabama: 595.3. Female, adult, 5 January, Alabama:
567.0. Female, immature, 29 November, Alabama: 708.7. Female, adult, 16 January,
Alabama: 708.7. Female, adult, 25 April, Alabama: 680.4.
Broad-winged Hawk (Buteo platypterus) — Male, adult, 13 July, Alabama: 340.2. Unsexed,
unaged, 20 April, Alabama: 311.0.
Golden Eagle (Aquila chrysaetos)- — Female, immature, 28 January, Alabama: 4,365.8.
Marsh Hawk (Circus cyaneus) — Male, adult, 17 November, Alabama: 3%.9.
American Kestrel (Falco sparverius) — Male, adult, 29 December, Alabama: 103.0. Male,
adult, 28 January, Alabama: 107.0. Female, adult, 18 September, Alabama: 118.0. Fe-
male, adult, 29 September, Alabama: 125.0. Female, adult, 20 October, Alabama: 111.0.
Female, adult, 9 December, Alabama: 117.0. Female, adult, 8 January, Alabama: 123.0;
Stewart and
Skinner
BIRD WEIGHTS
39
Table 1 {Continued)
Weights (Grams) of Birds with Species, Age, Sex, Date and State of Collection
113.0. Female, adult, 12 January, Alabama: 134.0. Female, adult, 26 January, Alabama:
131.0. Female, adult, 28 January, Alabama: 124.0. Female, adult, 18 March, Alabama:
119.0.
Coot iFulica americana) — Unsexed, adult, 11 December, Alabama: 617.0.
Killdeer (Charadrius voci ferns) — Female, adult, 8 January, Alabama: 104.0; 114.5. Un-
sexed, adult, 9 January, Alabama: 104.0.
Black-bellied Plover (Squatarola squatarola) — Male, adult, 4 January, Alabama: 198.0.
Common Snipe (Capella gallinago) — Male, adult, 4 January, Alabama: 86.0.
Least Sandpiper (Erolia minutilla) — Female, adult, no date, Alabama: 20.0.
Herring Gull iLarus argentatus) — Unsexed, adult, 17 March, Alabama: 1,234.0.
Ring-billed Gull iLarus delawarensis) — Male, adult, 15 February, Alabama: 499.0. Male,
immature, 15 February, Alabama: 464.0. Female, immature, 15 February, Alabama:
432.0.
Royal Tern iThalasseus maximiis) — Female, adult, 15 February, Alabama: 492.0.
Mourning Dove iZenaidura macroura) — Male, adult, 4 January, Alabama: 120.0.
Barn Owl ( Tyto alba) — Male, adult, 8 January, Alabama: 567.0.
Screech Owl iOtus asio) — Female, adult, 7 January, Alabama: 130.0.
Great Horned Owl {Bubo virginianus) — Male, adult, 6 February, Alabama: 1,291.0. Fe-
male, adult, Alarch, Alabama: 1,590.0.
Barred Owl iStrix varia) — Female, adult, 22 January, Alabama: 708.7. Unsexed, adult, 23
January, Alabama: 785.5.
Short-eared Owl (Asio jlammeus) — Male, adult, 3 February, Alabama: 340.2, Female,
adult, 15 January, Alabama: 368.5; 452.5. Unsexed, adult, 25 November, Alabama:
368.5.
Red-beaded Woodpecker (Melanerpes erythrocephalus) — Female, adult, 30 May, Alabama:
72.0.
Yellow-bellied Sapsucker i Sphyrapicus varius) — Male, adult, 12 January, Alabama: 47.3.
Downy Woodpecker ( Dendrocopos pubescens) — Female, adult, 17 March, Alabama: 21.0.
Acadian Flycatcher (Empidonax virescens) — Unsexed, adult, 8 July, North Carolina: 13.0.
Unsexed, adult, 10 July, North Carolina: 10.0; 12.0.
Least Flycatcher (Empidonax minimus)- — Male, adult, 28 April, Alabama: 10.0.
Blue Jay ( Cyanocitta cristata) — Male, adult, 7 May, Alabama: 75.0.
Tufted Titmouse (Parus bicolor) — Unsexed, immature, 9 July, North Carolina: 19.0; 19.0.
Brown-headed Nuthatch (Sitta pusilla) — Male, adult, 4 January, Alabama: 11.0.
Long-billed Marsh Wren (Telmatodytes palustris) — Male, adult, 22 January, Alabama:
11.0.
Short-billed Marsh Wren (Cistothorus platensis) — Male, adult, 22 January, Alabama: 8.0.
Catbird ( Dumetella carolinensis) — Male, adult, 24 April, Alabama: 35.0. Female, adult,
4 June, Alabama: 33.0.
Brown Thrasher (Toxostoma rufum) — Male, adult, January, Alaliama: 81.0. Female,
adult, 27 December, Alabama: 79.0.
Robin (Turdus migratorius) — Female, adult, 11 February, Alabama: 87.0.
Wood Thrush i Hylocichla mustelina) — Male, adult, 8 July, North Carolina: 44.0. Male,
adult, 10 July, North Carolina: 46.0. Female, adult, 8 July, North Carolina: 45.0; 48.0.
Female, adult, 9 July, North Carolina: 43.5; 45.0; 47.6.
40
THE WILSON BULLETIN
March 1967
Vol. 79, No. 1
Table 1 {Continued)
Weights (Grams) of Birds with Species, Age, Sex, Date and State of Collection
Hermit Thrush i Hylocichla guttata) — Female, adult, January, Alabama: 32.0. Female,
unaged, 11 February, North Carolina: 32.0.
Veery [Hylocichla fuscescens) — Male, adult, 9 July, North Carolina: 31.0. Male, adult, 10
July, North Carolina: 26.5; 29.5.
Colden-crowned Kinglet [Regulus satrapa) — Male, adult, 4 January, Alabama: 5.0.
Ruby-crowned Kinglet (Regulus calendula) — Male, adult, 8 April, Alabama: 8.0.
Water Pipit ( Anthus spinoletta) — Male, adult, 4 January, Alabama: 24.5; 24.5; 25.0.
Male, adult, 8 April, Alabama: 34.0; 37.0.
Cedar Waxwing (Bombycilla cedrorum) — Male, adult, 8 April, Alabama: 34.0; 37.0. Fe-
male, adult, 8 April, Alabama: 35.0. Unsexed, adult, 1 February, Alabama: 35.0.
Loggerhead Shrike (Lanius ludovicianus) — Male, adult, 3 February, Alabama: 38.0. Male,
adult, 10 March, Alabama: 49.0.
Starling (Sturnus vulgaris) — Unsexed, unaged, 7 January, Alabama: 71.0; 71.5; 73.0;
73.0; 73.0; 73.5; 75.0; 75.5; 76.5; 77.0; 77.0; 77.0; 77.5; 78.0; 79.0; 79.0; 79.5; 79.5;
80.0; 80.0; 80.0; 80.5; 81.0; 81.0; 81.0; 82.0; 82.0; 82.0; 82.5; 83.0; 83.0; 84.5; 84.5;
85.0; 88.5.
Solitary Vireo ( Vireo solitarius) — Female, immature, 9 July, North Carolina: 16.0.
Red-eyed Vireo {Vireo olivaceus) — Male, adult, 9 July, North Carolina: 15.0; 17.0. Fe-
male, adult, 10 July, North Carolina: 13.0; 14.0.
Black and White Warbler ( Mniotilta varia) — Unsexed, immature, 8 July, North Carolina:
8.0; 8.0; 9.0; 9.0; 10.0; 10.5; 11.0; 11.5.
Worm-eating Warbler (Helmitheros vermivorus) — Unsexed, immature, 10 July, North
Carolina: 12.0; 12.5; 12.5.
Blue-winged Warbler ( V ermivora pinus) — Male, adult, 27 April, Alabama: 9.0.
Brewster’s Warbler {V ermivora chrysoptera X V ermivora pinus) — Male, adult, 26 April,
Alabama: 9.0.
Orange-crowned Warbler iV ermivora celata) — Female, adult, 11 February, Alabama: 9.0.
Nashville Warbler ( V ermivora rujicapilla) — Male, adult, 26 April, Alabama: 8.0.
Black-throated Blue Warbler (Dendroica caerulescens) — Male, adult, 8 July, North Caro-
lina: 11.0. Unsexed, immature, 10 July, North Carolina: 8.5.
Black-throated Green Warbler (Dendroica virens) — Female, adult, 21 January, Alabama:
9.0.
Chestnut-sided Warbler (Dendroica pensylvanica) — Female, adult, 26 April, Alabama:
9.5. Unsexed, immature, 8 July, North Carolina: 9.5; 10.0.
Bay-breasted Warbler (Dendroica castanea) — Male, adult, 2 May, Alabama: 12.0.
Blackpoll Warbler (Dendroica striata) — Male, adult, 6 May, Alabama: 12.0.
Pine Warbler (Dendroica pinus) — Male, adult, 4 January, Alabama: 12.0. Female, adult,
4 January, Alabama: 12.5.
Ovenbird iSeiurus aurocapillus) — Male, adult, 9 July, North Carolina: 17.5; 19.0. Fe-
male, adult, 9 July, North Carolina: 17.0; 17.5; 17.5; 18.0; 18.5. Unsexed, immature, 9
July, North Carolina: 16.0; 16.0; 16.0; 16.5.
Kentucky Warbler (Opornis jormosus) — Male, adult, 8 July, North Carolina: 13.0. Fe-
male, adult, 9 July, North Carolina: 13.0. Unsexed, immature, 9 July, North Carolina:
13.0.
Yellow-breasted Chat (Icteria virens) — Male, adult, 13 May, Alabama: 25.0.
Stewart anil
Skinner
BIRD WEIGHTS
41
Table 1 {Continued)
Weights (Grams) of Birds with Species, Age, Sex, Date and State of Collection
Hooded Warbler ( W^ihonia citrina) — Male, adult, 9 July, North Carolina: 11.0; 11.5.
Canada Warbler {Wilsonia canadensis) — Male, adult, 5 May, Alabama: 10.0. Female,
adult, 8 July, North Carolina: 10.0; 11.0.
House Sparrow (Passer domesticus) — Male, adult, 4 January, Alabama: 37.5; 37.5; 39.0;
39.0; 40.0.
Eastern Meadowlark (Sturnella inagna) — Male, adult, 27 December, Alabama: 116.0. Fe-
male, adult, 11 February, 90.0. Female, adult, 27 December, Alabama: 85.0.
Western Meadowlark (Sturnella neglecta) — Male, adult, 28 February, Alabama: 112.0.
Female, adult, 3 February, Alabama: 99.0.
Redwinged Blackbird (Agelaius phoeniceus) — Male, adult, 11 February, Alabama: 71.0.
Male, adult, 14 February, Alabama: 65.0. Male, immature, 9 January, Alabama: 62.0;
64.0; 64.0; 65.0; 65.5; 66.0; 67.0; 67.0; 68.0; 68.5; 68.5; 68.5; 68.5; 69.0; 69.0; 69.0;
70.0; 71.0; 71.0. Female, adult, 22 December, Alabama: 41.0; 45.0; 46.8; 50.0.
Orchard Oriole (Icterus spurius) — Male, immature, 29 April, Alabama: 22.0.
Baltimore Oriole (Icterus galbula) — Female, adult, 6 May, Alabama: 40.0.
Rusty Blackbird (Euphagus carolinus) — Male, adult, 17 January, Alabama: 62.6. Male,
adult, 5 February, Alabama: 66.0. Female, adult, 5 February, Alabama: 54.5.
Common Crackle (Quiscalus quisciila) — Male, adult, 17 December, Alabama: 130.0.
Male, adult, 1 January, Alabama: 135.0. Male, adult, 27 January, Alabama: 112.0. Fe-
male, adult, 12 January, Alabama: 109.0.
Brown-headed Cowbird (Molothrus ater) — Male, adult, 6 January, Alabama: 42.0; 44.0;
44.0; 45.0; 45.0; 46.0; 47.0; 48.0; 48.0; 49.0; 49.0; 49.0; 50.0; 50.0; 50.0; 50.0; 50.0;
50.0; 51.0; 51.0; 51.0; 51.0; 51.5; 52.0; 52.0; 52.4; 52.5; 53.0; 54.0; 54.0; 54.0; 55.0;
56.0; 56.0; 56.5; 58.5; 58.5; 60.0. Female, adult, 22 December, Alabama: 40.1; 41.5;
44.2; 44.8. Female, adult, 6 January Alabama: 34.0; 35.0; 35.5; 37.5; 37.5; 37.5; 37.5;
39.0; 40.0; 40.5; 41.0; 42.0; 42.5.
Scarlet Tanager (Piranga olivacea) — Male, adult, 8 July, North Carolina: 29.5. Female,
adult, 10 July, North Carolina: 27.5; 29.0. Female, immature, 10 July, North Carolina:
28.0.
Cardinal ( Richmondena cardinalis) — Female, adult, 8 July, North Carolina: 40.0. Female,
immature, 10 July, North Carolina: 35.0.
Rose-breasted Grosbeak ( Pheucticus liidovicianus) — Female, adult, 2 May, Alabama: 43.0.
Male, adult, 30 April, Alabama: 46.0.
Indigo Bunting (Passerina cyanea) — Male, adult, 8 July, North Carolina: 12.5; 15.5. Fe-
male, adult, 8 July, North Carolina: 13.0; 13.0.
Purple Finch (Carpodacus purpureus) — Male, adult, 26 January, Alabama: 24.4. Female,
adult, 26 January, Alabama: 22.5; 23.6; 25.3; 25.9; 26.1; 26.4; 26.7; 26.9; 27.0; 27.2;
27.2; 27.3.
American Goldfinch (Spinus tristis) — Male, adult, 11 February, Alabama: 14.0. Male,
adult, 17 March, Alabama: 13.0.
Rufous-sided Towhee (Pipilo erythrophthalmus ) — Male, adult, 8 July, North Carolina: 42.0.
Savannah Sparrow ( Passerculus sandwichensis) — Female, adult, 4 January, Alabama:
23.0. Female, adult, 9 January, Alabama: 17.0. Female, adult, 26 February, Alabama:
16.0.
42
THE WILSON BULLETIN
Marcli 1967
Vol. 79, No. 1
Table 1 [Continued]
Weights (Grams) of Birds with Species, Age, Sex, Date and State of Collection
Grasshopper Sparrow iAmmocIramus savannarum) — Male, adult, 10 March, Alabama:
13.0.
Sharp-tailed Sparrow [ Ammospiza caudacutu) — Female, adult, 22 January, Alabama: 14.0.
Seaside Sparrow i Ammospiza maritima) — Male, adult, 22 January, Alabama: 20.0; 22.0;
22.0. Female, adult, 22 January, Alabama: 19.0.
Vesper Sparrow (Pooecetes gramineus) — Male, adult, 26 February, Alabama: 25.0.
Slate-colored Junco (Junco hyemalis) — Male, immature, 4 January, Alabama: 17.5.
Wbite-crowned Sparrow i Zonotrichia leucophrys) — Male, adult, 28 February, Alabama:
30.0
White-throated Sparrow i Zonotrichia albicollis) — Male, adult, 8 April, Alabama: 28.0.
Female, adult, 17 March, Alabama: 25.0; 38.8; 41.5. Unsexed, adult, 12 January, Ala-
bama: 29.4.
Fox Sparrow (Passerella iliaca) — Male, adult, 12 January, Alabama: 38.8; 41.5. Male,
adult, 27 December, Alabama: 42.0.
Song Sparrow [Melospiza melodia) — Male, adult, 3 February, Alabama: 25.0.
U.S. DEPARTMENT OF AGRICULTURE, AGRICULTURAL RESEARCH SERVICE, ENTO-
MOLOGY RESEARCH DIVISION, OXFORD, NORTH CAROLINA AND ALABAMA DE-
PARTMENT OF CONSERVATION, MONTGOMERY, ALABAMA. 22 SEPTEMBER 1965.
FOODS OF THE BLACK-BELLIED TREE DUCK IN
SOUTH TEXAS'
Eric G. Bolen and Billy J. Forsyth
The abundance and economic importance of many North American water-
fowl have lead to comprehensive studies of their food habits ( see Cot-
tam, 1939, Martin and Uhler, 1951, and others ( . Similar information for
protected and less common species is often scattered and derived from in-
frequent samples, and moreoften, entirely wanting. However, food habits
data from a limited series of samples gain value when these stem from local
populations of an uncommon species. Presented here are the results of food
analyses from a restricted population of the Black-bellied Tree Duck
(Dendrocygna autumnalis) nesting in South Texas.
METHODS
Tree ducks collected for food habits studies and other analyses (Bolen,
1964 ) were taken at Lake Corpus Christ! in Live Oak and San Patricio
Counties, Texas. The data reported were obtained from 22 stomachs and
11 crops analysed in the following manner:
The contents of the entire stomach, including grit, or crop were immersed in
water to measure the total volume by displacement. The materials were next
oven dried and separated. A visual estimate of volume by per cent of each
item was made using a grid system; the relative volume in milliliters was then
calculated from the total volume. Grit and food items were next weighed and
filed in a reference collection. Data were kept on separate file cards for each
stomach and crop studied. This proved an accurate yet rapid method for
handling the materials (Forsyth, 1965).
U.S. Standard Sieves were used to separate grit materials. Each size class
was then weighed and this figure expressed as a percentage of the total sample
from all stomachs.
Both stomach and crop contents were used to compute the volumes of
each food item. However, these data are separated into the larger categories
of plant and animal foods (Table 1 ( for comparisons with other studies
where foods were analysed from stomach or crop samples alone. Differences
in the contents of these organs result from the retention of the harder animal
parts in the stomach well after the softer plant materials have passed into
the lower digestive tract; foods found in the crop are more likely retained
without a selection favoring either plant or animal items. Computation of
each food’s frequency of occurrence was based only on stomach contents.
In this study all but 1 of tbe 22 birds collected were adults in fully matured
plumage. Tbe remaining bird was a young-of-the-year capable of flight yet
^ C.ontribution No. 10.3, Rob & Bessie Welder Wildlife P’otindation, Sinton, Texas.
43
44
THE WILSO^ BULLETIN
Marcli l'J67
Vol. 79. No. 1
Table 1
Pehckmage of Plant and Animal Piems Found in the Stomachs and Crops of
Black-bellied Thee Ducks
Type Stomachs (22) Crops (11) Total
of
food
ml
%
ml
%
ml
%
Plant
56.7
86.8
134.7
94.4
191.4
92.0
Animal
8.6
13.2
8.0
5.6
16.6
8.0
Total
65.3
100.0
142.7
100.0
203.0
100.0
still in drab juvenal plumage. The food items in this bird were enough like
those of adults collected during the same month ( September ) to he included in
the tabulations.
PLANT FOODS
Plant foods made up 92 per cent of the diet. Of these, the cultivated
grain, Sorghum vulgare. constituted nearly half of the total food volume
(Table 2). Wild and cultivated strains of Bermudagrass iCynodon dactylon )
collectively ranked secondmost in volume. Seeds of cultivated Bermudagrass.
while inseparable from the wild strain, are likely less important since this
hybrid produces few inflorescences (Gould and Box, 1965). Tree ducks
ingest both sorghum and Bermudagrass in large quantities, often to the
point that the crop is distended and visible immediately after feeding.
The incidence of corn ( Zea mays ) in our samples resulted from birds
feeding in stockyards rather than feeding directly in cornfields. Corn is not
a common field crop in South Texas. However, the importance of corn as
a tree duck food no doubt increases elsewhere in the bird’s range where this
crop is widely cultivated. Bent ( 1925 ) accordingly mentions that the Black-
bellied Tree Duck has earned the name, “pato maizal,” or cornfield duck
because of the depredation it supposedly inflicts on corn crops in Mexico.
Two species of millet, Echinochloa colonum and E. crusgalli, were found.
These constituted about 6 per cent of the total food volume. Both plants are
often associated with Bermudagrass in moist pasture habitats; grazing tree
ducks alternately strip seeds from the millets and Bermudagrass where these
grasses are both available.
Smartweeds, Polygonum lapathijolium and P. longistylum, together made
up less than 1 per cent of the total food volume.
At Lake Corpus Christi, shoreline beds of water stargrass ( Heteranthera
liebmanni) are favored feeding and loafing places for Black-bellied Tree
Ducks in late summer. Two growth forms of this plant are evident. One
45
Eric G Bolen and FOODS OF THE BLACK-BELLIED TREE DUCK
Billy J. Forsyth
occupies mudflats and lake margins in dense, carpet-like stands. Its aquatic
counterpart exhibits longer stems and leaves and grows in deeper water.
These differences are likely adaptive responses to changing water levels.
Seeds of water stargrass (6 per cent of the total volume) presumably came
from the shallow-water stands since these are more apt to flower than aquatic
beds of the same plant. Moreover, Black-bellied Tree Ducks typically wade
in shallow areas rather than venture into deeper water for food. Elsewhere,
Martin and Uhler (1951) reported that water stargrass may become a noxious
weed detrimental to other, more desirable plants; they considered it of slight
importance as a waterfowl food.
All plant foods found in either crops or stomachs consisted of seeds only.
There was little or no suggestion of leaves, stems, or root systems in the
samples. However, hand-reared tree ducks readily accept the leafy parts of
common vegetables as food items.
ANIMAL FOODS
Earlier references to Black-bellied Tree Duck foods appear as observational
data only (see Phillips, 1922; Bent, 1925; Kortright, 1942; Delacour, 1954;
and Bolen et ah, 1964 ) . Only plant foods are mentioned in these reports.
However, animal foods made up at least 8 per cent of our sample. Mollusks
and insects were represented, both groups often occurred in volumes so small
as to be immeasurable.
A single gastropod species, Physa anatiua, was identified from crop
materials; 16 individual snails of this species were found in the crop of a
single bird. Only small, unidentifiable bits of shell were usually present in
stomach contents. Thus, in Table 2, the mollusk foods are lumped without
further classification. We believe, however, that these are gastropod forms,
and probably Physa.
Insects composed the balance of the animal food volume. About one-half
of the insects, by volume, could not be identified. The remainder included
the following orders and families: Hemiptera (unidentified immature forms),
Neuroptera ( larva of Myrmeleontidae ) , Coleoptera ( Cicindelidae, Carabidae,
and Tenebrionidae ) , and Diptera (larva of Stratiomyidae ) . A flour beetle,
Tribolium castanatus, was identified from a crop filled with Bermudagrass
seeds. Insects are undoubtedly taken, perhaps passively, by birds feeding
in stands of water stargrass or when grazing in pastures.
frequi:n€y of occurrenci:
Plant foods occurred in all ( 100 per cent ) of the stomachs. 1’en ( I5.5
per cent ) stomachs contained some form of animal materials.
The frequency of individual food items is shown in Table 2. Bermudagrass
46
THE WILSON BULLETIN
March 1967
Vol. 79, No. 1
Table 2
Volume and Frequency of Food Fiems for the Black-bellied Tree Duck in
South Texas. Saaifle size in farenthesis ; T = Trace
Item
Volume (ml)
Occurrence — 22
stomachs
Stomachs
(22)
Crops
(11)
Total
%
No.
%
Cynodon dactylon
13.2
48.0
61.2
29.5
10
45.5
Sorghum vii/gare
17.9
82.5
100.4
48.3
7
31.8
Echinochloa spp.
9.8
2.0
11.8
5.7
4
18.2
Polygonum spp.
0.6
-
0.6
0.2
6
27.3
Heteranthera Uebmanni
12.2
1.0
13.2
6.3
5
22.7
Zea Til ays
3.0
1.2
4.2
2.0
1
4.5
-Mollusca {Physa anatina)
2.3
8.0
10.3
5.0
8
36.4
Insecta
6.3
T
6.3
3.0
5
22.7
Total
65.3
142.7
208.0
100.0
-
-
and sorghum again showed prominence as tree duck foods in South Texas.
Other plants appeared 18 to 27 per cent of the time. Corn, for reasons al-
ready mentioned, was found in only 1 (4.5 per cent I of the 22 stomachs.
Animal foods were found as often as most of the individual plant foods.
Mollusks occurred in 36 per cent of the stomachs and insects in nearly 23
per cent.
SEASONAL FOOD TRENDS
The Black-bellied Tree Duck population near Lake Corpus Christi repre-
sents an expansion of their northern range ( Bolen, et ah, 1964 ) . Here the
birds arrive irregularly in March or April and remain in large flocks near
cattle feedlots. They loaf on the shores of nearby farm ponds, but fly to
the stockyards at dawn and dusk for food. No stomach collections were
taken during this period for this reason. Instead, birds were collected fol-
lowing their spring dispersal to the lake proper. The distribution of these
collections was as follows: 5 birds taken in May, 6 in June, 4 each in July
and August, and 3 in September. These are inadequate for steadfast con-
clusions, but they indicated with field observations, a shifting trend in foods
well geared to plant phenology (Table 3).
Bermudagrass is the staple food in May. Stockyards receive further utiliza-
tion but native grasses begin drawing flocks of tree duck to pastures near
Lake Corpus Christi. In June, as the field crops ripen, sorghum enters the
diet. By late June and early July the sorghum harvest is underway and
field wastes lead to an abundance of this tree duck food. Stubble flights
are initiated; the birds embark on a daily schedule to the grain fields that
lasts into fall. Birds collected in July showed the most varied diet because
Eric G B..ien an.i FOODS OF THE BLACK-BELLIED TREE DUCK
Billy J. Forsyth
47
Table 3
Summary of Seasonal Food Trends for the Black-bellied Tree Duck in South
Texas. Data Combined from Crop and Stomach Analyses (1963) and Field
Observations (1962-1965)
Month
Major food
Comment
March and/or
April
Stock foods
Arriving birds congregate at stockyards; foods
May
Bermudagrass
exclusively grains until birds disperse
Flocks graze in pastures stripping seed beads;
June
Sorghum
some millets taken and some continued use of
stockyards
Grain harvest begins; birds start flights to fields
July
Sorghum & variety of
native food plants
Smartweeds, etc., but mainly sorghum
August
Sorghum & water
stargrass
Stubble flights continue; pairs with young
September
Sorghum & water
broods in beds of water stargrass
stargrass
Stubble flights prominent in entire tree duck
population, including flying young-of-the-year ;
large groups loafing in water stargrass during
mid-day hours; similar pattern continues into
fall
of the addition of smartweeds and the continued use of various grasses.
Water stargrass is late in setting seed and accordingly showed a distinctive
seasonal occurrence in the tree duck diet; it was found in birds taken during
late August and September.
No seasonal trend was shown in the occurrence of animal foods; these
prevailed with equal frequency throughout the sampling period.
GRIT
Grit varied from 0.8 to 2.4 grams per stomach. The mean weight was
1.4 grams for the 22 stomachs analysed. Grit was of both opaque and
translucent materials of considerable size variation (Table 4). Well over
one-half of the grit, by weight, passed through a No. 10 U.S. Standard Sieve
(less than 2000 microns). About 5 per cent was large enough to catch
in a No. 4 sieve (4760 microns). Besides the mineral contents, 1 stomach
contained 2 pieces of worn, smooth glass and another held a single No. 6
lead shot.
SUMMARY
The foods of the IBaek-hellied Tree Duck in South Texas were, }>y volume, 92 per
cent plant materials. Of thes(*, sortrliurn and Bermudafirass predominated in both
48
THE WILSON BULLETIN
Marrli 1967
Vol. 79, No. 1
Table
Size and Weight Distribution of 30.5
22 Black-bellied Tree
4
Grams of Grit
Duck Stomachs
Materials from
U. S. standard
Mesh size
Weight
Per
sieve number
( microns )
(g)
Cent
4
4760 and larger
1.5
4.9
8
2380
4.3
14.1
10
2000
1.2
3.9
16
1190
11.8
38.7
20
840
6.4
21.0
-
less than 840
5.3
17.4
Total
30.5
100.0
volume and percentage frequency. Other food plants included smartweeds, millets,
water stargrass, and a single incidence of corn. Plant foods consisted only of seeds
and did not include vegetative structures.
Animal foods (8 per cent by volume) consisted of insects and mollusks. Each of these
occurred about as often as the major plant foods. The snail, Physa anatina, seemed
singularly important.
Tree duck food habits change with the advance of the growing season. There is an
initial period of “artificial” feeding on stockyard grains after the spring migration.
This changes to Bermudagrass in May, then to sorghum in mid-summer. Daily stubble
flights to sorghum fields continue into fall hut the late summer diet is supplemented by
water stargrass.
Grit from tree duck stomachs averaged 1.4 grams per bird and showed considerable
size variation.
ACKNOWLEDGMENTS
We are indebted to both the Rob and Bessie Welder Wildlife Foundation and the
Frank M. Chapman Memorial Fund of the American Museum of Natural History for
support of this study. Clarence Cottam, W. Caleb Glazener, Jessop B. Low, and Franklin
C. Henze made many contributions. The following authorities kindly identified or con-
firmed our identifications of the items indicated: Leland Chandler and Willard Whit-
comb (insects), Anne W. Speers (mollusks), Francis M. Uhler (seeds), and Arthur
H. Holmgren and Fred B. Jones (plant taxonomy). The Soil Conservation Service
provided the use of soil sieves for grit measurements.
LITERATURE CITED
Bent, A. C.
1925 Life histories of North American wild fowl. Part 11. JJ.S. Natl. Mas. Bull. 130.
Bolen, E. G.
1964 Weights and linear measurements of Black-bellied Tree Ducks. Texas Jour.
Sci., 16:257-260.
Bolen, E. G., B. McDaniel, and C. Cottam
1964 Natural history of the Black-bellied Tree Duck in southern Texas. South-
western Naturalist, 9:78-88.
But L?orrvtr" foods of the BLACK-BELLIED TREE DUCK 49
COTTAM, C.
1939 Food habits of North American diving ducks. Tech. Bull. 643, U.S. Dept.
Agr., Washington, D.C.
Delacour, J.
1954 The waterfowl of the world. Vol. I. Country Life, Ltd., London.
Forsyth, B. J.
1965 December food habits of the Mallard (Anas platyrhynchos) in the Grand
prairie of Arkansas. Proc. Arkansas Acad. Sci., 19:74-78.
Gould, F., and T. W. Box
1965 Grasses of the Texas Coastal Bend. Texas A&M Univ. Press, College Station,
Texas.
Kortrigiit, F. H.
1942 The ducks, geese, and swans of North America. The Stackpole Co., Har-
risburg, Pa.
Martin, A. C., and F. M. Uhler
1951 Food of game ducks in the United States and Canada. Research Report
30, U.S. Fish & Wildl. Serv., Washington, D.C.
Phillips, J. C.
1922 A natural history of the ducks. Vol. I. Houghton Mifflin Co., Boston, Mass.
ROB & BESSIE WELDER WILDLIFE FOUNDATION, SINTON, TEXAS ( PRESENT ADDRESS:
DEPARTMENT OF AGRONOMY AND RANGE MANAGEMENT, TEXAS TECHNOLOGI-
CAL COLLEGE, LUBBOCK, TEXAS (BOLEN) AND DEPARTMENT OF ZOOLOGY, UNI-
VERSITY OF ARKANSAS, FAYETTEVILLE, ARKANSAS (FORSYTH) ), 11 JANUARY
1966.
WIND DRIFT, LEADING LINES, AND DIURNAL MIGRATION
Helmut C. Mueller and Daniel D, Berger
PERSONAL discussions with a number of North American students of bird
migration indicate that there is considerable confusion and misunder-
standing of the concepts of wind drift and leading lines. Recently, Murray
(1964) published a review in which he refutes wind drift, at least insofar
as it applies to the migration of Sharp-shinned Hawks {Accipiter striatus)
in the northeastern United States. The present review is an attempt to: (1)
define and show the implications of theories of wind drift and leading lines,
in particular as to how they affect hawk migration; (2) discuss some of
the evidence for the theories; and (3) show that the theories are consistent
with the observations of hawk migration in the northeastern United States
and show that Murray’s (1964) hypothesis is inadequate. This paper is in
part an attempt to extract generalizations from the available evidence. How-
ever, generalizations are rarely valid for all species and situations; and,
further, generalizations based on little data are often shown to be unwarranted
when more evidence becomes available.
WIND DRIFT: DEFINITION
Trowbridge ( 1895, 1902 ) may have been the first to discuss explicitly
the influence of wind drift on bird migration. The theory received further
analysis and support from Baxter and Rintoul (1918). There are a great
number of recent works concerned with drift, and we slight many excellent
papers by mentioning only Rudebeck (1950) and Williamson (1955) as
examples. Lack and Williamson (1959 ) have defined drift as the “Displace-
ment of a migrant from its normal route by the wind, . . .” We do not like
this definition because of the implications of the adjective “normal.” It is
our belief that, at least for many species of migrants, drift is a normal
phenomenon. We maintain that the route taken by a bird is the result of:
(1) the “standard direction” (Thomson, 1953) of migratory flight; (2) wind
drift, which may influence some birds more than others; and (3) at least
in the case of many diurnal migrants, the topography. Data from banded
birds suggest that most birds return to the same summer area year after
year (Nice, 1937; Werth, 1947; Austin, 1949; Lohrl, 1959) and also that
many birds return to areas in which they have previously spent the winter
(Wharton, 1941; Petersen, 1953; Schwartz, 1963; Mewaldt, 1964). We
know of no data, except possibly those from some species of waterfowl ( see
e.g. Hochbaum, 1955, p. 110-111), which offer good evidence for the
hypothesis that an individual bird follows the identical migratory route year
after year. We have banded over 50,000 birds at the Cedar Grove Ornithologi-
50
Mueller and
Berger
DIURNAL MIGRATION
51
cal Station and have recaptured only three migrants in a subsequent season.
Thus it appears that the end points of the migration are fixed and that the
path pursued by a bird between these two points varies considerably from
year to year. This idea was stated explicitly by Baxter and Rintoul 11918)
and gains further support from current studies of the recoveries of banded
birds ( Mueller and Berger, in press, a,b ) . Since we believe that the route
of a migratory bird normally is determined in part by drift, we prefer to
define drift simply as the displacement of a bird due to wind.
LEADING LINES: DEFINITION AND CHARACTERISTICS
Effects of the underlying terrain on the flight of diurnal migrants have
been noted by many observers. For the moment we shall restrict our atten-
tion to effects of the terrain on the direction of flight. Land birds apparently
are reluctant to fly out over water and sea birds appear to be reluctant to
fly in over land (van Dobben, 1953; Svardson, 1953). Similarly, birds of
open country seem to be reluctant to fly out over wooded areas and forest
birds apparently are reluctant to fly out over treeless terrain ( Deelder and
Tinbergen, 1947 ; Malmberg, 1955 ) . An isolated area of suitable habitat
can attract and change the course of a diurnal migrant, acting as a “leading
point” (Malmberg, 1955).
Far more important and interesting is the phenomenon of the “leading
line.” The leading line or Leitlinie was first defined by Geyr (1929). In the
process of translation into Dutch, English, and other languages the meaning
and definition of Leitlinie was altered. Some translations, such as the “diver-
sion line” of Lack and Williamson ( 1959), have misleading connotations and
cannot be applied readily to all types of leading lines. Geyr ( 1963 ) has
authorized the following translation and definition: “Leading lines are
topographical features, usually long and narrow, with characteristics that
induce migrating birds to follow them. The birds are influenced by these
lines in choosing their direction of flight, being so to speak led by them.”
The most common type of leading line is a boundary between suitable
and unsuitable habitat. The most striking example of this is a coastline,
where the aversion that land birds have for water results in a concentration
of migrants along the coast ( Rudebeck, 1950; Mueller and Berger, 1961).
Habitat boundaries, such as the edge between a forest and an open field or
marsh, also act as leading lines (Geyr, 1963; van Dobben, 1955; Allen and
Peterson, 1936 ) .
Another type of leading line is that which provides conditions which
expedite the passage of the birds. An outstanding example of this is the
mountain ridge, which deflects the horizontal wind and provides updrafts for
soaring birds (Robbins, 1956; Ulfstrand, 1960). The abundance of food
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THE WILSON BULLETIN
March 1967
Vol. 79, No. 1
along coasts and rivers may aid the passage of migrants that feed while
migrating (von Westernhagen, 1957; Hurrel, 19551.
Lastly, there appear to be leading lines which do not border unfavorable
habitat or offer any obvious advantage to the migrant except that they ap-
proximately parallel the flight direction of the bird. Examples of this include
river valleys ( Svardson, 1953 ) and dunes and dykes ( van Dobben, 1953 1 .
Thus, there is apparently a tendency for birds to follow^ leading lines, quite
apart from the aversion of the bird to hostile habitat, or the attraction of up-
drafts, food abundance, or other conditions which might aid migration. Land
migrants coming inland from flight over bodies of water have been ob-
served to turn and fly along the coast (van Dobben, 1953; Lack, 1962; Wil-
liamson, 1962; Mueller and Berger, in preparation ) . Leading lines may help a
bird orient during migration and may help it avoid excessive wind drift
(Svardson, 1953; van Dobben, 1955; Nisbet, 1957; Williamson, 1962).
EFFECTIVENESS OF LEADING LINES
A bird is, of course, not compelled to follow a leading line; it can cross,
or turn back from, the line. The effectiveness of a leading line varies; some
of the variables involved are listed below:
( 1 ) The linearity of the leading line. Straight, well defined, and un-
interrupted lines are most effective. An irregular and dissected coast, for
example, leads few birds while a straight coastline with little variance in
habitat type is highly effective ( Rudebeck, 1950 ) .
( 2 I The length of the leading line. The longer the line, the greater the
number of birds that might encounter and follow the line.
( 3 ) The angle formed between the leading line and the direction of flight
of the bird. The greater the angle, the less the tendency for the bird to follow
the line (Deelder, 1949; Svardson, 1953).
( 4 ) The prominence of the leading line. The coast of the ocean is
obviously more effective than the shore of a narrow embayment; an abrupt,
high ridge is more effective than a low, gentle slope.
( 5 ) The bird’s motivation to migrate. The higher the migratory impulse,
the lower the attractiveness of the leading line (Rudebeck, 1950; Thomson,
1953).
(6) The geographic location in relation to the bird’s origin and destina-
tion. Birds seem to react more strongly to the coastline in Norway, where
sea crossing is undesirable, than in Holland, where sea crossing is a normal
part of migration ( Nisbet, 1957 ) .
(^7) Wind direction. Chaffinches {Fririgilla coelebs) cross the Dutch
Mueller and
Berger
DIURNAL MIGRATION
53
coast and head out over the English Channel in greater numbers in a tail-
wind than in a headwind ( Deelder, 1949 ) . The opposite is true for hawks
crossing a strait or bay ( Rudebeck, 1950; Stone, 1937).
(8) The time of day. Hawks appear to be less willing to cross water
later in the day than they are early in the morning ( Rudebeck, 1950 ) .
(9) The height of flight. The greater the altitude of flight, the less the
bird is influeneed by leading lines ( Deelder and Tinbergen, 1947 ; Rudebeck,
1950 ) .
Chaffinches react to the Dutch coastline when it is up to 5 km away and
when its surface subtends an angle of less than 50' ( Deelder and Tinbergen,
1947). Rudebeck (1950) has observed hawks flying parallel to the Swedish
coast, but some distance from it. Birds might thus follow, or parallel, a
leading line at quite some distance from the line, and an observer on the
line might be unaware of such a parallel flight.
HEIGHT OF FLIGHT
The height of flight of diurnal migrants influences not only their reaction
to leading lines but also their probability of being observed. Some of the
factors which influence height of flight are listed below:
(1) Wind direction. Birds fly higher in a tailwind and lower in a head-
wind or crosswind (Trowbridge, 1902; Deelder and Tinbergen, 1947; Rude-
beck, 1950).
(2) Wind speed. Birds fly lower in strong winds (Deelder and Tinbergen,
1947 ) .
(3) The underlying terrain. Sea birds fly higher over land than over
the sea, land birds fly higher over the sea than over land ( Svardson, 1953 ).
Forest birds fly higher over open, than over wooded, terrain (Deelder and
Tinbergen, 1947 ) . Hawks fly much higher over cities than over wooded
terrain (Trowbridge, 1902).
(4) Leading lines. Birds flying along a leading line usually fly quite
low ( Deelder and Tinbergen, 1947 ) . Hawks have been observed to descend
to lower altitudes when they encounter a coast ( Allen and Peterson, 1936 ) .
These observations suggest that the leading line might induce lower flight.
(5) Visibility. Chaffinches fly lower in fog and heavy rain (Deelder
and Tinbergen, 19 17 ) .
EVIDENCE OF DRIFT
Most of the data in support of the theory of wind drift provide indirect
evidence; it is exceedingly difficult to observe drift in progress. Before one
can evaluate a direct observation which seems to indicate drift one must be
certain of the following: (1) that the bird was actually migrating. (2) the
54
THE WILSON BULLETIN
March 1967
Vol. 79, No. 1
Standard migratory direction of the bird. 1 3 ) that the bird was not being
influenced by topography. These conditions are almost impossible to meet.
hether or not a bird is actually migrating can be determined only sub-
jectively no matter how well the migratory habits of the species observed
are known, and no matter how experienced the observer. The standard
migratory direction can only be inferred from the distribution of band
recoveries or from observations of birds in flight, both of which are influenced
by drift and topography. Attempts to determine the standard direction by
experimental means may produce misleading results l see Kramer, 1950:
Matthews. 1961 1 . Absolutely featureless terrain does not exist, and the
possibility that a bird is being influenced by topography cannot be dismissed
completely.
ith the above difficulties in mind, we submit below some observations
which might be interpreted as offering some direct evidence of drift. Over
the past several years we have collected 14 observations of hawks flying over
relatively featureless terrain, away from obvious leading lines, and during
the time of year when the species is normally migrating. Each of the hawks
moved in a relatively constant direction for a considerable distance and was
thought to be migrating. The 14 observations were of the following species
and individuals: three Marsh Hawks [Circus cyaneus), seven Red-tailed
Hawks \Buteo jamaicensis ) . four Rough-legged Hawks [Buteo lagopus). and
more than 500 Broad-winged Hawks \ Buteo platypterus) . Two of the Red-
tailed Hawks were flying south on a calm autumn day. The Broad-winged
Hawks were moving southward on an autumn day in a light northerly wind.
Of the remaining individual observations, four birds were moving downwind
in an inappropriate direction ( at least 90° from the “expected direction" of
north in spring, south in autumn I . Another three birds were moving upwind
in an inappropriate direction, and two birds were moving upwind in the
appropriate direction. Only three birds, two low flying Marsh Hawks and
one low flying Rough-legged Hawk, were observed to quarter the wind. Each
of these three birds was moving in essentially the appropriate direction. The
above observations suggest that some hawks fly up- or downwind. Maximum
drift can occur if birds fly downwind. Considerable displacement can also
occur if the birds fly into the wind. Further observations of migration away
from leading lines are needed.
Rainey ( 1960 1 analyzed photographically the flight of two European
Storks \Ciconia ciconia\ over a brief interval of time and concluded that the
birds were being drifted by the wind. However, the date and location of
observation were not given, and it is impossible to state whether or not the
birds were migrating. Lack (1960) concluded that his radar observations
offered evidence for the wind drift of migrating birds. He usually found no
Mueller and
Berger
DIURNAL MIGRATION
oo
differences in the flight directions over land and over sea of both nocturnal
and diurnal migrants.
WIND DRIFT THEORY
The lack of good, direct evidence does not prevent the elucidation of the
mechanisms of drift by theoretical means. For purposes of discussion we can
consider drift to be of three types: (1) Downwind drift. The birds simply
fly downwind. This mode of flight has been suggested by Williamson (1955)
and, somewhat differently, by Mueller and Berger (1961). (2) Free drift.
The bird flies through the air in the standard migratory direction. The
flight path, or track, relative to the earth is a resultant of the standard migra-
tory direction and the wind. Lack ( 1960 ) presents evidence from radar ob-
servations which suggests that this type of drift is common over the North
Sea. ( 3 I Compensated drift. The bird attempts to compensate partially for
drift by altering its direction of flight through the air so that its path relative
to the earth more nearly approximates the standard migratory direction. This
presumably would be very difficult without reference to landmarks. Leading
lines and a low altitude of flight would aid attempts at compensation. Flight
at high altitudes and with a paucity of suitable landmarks would make com-
pensation difficult. Lack ( 1960 ) , in writing of the diurnal migrations of
Starlings (Sturnus vulgaris), concluded with: “Evidently, however, they
can correct for drift over the land only when flying low, since radar observa
tions in 1959 suggested that drift normally was as extensive over the land
as over the sea.”
Birds utilizing updrafts in flight are extremely subject to drift. In the
presence of a horizontal wind, with its resulting shear, thermal updrafts are
tilted downwind. Birds which soar in circles, such as hawks of the genus
Biiteo, are subject to considerable drift in the relatively slow ascent in an
updraft. The direction taken in the rapid glide when the bird leaves the
updraft varies with the wind direction and the orientation of leading lines.
The mean flight direction resulting from several ascents and descents is not
easy to discern. The flight direction in one part of such a flight pattern often
is very different from the mean flight direction. More than a few students
of hawk migration have been misled by this phenomenon. A detailed discus-
sion of the action of wind drift on birds that soar in circles can be found in
Rudebeck (1950).
At higher horizontal wind velocities birds no longer soar in circles. In an
earlier paper ( Mueller and Berger, 1961 ) we suggested that, at higher wind
velocities, updrafts form into longitudinal strip-like cells of updrafts and
downdrafts, oriented up- and downwind (see also oodcock. 1912). Lnder
these conditions it is considerably easier for a bird to fly up- or downwind.
56
THE WILSON BULLETIN
March 1967
Vol. 79, No. 1
than it would be for it to fly across the wind direction, and thus presumably
the effects of wind drift would be increased.
Space prohibits the citation of all of the papers utilizing wind drift in the
analysis of migration data. The indirect evidence for the theory of wind
drift is considerable. There appears to be only one attempt at refutation of
the theory, that of Murray (1964), an analysis of which follows.
WIND DRIFT AND SHARP-SHINNED HAWK MIGRATION ALONG THE
NORTHEASTERN COAST OF THE UNITED STATES
In his review of studies of Sharp-shinned Hawk migration along the
Atlantic coast, Murray (1964) states that: “Trowbridge (1895, 1902),
Stone (1922), and Allen and Peterson (1936) hypothesized on the basis of
their observations that: (1) Sharp-shinned Hawks normally migrate inland;
(2) northwesterly winds drift (“lateral displacement” of Lack and William-
son, 1959) the hawks to the coast; and (3) once at the coast they continue
along the coast.” Our interpretation of the works of Trowbridge, Stone, and
Allen and Peterson differs from that of Murray. We find that: (1) only
Allen and Peterson mention the concept of a normal inland route, and it is
not essential to our concept of wind drift. ( 2 ) Although Stone ( 1922 ) sug-
gests the possibility of hawks flying along the coast, he apparently abandoned
this idea in a later publication (Stone, 1937). Only Trowbridge (1895,
1902 ) directly mentions hawks following the coast. We quote from Trow-
bridge ( 1902 ) : “They then turn westward and follow the Connecticut shore
until they have reached New York and New Jersey, where they gradually
separate and pass on southward.” It would seem that Trowbridge, Stone,
and Allen and Peterson were aware that hawks did not follow the coasts
exactly and invariably. Murray argued that the above hypotheses were not
supported by the data and offered “an alternative hypothesis that explains all
of the observations.”
Murray states his hypothesis in this form: “The published evidence sup-
ports the view that Sharp-shinned Hawk migration proceeds on a broad front
in a generally soutbwestward direction ( in the northeastern United States )
at an altitude that makes observation difficult, and that the observed ‘con-
centrations’ or ‘flights’ are manifestations of the diversion line phenomenon.”
There is evidence that Sharp-shinned Hawks often migrate at a considerable
height (Allen and Peterson, 1936), but the remaining components of Mur-
ray’s hypothesis are unsupported by published evidence. The “diversion line
phenomenon” is simply a variant of the leading line, in which only a portion
of the birds follow the line, the remainder crossing the line. Murray’s hy-
pothesis is apparently based on the observations of a number of Dutch
workers on the flight behavior of the Chaffinch and summarized by van
Dobben (1953).
Mueller anil
Berger
DIURNAL MIGRATION
57
The “diversion line ’ for hawks at Cape May differs from the Chaffinch-
diversion lines in Holland in the following important characteristics: (1)
It is very short; (2) Birds decrease rather than increase in numbers as one
proceeds “downstream” along the line, in fact the numbers of birds appear
to be at a maximum at the beginning of the diversion line; (3) The angle
between the presumed migratory direction and the diversion line exceeds
90°, or, in other words, the diverted birds appear to be flying in the wrong
direction along the line; (4) More birds fly out over, and across the water
barrier in a head wind and more birds are “diverted” in a tail wind. These
differences suggest that the concentration of hawks at the tip of Cape May is
due to something other than the Murray-van Dobben model of the diversion
line.
Murray postulates a broad front movement, apparently not concentrated
by wind drift. Thus, we would expect similar numbers of hawks to occur
over the entire northeastern United States. Local “concentrations” are thus
merely the result of a partial diversion of the stream of migrants passing
overhead. If we know the length of the “diversion line” we should be able
to get a partial estimate of the numbers of birds passing overhead, and, since
it is a broad-front movement, an estimate of the entire population. At Cape
May, an all-autumn count taken in 1935 largely within one mile of the
beginning of the “diversion line” yielded a total of 8,026 Sharp-shinned
Hawks (Allen and Peterson, 1936). Probably not all of the hawks passing
Cape May were counted, and, as Murray indicates, only a portion were
diverted. However, let us conservatively estimate that all of the Sharp-shinned
Hawks that passed over the one mile “front” at Cape May were counted in
the autumn of 1935. The available information on the breeding distribution
of the Sharp-shinned Hawk, and the distribution of suitable habitat, offer no
reasons to believe that these hawks are more common to the northeast of
Cape May than they are anywhere else in northern North America. The
continent is about 2,500 miles wide. We would thus expect the North Ameri-
can Sharp-shinned Hawk population to be at least 20 million birds. Peterson
(1948, p. 65 ) has estimated the total population of birds of the continent
north of Mexico to number about 12 to 20 billion. It seems unlikely that one
out of every 600 to 1,000 birds in North America is a Sharp-shinned Hawk.
Indeed, it seems unlikely that one out of every 6,000 to 10,000 birds in North
America is a Sharp-shinned Hawk. It is more reasonable to believe that the
hawk observations at Cape May are of concentrations of birds, and that on
the average, seen and unseen, more Sharp-shinned Hawks fly over Cape May
than over most other localities.
We present below our tentative analysis of the migrations of Sharp-shinned
Hawks along the northeastern coast of the United States, based on the con-
58
THE WILSON BULLETIN
March 1967
Vol. 79. No. 1
cepts of leading line and wind drift. Concentrated flights of hawks occur
only in a few localities along the Atlantic coast because the frequent embay-
ments, marshes, irregularities, urban, and industrial areas make most of the
coast a poor leading line. Both Cape May and Cape Charles are at the
southern tips of huge, gradually narrowing peninsulas. The tapering forms
of the Delaware-Maryland-Virginia peninsula and the New Jersey peninsula
tend to funnel southbound, water-shy, diurnal migrants, in spite of the ab-
sence of good leading lines along the coasts. Concentrations of Sharp-shinned
Hawks are not obvious north of Cape May and Cape Charles because ( 1 1
the frequent marshes, embayments, and tidal areas are unsuitable habitat for
the hawks and they fly relatively high, and ( 2 I the irregular borders between
land, marsh, water, etc., do not form good leading lines, and hawks arriving
at the coast are continually being dispersed inland. Allen and Peterson
( 1936 ) have shown that the hawks arrive at Cape May Point at considerable
altitude, and that the flights north along Delaware Bay are rapidly dispersed
because the hawks avoid crossing marshes and tidal creeks.
The tendency for a hawk to attempt or avoid a given water crossing is
affected by a number of factors, including the bird’s motivation to migrate,
the time of day, and, perhaps most importantly, the wind direction. Allen
and Peterson ( 1936 ) found that, at Cape May, Sharp-shinned Hawks crossed
Delaware Bay when the wind was blowing from somewhere between ENE
and SW and avoided the water crossing on NW to NE winds. Birds crossing
Delaware Bay from Cape May often flew very high, “usually from 500 feet
to the limit of vision” (Allen and Peterson, 1936). Birds avoiding the
crossing also arrived at Cape May Point at a rather high altitude, dropped
to a lower altitude, and moved north along the bay side of the cape ( Allen
and Peterson, 1936 ) . Usually, the greatest numbers of hawks were seen at
Cape May on northwesterly winds (Allen and Peterson, 1936; Stone, 1922,
1937 ) . Good flights often occurred on southerly winds but, at least in 1935,
these invariably occurred on days immediately following days of north-
westerly winds. This suggests that essentially all of the major flights (except-
ing only two, which occurred on northerly winds ) recorded by Allen and
Peterson in 1935 were correlated with northwesternly winds. We believe that
this correlation can be reasonably well explained by our version of the con-
cept of wind drift. Stone ( 1922, 1937 I also found that hawk flights at Cape
May were correlated with northwesterly winds, indicating that the data of
Allen and Peterson for 1935 were not peculiar.
Rusling ( 1937 ) found that the greatest flights of Sharp-shinned Hawks at
Cape Charles, Virginia, in the autumn of 1936 occurred on northeasterly
winds, and only small flights occurred on northwesterly winds. Murray
(196T) considered Rusling’s (1937) evidence and conclusions an excellent
Mueller and
Berger
DIURNAL MIGRATION
59
Hawk Flights
Table 1
ON THE Mid-Atlantic Coast in 1936
Date
Cape May
Cape Charles
Hoope
r Island
Rank
Hawks
Rank
Hawks
Rank
Hawks
25 Sept.
N-NE
1
300
6
363
1
800
13 Oct.
NE-ESE
2
174
9
246
9
75
29 Sept.
NE-ENE
3
150
10
177
-
Few
2 Oct.
N-NE
4
140
1
1,177
-
2
11 Sept.
Var.
5
120
-
*
-
*
19 Sept.
NW
6
no
-
=:=
-
*
26 Sept.
E-NE
7
100
5
418
3
700
10 Sept.
NE
8
100
-
*
-
5 Nov.
N
9
90
-
24
-
0
13 Sept.
N
10
90
-
*
-
*
4 Oct.
ENE
-
30
2
865
-
2
5 Oct.
ENE
-
18
3
714
-
0
3 Oct.
NE
-
80
4
612
-
30
1 Oct.
W-N
-
8
7
359
-
0
14 Oct.
E
-
16
8
322
-
14
24 Oct.
NE-N
-
70
-
160
2
800
31 Oct.
NW
-
5
-
4
4
600
21 Sept.
NW-N
-
20
-
5
300
10 Oct.
SW-W
-
0
-
0
6
200
1 Nov.
sw
-
0
-
1
7
125
9 Nov.
NE
-
3
-
9
8
100
17 Oct.
w
-
0
-
6
10
75
12 Oct.
NW
-
30
-
134
-
0
18 Oct.
NW
-
40
-
98
-
40
30 Oct.
NW
-
0
-
5
-
50
* No data available. The data in this table are from Rusling (1937).
argument against wind drift, particularly when compared with observations
from Cape May and Hooper Island, where hawks are known to occur pre-
dominately on northwesterly winds. However, in the autumn of 1936, six
of the ten largest flights of Sharp-shinned Hawks at Cape May and five of
the ten largest flights at Hooper Island occurred on days with northeasterly
winds (Table 1 ) . The fact that nine of the ten largest flights at Cape Charles
occurred on northeasterly winds is not remarkable when compared with the
above. At least the three greatest counts of Sharp-shinned Hawks for 1936
occurred on northeasterly winds in all three of the above localities (Table
1 I . It is remarkable that the highest counts of Sharp-shinned Hawks at
Hooper Island and Cape May occurred on northeasterly winds rather than,
as in previous years, on northwesterly winds. It is further interesting that
only 2,269 Sharp-shinned Hawks were seen at Cape May in 1936 ( Rusling.
60
THE WILSON BULLETIN
Maich 1967
Vol. 79, No. 1
1937), as compared with 8,206 in 1935, 5,675 in 1932, and 10,000 in 1931
(Allen and Peterson, 1936). Strong northwesterly winds and clear skies
prevailed on only three days during September and October 1936 at Cape
Charles ( Rusling, 1937 ). These conditions usually produce great numbers
of hawks at Cape May and, presumably, at Hooper Island ( Allen and Peter-
son, 1936 ) . On all of these days relatively few Sharp-shinned Hawks were
seen at Cape May, Hooper Island, and Cape Charles, but greater numbers
were seen at Cape Charles than at the other two localities on two of the three
occasions (Table 1). In all, 1936 seems to have been a very unusual autumn
for hawk migration along the mid-Atlantic coast of the United States. It
would be interesting to see the characteristics of the Sharp-shinned Hawk
migration at Cape Charles in a more usual year.
Because of the configurations of the peninsulas, we would expect concen-
trations of hawks at Cape May and Cape Charles in autumn if three con-
ditions prevail: (1) reasonable numbers of hawks exist on, or arrive on.
the New Jersey and Delaware-Maryland-Virginia peninsulas, (2) the birds
migrate in some southerly direction, and ( 3 ) the birds exhibit some reluctance
to cross bodies of water. We have previously discussed the third factor and
the second safely can be assumed to occur. The first factor, however, can
be analyzed only indirectly. The interaction of wind and leading lines in
affecting the flight paths of hawks in the areas north of the New Jersey and
Delaware-Maryland-Virginia peninsulas undoubtedly plays a major role in
determining the abundance of hawks on the peninsulas. The strong leading
lines provided by the Appalachian ridges lie but a short distance to the west
of the Atlantic coast; and, farther to the north, the Great Lakes and the Gulf
of St. Lawrence probably affect the flight paths of hawks. The frequent
embayments on the coast and gaps in the ridges of the Appalachians add
further complications. More observations of hawk migration at localities
north and west of the coastal concentration points are needed before all
questions can be answered. However, it is interesting to note that 4,611
Sharp-shinned Hawks, or 67 per cent of the total observed at Cape Charles,
were counted in the two periods between 1 and 5 October, inclusive, and
12-15 October, inclusive. Both of these periods began with, or were pre-
ceded by, at least one day of westerly winds over the entire region ( Rusling,
1937 ) . We believe that this suggests that wind drift may have been a factor
in bringing hawks to the Delaware-Maryland-Virginia peninsula, and, once
there, they continued southward to Cape Charles, producing concentrations
at the cape for several subsequent days.
In addition to the ahov^e, we would expect differences in the flights at Cape
May and Cape Charles because ( 1 ) the New Jersey peninsula has a relatively
broad base whereas the Delaware-Maryland-Virginia peninsula has a rela-
Mueller and
Berger
DIURNAL MIGRATION
61
lively narrow connection with the mainland, (2) Chesapeake Bay is longer
and generally wider than Delaware Bay, and ( 3 ) Cape Charles is about four
times as long as Cape May and is extremely narrow at several points con-
siderable distances from the tip.
In conclusion, we fail to see how Murray (1964) has produced any evi-
dence which can be used to argue that wind drift is not a factor in producing
concentrations of Sharp-shinned Hawks at selected points on the coast of the
northeastern United States. The alternative hypothesis proposed by Murray
is unsupported by, and inconsistent with, the available evidence.
SUMMARY
This paper attempts to: (1) define the concepts of wind drift and leading lines, (2)
present the characteristics of each of these phenomena, (3) elucidate the various factors
influencing wind drift and leading line behavior, and (4) document the above with a
brief review of the literature of migration. In addition, the hypothesis of Murray (1964)
is critically evaluated as an alternative to wind drift theory and rejected as being in-
consistent with available information.
ACKNOWLEDGMENTS
This paper began as the discussion section of an early draft of a research report on
Sharp-shinned Hawk migration at Cedar Grove, Wisconsin (Mueller and Berger, in
press, b). Financial support for the latter study was provided by the National Science
Foundation (Grant GB-175). We are indebted to Professor John T. Emlen for advice
and assistance in various aspects of the study.
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1936 The hawk migrations at Cape May Point, New Jersey. Auk, 53:393-404.
Austin, 0. L.
1949 Site tenacity, a behaviour trait of the Common Tern {Sterna hirundo Linn.)
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Baxter, E. V., and L. J. Rintoul
1918 The birds of the Isle of May: a migration study. Ibis, 6, ser. 10:247-287.
Deelder, C. L.
1949 On the autumn migration of the Scandinavian Chaffinch, (Fringilla c. coelebs
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Deelder, C. L., and L. Tinbergen
1947 Waarnemingen over de vlieghoogte van trekkende Vinken, Fringilla coelebs
L., en Spreeuwen, Sturnus vulgaris L. Ardea, 35:45-78.
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1953 Migration in the Netherlands. Ibis, 95:212-234.
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THE WILSON BULLETIN
March 1967
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Hochbaum, H. a
1955 Travels and traditions of waterfowl. U. Minnesota Press, Minneapolis.
Hukrel, H. G.
1955 Simultaneous migration watches for Swifts in the British Isles. Acta XI
Congr. Internatl. Ornith. Basel :640~6i2.
Kramer, G.
1950 Weitere Analyse der Faktoren, welche die Zugaktivitat des gekafigten Vogels
orientieren. Naturwiss., 37:377-388.
Lack, D.
1960 Migration across the North Sea studied by radar. Part 2. The spring de-
parture 1956-59. Ibis, 102:26-57.
1962 Radar evidenee on migratory orientation. Brit. Birds, 55:139-158.
Lack, D., and K. Williamson
1959 Bird-migration terms. 76/5,101:255-256.
Lohrl, H.
1959 Zur Frage des Zeitpunktes einer Pragung auf die Heimatregion beim
Halsbandschnapper i Ficedula alhicollis) . J. Ornith., 100:132-140.
Malmberg, T.
1955 Topographical concentration of flight lines. Acta XI Congr. Internatl. Ornith.
fee/: 161-164.
Matthews, G. V. T.
1961 ‘Nonsense’ orientation in Mallard and its relation to experiments in bird
navigation. Ibis, 103a :21 1-230.
Mewaldt, L. R.
1%4 California sparrows return from displacement to Maryland. Science, 146:
941-942.
Mueller, H. C., and D. D. Berger
1961 Weather and fall migration of hawks at Cedar Grove, Wisconsin. Wilson Bull.,
73:171-192.
in press, a. “Navigation” of hawks: evidence from spring migration observations
and band recoveries.
in press, b. Migration of Sharp-shinned Hawks: analysis of data from Cedar Grove,
Wisconsin.
in preparation. Analysis of concentrations of nocturnal migrants along a coastline.
Murray, B. G., Jr.
1964 A review of Sharp-shinned Hawk migration along the northeastern coast
of the United States. Wilson Bull., 76:257-264.
Nice, M. M.
1937 Studies in the life history of the Song Sparrow. I. Trans. Linnaean Soc.
New York, 4:1-247.
Nisbet, I. C. T.
1957 Passerine migration in South Scandinavia in the autumn of 1954. Ibis, 99:
228-268.
Petersen, E.
1953 Orienteringsforspg med Haettemage i Larus r. ridibundus L. ) og Stormmage
iLarus c. canus L. ) vinterkvarteret. Dansk Ornithol. Forenings Tidsskrijt,
47:153-178.
Peterson, R. T.
1948 Birds over America. Dodd, Mead, New ^ork.
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Berger
DIURNAL MIGRATION
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Rainey, R. C.
I960 Applications of theoretical models to the study of flight-behavior in locusts
and birds. Symposia Soc. for Expl. Biol., XIV: 122-139.
Robbins, C. S.
1956 Hawk watch. Atlantic Naturalist, 11:208-217.
Rudebeck, G.
1950 Studies on bird migration. V ar Fagelvdrld, Supplementum I.
Rusling, W. J.
1937 The study of the habits of diurnal migrants, as related to weather and
land masses during the fall migration on the Atlantic coast, with particular
reference to the hawk flights of the Cape Charles (Virginia) region. Unpub-
lished manuscript in the library of the National Audubon Society, New York.
SCIIM^ABTZ, P.
1963 Orientation experiments with Northern Waterthrushes wintering in Venezuela.
Proc. XIII Internatl. Ornith. Congr. 481-484.
Stone, W.
1922 Hawk flights at Cape May Point, N. J. Auk, 39:567-568.
1937 Bird studies at old Cape May, Vol. 1. Delaware Valley Ornith. Club, Acad.
Nat. Sci. Philadelphia.
SVABDSON, G.
1953 Visible migration within Fenno-scandia. Ibis, 95:181-211.
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1953 The study of the visible migration of birds. Ibis, 95:165-180.
Tbowbridge, C. C.
1895 Hawk flights in Connecticut. Auk, 12:259-270.
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1%0 Migration of African kites Milvus migrans ( Bodd. ) — M. aegyptius Sharpe
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Tanganyika. Kungl. Fysiografiska Sdllskapets I Lund Fdrhandlingar, 30:31-39.
Wertii, I.
1947 The tendency of Blackbird and Song Thrush to breed in their birthplaces.
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1957 Planbeobachtungen des Vogelzuges Herbst 1955. Mitt. Faun. Arbeitsgem.
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1941 Twelve years of banding at Summerville, S. C. Bird-banding, 12:137-147.
Williamson, K.
1955 Migrational drift. Acta XI Congr. Internatl. Ornith. Basel :\19-\2>6.
1962 The nature of ‘leading line’ behavior. Bird Migration 2:176-182.
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1942 Soaring over the open sea. Sci. Mon., 55:226-232.
DEPAFtTMENT OF ZOOLOGY, UNIVERSITY OF WISCONSIN, MADISON, WISCONSIN,
AND THE CEDAR GROVE ORNITHOLOGICAL STATION, ROUTE 1, CEDAR GROVE,
WISCONSIN. ( PRESENT ADDRESS: ( MUELLER ) , DEI’ARTMENT OF ZOOLOGY. UNI-
VERSITY OF NORTH CAROLINA, CHAPEL HILL, NORTH CAROLINA.), 13 JAN-
UARY 1966
THE CONTEXTS OF SONGS IN BLACK-THROATED
GREEN AND BLACKBURNIAN WARBLERS
Douglass H. Morse
SOME recent studies of the family Parulidae demonstrate that in several
species there is more than one type of male song; these song types evi-
dently result from different motivations ( Ficken and Ficken, 1962, 1965:
Morse, 1966 1 .
The purposes of this investigation were to observe a situation where two
or more closely related species are found within a homogenous, floristically
simple habitat in order to determine the motivations of their songs, the
relationship of the songs to the environment, and the degree of effect that
the congeners have upon each others’ songs. In the northeastern Lnited
States Black-throated Green Warblers [Dendroica virens) and Blackburnian
Warblers ( D. fusca I are characteristically birds of the conifers, and while
they may be found in mixed forests, it is in the coniferous forests that they
reach their highest densities. Here they sometimes form the most prominent
element of the local avifauna. Several other Dendroica warblers also occur
in these forests. The pure spruce forests probably represent one of the
simplest of arboreal habitats to support such an impressive array of closely
related species of breeding birds.
It appears probable that the existing ecological and behavioral relationships
between Black-throated Green and Blackburnian warblers are the result of
a past history of intense interactions between themselves and the other closely
related sympatric species. As song appears to be an important part of
warbler communication during the breeding season, an examination of
vocalizations of these birds appeared to be a fruitful subject for study.
These studies were made in the spring and summer from 1962 to 1965.
^lost of the work was done on Hog Island (Todd Wildlife Sanctuary I ,
Bremen, Lincoln Gounty, Maine, with additional work being done in several
other areas in Maine, including the adjacent mainland and other coastal
islands in Lincoln Gounty. Further brief observations were made at Tremont,
Hancock Gounty, and Webster, Androscoggin County.
Most of the area studied on Hog Island is a mature red and white spruce
iPicea ruhens and P. glauca I forest, with the larger trees reaching a maximum
height of 18 to 25 meters. The hurricanes of 1954 and winds of following
years have severely damaged the forest on many parts of the island, but
most of the work in this paper was conducted in relatively undisturbed areas.
The growth of such a spruce forest is quite dense and results in considerable
difficulties in studying and following birds. The warblers of similar stands
64
CONTEXT OF SONGS IN WARBLERS
65
Doiifilass H.
Morse
PERCENT OF OBSERVATIONS
Fig. 1. Foraging height.
of trees were studied briefly in other areas, and they were studied also in
mixed white pine i Piniis strohus) — deciduous forests on the mainland.
SPACE OCCUPIED IN THE HABITAT
The foraging area of both species ( and other spruce-woods warblers )
was figured and discussed by MacArthur ( 1958 1 , who found that Black-
burnian Warblers usually foraged at greater heights in the spruce forest than
did Black-throated Green Warblers. In my study area, Blackburnian Warblers
foraged higher than did any other species present, and Black-throated Green
Warblers worked directly below them (Figure 1), with the other two
congeners, Magnolia (D. magnolia) and Myrtle (/I. coronata) warlilers.
usually foraging noticeably lower. While the centers of foraging of all species
studied differed, there was considerable overlap in each instance. Cape May
( I). tif^rina I and Bay-hreasted ( I), castanea I warblers, two other spruce-
woods species treated by MacArthur, were absent in the })rinci|)al study area.
In addition to some songs that were given when the birds were foraging.
66
THE WILSON BULLETIN
March 1%7
Vol. 79, No. 1
both species did a large percentage of their singing in a stationary or nearly
stationary position from the top, or the tip of a high exposed limb, of a
spruce tree. Both species sang for considerable periods in this sort of situation,
remaining motionless except for “fidgeting” in the immediate vicinity of
their song perch. Fidgeting here refers to an action in which an individual
frequently flicks its wings and tail, hops about very deliberately within a
limited area, and regularly pecks at the foliage, though apparently not feed-
ing. These movements are frequently accompanied by songs and chipping
notes. The term will be used in this sense throughout this paper.
RELATIVE DENSITY OF THE TWO SPECIES
The relative density of from two to three and one-half Black-throated
Green Warblers to one Blackburnian Warbler found by Cadbury and
Cruickshank ( 1937) in their long series of breeding-bird censuses on one
part of this island probably is an accurate estimate of the present population.
Frequent counts of the number of Black-throated Green and Blackburnian
warbler songs heard along a transect through the middle of this forest sug-
gested a similar or even greater ratio. Since their principal foraging areas
are above the Black-throated Green Warblers, Blackburnian Warblers did
not have as great an area in these spire-shaped trees in which to forage as
did Black-throated Green Warblers, and this factor may account for part
of the difference in density. Let us take an 18 meter spruce for an example,
and assume that the Black-throated Green Warblers did the majority of their
foraging at a height of between 5.4 and 12.6 meters ( 30-70 per cent of the
height of the tree), and Blackburnian Warblers foraged from 9.0 to 16.2
meters ( 50-90 per cent of the height of the tree ) . Black-throated Green
Warblers would then have approximately two and one-half times as great
a volume of both bark surface and foliage in which to forage if this tree
with its foliage had a normal radius of 3.4 meters at the minimum height
here considered, 5.4 meters.
SONG PATTERNS
Both the Black-throated Green and Blackburnian warblers in this popula-
tion possess two distinct song patterns, a male of either species typically
rendering either one or the other, depending upon the motivation involved.
To remain consistent with the literature. Black-throated Green Warbler songs
are referred to as Type A Songs and Type B Songs (see Nice and Nice, 1932;
Stein, 1962). Peterson (1947) described the Type A Songs as zoo zee zoo
zoo zee and the Type B Song as zee zee zee zee zoo zee. Since the two Black-
burnian Warbler songs are given in contexts essentially similar to those of
the Black-throated Green Warbler, they will also be referred to as Type A
Douglass H.
Morse
CONTEXT OF SONGS IN WARBLERS
67
Songs and Type B Songs, but this designation is not intended to imply that
these songs are necessarily homologous to those of Black-throated Green
Warblers. Peterson (1947) described the Blackburnian Warbler Type A
Song as zip zip zip zip titi tseeeeee and the Type B Song as tizip tizip tizip
tizip zizizizizizizizi.
Songs classified as intermediate between Type A and Type B, comparable
to “Intermediate Song” of the Yellow Warbler {Dendroica petechia) (Morse,
1966) , were not recorded from either species. While the Yellow Warblers
sometimes sang Intermediate Songs while switching from one major song
pattern to the other. Black-throated Green and Blackburnian warblers were
not observed to do this. Occasionally a bird of either species would sing
only part of a song pattern and then become silent. At the end of the breed-
ing season many aberrant songs were heard, including some songs that were
approximately intermediate to the two major patterns. However, these songs
were not heard during the breeding season. Blackburnian Warblers oc-
casionally rapidly alternated their two basic song patterns, but Black-throated
Green Warblers were not observed to do so.
STRATIFICATION OF SONGS
A noticeable stratification of individuals singing either of the two song
patterns into distinct parts of the habitat occurred in the Black-throated
Green Warbler ( Fig. 2 ) . The Type A Song was strongly associated with the
treetops and almost all Type A Songs were given from a high elevation. This
song was usually given while the bird was nearly stationary in the treetops,
but sometimes it was given while the singer alternately foraged. Type B
Songs were strongly associated with a lower position ( moderate height ) dur-
ing most of the season, and in contrast to Type A Songs were usually given
while the bird was actively foraging. Early in the season during the period
in which males were setting up territories and acquiring mates, stationary
birds in high exposed positions frequently gave Type B Songs, probably
acting as an advertising song.
The two basic song patterns of Blackburnian Warblers ( Fig. 3 ) occurred
in situations rather similar to those of Black-throated Green Warblers. Type
A Songs were also most frequently given while stationary in the top of
spruces, and Type B Songs were most frequently sung while foraging. How-
ever, the tendency for this species to forage higher than any other species in
the study area led to a superficial difference from Black-throated Green
Warblers in that there was a strong tendency for the Type B Song (the
foraging song ) to be given from a considerable height. The two songs some-
times were even alternated by a single bird at a high elevation. There also
was a strong tendency for this species to sing Type B Songs while in a
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THE WILSON BULLETIN
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Vol. 79. No. 1
Fig. 2. Singing height of Black-throated Green arbler.
Stationary position early in the season in conjunction with its apparent role
as an advertising song at that time. The heavv incidence of Type B Song
recorded in or near the top of the trees is attributable to this effect in both
Black-throated Green and Blackburnian warblers.
BEHAVIOR ACCOAIPANYING THE SONGS
Black-throated Green arbler Type A Songs were most frequentlv heard
from stationary birds in exposed positions that appeared to sing this pattern
as a territorial proclamation. These songs were also associated with activities
related to direct territorial defense. henever a male Black-throated Green
W arbler became conspicuous to other Black-throated Green arblers at close
range i except in the case of apparently unmated birds i . they responded with
Tvpe A Songs from a prominent position, even if they had previously been
singing Type B Songs. This song (sometimes muted I followed fights and
chases between male Black-throated Green arblers and also the less frequent
interspecific fights or chases with Parula iParula americana). Myrtle, or
Blackburnian warblers (Table li. ’’Muted Songs'* almost always followed
Douglass H.
Morse
CONTEXT OF SONGS IN WARBLERS
69
Type B
Song
N=47
10 15 20 25 30 35 40 45 50 0 5 10
PERCENT OF OBSERVATIONS
Fig. 3. .Singing height of Blackburnian Warbler.
15 io 25 30
the same contexts as normal volume songs did, though usually being given
in particularly strong or long encounters. In the course of a single fight
between two male Black-throated Green Warblers, both Muted Type A Songs
and Muted Type B Songs were heard. During such encounters, frequent
“Metallic Double Chips” were given between Type A Songs, and at times
of most intense aggression and excitement the song was sometimes even
temporarily suspended. These chips, which are of a distinctly metallic char-
acter, are usually given rapidly in groups of two.
Type B Songs frequently appeared directed toward females in one way or
another. On the few occasions that the male was seen singing in the direct
company of a female of the same species. Type B Songs were always given
(Table 1). These meetings probably occurred upon the frequent other oc-
casions when males dropped out of sight to lower positions from treetop
singing perches and changed from Type A to Type B patterns. Type B Songs
are the typical foraging songs, and most foraging is performed at the height
where females are most frequently encountered and where nesting occurs
( see Cruickshank, 1956 ) . Metallic Double Chips never accompanied this
song, a characteristic noted also by Nice and Nice (1932). Occasional in-
dividuals that sang Type B Songs while stationary in the treetops for several
minutes at a time into mid-June appeared to be unpaired birds. A noticeable
decrease of this behavior occurred during early June.
Blackburnian Warbler Type A Songs usually were correlated with activities
quite similar to those of Black-throated Green Warblers while singing l ype
A Songs (Table 2), occurring in both interspecific and intraspecific situa-
tions. A larger fraction ( 40.0 per cent ) of the strong or long encounters were
interspecific in this species than in Black-throated Green Warblers ( 22. 1 per
cent). Blackburnian Warblers tended to remain in one jiosition while singing
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Vol. 79, No. ]
Table 1
Apparent Context for Some Songs of Male Black-throated Green Warblers*
Number of
Activity responses
Type A Song
Fight with male Black-throated Green Warbler 32 (8 muted)
Extremely close contact with male Black-throated Green Warbler 4
Close contact with male Black-throated Green Warbler many
Song suspended and only metallic double chips given accompanying
fight with male Black-throated Green Warbler 2
Fight with male Blackburnian Warbler 4
Extremely close contact with male Blackburnian Warbler 2
Fight with male Myrtle Warbler 1 (muted)
Extremely close contact with male Myrtle Warbler 2 (1 muted)
Fight with male Magnolia Warbler 1
Fight with male Parula Warbler 1
Interference of observer 2
Type B Song
Following copulation with female Black-throated Green Warbler 1
Following courtship of female Black-throated Green Warbler 2 (1 muted)
Extremely near female Black-throated Green Warbler 3 (1 muted)
Continual singing early in the season from an exposed perch many
N
* Upon one occasion, after two male Black-throated Green Warblers fought they alternated
Muted Type A and Muted Type B Songs.
Type A Songs somewhat longer than did Black-throated Green Warblers,
averaging 4.8 minutes per singing station, while Black-throated Green War-
blers averaged 3.9 minutes per singing station. Blackburnian Warbler en-
counters with Parula Warblers, as well as with Black-throated Green War-
blers, were observed. Under circumstances resulting in high aggression,
frequent chipping, occasionally of a double nature, was given. The birds
sometimes foraged at this time.
In this species also. Type B Songs were the ones given in the immediate
presence of females (Table 2). Individuals consistently singing this song
for long periods of time in the treetops were probably birds that had not
obtained a mate. Two birds sang in such a manner through most of June,
though most ceased this pattern by early June. Only on very rare occasions
(two observations) were the chips heard accompanying Type B Songs.
DISCUSSION
The contexts in which both species sing Type A Songs and Type B Songs
suggest that the Type A Songs are given in situations where there is a high
attack tendency or a conflict of attack and escape tendencies. Type B Songs
Douglass H.
Morse
CONTEXT OF SONGS IN WARBLERS
71
Table 2
Apparent Context for Some Songs of Male Blackburnian Warblers
Number of
Activity responses
Type A Song
Fight with male Blackhurnian Warhler 4
Extremely close contact with male Blackhurnian Warbler 8
Close contact with male Blackburnian Warbler many
Fight with male Black-throated Green Warhler 4 (2 muted)
Extremely close contact with male Black-throated Green Warbler 2
Extremely close contact with male Parula Warbler 2
Type B Song
Following copulation with female Blackburnian Warhler 1
Following female Blackburnian Warbler 1
Extremely close contact with female Blackburnian Warbler 1 (muted)
Continual singing early in the season from an exposed perch many
A = 23
appear to be given under circumstances in which these tendencies are less
strongly activated, and in which sexual tendencies may be high. Type A
Songs appeared to be the territorial songs and were usually delivered from
exposed perches while nearly stationary. Type B Songs were typically forag-
ing songs and were also given in the presence of females. They were also
given as apparent advertising songs early in the season from exposed positions.
The contexts of the Type A Songs of the Black-throated Green and Black-
burnian warblers most closely resemble those that accompanied the Yellow
and Chestnut-sided (Dendroica pensylvanica) warbler Unaccented Ending
Songs (see Morse, 1966), all of these songs usually being given in the close
presence of other males of the same species. Type B Songs occurred in
contexts suggesting those in which Yellow and Chestnut-sided warblers sang
Accented Ending Songs; however, there appeared to be no distinction made
by Black-throated Green and Blackburnian warblers in response to other
closely related species nesting in the same areas. The difference between a
response of a Black-throated Green Warbler male to another male of its
species and to one of some other species was not marked, both intraspecific
and interspecific hostile activities usually being accompanied by the same
song pattern (Type A Song). In several populations in Maine, Yellow
Warblers responded to their most closely related sympatric species, the Chest-
nut-sided Warbler, with the same song pattern that they directed toward the
female.
The factors governing the singing of a particular song pattern differ
somewhat in the two cases. The level of hostile behavior among spruce-woods
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March 1%7
Vol. 79, No. 1
Dendroica warblers probably is considerably more intense than it is between
Yellow and Chestnut-sided warblers, and the problem of frequent inter-
specific interaction may be more important than is that of simple recognition.
The habitat separation between Yellow and Chestnut-sided warblers is more
clearly delimited than it is between the spruce-woods Dendroica species, only
limited habitat overlap occurring in the populations studied. Black-throated
Green and Blackburnian warblers both utilize very similar habitats, having
their principal foraging and nesting areas at slightly different heights
( Cruickshank, 1956 1 and parts of the trees, and foraging somewhat differ-
ently ( see MacArthur, 1958 ) . hut nevertheless overlapping considerably in
all these characteristics. Many more closely related species are found in the
spruce forests than in the favored wet bushy habitat of the Yellow Warbler.
Thus, a high level of interspecific interaction among the birds of the spruce
forest may result in stronger attack or escape tendencies than occur in Yellow
or Chestnut-sided warblers.
The slight difference in context accompanying a particular song pattern
or foraging in these two species may he partly attributable to the difference
in the part of the habitat foraged by them. The stratification of birds singing
the two song types was less marked in Blackburnian Warblers than in Black-
throated Green Warblers, and the former spent most of their time within an
area in which it was customary to give either song or to forage. They were
thus exposed to a slightly different set of stimuli at this height than were
Black-throated Green Warblers both in the treetops and at lower heights.
This difference in foraging height is in turn probably enforced by inter-
actions between the two species.
The context of muted songs in both of these species, based upon a limited
number of observations (see Tables 1 and 2), was slightly more predictable
than in Yellow Warblers (see Morse, 1966). The difference is perhaps a
result of the heavy incidence of interspecific interactions in the spruce forest.
The higher ratio of interspecific fights and chases to intraspecific ones in
the Blackburnian Warbler in comparison to the Black-throated Green War-
bler was probably largely the result of the lower density of the Blackburnian
Warbler in the study area. The somewhat longer periods of stationary sing-
ing in Blackburnian Warblers may also be the result of this low density. No
noticeable difference in the intensity and duration of hostile activities was
noted between the two species.
Because of their particular foraging station. Black-throated Green Warblers
would experience more potential conflicts with Magnolia and Myrtle warblers
than would Blackburnian Warblers. However, the foraging of Magnolia
Warblers ( pers. obs. I and Myrtle Warblers ( MacArthur, 1958) is not as
similar to Black-throated Green Warbler foraging as is Blackburnian Warbler
Douglass H.
Morse
CONTEXT OF SONGS IN WARBLERS
73
foraging, and much of the Black-throated Green Warbler foraging is per-
formed above the major foraging areas of Magnolia and Myrtle warblers.
Fewer Black-tbroated Green Warbler encounters with Magnolia and Myrtle
warblers were noted than between Black-throated Green and Blackburnian
warblers. Magnolia and Myrtle warblers also were not as abundant as were
Black-tbroated Green and even Blackburnian Warblers in the study area.
Thus Blackburnian Warblers expend more energy in interspecific encounters
( at least their fights and chases ) in this forest than do Black-throated Green
Warblers.
It is not definite whether the warblers of tbis forest are utilizing limited
food sources at this season, but they definitely interfere with each other in
the procurement of quite similar food sources. Thus they fulfill requirements
for competition laid out by Birch ( 1957 ) . The most important competitor
of the Blackburnian Warbler in this forest probably is the Black-throated
Green Warbler, the only species of warbler it frequently comes into contact
with, and which forages in a manner suggestive of, though not identical to,
its own species. Conversely, Blackburnian Warblers probably are the most
important competitors of Black-throated Green Warblers in this forest, but
because of their lower density their effect is quantitatively less important
than the effect that Black-throated Green Warblers have upon Blackburnian
Warblers. This pattern will necessarily be modified depending upon the local
species compositions, but it appears likely that these two species have more
foraging similarities than do any other Dendroica warblers in tbe spruce
forests of tbe northeast.
SUMMARY
Songs and accompanying behavior of Black-throated Green and Blackburnian warblers
were studied in Maine from 1962 to 1965. Work was concentrated in a climax spruce
forest containing two additional species of Dendroica, Magnolia and Myrtle warblers.
Blackburnian Warblers foraged higher than did other species, with Black-throated Green
Warblers directly below them. Both possess Type A and Type B Songs, usually sing-
ing Type A Songs in the presence of other singing warlders of either their own or other
species. These vocalizations appeared to he the territorial songs and were usually de-
livered from exposed perches while nearly stationary. Metallic Double Chips often
aceompanied Type A Songs. Type B Songs were typically foraging songs and were
also given in the presence of females. They were also given as apparent advertising
songs early in the season from exposed positions. Type A Songs were apparently sung
when a high attack tendency or a conflict of attack and escape tendencies existed;
Type B Songs oecurred when these tendencies were less strongly activated, and when
sexual tendencies were high. The slight difference in context accompanying certain
responses in the two species may he partly attributable to their differences in foraging
j height. Black-throated Green Warblers were more abundant than Blackburnian
j Warblers in the study area, and a greater portion of their hostile activities were intra-
I specific. Both species j)rohahly were the other’s mo‘;t important comj)etitor.
1
I
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THE WILSON BULLETIN
March 1%:
Vol. 79, No. 1
ACKNOWLEDGMENTS
I wish to thank Drs. M. S. and R. W. Ficken for timely discussion and criticism of
the manuscript. The National Audubon Society kindly permitted the study to he con-
ducted on Hog Island. This study was partially supported by the National Science
Foundation (GB-3226).
LITERATURE CITED
Bmcii, L. C.
1957 The meanings of competition. Am. Naturalist, 91:5-18.
Cadbury, J. M., and A. D. Cruicksiiank
1937 Climax red and white spruce forest. Bird Lore, 39:384 (and subsequent years
through 1958).
Cruicksiiank, A. D.
1956 Nesting heights of some woodland warblers in Maine. Wilson Bull., 68:157.
Ficken, M. S., and R. W. Ficken
1962 The comparative ethology of the wood warblers: a review. Living Bird, 1:
103-122.
1965 Comparative ethology of the Chestnut-sided Warbler, Yellow Warbler, and
American Redstart. Wilson Bull., 77:363-375.
MacArtiiur, R. H.
1958 Population ecology of some warblers of northeastern coniferous forests.
Ecology, 39:599-619.
Morse, D. H.
1966 The context of songs in the Yellow Warbler. Wilson Bull. 78:444-455.
Nice, M. M., and L. B. Nice
1932 A study of two nests of the Black-throated Green Warbler. Bird-banding,
3:95-105, 157-172.
Peterson, R. T.
1947 A field guide to the birds. Floughton Mifflin Co., Boston.
Stein, R. C.
1962 A comparative study of songs recorded from five closely related warblers.
Living Bird, 1:61-71.
DEPARTMENT OF ZOOLOGY, UNIVERSITY OF MARYLAND, COLLEGE PARK, MARY-
LAND, 1 DECEMBER 1965
DAMAGE BY GOLDEN-FRONTED AND LADDER-BACKED
WOODPECKERS TO FENCE POSTS AND UTILITY POLES
IN SOUTH TEXAS
John V. Dennis
OODPECKER damage to utility poles is a matter of serious economic
W concern in many parts of North America. The problem dates back into
the last century, and periodically has received serious attention from ornithol-
ogists and utility engineers. An early study by McAtee (1911) showed that
poles treated with a preservative as well as untreated poles are attacked, and
that at least eight species of woodpeckers are responsible for damage.
However, neither McAtee nor other early writers seem to have recognized
the situation existing in south Texas where two pole-damaging species of
woodpeckers occupy the same habitat. Most writers blame the Golden-fronted
Woodpecker {Centurus aurijrons) (Fig. 1) for the extensive damage that
occurs. Sennett ( 1878u ) , for example, reported that utility poles were a
favorite nesting place of the Golden-fronted and that “hardly a pole” was free
of their holes. He concluded that telegraph pole excavations by this species
were made “in search of a large species of borer that works in dry wood”
( Sennett, 18786 ) .
The only other resident woodpecker of the lower Rio Grande Valley is a
sparrow-sized bird, the Ladder-backed Woodpecker ( Dendrocopos scalaris) .
Sennett ( 1878a) implied that this species also nested in utility poles. Simmons
( 1925 ) , writing of the region of Austin, Texas, states that “when suitable
trees are not to be found” the Ladder-backed nests in cedar fence posts or
telegraph poles. McAtee (1911) and Pearson et al. (1936) mentioned the
Ladder-backed in connection with utility pole nesting. Until recently the
Golden-fronted has received much more blame for utility pole damage
( Bendire, 1895; McAtee, 1911; Friedmann, 1925; Simmons, 1925; Pearson
et al., 1936; Quillin in Bent, 1939).
The present paper attempts to define the roles played by the Ladder-backed
and Golden-fronted woodpeckers in regard to utility pole and fence post
damage in Texas from about Victoria and San Antonio southward. Other
objectives are to describe damage and to explore reasons for attack. These are
subjects discussed earlier by Dennis (1961), but which have now been ex-
amined further. Methods of preventing attack are beyond the scope of the
present paper and will not be covered.
Observations in south Texas now cover three nesting seasons as well as
appreciable periods during the non-nesting season. During the winters of
1960-1961 and 1961-1962, observations were made in parts of the Lower
75
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THE WILSON BULLETIN
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Vol. 70. No. 1
Fig. 1. Female Golden-fronted Woodpecker at nest hole in a small electric distribution
pole. Hole is about six feet from the ground.
John V.
Dennis
WOODPECKER DAMAGE IN TEXAS
77
Rio Grande Valley and south Texas where both the Golden-fronted and
Ladder-hacked are abundant. During the late winter and spring of 1965, the
writer with Robert L. Rumsey of the Southern Forest Experiment Station,
established a number of tests in south Texas for the purpose of comparing
susceptibility of certain woods and treated versus non-treated woods to attack
by Golden-fronted and Ladder-backed woodpeckers. This work was part of a
much wider program to find better methods of protecting wooden utility poles
from damage by woodpeckers. The program is under the direction of the
Southern Forest Experiment Station at Alexandria, Louisiana, and is financed
by several electric utility companies and a lumber company.
HABITAT AND NUMBERS
In Mexico the Ladder-backed is said to be found “virtually country-wide
in arid districts,” and the Golden-fronted in “dry districts with sparse or
second-growth timber” (Blake, 1954). In Texas the two are almost always
associated with the mesquite-dominated chaparral that extends northward from
Mexico into the hot, arid, southern, central, and western parts of the State.
Although land clearing has destroyed vast areas of mesquite, it seems probable
that more mesquite scrubland exists today than at the time of Sennett’s
writings in 1878. Since mesquite spreads with intensive grazing, it is not
surprising that it has become established widely over the more arid rangeland
of Texas. Brooks ( 1933 ) , writing of the Brownsville region, mentions the
rapid invasion of mesquite over the once wide coastal prairies.
Oaks and mesquite are the species usually mentioned as affording habitat
for the two species. Simmons ( 1925 ) , besides listing oaks and mesquite,
states that the Golden-fronted is partial to pecan groves and the Ladder-backed
to cottonwoods and hackberry. In extremely dry and treeless sections of the
Southwest the Ladder-backed is found closely associated with yucca and agave.
Grinnell and Swarth ( 1913 ) state that the birds nest in the dried stalks of these
plants in desert regions of southern California. Bancroft ( 1930 ) reports that a
race of the Ladder-hacked in lower California confines its nesting to the
saguaro cactus.
Neither the Ladder-backed nor Golden-fronted has adapted to the more
intensively cultivated parts of the Rio Grande Valley and Texas coast, hut
both have responded to shade tree plantings. The Golden-fronted, in particular,
has resj)onded to man-created environments, and shows a strong affinity for
introduced palm trees.
Both Sennett (18785) and Bendire (1895) found that the Ladder-hacked
was much less numerous than the Golden-fronted in the Lower Rio (irande
Valley. While their conclusions may he accurate, it should he enq)hasized that
the larger, more colorful and vocal Ciolden-fronted often disphns in the oj)cn.
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THE WILSON BULLETIN
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Vol. 70. No. 1
easily conveying an exaggerated impression of its numbers. The less con-
spicuous Ladder-backed, on the other hand, is apt to be overlooked. In a
random selection of Christmas Bird Counts, the writer has noted that total
numbers of the two were about the same at 12 localities in Texas reporting
both species — 187 Golden-fronted Woodpeckers and 182 Ladder-backed \^^ood-
peckers (Cruickshank et ah, 1958). These recent results agree with those
obtained by the writer, who found the two species to be about equally
numerous throughout south Texas.
ROLE OF THE LADDER-BACKED VERSUS THE GOLDEN-FRONTED
Special attention was given to the comparative roles played by the Ladder-
backed and Golden-fronted Woodpeckers in damage to poles and posts. It was
concluded that the Golden-fronted rarely initiates attack, but rather appropri-
ates and enlarges holes already made by the smaller Ladder-hacked. Support-
ing evidence may be summarized as follows:
1. Golden-fronted Woodpeckers have appeared as occupants of sites where
Ladder-backs were actively at work earlier in the same nesting season.
2. There is no evidence of damage to utility poles or crossarms in towns
and cities in the Rio Grande Valley where the Golden-fronted is reason-
ably common and the Ladder-backed is rare or absent.
3. Golden-fronteds are rarely seen working on utility poles. They spend
much of their time on poles, but this time is utilized chiefly in such
activities as guarding nesting sites, “loafing,” searching for food in
checks, and taking part in courtship displays. Ladder-backs, however,
when seen on poles or fence posts, are rarely engaged in anything but
hole excavating activity.
LOCATION OF DAMAGE
Each of the several species of woodpeckers that attack utility poles has its
special mode and place of attack; the Pileated { Dryocopus pileatus) concen-
trates on the mid- and upper-mid portions of transmission poles; the two
flickers iColaptes cajer and C. auratus) on lower portions of the pole, often
close to the ground; and other pole-damaging species have equally rigid zones
of attack ( Dennis, 1964 1 .
The Ladder-backed conforms to this pattern by concentrating its attack at
special localized points on poles, fence posts, and other structures. However, it
exceeds all other pole-damaging species in the wide diversity of its attack.
Among its targets are every wooden utility pole attachment, road marker
posts, sign posts, fencing boards, wooden railings, and clapboard on houses.
Lurthermore, the writer has been told by utility engineers within the Ladder-
hacks’ range that lead sheathing on overhead cables is sometimes damaged.
John V.
Dennis
WOODPECKER DAMAGE IN TEXAS
79
Fig. 2. Distribution of holes on this telephone pole is typical of Fudder-hacked's work.
Heaviest attack is near the top of pole. A few holes are found on the lower portion and
heginning almost from the firound level.
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THE WILSON BULLETIN
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Vol. 79, No. 1
Attack on utility pole structures by the Ladder-backed is characterized by
heavy damage to crossarms and braces, and frequent heavy damage to the top
2 or 3 feet of the pole. Damage sometimes extends from ground level to the
top of the pole ( Eig, 2 ) . Attack on crossarms and braces always originates
on the underside, never the sides or top. Typically, a crossarm is drilled at a
site on the underside from 6 to 18 inches from the end. The purpose of this
drilling is apparently the excavation of a roosting or nesting hole. Rarely are
these holes completed. Often the bird “misjudges” the dimensions of the
crossarm and breaks “windows” in one or both sides, or breaks a hole in the
top. In other cases, the bird appears to tire of its work and discontinues after
drilling only an inch or two. In the rare instances that a cavity is completed,
the tunnel always leads from the entrance toward the pole — never away from
the pole. Completed cavities in crossarms are from 6 to 10 inches in length.
Attack on fence posts is much like that on utility poles. Roosting and
nesting holes are largely confined to the top few inches of the post, and many
more are started than are completed. Damage to utility poles and fenceposts
can be described best under three headings: (1) small poles with crossarms
( electric distribution and telephone poles ) , ( 2 ) large poles with crossarms
(electric transmission poles), and (3) fence posts.
Small poles. — A total of 155 small poles in seven separate electric distribu-
tion lines were checked for location of damage and severity of damage in rela-
tion to habitat. The poles had been in service from 4 to 19 years and ranged
from 20 to 40 feet tall; each had a single crossarm attached. With the excep-
tion of one line in which the treatment was pentachlorophenol, all poles were
treated with creosote. Poles were southern pine and crossarms were penta-
treated Douglas fir. All but a few poles were damaged ( only holes 2 inches
or more in diameter were tallied ) . The heaviest damage occurred through
dense mesquite shrub, where poles had an average of 3 holes each. Lightest
damage — 0.5 hole per pole — was found in a line through small bottomland
hardwoods along the Rio Grande. Damage was intermediate where lines
passed through habitats with predominately large hardwood, and mixed oaks
and mesquite.
One hundred and seven pressure-treated, southern pine telephone poles were
examined on six different lines. The poles ranged from 15 to 30 feet tall and
had two to three crossarms. Only 0.8 hole per pole was found where lines
were surrounded by solid stands of oak; in contrast an average of 2.5 holes per
pole occurred in lines through mesquite scrub. Severity of damage was about
the same as on the electric distribution lines.
Combining data from telephone and electric distribution lines, about 26 per
cent of all holes were in the top foot of poles, 30 per cent were at the crossarm
level, 30 per cent were in crossarms, and the remainder below the crossarms.
John V.
Dennis
WOODPECKER DAMAGE IN TEXAS
81
Overall, 80 per cent of the damage was in the top 3 feet and in the crossarms.
Large poles. — Several kinds of transmission pole constructions are found in
south Texas. The poles are southern pine, pressure-treated with creosote, and
typically 55 feet in height. The various braces and crossarms are penta-treated
Douglas fir. In April 1965, 30 consecutive 2-pole, H-frame structures of a
transmission line west of Falfurrias were checked for woodpecker damage. As
was the case with the smaller poles, this line seemed to be a typical example of
the kind of woodpecker damage to be expected where adjacent habitat supports
a large population. Habitat along this line consisted of dense mesquite scrub.
Approximately 75 per cent of the larger holes were found in X- and V-brace
structures, only 24 per cent in the pole, and 1.6 per cent in the crossarms.
This is in marked contrast to the heavy damage typically found in crossarms
on electric distribution lines and telephone lines. That Douglas fir crossarms
on this line and other transmission lines examined have been free or nearly
free of attack defies explanation. Whether a factor, such as elevation from
the ground or the thickness of the crossarm, plays a role in degree of attack
on the different structures in unknown. However this may be, the damage to
the pole itself on transmission lines has seldom been found to be severe and is
largely confined to the top few feet.
Fence posts. — Although several species of woodpeckers attack both utility
poles and fence posts, attack upon creosoted pine fence posts for the purpose
of making roosting and nesting holes seems to be a highly restricted habit that
is perhaps confined to only the Ladder-backed Woodpecker. Numerous in-
stances were found in which the Golden-fronted had occupied holes in creosoted
pine fence posts, but from all evidence, such holes were originally the work of
the Ladder-backed.
Creosoted pine posts have been used on a large scale in south Texas only
during the last 10 to 20 years. The traditional fence posts of the region are
red cedar { Juniperus virginiana) and mesquite iProsopis juliflora) which
are naturally resistant to decay. Pressure-treated creosoted pine, however, is
becoming more popular as a fence post material. Pressure-treated penta-pine
posts also are beginning to make an appearance. Red cedar, the most widely
used fencepost material, is virtually immune to woodpecker attack. Occasion-
ally a roosting or nesting hole is found in a red cedar post, hut upon examina-
tion the post is usually found to he in an advanced state of internal decay.
More often, a few “probe holes,” which rarely penetrate any deeper than the
sapwood, are found in sound posts. In response to an inquiry to the L.S.
forest Products Laboratory at Madison, Wisconsin, John W. Rowe ( i)ers.
comm., 5 April 1961) furnished the following information regarding possible
reasons why red cedar is so seldom attacked by woodpeckers:
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THE WILSON BULLETIN
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Vol. 79, No. 1
“Woodpeckers apparently attack wood either to find insects or when they hear a hollow
sound such as might come from either heartwood rot or shake (the ease of hollowing out
for nesting?). These Juniperus species contain a high percentage of heartwood which
is rich in toxic extracts . . . They are considered fairly resistant to attack hy micro-
organisms and fungi, and are probably also fairly resistant to insect attack . . .
The heartwood is thus resistant to rot, and in addition is relatively hard and does
not commonly form shake cavities. This should all tend to render these Juniperus spp.
relatively unattractive to woodpeckers.”
Mesquite fence posts, readily recognized by their crookedness, are also
widely used in south Texas. They are somewhat more subject to woodpecker
attack than red cedar. Roosting and nesting holes are sometimes found, and if
the post has a marked lean or crook, the hole is invariably on the undersurface.
Solid posts without decay seem to be avoided. Mesquite posts generally seem
to be free of small “probe” holes and miscellaneous damage. However, in
some parts of south Texas, for example along the highway between Alice
and George West, attack upon mesquite posts is quite common.
By far the heaviest attack is upon creosoted pine. Wherever such fence lines
were checked in mesquite-scrub habitat, there was evidence of damage similar
to that found on utility poles, specifically holes near the top, widening of
checks, minor surface peck marks and scaling. The ratio of completed to un-
completed holes does not vary strikingly from that found on utility poles and
crossarms. For example, in a check of 50 distribution poles and 60 crossarms
at the Welder Refuge near Sinton, only 5 per cent of all holes were completed
roosting and nesting cavities (Dennis, 1964). On 525 creosoted pine fence
posts at the Laguna Atascosa National Wildlife Refuge near San Benito, Texas,
11 per cent of all holes were completed roosting and nesting cavities. The
poles and crossarms had been in place approximately four years and the fence
posts about seven years.
A higher percentage of poles than posts is attacked. In areas of severe
damage it is not uncommon for 100 per cent of utility pole structures to show
signs of attack. The incidence is lower in fence posts which are spaced closer
together. For example, in a part of the Laguna Atascosa Refuge where every
utility pole showed substantial damage, only 17 per cent of the fence posts
contained damage. The fence posts were one rod apart while the utility poles
were approximately 500 feet apart.
Approximately 16 per cent of 1,887 creosoted pine posts in six lines at
the Laguna Atascosa Refuge were damaged. Furthermore, 2.5 per cent con-
tained completed roosting or nesting holes. The posts had been in place from
two to seven years.
Damage was most severe on fence lines where there were either solid stands
of mesquite-scrub or mesquite-scrub bordered by grassland. Less damage was
John V.
Dennis
WOODPECKER DAMAGE IN TEXAS
83
found on lines where at least one side of the fence line was bordered by a
cultivated field. Wherever fence lines departed from chaparral, woodpecker
damage ceased within 40 to 50 yards.
RELATIONSHIP OF DAMAGE TO WOOD TREATMENT
C. T. Day, a utility engineer in Sonora, Mexico, (in McAtee, 1911)
describes woodpeckers “getting fat” on creosote and the inside of poles being
“entirely eaten away.” Although this may be an exaggerated account, the
idea that creosote makes a pole more susceptible to woodpecker damage has
persisted.
A program to test this theory was established at the Laguna Atascosa
National Wildlife Refuge with the cooperation and assistance of the U.S. Fish
and Wildlife Service. In February 1965, 58 pressure-treated creosoted south-
ern pine posts and 42 untreated southern pine were placed about 20 yards
apart along edges of existing fence rows or along clearings through dense
chaparral growth. In most instances treated and untreated posts were alter-
nated.
After approximately two months, the posts were examined for signs of
attack. Of the untreated posts, 7.3 per cent contained holes or sign of attack
and 36.2 per cent of the treated posts contained holes or sign of attack. The
extent and degree of damage varied little between treated and untreated posts.
None contained completed nesting holes. For the most part, holes went
straight into the post for varying distances and did not extend downward.
In some cases, attack was limited to a few peck marks or the scaling-off of thin
layers at surface of the post.
The fact that the creosoted posts sustained approximately five times as much
damage in the first two months suggests that there is a basis for the belief that
the wood preservative in some way contributes to making a pole more vulner-
able to woodpecker attack. This does not necessarily imply, however, that
creosote per se is the attractant. Changes in wood structure during the
treating process may be a factor in making a pole more vulnerable. For ex-
ample, Wood et al. (1960) speak of defects in poles, such as shakes, “that are
induced by conditioning and preservative treatment.”
Poles and posts with small internal cavities in the form of ring sejjarations
in the wood (or shakes) have often been thought to be particularly susceptible
to woodpecker attack. In the letter from John W. Rowe quoted earlier, it was
suggested that the presence of either heartwood rot or shake made for con-
ditions that stimulated woodpecker attack. This is a theme amplified uj)on by
Dennis ( 1964), who believed that woodpeckers primarily attack poles to make
roosting and nesting cavities, but, because of the presence of shake and other
I
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Vol. 79, No. 1
internal defects, are stimulated to make far more holes than they would in
natural tree sites.
It should be added that there is much yet to be learned about a possible
connection between the preservative treatment and the susceptibility of a
pole to woodpecker attack. Testing has barely begun on this aspect of the prob-
lem and any conclusions will have to await long-term results with many more
test poles. In April 1965, the number of test posts in the experiment at the
Laguna Atascosa Refuge was doubled.
RELATIONSHIP OF DAMAGE TO RESONANCY EFFECTS
Other fence post experiments at Laguna Atascosa were designed to test
resonancy or sound effect. McAtee (1911), who expressed the belief that
“hum of the wires” had something to do with attracting woodpeckers to
utility poles, was repeating a widely held assumption that has persisted to
this day. Recent writers have discounted the role of hum or vibration and have
substituted other reasons that seem more convincing (Turcek, 1960; Dennis,
1964).
Observations along electric distribution and telephone lines in south Texas,
as well as of posts bearing metal signs, have shown that the Ladder-backed
frequently selects sites close to metal attachments as places to commence hole
drilling. So pronounced is this tendency that attack is often limited almost
entirely to the immediate proximity of a metal attachment and is absent
elsewhere. A number of examples may be mentioned.
1. In a sample of 17 poles in a heavily damaged electric distribution line,
88 per cent of holes were opposite metal attachments.
2. In a sample of 50 poles in a heavily damaged telephone line, all holes
were opposite metal attachments on the crossarms.
3. At Laguna Atascosa Refuge about 2.5 per cent of the creosoted pine
posts bear official metal U.S. Fish and Wildlife Service boundary marker
signs. In a fence line containing 525 posts, 13 with signs attached
sustained a damage rate of 84.6 per cent; the 512 posts without metal
signs sustained a damage rate of 15.4 per cent.
This tendency to attack locations opposite metal attachments was tested on
a small scale in fence post experiments at the Laguna Atascosa Refuge. A slit
5 inches deep was sawed into the top of 10 creosoted pine fence posts. A
5-inch square of sheet metal was inserted into each slit. Posts containing the
hidden metal plates were placed in test strips with 30 unaltered creosoted pine
fence posts. As with the other test posts, placement was made in late Febru-
ary and posts were checked in late April. Of the 30 unaltered posts, six (20
per cent) had been attacked; of the 10 posts with metal plates, seven (70 per
Jolin V.
Dennis
WOODPECKER DAMAGE IN TEXAS
85
Fig. 3. A flat metal plate has lu'en inserted into a jiroove cut into tlie top of tliis
ereosoted pine fence post. A woodjiecker has drilled a hole to tin* plate, .'''mail hoh's
are scatt(‘red about near the lar ierra where
it often frequents slash-burned sections in which stumps and fallen trees provide cover.
Gommon Mockingbird (Mimas polyglottos) 1 he only mockingbird I observed in
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Vol. 79, No. 2
the Sierra was one at Playa Azul on 2 April 1960, during a norther. It was a typical
individual of this species.
White-throated Robin (Turdus assimi/is). — On 5 June 1962, I discovered a nest in
the understory of montane rain forest on Volcan San Martin Tuxtla at 750 m elevation.
It was constructed of green moss, supported by a vine and small branches, and situated
about 3.5 m above ground against the trunk of a tree 30 cm DBH. I could not de-
termine its contents. At the time robins were feeding two-thirds grown young in the
rain forest as were Ivory-billed Woodcreepers {Xiphorhynchus flavigaster) , Red-legged
Honeycreepers iCyanerpes cyaneus) , and Chestnut-capped Brush-Finches ( Atlapetes
brunneinucha) . In July T. assimilis was the most common species I noted in this
rain forest on the volcano. It is of interest that Skutch (1960:85) could find no pub-
lished record of the nesting of this species in Central America, and the seven nests
that he observed were apparently not in forest habitat.
Black Robin i Turdus injuscatus) . — 1 collected a male with testes each 3.5 mm in
elfin forest at 1600 m on Volcan San Martin Tuxtla on 26 August 1962. Another bird,
possibly the female, was calling and exhibiting alarm in the same place. Two others
were seen at slightly lower elevations. The small areas of cloud forest in the Sierra
limit the available habitat for this species.
Tropical Parula Warbler (Parula pitiayumi) . — This warbler is a widespread resident
in humid and drier forests. I collected a singing male in breeding condition near
Barrosa on 16 June 1962. These warblers habitually sing late into the morning and
often in the afternoon on hot days when most species are quiet. The Mexican Check-
list (Miller et ah, 1957:243-244) records the species as only casual in northeast
Oaxaca and central and southern Veracruz.
Golden-crowned Warbler (Basileuterus culicivorus) . — I found a nest at 730 m in
the forest on Valcan San Martin Tuxtla on 5 June 1962. It was on the ground in an
open section of the forest among leaves and low herbaceous plants. Construction was of
leaves, grasses, and rootlets in a dome shape with the interior 7.5 cm in diameter and
lined with fine rootlets. The three eggs were pinkish-white with reddish-brown flecks
over the entire surface but concentrated in a ring near the large end. One measured
18 by 13 mm.
Cbestnut-headed Oropendola iZarhynchus wagleri). — Sclater (18576:228) reported
this species from San Andres Tuxtla, and Ramirez collected a female and male at Dos
Amates on 14 and 23 November 1961. Apparently the species is very rare and local
in the Sierra.
Wagler’s Oriole ilcteriis wagleri). — Davis (1952:315) reported this species south of
Lake Catemaco in 1952, the only record. Although the Mexican Check-List does not
list this oriole for Veracruz, it seems likely that it would occur there in highlands in
view of its known overall distribution.
Hooded Oriole (Icterus cucullatus). — Dickerman reported four birds north of
Sontecomapan on 7 August 1962, the only record for the Sierra.
Blue-hooded Euphonia (Euphonia musica) . — On 22 March 1960, I observed a pair
above Dos Amates, saw a male on 20 March 1962, above Colonia Huatusco, and another
individual on 30 October 1962, above Ocotal Chico. Phillips reported about eight and
collected a male above Ocotal Chico on 8 December 1962. Another was taken by
Ramirez near Dos Amates on 6 November 1963. Since the Mexican Check-List (Miller
et ah, 1957:298) lists the species only from La Joya in Veracruz, apparently these are
the first records outside the west-central mountains of the state.
Yellow-throated Euphonia (Euphonia lauta) . — On 2 May 1962, I discovered a nest
Robert F.
Andrlc
BIRDS OF VERACRUZ
185
along the Lake Catemaco shore at Playa Azul, 2 m above ground on the underside of a
large, horizontal tree limh. It was supported hy a large, pendent herh and was oval in
shape, 17.7 cm in maximum outside diameter with a 5 cm diameter entrance on the
side. The nest was thin and loosely woven of rootlets, fine twigs, and a few grasses
and contained four young two or three days old. Two of these were being fed out of
the nest on 22 May. This nest was considerably larger than the only one for
which Skutch (1954:248) gives measurements. He remarks on the variety of nest sites
chosen hy this tanager, mentioning fence post tops, palm frond, and holes in earth
banks.
Red-crowned Ant-Tanager (Habia riibica) . — I found a semi-pensile nest in heavy
forest above Dos Amates at about 500 m altitude on 5 May 1962. It was 2 m above
ground in the fork of a sapling in open understory and was constructed of grasses,
rootlets, and small twigs with exterior dimensions of 10.2 hy 12.7 cm. The four eggs
were white with faint brown flecks more concentrated and pronounced at the large
end where they formed a wreath. One measured 25 hy 18 mm. It is of interest that
neither Skutch (1954) nor Willis (1961) reported more than three eggs in the 20
nests of this species they observed. The female was still incubating in this nest on
8 May and four young about four or five days old were in it on 20 May.
SUMMARY
The Sierra de Tuxtla is a small, comparatively low mountain range in southern
Veracruz whose rich avifauna heretofore has been investigated only in restricted areas.
This paper deals with the status of nontransient birds in the entire range, covering
about 4,200 square km, and lists 251 species known to have been recorded, including 55
not previously reported.
The Sierra’s topography of volcanic cones, ridges, gorges, and valleys provides a
varied physical base to interact with climatic elements, chief of which are trade and
continental winds and northers. An important aspect of the climate is the orographic
rainfall resulting from the barrier formed by the four major volcanoes and subsidiary
peaks. Precipitation ranges from about 1,700 to over 4,000 mm annually, being greatest
on the Gulf slopes. Although temperatures occasionally reach the freezing point at
high elevations, the climate is moderated hy warm Gulf water, frequent clouds on
the mountains, and extensive forests.
A diverse plant cover exists owing partly to vegetation destruction and modification
hy man over more than half the range. Fertile volcanic soils contribute toward a more
homogeneous vegetation typified hy rain forest; this comprises one of the two most
extensive habitats and supports much of the avifauna. Also supi)orting important
numbers of species are large nonforested sections and water bodies, chiefly Lake Gat-
emaco and Bahia Sontecomapan.
The Sierra lies entirely in the Tropical Life Zone with Humid Upper Tropical and
Arid divisions present, the former restricted to higher parts of the mountains and the
latter to inland slopes. Boundaries of these zones are ill-defined with resj)ect to
avifaunal distribution.
Faunal mixing probably occurred in the Sierra during its history so that avian forms
of both northern and southern affinities were represented. Since its climate was probably
never cooler than warm temperate, even during the Pleistocene, it is unlikely that
bird life in the range was ever completely displaced. Shifting of tropical and northern
vegetation elements caused hy climatic changes also affect(‘d the avifauna. This is now
composed of a large number of s|)eci(“s in Widely Distributed and Pantro|)ical elements
186
THE WILSON BULLETIN
June 1967
Vol. 79, No. 2
of unknown or uncertain origin, hut apart from this, species of prohahle southern origin
predominate in comparison to those with northern affinities. The Tyrannidae, with
26 memliers, and six other families with 13 or 14 members each, comprise almost half
of the avifauna.
Six major avian habitats are outlined. Lists are given of the species primarily
associated with each including estimates of their relative observable abundance and
aproximate elevation ranges. Continuing deforestation is resulting in areal expansion
and increase in total numbers of nonforest species at the expense of forest birds. The
distribution and nature of plant formations largely governs altitudinal ranges of many
species, and the majority normally occur below 1,000 m. Among factors influencing
abundance and distribution of birds are human alterations of plant cover and flowering
and fruiting of plants. The long breeding season, though having a peak period of
activity, is expectedly less well defined and more prolonged than those in more northern
latitudes.
Differentiation of the few endemic bird species was assured in the Sierra by
physical and ecological isolation. Their survival despite volcanic action was possibly
aided by dispersal in both massifs and probably permitted by the restricted nature of
volcanic disturbances.
ACKNOWLEDGMENTS
I extend my thanks to the many persons who aided jne, especially Drs. Robert C.
West and George H. Lowery, Jr., of Louisiana State University, and Fred T. Hall,
Director of the Buffalo Museum of Science. I am indebted to many persons in Mexico,
particularly the late Ing. Luis M. Arellano, Profs. Enrique Beltran, Othon Arroniz,
Carlos F. Ramirez, Raphael G. de la Cruz, and Ing. Roberto G. Gil. Dr. Velva E. Rudd,
of the U.S. National Museum, and her colleagues identified my plant collections, and
I also thank Drs. Harold H. Axtell, Robert W. Dickerman, Ernest P. Edwards, John W.
Hardy, Byron E. Harrell, A. Starker Leopold, Walter P. Nickell, Allan R. Phillips,
and Richard E. Tashian. I am grateful to L. Irby Davis, Mr. and Mrs. John Lind,
Gary N. Ross, A. J. Wright, and Air. and Airs. Frederic K. Wykes for their interest
and assistance. Aly 1960 work was supported by the Buffalo Society of Natural Sciences
and the study in 1962 by the National Research Council of the National Academy of
Sciences (Subcontract 54).
LITERATURE CITED
Andrle, R. F.
1966 North American migrants in the Sierra de Tuxtla of southern Veracruz,
Alexico. Condor, 68:177-184.
Beard, J. S.
1944 Climax vegetation in tropical America. Ecology, 25:127-158.
Davis, L. I.
1952 Tropical woods. Sixteenth Breeding-Bird Census, Audubon Field Notes,
6:314-315.
Dorf, E.
1959 Climatic changes of the past and present. Contrib. Mus. Paleontol. Univ.
Michigan, 13:181-210.
Edwards, E. P., and R. E. Tashian
1959 Avifauna of the Catemaco basin of southern Veracruz, Alexico. Condor,
61:325-337.
Robert F.
Audi le
BIRDS OF VERACRUZ
187
Eisenmann, E.
1955 The species of Middle American birds. Trans. Linnaean. Soc. New York, 7.
Friedmann, H., L. Griscom, and R. T. Moore
1950 Distributional check-list of the birds of Mexico. Pacific Coast Avifauna,
No. 29.
Griscom, L.
1950 Distribution and origin of the birds of Mexico. Bull. Mus. Comp. Zook,
103:341-382.
Holdridge, L. R.
1947 Determination of world plant formations from simple climatic data. Science,
105:367-368.
Leopold, A. S.
1959 Wildlife of Mexico; the game birds and mammals. Univ. of California Press,
Berkeley, California.
Loetscher, F. H., Jr.
1941 Ornithology of the Mexican state of Veracruz with an annotated list of the
birds. Unpublished thesis. Cornell Univ., Ithaca, N. Y.
Lowery, G. H., Jr., and W. W. Dalquest
1951 Birds from the state of Veracruz, Mexico. Univ. of Kansas Publ. Mus. Nat.
Hist., 3:531-649.
Lowery, G. H., Jr., and R. J. Newman
1949 New birds from the state of San Luis Potosi and the Tuxtla Mountains of
Veracruz, Mexico. Occ. Papers Mus. Zool. Louisiana State Univ., 22:1-10.
Mayr, E.
1946 History of the North American bird fauna. Wilson Bull., 58:3-41.
Miller, A. H., H. Friedmann, L. Griscom, and R. T. Moore
1957 Distributional check-list of the birds of Mexico. Pacific Coast Avifauna,
No. 33.
Miranda, F., and E. Hernandez X.
1963 Los tipos de vegetacion de Mexico y su clasificacion. Bol. Soc. Bot. Mexico,
28:29-179.
SCLATER, P. L.
1857ff List of additional species of Mexican birds, obtained by M. Auguste Salle
from the environs of Jalapa and San Andres Tuxtla. Proc. Zool. Soc. London,
Part 25:201-207.
18576 On a collection of birds received by M. Salle from southern Mexico. Proc.
Zool. Soc. London, Part 25:226-230.
SHELFORD, V. E.
1941 List of reserves that may serve as nature sanctuaries of national and inter-
national importance, in Canada, the United States, and Mexico. Ecology,
22:100-110.
Skutcii, a. F.
1954 Life histories of Central American birds. Pacific Coast Avifauna, No. 31.
1960 Life histories of Central American birds H. Pacific Coast Avifauna, No. 34.
Wetmorp:, a.
1943 The birds of .southern Veracruz, Mexico. Proc. U.S. Natl. Mus., 93:215 310.
Willis, E.
1961 A study of nesting ant-tanagers in British Honduras. Condor. 63:479-503.
liUP’FAIA) MUSEUM OF SCIENCE, BUFFALO, NEW YOBK, 10 MARCH 1066.
AGE-SPECIFIC DIFFERENCES IN THE BREEDING BEHAVIOR
AND ECOLOGY OF THE AMERICAN REDSTART
Millicent S. Fickex and Robert W. Fickex
Maturation rates in birds are controlled by natural selection ( Lack.
1954: Orians. 1961: Amadou. 1964: Selander. 19651. Slow matura-
tion rates evolved in species where there is strong intraspecific competition
for food (Amadou. 1964!. species with high population densities (Orians.
1961: V ynne-Edwards. 1962 1 and in some icterid species as an outcome
of a polygamous mating svstem i Selander. 1965 ) . The American Redstart
I Setophaga ruticilla I has a slower maturation rate than other parulids. many
males not breeding until their second spring. The purposes of this paper are
( 1 I to investigate the relationship between age of males (first-year vs. older I
and type of habitat utilized, and (2) to suggest the proximate and ultimate
factors responsible for the complex relationships of plumage, behavior, and
ecology in this species and some other passerines.
The American Redstart has an extensive breeding range and in many
areas is one of the most abundant breeding birds. It is found in a variety
of habitats including willow and alder thickets, deciduous, mixed decidu-
ous and coniferous, and even primarilv coniferous forests ( Bent. 1953 1 .
The biology of the redstart is of special interest in relation to the evolution
of adaptations leading to success as measured by broad geographic range,
utilization of a variety of habitats and high population density.
METHODS
This study was conducted in two different areas. Reproductive behavior
was studied from the arrival of males until the fledging of young in a
deciduous swamp forest in Ithaca. New York. This stand was dominated by
a nearly closed canopy of mature deciduous trees and an understory of
saplings which reached 20 feet in height. Dense stands of saplings occurred
in areas where the canopy was interrupted. Redstarts occurred in both types
of habitats. Information was obtained on the relative number of first-year
males, their behavior, and mating success.
Censuses of redstarts in a variety of habitats in Maine were conducted
between 10 June and 19 June 1965. near Damariscotta (Lincoln Co.) and
in the primarily coniferous forests on Mt. Desert Island (Hancock Co.).
Since first-year males arrived later than older males, we selected the initial
date of the census late enough to insure that all breeding males had arrived.
All of the males censused behaved like territorial birds, singing loudly in a
restricted area. Although we saw the mates of some birds, both first-year
and older, it was not possible to determine the proportion of mated birds.
188
F'icken and
Ficken
REDSTART BEHAVIOR AND ECOLOGY
189
After hearing a male sing, its immediate habitat was described; then the
bird was approached and its age determined on the basis of plumage.
Habitats in Maine were classified in the following manner: (1) deciduous
forests — some trees taller than 30 feet, an understory of saplings to 20 feet
and sometimes up to 10 per cent conifers (white pine, spruce) ; (2) immature
deciduous forests — tallest trees smaller than above, understory not as well
developed and often more open ; ( 3 ) alder thickets — dense shrub growth
usually to 15 feet in height, often with some willow and other deciduous
growth; (4) mixed forest — more than 10 to 60 per cent conifers (white pine,
and/or spruce), with rest deciduous; (5) coniferous forest — more than 60
per cent coniferous, including some virtually pure spruce forest.
All the New York birds occurred in habitat categories 1 and 2; no effort
was made to distinguish between them.
OBSERVATIONS
Molt and plumage. — A hand-raised male and female were observed from
eight days of age until 10 months. The male obtained a few black spots on
the face and breast during the first pre-alternate molt in early spring but
otherwise retained a female-like plumage. This observation supports the
assertion in the literature that first-year males retain a female-like plumage
but generally with additional black feathers on the breast and chin, lores,
cheeks, or crown (Chapman, 1907). Unfortunately we were unable to follow
this male through the pre-basic molt in the fall, but according to Chapman
(1907) the adult male plumage is attained at this time. The possibility
remains that some first-year males molt into adult plumage at their first pre-
basic molt or that some males are delayed beyond the end of their first
breeding season in attaining adult male plumage. Ossification of the skull
progresses more slowly in the redstart than in most other parulids ( S. Eaton,
pers. com.). David Bridge (pers. com.) reports that there are rare cases
of males in immature plumage during the fall migration which had com-
pletely ossified skulls, indicating that at least some males do not attain adult
male plumage until their third pre-basic molt. However, for the purpose of
this study, we term males with a female-like plumage “first-year.” They
are easily distinguished from females in the field by the presence of a few
black spots.
Eirst-year females in the spring often show less yellow in the wing than
older females (Chapman, 1907) and our captive l)ird also had less vellow
on the sides of the breast. Birds with these characters which were observed
in the field were considered to be first-year females. However, it is not known
if all first-year females have this j)lumage or if older females also sometimes
do.
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THE WILSON BULLETIN
June 1967
Vol. 79, No. 2
Time of arrival on territory. — The usual order of arrival, although there
was some overlap, was older males, older females and first-year males. The
arrival time of first-year females was less certain but some arrived after
the first-year males. The delay between the mean arrival date of the older
males and first-year males was about two weeks in both New York and Maine.
Territorial behavior. — Redstarts are very aggressive and maintain rather
rigid territories, tolerating no intrusion by conspecific males ( Licken, 1962a ) .
Displays and fighting are common. The redstart is more aggressive than
several other parulids which we studied [Dendroica petechia, D. pensylvanica,
D. virens, Vermivora pinus, and V. chrysoptera) (Licken and Licken, 1965).
In New York, older males first settled on territories in tracts of mature forest.
Later, when first year males arrived, only peripheral areas, usually where the
forest was open and low in stature, were available. The young males were
usually restricted to these peripheral habitats by the aggressiveness of the
older males. Older males appeared to be more aggressive than the young;
they always won encounters with younger males.
Territory size. — Little is known about the territory size of first-year males
as compared to older males. However, in the New York study area we found
that the territory size of the two age classes was not markedly different, ex-
cept that the smallest territory observed belonged to a first-year male. Hickey
(1940 ) also noted that the territory size of the two age classes was similar.
Redstart territories are quite small when compared to those of other war-
blers (Mayfield, 1960) even those coniferous forest species during spruce
bud worm outbreaks (Kendeigh, 1947). In our New York study area they
averaged about 0.75 acres, and Hickey (1940) reports territories were one
acre or less on a “heavily wooded slope” in Westchester County, New York.
Sturm (1945) found very small territories; one group in a second growth
deciduous forest averaged 0.24 acre and another 0.16 acre. Thus deciduous
woodlands with much second growth appear to be optimal lor the species as
such habitats support the maximum population densities. However, most
territories in mixed and coniferous forests in Maine were over an acre in
size and even in the deciduous habitats many males were isolated or had only
one neighboring male in an area of several acres.
Mating success. — All older males (52) in our New York study area ob-
tained mates while only three out of 7 ( 43 per cent ) first-year males did so
(Licken, 1962a). Similarly, Sturm ( 1945) noted that only three out of 5 (60
per cent ) first-year males were mated in an Ohio woodland. However, the
four first-year males studied by Hickey (1940) obtained mates. In our New
York study area, first-year males that did not obtain mates remained only
about two weeks on territory, then left.
Floaters. — In other species of warblers it has been shown that there is a
Fickcii and
Ficken
REDSTART BEHAVIOR AND ECOLOGY
191
population of non-breeding males which will occupy territories when space
is available (Stewart and Aldrich, 1951; Hensley and Cope, 1951). First-
year male redstarts are sometimes ‘‘floaters,” at least in deciduous woodlands.
We have on several occasions seen unmated males in sub-optimal habitats in
June. Each was there for a few days and usually silent or singing only muted
song fragments. Hickey (1940) reports a first-year male that was singing
softly and was “furiously driven off by males and females whenever it
passed through their territories.” Some of these floaters may not have found
suitable areas for the establishment of territories because of the aggressive-
ness of older males. Others may have abandoned territories when they did
not obtain mates. There is also the possibility that some first-year males do
not even attempt to set up territories but are floaters from the start.
Nesting success. — We did not obtain quantitative data on nesting success
in the two age classes but have a few observations which show that pairs of
first-year birds are less successful. One such pair constructed and subse-
quently abandoned seven nests, at least twice after the female had begun
incubation. Finally, this pair left the area in late July and presumably made
no further breeding attempts that year. The cause for the nest abandonments
was not known, but this behavior was not noted in older pairs. The nest of
another first-year female was blown away by winds that destroyed no other
nests in that area. This was probably due to its insecure anchorage, since the
female had selected a two-pronged rather than a typical three-pronged crotch
< Ficken, 1964 ) .
Foraging behavior. — It is generally agreed that redstarts prefer deciduous
woodland with a good undergrowth of bushes and young trees (Chapman,
1907; Bent, 1953; Griscom and Sprunt, 1957). Redstarts forage at medium
elevations, usually between 10 and 30 feet, hut occasionally near the ground
or on low herbaceous plants ( Ficken, 19625 ) . Insects are obtained by glean-
ing, hovering, and flycatching. Flycatching makes up over 80 per cent of
the foraging patterns before the leaves are out in May, hut the other patterns
are more prevalent as the season progresses.
Relation oj age and habitat. — The relative number of first-year territorial
males in deciduous woodlands in New York and Ohio is surprisingly small,
averaging 12 per cent in the three studies with large samples of birds (Table
1). Table 2 shows the incidence of first year males in a variety of Maine
habitats. Deciduous forests in Maine contain a higher percentage of first-
year males than do deciduous forests in New York and Ohio hut are com-
})arable to the findings for Michigan. There are differences in the frecpiencN
of first-year males in different habitats in Maine. First-year males are least
common in alder thickets and relatively mature deciduous forests and
more common than older males in immature deciduous. mi\(‘d. and coniferous
192
THE WILSON BULLETIN
June 1967
Vol. 79, No. 2
forests. The difference between the number of first-year males in deciduous
and mixed forests is statistically significant (P<0.05) while that between
alder and deciduous is not ( P > 0.05 ) . Numbers were insufficient for a
statistical analysis of mixed vs. coniferous and deciduous vs. immature de-
ciduous forests.
The distribution of the two age classes of redstarts in Maine habitats ap-
pears to be related to the amount of deciduous foliage. Habitats which have
a high deciduous foliage density in the vertical foraging range of the redstart
are alder and mature deciduous. Immature deciduous (often more open I
and mixed woodlands are intermediate. Of course, forests consisting of more
than 60 per cent conifers have the lowest deciduous foliage density. The
frequency of first-year males parallels this foliage density, being higher
where the deciduous foliage density is lower. MacArthur et al. (1962)
suggested that species abundance in birds is related to the foliage density of
vegetation in deciduous forests and this example shows that age classes
within a species may also be so related.
DISCUSSION
Our hypothesis is that originally, before the evolution of a special plumage,
first-year males had lower reproductive success than older males. Such a
situation exists in many birds and is probably widespread (e.g., Nice, 1937;
Snow, 1958; Coulson and White, 1958; Wynne-Edwards, 1962). For ex-
ample, in Song Sparrows [Melospiza rnelodia) first-year males often arrive
later than older males, are less aggressive, and in many cases their females
lay fewer eggs than older ones (Nice, 1937).
With intense intraspecific competition, those individuals which were the
least efficient would produce too few young to balance the “expense” of
breeding. Selection would favor a system for lowered reproduction in young
birds if this led to enhanced reproductive success in subsequent years. The
first evolutionary step is probably the establishment of a hormonal mecha-
nism. Some support for this is found in studies of Red-winged Blackbirds
{Agelaiiis plioeniceus). Testes of first-year males, which usually do not
breed, attain their maximum development three weeks after older males. Also
their maximum size is only two-thirds that of older males, although they do
undergo spermatogenesis ( Wright, 1944 ) . A lowered hormone level and a
delay in testes development might have many effects in first-year birds in-
cluding lowered aggressiveness, later arrival on the breeding grounds and
retention of a female-like plumage.
In many species molt into breeding plumage is at least partly controlled
by androgens (Witschi, 1961). Miller (1933) suggested that the great vari-
ability in melanin deposition in first-year male Phainopeplas ( Phainopepla
Ficken and
Fieken
REDSTART BEHAVIOR AND ECOLOGY
193
Table 1
Percentage of Territorial First-Year Males in Deciduous Habitats
Per cent territorial
first-year males
Total number
of males
Habitat
Reference
12
59
deciduous — N. Y.
Ficken, 1962a
0
10
mixed— N. Y.
Kendeigh, 1945
8
48
deciduous — N. Y.
Hickey, 1940
29
7
deciduous — Mich.
Baker, 1944
15
34
deciduous — Ohio
Sturm, 1945
nitens ) was due to a variable amount of testicular hormone at the time of
the molt. The possession of a female-like plumage in first-year males which
do not breed probably has not been selected for directly but is the outcome
of selection for slower maturation ( Orians, 1961 ) . The plumage of the first-
year male redstart seems to confer no direct advantage in the competitive
situation with older males since first-year males are reacted to just as aggres-
sively as older males. Male redstarts also react very aggressively toward
females initially (Ficken, 1963) and this again illustrates that a female-like
plumage is reacted to aggressively. Since first-year males sing, this probably
enhances their aggressive releasers as compared to females. In Orchard
Orioles [Icterus spuriiis) which also have a female-like plumage their first
year ( but it is not known what proportion of first-year males breed ) fights
between first-year and older males are intense, although the species is in
general non-territorial (Dennis, 1948). Thus, first-year male plumage in this
species as well apparently does not reduce aggression by other males. It
might be expected that it would be advantageous for floaters not to be re-
acted to aggresively by other males, but as Hickey (1940) observed, redstart
floaters are attacked despite their plumage. However, a female-like plumage
is much more cryptic than the red and black of the adult male, at least to the
human observer, and this crypticity might be of value in reducing predation
on first-year males.
Later arrival may lead either to failure to procure a mate or to mating
with first-year females. Since first-year males arrive later than most females,
mating may be partly a matter of availability of females at the time of
arrival of males. However, other factors are probably involved. Females
may not be as sexually responsive to males in a female-like plumage. Also
the lowered aggressiveness of first-year males may reduce chances of pairing
since an initial strong aggressive response of the male toward the female ma\
be necessary for pair formation to occur in this species (Ficken. 1963).
Late arrival may contribute to the inability of first-year males to compete
successfully with older males in several wavs. One is that often all suitable
]94
THE WILSON BULLETIN
June 1967
Vol. 79, No. 2
Table 2
Frequency of Territorial First-Year Male Redstarts in a Variety
OF Habitats in Maine
Habitat
Total no. of males
No. of first-
year males
Percentage of
first-year males
Alder
14
1
7
Deciduous
14
3
21
Immature deciduous
7
5
71
Mixed coniferous-deciduous
15
9
60
Coniferous
11
9
82
territories are occupied. Another is that all older males are recently mated
and territorial aggressiveness seems to reach its peak at just that time ( Ficken,
1962a ) so they are likely to be more aggressive to first-year males than they
were to each other initially.
The reduced aggressiveness of the first-year males probably also affects
their ability to obtain suitable territories. Experience plays a part in success
in aggressive encounters of many animals (Scott, 1958), and lack of experi-
ence probably reduces success in encounters between first-year and older
male redstarts. The inability to compete successfully with older males prob-
ably leads to some wandering and males either become floaters or sub-
optimal habitats are found and territories are established there where com-
petition with other males is reduced or absent. First-year male redstarts are
more often found in late spring outside their normal breeding range in Cali-
fornia than are older males ( Root, 1962 ) , indicating that the young males are
probably the pioneers in range and habitat extensions. The utilization of sub-
optimal habitats probably reduces breeding success further. One way may be
through reduction of the amount of food available since the deciduous foliage
density is lower. In some species choice of a mate by the female is at least
partially determined by the quality of the habitat of potential mates (Verner,
1963; Tompa, 1962). If this is true in the redstart, mating success will be
further reduced by the possession of territories in sub-optimal habitats.
Thus the ultimate cause of the interrelated effects of female-like plumage,
low reproductive success, less aggressive behavior and utilization of sub-
optimal habitats is selection against breeding of what were originally slightly
less successful birds. The question naturally arises as to why first-year males
attempt to breed at all. However, if they breed where they are not competing
with older males, and even some small fraction is successful, this would be ad-
vantageous. Also, there may be much learning necessary for reproductive
success. By attempting to breed or just getting through some of the stages
Ficken and
Ficken
REDSTART BEHAVIOR AND ECOLOGY
195
of breeding, first-year males may have a better chance for breeding in sub-
sequent years as a result of this experience ( Selander, 1965 ).
Many aspects of the redstart system are not unique. Wynne-Edwards
( 1962) has pointed out that slow maturation rates are often found in species
with high population densities. However, he postulates a system based on
group selection while it probably can best be explained by natural selection
at the individual level ( Amadon, 1964; Selander, 1965 ), as a result of the
system older and more experienced breeders having reduced competition for
territories. Orians (1961) studied the population structure of blackbirds
[Agelaius phoeniceus and A. tricolor) and extended his conclusions to other
species as well. He suggested that slow maturation of first-year males is
“characteristic of species in which breeding sites are limited. Probably
these are all species which are ineffectively controlled between breeding
seasons so that surpluses of breeding birds are regularly present.” Selander
( 1965 ) , from his studies of polygamous Cassidix species suggests that “be-
cause the probability of a young male obtaining mates in competition with
older experienced males is very low, males which postpone breeding may
ultimately have greater reproduction; and through selection first-year males
have become adaptively ‘handicapped’ physiologically and morphologically
in competition with adult males for mates.”
Delayed maturation occurs in some icterids ( Orians, 1961 ; Selander,
1965) and although in some cases it seems to be associated with a high
population density the situation is further complicated by the type of mating
system, delayed maturation being more common in non-monogamous species,
although this is probably a consequence rather than a cause of delayed
maturation (Selander, 1965). For example, delayed maturation occurs in
the grackles Cassidix major and C. mexicanus which have a plumage
intermediate between the juvenile-female and the adult male, and the males
do not breed until their second year (Selander, 1965). The Red-winged
Blackbird (Agelaius phoeniceus), the Tricolored Blackbird (A. tricolor],
and the Yellow-headed Blackbird (Xanthocephalus xanthocephalus) bave
delayed maturation, are colonial with high breeding densities and breeding
sites are at a premium in some localities. Male Red-winged Blackbirds do
not normally breed until two years of age, although first-year males may
occur at the periphery of the colony. Some obtain territories and a few
breed. In the Tricolored Blackbird yearling males regularly establish ter-
ritories, but as in the redstart they are crowded into the less desirable sites
and are less successful in obtaining mates (Orians, 1961).
Orians’ hypothesis of a relationshij) between high breeding po|)ulation
densities and delayed maturation seems to be a|)plicable to eases where there
is little information available on breeding behavior. For exam|)le. a dela\
196
THE WILSON BULLETIN
June 1967
Vol. 79, No. 2
in attaining adult male plumage occurs in the Orchard Oriole [Icterus
spurius) but not in the Baltimore Oriole (/. galbula) , and the Orchard Oriole
seems to have intense intraspecific competition in some areas. For example,
Dennis (1948) reports that males of this species are not territorial and one
population which he studied attained a density of 114 males in 7 acres, with
as many as 20 nests in one tree. The femaledike plumage of first-year male
crossbills Loxia curvirostra and L. leucoptera may also be related to locally
high population densities in these semicolonial breeders. First-year male
Purple Martins [Progne subis ) differ in plumage from older males. This
species nests in colonies, and there is probably also a shortage of nest sites.
The species with delayed maturation which we have discussed are those
in which there is a color difference between the age classes and non-breeding
first-year males are more noticeable. However, there are cases such as that
noted by Selander ( 1964) where some species of the wren genus Campylorhyn-
clius breed the first year while others do not. Whether this is related to breed-
ing population densities and intraspecific competition is not known.
The evolution of delayed maturation rates in birds might be expected more
commonly in species with a long life span as is the case with certain sea
birds, many of which do not breed until they are several years old (e.g.,
Wynne-Edwards, 1962 ). These species also often have high population den-
sities. In such species the enhancement of breeding success in older birds by
reduced competition with younger ones would occur over several breeding
seasons, although there are undoubtedly many other variables influencing
their reproductive success. However, it is probably not surprising that rela-
tively few of the small passerines, with their relatively short life span, have
evolved such a system.
Our findings also have implications for studies of habitat “preference.”
The habitat difference between first-year and older males is obviously not
innate. However, in the species as a whole there is probably an innate basis,
although with learning also involved, for responding only to certain types
of habitats. Even first-year males are selective, and are not found breeding
in just any habitat. It is misleading to refer to a “preference” or “selection”
in the case of first-year redstarts. They often seem to initially occupy
habitats where older males are also breeding but through competition must
go elsewhere. It would seem advantageous for a species to be somewhat
flexible and to be able to respond to a variety of habitats ( Svardson, 1949).
Thus the redstart has evolved a system of interrelated physiological, be-
havioral, and ecological adaptations which are related to intraspecific com-
petition and to its extensive and diverse geographic range and which con-
tribute to making it one of the most successful North American passerines.
Ficken and
Fickcn
REDSTART BEHAVIOR AND ECOLOGY
197
Other species with intense intraspecific competition may have similar systems,
although differing in some respects from that proposed for the redstart.
SUMMARY
First-year male American Redstarts are relatively uncommon as compared to older
males as breeders in deciduous forests in the eastern and central United States. How-
ever in Maine they occur more frequently than older males in suh-optimal habitats.
In New York first-year males arrive later than older males, are less aggressive and
consequently at a disadvantage in competing with older males for territories in optimal
habitats. They are also less successful in obtaining mates, at least partly due to their
later arrival. A system is proposed to explain the interrelated effects of a female-like
plumage, late arrival, lowered aggression, and use of sub-optimal habitats. It is sug-
gested that delayed maturation, probably involving a lowered androgen level, evolved
as a result of intense intraspecific competition in this species, and that selection acts
against first-year males breeding in optimal habitats. Other passerines in which first-
year males differ in plumage from older males also have high population densities
and were probably subjected to similar selective pressures.
ACKNOWLEDGMENTS
This study was aided financially by a Sigma Xi Grant-in-Aid and by National Science
Foundation Grant GB-3226. We wish to thank Douglass H. Morse and Richard Root
for their criticisms of the manuscript and Stephen Eaton and David Bridge for their
unpublished data.
LITERATURE CITED
Amadon, D.
1964 The evolution of low reproductive rates in birds. Evolution, 18:105-110.
Baker, B. W.
1944 Nesting of the American Redstart. W ilson Bull., 56:83-90.
Bent, A. C.
1953 Life histories of North American wood warblers. V.S. Natl. Mus. Bull., 203.
Chapman, F. M.
1907 The warblers of North America. Appleton and Co., New \ork.
CoULSON, J. C., AND E. WlIITE
1958 The effect of age on the breeding biology of tbe Kittiwake Hissa tridactyla.
Ibis, 100:40-51.
Dennis, J. V.
1948 Observations on the Orchard Oriole in lower Mississippi delta. Bird-Banding.
19:12-21.
Ficken, M. S.
1962r/ Agonistic behavior and territory in the American Redstart. Auk, 79:607-632.
19626 Maintenance activities of the American Redstart. WA'lson Bull., 74:153 165.
1963 Courtship of the American Redstart. Auk, 80:307-317.
1964 Nest-site selection in the American Redstart. W ilson Bull., 76:189.
Ficken, M. S., and R. W. Ficken
1965 Comparative ethology of the Yellow Warbler, (4iestnut-sided Warbler and
American Redstart. W' ilson Bull., 77:363-375.
198
THE WILSON BULLETIN
June 1967
Vol. 79, No. 2
(/HISCOM, L., AND A. SpRUNT
1957 The warblers of America. Devin-Adair Co., New ^ork.
Hensley, M. M., and J. B. Cope
1951 Further data on removal and repopulation of the breeding birds in a spruce-
fir forest community. Auh, 68:483-493.
Hickey, J. J.
1940 Territorial aspects of the American Redstart. Auk, 57:255-256.
Kendeigh, S. C.
1945 Nesting behavior of wood warblers. WAlson Bull., 57:145-164.
1947 Bird population studies in the coniferous forest biome during a spruce bud-
worm outbreak. Biol. Bull. No. 1, Dept, of Lands and Forests, Ontario,
Canada.
Lack, D.
1954 The natural regulation of animal numbers. Oxford Lniv. Press, Oxford.
MacArtiiur, R. H., j. W. [MacArthur, and J. Freer
1962 On bird species diversity. II. Prediction of bird census from habitat measure-
ments. Amer. Nat., 96:167-174.
Mayfield, H.
1960 The Kirtland’s Warbler. Cranbrook Inst. Science, Bloomfield Hills, Michigan.
Miller, A. H.
1933 Postjuvenal molt and the appearance of sexual characters of plumage in
Phainopepla iiitens. Unit. California Puhl. Zool., 38:425-446.
Nice, M. M.
1937 Studies in the life history of the Song Sparrow\ I. Trans. Linnaean Soc.
New York.
Orians, G. H.
1961 The ecology of blackbird iAgelaius) social systems. Ecol. Monogr., 31:
285-312.
Root, R. B.
1962 Comments on the status of some western specimens of the American Red-
start. Condor, 64:76-77.
Scott, J. P.
1958 Aggression. Univ. Chicago Press, Chicago.
Selander, R. K.
1964 Speciation in wrens of the genus Campylorhynchus. Univ. California Publ.
Zool, 74:1-289.
1965 On mating systems and sexual selection. Amer. Nat., 99:129-141.
Snow, D. W.
1958 The breeding of the Blackbird Turdus merula at Oxford. Ibis, 100:1-30.
Stewart, R. E., and J. W. Aldrich
1951 Removal and repopulation of breeding birds in a spruce-fir forest community.
Auk, 68:471-482.
Sturm, L.
1945 A study of the nesting activities of the American Redstart. Auk, 62:189-206.
Syardson, G.
1949 Competition and habitat selection in birds. Oikos, 1:157-174.
Tompa, F. S.
1962 Territorial behavior: the main controlling factor of a local Song Sparrow
population. Auk, 79:687-697.
Ficken ami
Ficken
REDSTART BEHAVIOR AND ECOLOGY
199
Verner, J.
1963 Song rates and polygamy in the Long-billed Marsh Wren. Proc. 13th Internatl.
Ornith. Congr., 299-307.
WiTSCHI, E.
1961 Sex and secondary sexual characters, p. 115-168. In: Marshall, A. J. (ed.).
Biology and comparative physiology of birds. Academic Press, New York.
Wright, P. L., and M. H. Wright
1944 The reproductive cycle of the male Red-winged Blackbird. Condor, 46:46-59.
Wynne-Edwards, V. C.
1962 Animal dispersion in relation to social behaviour. Oliver and Boyd, Edin-
burgh.
DEPARTMENT OF ZOOLOGY, UNIVERSITY OF MARYLAND, COLLEGE PARK, MARY-
LAND, 5 FEBRUARY 1966.
JOSSELYN VAN TYNE MEMORIAL LIBRARY
The following gifts have been recently received. From:
Oliver L. Austin, Jr. — 1 journal
Andrew J. Berger — 3 reprints
C. T. Black — 40 journals, 5 reprints
R. K. Brooke — 3 reprints
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tions
S. C. Kendeigh — 2 reprints
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phlets, 62 reprints
John L. Zimmerman — 2 reprints
AN EC01,0GICAL STUDY OF WINTER FLOCKS OF BLACK-
CAPPED AND CHESTNUT-BACKED CHICKADEES
Susan M. Smith
Most living species have developed special adaptations A\hich enable
them to fit into a particular mode of life, or niche. Two closely
related species are very likely to have similar structural features, behavioral
responses, and so on. which lead to correspondingly similar ecological re-
quirements. The more closely related two symatric species are, the more
need there will be for differences to evolve which will keep their modes of life
separate and prevent overlap of requirements.
Ecological isolation is important to closely related avian species for two
reasons. By avoiding niche overlap, interspecific competition is practmally
eliminated. Secondly, ecological isolation reduces the possibility of hybridiza-
tion. As hybrids tend to have reduced viability and will be poorly adapted
to either parental niche, hybridization, as shown by many writers, is selected
against.
Several differences have evolved among closely related sympatric passerines
which aid in preventing ecological overlap. Differences in anatomy such as
the leg muscles of the Goldcrest ( Regiihis regulus I and the Willow Tit ( Parus
montanus) I Palmgren, 19321. or the beak shape of Eurasian tits (Snowy
195461 prevent overlap of feeding niche. Differences in color, voice, and
behavior (especially reproductive behavior I also serve to separate closely
related species.
Peterson, Mountfort. and Hollom (19541 list nine species of the genus
Parus in Europe, six of which occur in Great Britain. Many of these are
sympatric over much of their range. European studies on the comparative
ecology of these titmice have shown that each of them has evolved its separate
niche enabling it to live in close contact with other tit species, >et at the
same time avoid serious interspecific competition (Gibb, 1954; Haftorn,
1956: Hartley, 1953: Snow. 1954u, 19546; and others).
Xearctic titmice have not developed nearly this degree of SYinpatr). Hoi\-
ever, along the Pacific coast of North America the ranges of the Black-
capped Chickadee i Parus atricapillus) and the Chestnut-backed Chickadee
[Parus rufescens) overlap. In describing the habitat of the Black-capped
Chickadee in California, Grinnell and Miller ( 1944 ) write “Chiefly deciduous
timber, especially willows and alders, along large or small water courses.”
Gabrielson and Jewett (1940) write of it in Oregon: “. . . The Oregon
Chickadee replaces the Chestnut-backed Chickadee in the cottonwood bot-
toms.” Jewett, Taylor, Shaw and Aldrich (1953) write of it in Washington:
“Tree alders and deciduous woods are favorite foraging grounds ...”
200
Susan M.
Sinitli
CHICKADEE WINTER ECOLOGY
201
The habitat of the Chestnut-backed Chickadee seems to be somewhat dif-
ferent. Grinnell and Miller (1944) describe its habitat in California as
“Coniferous forest and adjacent woodland.” Jewett et al. (1953) write of it
in Washington: “While preferring the dense shade of the coniferous forests
of the Pacific coastal belt to any other habitat, the chestnut-backed chickadee
is found rather broadly through the timbered sections . . . ordinarily it re-
mains high in the trees . . .” While these descriptions indicate a general
difference in the habitat of these two species, no more specific analysis of
this seems to have been made.
In Vancouver, British Columbia, it is possible to find both of these species
living side by side. They even forage in mixed flocks during the winter.
This study has been conducted on winter flocks of these species in an attempt
to find factors producing ecological isolation between them.
Field work was carried out on an area of mixed second growth forest
adjacent to the University of British Columbia campus, and covering ap-
proximately 0.75 square miles. The vegetation of the area can be classified
as the wet subzone of the Coastal Douglas Fir Zone, with transitional char-
acteristics of the Coastal Western Hemlock Zone (Krajina, pers. comm.).
Based on a strip survey made on a portion of the study area, the vegetation
is 55.4 per cent deciduous and 44.6 per cent coniferous. The main conifers are
Douglas-fir iPseudotsuga menziesii) , western hemlock {Tsug,a heterophylla) ,
red cedar {Thuja plicata), and grand fir {Abies grandis). Broad-leafed
maple {Acer macrophyllum) and red alder {Alnus rubra) make up virtually
all the deciduous trees on the area, and the main shrubs are redberry elder
iSambucus pubens), thimbleberry and salmonberry {Rubus spp. ) .
Observations were made at least once weekly, for two to four hours each
time, from 21 September 1962 to 15 March 1963. When a flock of chickadees
was found, its size and composition were noted. A separate record was made
for each feeding chickadee including the following information: species,
height above ground, height and species of feeding site, and position within
the feeding site.
RESULTS
Although feeding in the same area, individuals of the two species showed
definite differences in selection of feeding sites. One of the main differences
was in the type of tree chosen (Table 1). There are slightly more than 3.5
times as many records of Black-capped Chickadees in deciduous as in conif-
erous trees, while there are more than five times as many records of Chestnut-
hacked Chickadees in coniferous as in deciduous trees.
The second major difference in the feeding behavior of the two species
was found to be in the choice of height of the feeding site. Figure 1 shows
202
THE WILSON BULLETIN
June 1967
Vol. 79, No. 2
Frequency
Table 1
OF Records in the Three Main
Feeding Sites
Black-capped Chickadee
Chestnut-backed Chickadee
Coniferous trees
21.0 per cent
84.1 per cent
Deciduous trees
76.4 per cent
15.9 per cent
Ground
2.6 per cent
Number of records:
598
327
the percentages of each species’ records at various distances above the ground.
This shows a definite separation of the two species. The peak of the Black-
capped Chickadee records occurs at the 0-5 foot class, and no Black-capped
Chickadee was recorded above 70 feet: while the peak of the Chestnut-backed
Chickadee records occurs at the 45-50 foot class, and 12.0 per cent of the
records are for above 70 feet. Application of the Student’s t-test has shown
these peaks to be significantly different at the 0.01 level.
Figure 2 shows the percentage of records of each species at various
distances from the top of the feeding site. In this figure no records of birds
in Rubus spp. were included, since these shrubs are seldom over five feet
hish. so that virtually all records for these sites would fall in the class of five
felt or less from the top of the site. As seen from the figure, there is very
little difference between the two species in this respect, although a slightly
larger percentage of Chestnut-backed (28.9 per cent) than of Black-capped
( 22.0 per cent ) Chickadees was found five feet or less from the top of the
feeding site. During the study, flocks of chickadees were frequently observed
travelling at a fairly uniform height above ground, often seemingly regardless
of the height of tree through which they were passing. Thus in this study
area this factor is possibly of less value in maintaining ecological isolation
between the two species than is the height above ground.
Table 2 shows the percentage of records of each species with regard to
their position within the tree. Both species spent the majority of their time
in the thin outer twigs of trees. However, Chestnut-backed Chickadees were
seen foraging on “thick” ( i.e. two inches or more in diameter) branches less
often than were Black-capped Chickadees, while 4.1 per cent of the records
of Black-capped Chickadees are for gleaning on the main trunk, but there
are no records of Chestnut-backed Chickadees gleaning on this position. Both
species were seen feeding on conifer seeds directly from the cones m western
hemlocks and Douglas-firs: these records were considered as “thin branches
in Table 2.
“Mixed flocks” (those containing both species of chickadees moving to-
aether I were commonly seen during the study, being observed on all but
Susan M. CHICKADEE WINTER ECOLOGY 90S
Smith
HEIGHT (feet)
Fig. 1. Comparison of feeding heights of Black-capped and Chestnut-backed chicka-
dees.
five days. The average mixed flock consisted of 11.8 Black-capped and 7.7
Chestnut-lDacked chickadees. The average number of chickadees in a pure
flock of Black-capped Chickadees was 8.7, and the average number in a
pure flock of Chestnut-backed Chickadees was 8.T. Thus it seems likely
that mixed flocks are relatively unstable units made up of two chickadee flocks.
Neither species seemed to be influenced by the presence or absence of
members of the other species, in either their choice of type or of height of
feeding site. No significant difference between pure and mixed flocks was
found in either consideration.
Very little aggression of any kind was observed during this study. In-
traspecific aggression was observed three times among Black-capped Chicka-
dees, and only once among Chestnut-backed Chickadees. However, at no
time during the study period was any aggression observed between the two
chickadee species.
During the study period no extremes in weather occurred. I here was no
correlation between the date of the records and the average height of the
records, or of choice of type of feeding site.
204
THE WILSOX BULLETIX
June 1967
Vol. 79. No. 2
DISTANCE FROM TOP OF TREE (feet)
Fig. 2. Comparison of distance from top of feeding site of Black-capped and Qiest-
nut-backed chickadees.
DISCUSSION
There are seven species of chickadees, i.e. members of the subgenus Poecile
of the genus Parus (Dixon. 19611 in Xorth America. Lnlike the palearctic
parids, most of these are allopatric. the most notable exception being the
sympatry of the Black-capped and Boreal ( P. hudsonicus i chickadees. These
two species are the only Xorth American chickadees with continent-wide
range, and there is a broad overlap in their occurrence.
Lack ( 19441. Dixon 1 1954. 1961 1, and others have stressed the importance
of adjustments in behavior, especially feeding behavior, if two similar forms
are to coexist in the same area. Dixon 1 1961 1 writes that the Boreal Chicka-
dee is reported to forage higher in the trees than the Black-capped Chickadees
Susan M.
Smith
CHICKADEE WINTER ECOLOGY
205
Frequency of
Table 2
Records at Various Positions Within the Tree
Trunk
Thick branches
Thin branches
Black-capped Chickadee
4.1 per cent
2.8 per cent
93.1 per cent
Chestnut-backed Chickadee
—
1.2 per cent
98.8 per cent
do. He also shows that there are marked differences in the habitat preferences
of these two species, and he suggests that this is their principal means of
ecological isolation. Most writers agree that the preferred habitat of the
Black-capped Chickadee is open deciduous or mixed forest. On the other
hand, the Boreal Chickadee, like the Chestnut-backed Chickadee, is most
numerous in moist shaded coniferous forest (Dixon, 1961). This similarity
of habitat choice between the Chestnut-backed and Boreal chickadees was
a major factor in Grinnell’s (1904) postulating that they both arose from
a common ancestor which he named Parus prehudsonicus.
Apart from the Black-capped and the Boreal chickadees, the pair with the
greatest range overlap seems to be the Black-capped and the Chestnut-backed
chickadees, for the former occurs over much of the latter’s range. In this
study it was found that in winter flocks of these two species there are marked
differences in feeding behavior, which are very similar to those observed
between the Black-capped and Boreal chickadees. Dixon (1961) writes that
the Black-capped and Boreal chickadees seem to have achieved the closest
approach to “ecologic compatibility” of any pair of North American chicka-
dees. The data of this study suggest that a similar ecologic compatibility
exists between the Black-capped and the Chestnut-backed chickadees, which
is achieved by essentially the same differences, i.e. tree species selection and
height selection of the feeding sites. This separation is naturally augmented
by differences in color and in voice. It is interesting to note that the tone
of the Boreal Chickadee is reported to be very similar in quality to that of
the Chestnut-backed Chickadee.
It cannot be said from these data that there is competitive exclusion or
habitat adjustment as a result of overlap in range of these species. These
differences in feeding habits probably do apply equally well to areas where
only one of these two species occurs. Studies on Chestnut-backed Chickadees
on Pacific coastal islands such as Vancouver Island ( vvhere no Black-capped
Chickadees occur ) may throw some light on this matter. More work is also
necessary to find out whether these differences occur during other seasons
of the year. Nevertheless, these differences may well be the major factors
which allow stable range overlap of these two species.
206
THE WILSON BULLETIN
June 1967
Vol. 79, No. 2
SUMMARY
W inter flocks of Black-capped and Chestnut-hacked chickadees were studied in an
attempt to find factors producing ecological isolation between the two species.
Two major differences were observed between these chickadees. Although the study
area woods were approximately 50 per cent deciduous and 50 per cent coniferous, 76
per cent of the feeding records of Black-capped Chickadees were in deciduous trees,
while 83 per cent of the Chestnut-backed Chickadee records were in coniferous trees.
Secondly, the peak of records of Black-capped Chickadees was between 0 and 5 feet
above the ground; that of Chestnut-hacked Chickadees was between 45 and 50 feet
above the ground.
Black-capped Chickadees were recorded foraging on thick branches and main trunks
slightly more often than were Chestnut-hacked Chickadees. Black-capped Chickadees
were also recorded feeding on the ground in 2.5 per cent of the records: there were no
records of Chestnut-backed Chickadees feeding on the ground.
Being in mixed flocks had no significant effect on either species, for any measured
variable. No interspecific aggression was observed.
It is suggested that the differences between the two species' choice of kind and
height of feeding site are major factors in maintaining ecological isolation between these
species in areas of sympatry.
ACKNOWLEDGMENTS
I am grateful to Dr. M. D. F. Udvardy, for his suggestions on the problem as well
as his criticism of the manuscript. Thanks are also due to Dr. V. Krajina and Dr. L.
Orloci for information on the vegetation of the study area, and advice on the methods
of its survey. In addition I would like to thank Dr. D. H. Chitty for ideas derived from
personal communications.
LITERATURE CITED
Dixon, K. L.
1954 Some ecological relations of chickadees and titmice in central California.
Condor, 56:113-124.
1961 Habitat distribution and niche relationships in North American species of
Parus. In : Vertebrate Speciation. a University of Texas Symposium. W. F.
Blair, Ed. University of Texas Press, Austin.
Gabrielson. I. N., AND S. G. Jewett
1940 Birds of Oregon. Oregon State College Press, Corvallis.
Gibb. J.
1954 Feeding ecology of tits, with notes on Treecreeper and Goldcrest. Ibis,
96:513-543.
Grinnell, J.
1904 The origin and distribution of the Chestnut-hacked Chickadee. Auk. 21:364-
382.
Grinnell, J.. and A. H. Miller
1944 The distribution of the birds of California. Pacific Coast Avifauna, 27:1-608.
Haftorn, S.
1956 Contribution to the food biology of tits especially about storing of surplus
food. Part IV. A comparative analysis of Parus atricapillus L., P. cristatus
L. and P. ater L. Xorsk. J'idensk. Selsk. Skr., 4:1-54.
Susan M.
Smith
CHICKADEE WINTER ECOLOGY
207
Hartley, P. H. T.
1953 An ecological study of the feeding habits of the English titmice. J. Anim.
EcoL, 22:261-288.
Jewett, S. G., W. P. Taylor, W. T. Stiaw, and J. W. Aldrich
1953 Birds of Washington State. University of Washington Press, Seattle.
Krajina, V. J.
1959 Bioclimatic zones in British Columbia. University of British Columbia
Botanical Series, No. 1.
Lack, D.
1944 Ecological aspects of species-formation in passerine birds. Ibis, 86:260-286.
Palmgren, P.
1932 Zur Biologic von Regulus regii/ns regulus Linnaeus und Petrus atricapillus
Selys. Eine verglichend-okologische Untersuchung. Acta Zoologica Fennica,
14:1-113.
Peterson, R. T., G. Mountfort, and P. A. D. Hollom
1954 A field guide to the birds of Britain and Europe. Collins, London.
Snow, D. W.
1954« Trends in geographical variation in palearctic members of the genus Pants.
Evolution, 8:19-28.
19546 The habitats of Eurasian tits ( Pants spp.). Ibis, 96:565-585.
DEPARTMENT OF ZOOLOGY, UNIVERSITY OF BRITISH COLUMBIA, VANCOUVER 8,
BRITISH COLUMBIA, CANADA. (PRESENT ADDRESS: DEPARTMENT OF ZOOLOGY,
UNIVERSITY OF VFASHINGTON, SEATTLE, WASHINGTON 9810,5), 31 JANUARY
1966.
BREEDING BIOLOGY AND ECOLOGY OF THE HORNED
LARK IN ALPINE TUNDRA
XlCOLAAS A. M. Verbeek
Aspects of the breeding biology of the Horned Lark { Eremophila
alpestris) are reported by Kelso l 1931 L Dubois (1935, 1936)
and Bent t 1942 1 . DuBois' and Kelso’s studies dealt with prairie-nesting
populations. The study here reported was conducted in alpine tundra during
the summers of 1963 and 1964. Data were collected incidental to a study of
the Water Pipit (Anthus spinoletta) (Verbeek, MS). In the summer of
1963 little time was spent on the larks and only four nests were located.
In 1964. larks were much more abundant and 12 nests were located, 11 of
which were on the study area proper and one outside.
STUDY AREA
The study area < Fig. 1) consisted of about 116 hectares of alpine meadow about one
km XE of Beartooth Pass on the Beartooth Plateau, Park County. Wyoming. A detailed
description of the vegetation and geologv' of the Plateau is given by Johnson and
Billings 1 1%2 ) . The average altitude was about 3.200 m. The Beartooth Highway
houndTd the study area on the south and the edge of the plateau above Rock Creek
Canyon formed the western boundary. On the east. Pipit Hill, so named by us, formed
part' of the study area up to about 3.262 m. The face of Pipit Hill was a dry meadow,
although in places, below pockets of snow, there were isolated areas of moist meadow.
‘Scattered along the face of the hill were rock outcrops, rock polygons and solifluction
terraces. On the north, the boundary ran about 100 m north of the main channel
which drained the whole area. This main channel had a maze of narrow branches,
manv of which were drv toward the end of the season. Frost hummocks were char-
acteristic of this wet area. The vegetation consisted of plants such as Salix planifolw,
Sediim rhodanthunu and Caltha leptosepala. Besides the low wet area in the north
and Pipit Hill, there was the Central Ridge running through the center of the area
and West Hill’ in the southwest. The Central Ridge and West Hill both had areas
with fellfield characteristics such as cushion plants and much exposed rock and gravel
on the western exposure. Extensive snow accumulation areas between Pipit Hill and
the Central Ridge and between the latter and West Hill were bare except for some
sparse vegetation in late summer when the snow had melted from part of these areas.
TERRITORY AND HABITAT
The larks occupied the whole study area and their nests were located m
all cover types except exposed snow accumulation, frost hummocks and T\et
meadow. The distribution of the nests is shown in Figure 1. For each of
11 nests in 1964, I noted the plants growing within a 30 cm radius of the
nests (Table 1 1 . The nests are placed in one of four categories: ( a I Fellfield
nests, characterized by cushion plants and exposed rock, (b) Di} Xleadois
nests, characterized by a general absence of cushion plants; (c) Moist
208
Nicolaas A. \I.
Verbeek
HORNED LARK BREEDING BIOLOGY
209
r I DRY MEADOW MOIST MEADOW SNOW
GZH] WET MEADOW RW1 FELLFIELD ^^ACCUMULATION
Fig, 1. Distribution of nests of the Horned Lark found in 1%3 (dots) and in 1%4
Lipen circles). The sifuares are suspeiUed locations of nests in 1964. (iontour lines
are 12.2 m apart.
210
THE WILSON BULLETIN
June 1967
Vol. 79, No. 2
Meadow nests, characterized by moisture loving plants such as Carex
scopulorum; and (d) an intermediate type between Dry and Moist Meadow.
Of all the nests, including those of 1963, nine were located in a dry habitat,
five in a moist habitat and one in an intermediate type. The presence of
five nests in a moist habitat is unusual since heretofore lark nests have been
associated only with dry and gravelly sites. Two nest territories and the
areas occupied by 22 pairs reported by Drury ( 1961 ) were all located
in the most exposed places “where most of the surface was tan angular rock.”
Pickwell (1931) writes: “The Prairie Horned Lark selects the bleakest
barrens available” and he feels that bare ground is the most essential con-
dition required. The fact that nests were found in moist habitat in both
years eliminates the possibility of increased population pressure in 1964
forcing the birds to occupy less favorable habitat. It seems that in an alpine
population of this species, a wider range of habitat is utilized.
Horned Larks have very large territories. Besides the 11 nests found in
1964 there were at least four more known territories the nests of which were
not located. Because large areas on the study plot were not suitable lark
habitat, it is not possible to calculate the average size of each territory by
simple division. The average distance between two nests in the same con-
tinuous habitat type, for instance between N16 (Nest 16) and N8, and
between N8 and N7, etc., was about 142 m. If we take the nest as the center
of the territory, then each territory occupied about 1.5 hectares.
Larks defend their territory with great persistence throughout the breeding
cycle from the moment the territory is established till the time the young
leave the nest. Males chase each other with great speed, often close to the
ground. Sometimes several birds participate in these chases. On 5 July
1964, two males fought by standing close together and beating one another
by suddenly extending one wing. After each blow they would walk away
from each other for about 30 cm and then walk back again to repeat the
performance. Two males can often be seen to start a fight on the ground and
then continue it in the air, climbing higher and higher up to about 20 m
at times. This behavior was noted also by DuBois (1935).
SONG
In the alpine zone larks are the first birds to sing in the morning and the
last to cease in the evening. The flight song is given from the ground as well
as from the air. On the ground, males sing while perched on some pro-
jection, usually a rock. In the air, the bird sings while his wings and tail
are spread wide open and in between bursts of song he hovers to maintain
altitude. The duration of the only flight song timed was 11 minutes, twice
as long as that given by Pickwell for E. a. praticola and my impression is
Nieolaas A. M.
V'erbeek
HORNED LARK BREEDING BIOLOGY
211
Table 1
Species of Plants Recorded Within 30 cm Radius of 11 Nests of the Horned Lark
Species
5
Fellfield
nests
6 9
11
Dry
7
meadow
nests
8 10
Moist meadow
nests
13 14 15
Intermediate
meadow
nest
16
Rock
1
1
1
1
Geum rossii
1
1
1
1
1
1
1
1
1
Smelowskia calycina
1
1
1
1
1
Potentilla diver sifolia
1
1
1
1
1
1
Antennaria sp.
1
Mertensia alpina
1
1
1
1
1
Silene acaulis
1
1
1
Polygonum bistortoides
1
1
1
1
1
1
1
Douglasia montana
1
Eritrichium alpinum
1
Castilleja sp.
1
1
1
1
Carex sp.
1
1
1
1
1
Myosotis alpestris
1
1
Pedicularis oederi
1
1
Lloydia serotina
1
1
1
Phlox caespitosa
1
1
1
1
Erigeron caespitosa
1
Stellaria crassifolia
1
Claytonia lanceolata
1
1
1
1
Senecio fuscatus
1
1
Draba sp.
1
1
Lupinus monticola
1
1
Cerastium sp.
1
Aster alpi genus
1
Carex scopulorum
1
1
Caltha leptosepala
1
1
1
Artemisia scopulorum
1
1
1
1
Gentian algida
1
1
Dodecatheon pauciflorum
1
Sedum stenopetalum
1
Trijolium parryi
1
that all of the flight songs were longer than the five minutes reported as a
maximum by PickwelL
NESTS
Before the actual nest is built, a nest cavity is scratched out in the ground.
The depth of this cavity varies with the substrate. In some cases a rock
prevented any deeper excavation. The average depth of seven nest cavities
was 5.0 cm (1.3 to 6.2). The nest is made of dead forbs and grasses. No
212
THE WILSON BULLETIN
June 1967
Vol. 79, No. 2
hair or feathers are used to line the inside. One nest was lined with an
unidentified felt-like plant material. Drury ( 1961 ) reports the use of feathers
in E. a. alpestris.
All nests found were constructed so that there was some protective
feature such as a projecting rock or a tuft of grass on the windward side.
The nest entrance of 12 nests in 196T all faced between NNW and E; one
faced NNW, three N, one NNE, four NE, two ENE, and one E. The pre-
dominant winds were from the S and SW. A similar orientation with respect
to the wind was reported by DuBois ( 1935 ( , who found nests facing between
NE and SSE under prevailing W winds. I did not notice any evidence of a
“pavement” of stones or mud as reported by DuBois ( 1935 I and Pickwell
(1931).
Eleven finished nests had an average width of 7.0 cm (6.5 to 7.6 1 and
ten nests had an average depth of 3.8 cm (3.2 to 4.7). The average thickness
of seven nests of which both the depth of the scooped-out nest cavity and
the completed nest were known was 1.0 cm (0.3 to 1.7) . These measurements
were taken after the young had left the nest.
EGGS AND INCUBATION
Eggs were laid early in the morning, some time before 0730 hours. The
clutch size varied from two to four eggs ( one with two eggs, ten with three
eggs and three with four eggs).
Only two of the 16 nests were found before the clutch was completed. In
N5, the third and last egg was laid in the morning of 29 June. All three
eggs had hatched before 0530 hours on 10 July. In N8, the last of three
eggs was laid in the morning of 2 July and the first egg hatched 13 July
before 0930 hours. The other two eggs in this nest never hatched. The
incubation period is taken to be about 11 days. DuBois (1935) gives an
incubation period of 10 to 11 days and MacDonald (1916) states 11 days.
Silloway ( 1903 ) states that both male and female incubate the eggs. My
own observations make me believe that only the female incubates. There
is only one clutch per season in contrast to the two clutches reported by
DuBois (1935) at lower altitudes. In 1964, all eggs were laid between 25
June and 10 July.
NESTLINGS
The nestling period varied from 9 to 12 days with an average of 10.2
days. This is a very short period but it agrees well with the results obtained
by DuBois 1 1935 ) . The young leave the nest when they have hardly any tail
and when the primaries and secondaries are only one-third to one-half
grown. The young are incapable of flight at first but walk readily. I caught
Nicolaas A. M.
\’erbeck
HORNED LARK BREEDING BIOLOGY
213
AGE OF YOUNG IN DAYS
Fig. 2. Growth curves of two, three and four young in three nests of the Horned Lark.
one color-marked young five days after it had left the nest. It could only
fly a few meters at the time and was soon exhausted.
Nestling development is very rapid. The average gain in weight of nine
young was 1.9 g per day (0.52 to 3.45). When the young reach a weight of
about 20 g, they seem to have developed sufficiently to leave the nest. Growth
curves for the young of three nests are shown in Figure 2. Earlier departures
(Fig. 2) are due to disturbance caused by handling the young. One young
of N9, which left when it weighed 17.6 g was recaptured 5 days later when
it weighed 20.2 g. The average weight of 15 adult males in the University
of Montana Zoological Museum, taken on the study area in June, July, and
August, was 32.3 g and the average weight of 7 adult females of the same
period was 30.6 g. The young then leave the nest when they are about two-
thirds the adult weight. Sexual difference in weight in adult larks has been
shown by Behle (1943) and Montagna (1943).
The eyes open when the young are 3.6 days old (average of 10 nests I .
The primaries and secondaries break the sheaths when the young are 6 days
old ( average of 2 nests ) .
During 128 minutes of observation from a blind when the young were one
day old, the female brooded them for 78 minutes or about 61 per cent of the
time. The average length of the brooding jieriod was 11 minutes (6 to 17).
When the female was not brooding she was off gathering food for the \oung
214
THE WILSON BULLETIN
June 1967
Vol. 79, No. 2
and presumably for herself. If the male came to the nest while the female
brooded, she would step off the nest till the male was finished feeding the
young, after which she would resume brooding. When the young were four
days old, no brooding occurred during one hour of observation, but the
female provided shade by standing over the young in the nest. No shading
or brooding occurred when the young were 8 days old. Both parents fed
the young and both removed feces.
W^hen approaching the nest to feed the young both male and female land
at some distance, about 3 to 5 m, from the nest and then walk toward it.
The female approaches without any vocalization, while the male makes a
soft tjreeh call which seems to be a call used around the nest. After feeding
is finished the female tends to walk away from the nest but sometimes she
flies away from within about 30 cm of the nest. The male flies from the
nest more often than he walks.
The food of six nestlings in July consisted of 100 per cent insects, while
12 adults taken between 14 June and 1 September had stomach contents of
78 per cent insects and 22 per cent seeds. The 12 adults had an average of 0.15
(0.03 to 0.26 ) grams of grit in their stomachs and the nestlings had an aver-
age of 0.10 (0.01 to 0.17 I grams of grit.
Newly hatched larks are richly covered with a creamy-white natal down.
The distribution of natal down of a young just hatched is shown in Table 2.
Wetherbee ( 1957, 1958 1 has summarized the information regarding natal
pterylosis of the Horned Lark. To his list of tracts present can be added:
crural, rectrices, and upper tail coverts. My specimen did not have the ocular
tract reported by Wetherbee ( 1958 ) .
The young made begging sounds on my approach to the nest, at about
4.5 days. They directed their beaks to human sounds when 3 days old and
before their eyes had opened. When about 5 days old, they followed the
movement of my hand over the nest without the accompaniment of human
sound. After about 6.5 days, the young no longer react to human sound and
movement. After this time, when one approached they remained silent and
immobile or tended to crouch deeper in the nest.
Sutton and Parmelee (1955 ) report finding one instance of nestling larks
out of the nest and they suggest that the unprotected and poorly lined nature
of this particular nest could have been the cause of this. Observations from
my blind, however, showed that the two 8-day old young of N13 left the
nest whenever a parent came to the nest with food. They went as far as 30
to 40 cm from the nest and then crawled back again. At this age they do
not leave the nest until the parent is about 100 cm from the nest. In N2, one
of the four young appeared to be smaller and weaker. This bird died on 20
July when two large nestlings were outside of the nest while a third weak
Nicolaas A. M. HORNED LARK BREEDING BIOLOGY
\ erbeek
215
Table 2
Tract Distribution of Natal Down Feathers of a Horned Lark
Nestling (Just Hatched)
Tract
Left
Right
Coronal
14
13
Occipital
12
11
Dorsal
22
22
Spinal
7
Rectrices
6
6
Upper tail covert
2
3
Humeral
12
14
Greater secondary covert
9
10
Middle secondary covert
8
6
Carpal remex covert
1
1
Femoral
15
13
Crural
2
2
Abdominal
2
2
nestling was in the nest. The latter nestling died the next day. In N14, on
12 July, three of the four young were out of the nest, the smallest one farthest
away, about 30 cm. The next day this one had died, while the other three
were back in the nest. It seems that nestling larks leave the nest in com-
petition for food.
When the young were about 4 days old, they panted when the sun shone
in the nest. Panting could have started at an earlier age but was not observed.
FLEDGLINGS
Newly fledged young are more often heard than seen after they leave the
nest. They call their parents with a single loud peep which sounds as if it
comes from far away, although the young in actuality may only he a few
meters away. The young are very well concealed and crouch when ap-
proached. One young of N6 left the nest when it was 9 days old and I
saw it fly about 75 m when it was 15 days old. Young larks fly in an un-
dulating manner, more so than the adults do. When they alight they face
the intruder and they have a habit of bowing their heads, as if looking at
their feet. This bowing is repeated about once every four seconds.
BREEDING SUCCESS
There was a great difference in breeding success between 1963 and 1961.
In 1963, of 13 eggs laid in 4 nests, 10 young hatched, only four of which
fledged, a success of 31 per cent. In 1961. out of 31 eggs in 11 nests. 31
2J6
THE WILSON BULLETIN
June 1067
Vol. 79. No. 2
Table 3
Summary of Breeding Data of
THE Horned Lark
1963
Number Percent
1964
Number Percent
Nests
4
11
Eggs laid
13
100.00
34
100.00
Eggs per nest
3.25
3.09
Eggs hatched
10
76.92
31
91.18
Eggs hatched per nest
2.50
2.82
Eggs not hatched
0
0.00
2
5.88
Eggs lost before hatching
3
23.08
1
2.94
Young fledged of eggs hatched
4
40.00
21
67.74
Young fledged per nest
1.00
1.82
Young lost before fledging
6
60.00
10
32.26
Young fledged of eggs laid
4
30.77
21
61.76
hatched, 21 of which fledged for a breeding success of 62 per cent. Details
are shown in Table 3.
Causes of mortality were twofold. In 1963, 3 eggs and 6 of the 10 young
that hatched were eaten by mammalian predators, probably the deer mouse
(Peromysciis maniculatus) ^ which was abundant that summer ( Pattie, MS).
No nestlings were lost to mammalian predators in 1964.
The loss of 8 nestlings in 1964 was due to blowfly larvae. The average
age at death in infested nests was 8.6 days. In each of two nests one young
survived. These young showed evidence of having suffered from the larvae.
Their development was slowed down and the nestling period extended to
11 and 12 days. In one nest the larvae did not seem to have harmed the
nestlings at all, although there were 29 larvae in the nest. Early fledging
could be advantageous in escaping blowfly predation. Dead young are
removed by the adults.
POST-NESTING PERIOD
Toward the middle of August when the young are independent of the
adults, flocks begin to form. These flocks are very loose in nature with 10
to 20 birds scattered out in ones and twos over about 30 to 40 sq m. Whereas
earlier in the season larks are found in many habitats, toward the end of
the summer they are found almost exclusively in Eellfield and Dry Meadow,
in this order.
SUMMARY
An account is given of the breeding biology of the Horned Lark in alpine meadows
at an altitude of 3,200 m on the Beartooth Plateau, Park County, Wyoming. Of a total
\icoIaas A. M.
Verbeek
HORNED LARK BREEDING BIOLOGY
217
of 15 nests, 9 were located in a dry habitat, 5 in a moist habitat and one in an inter-
mediate type. Lark territories were large and in 1964 each occupied about 1.5 hectares.
All nests faced between NNW and E, away from the predominant S and SW winds.
Each nest had some protective feature in the form of a rock or vegetation on the wind-
ward side. The average clutch size was 3.1. The incubation period was about 11 days
in two nests. Only the female incubates and there is only one clutch per season. The
average nestling period was 10.2 days. Young develop rapidly and gain on the average
1.9 g per day. Young leave the nest when they weigh about 20 g. The eyes open on
the average when the young are 3.6 days old and the primaries and secondaries break
their sheaths when the young are 6 days old. Nestling mortality in 1963 was believed
due to the deer mouse, while in 1964, nestlings were lost due to predation by blow-
fly larvae. Young leave the nest before they are able to fly and they become independent
of the adults by the middle of August at which time flocks begin to form.
ACKNOWLEDGMENTS
This study was made possible by a grant from the Frank M. Chapman Memorial
Fund of the American Museum of Natural Flistory and a Louis Agassiz Fuertes Research
Grant of the Wilson Ornithological Society. I also wish to acknowledge funds from
National Science Foundation Grant No B14098 directed by Drs. R. D. Taber and R. S.
Hoffmann.
Special thanks are due to Mr. D. L. Pattie and Mr. C. I. Fudge for their companion-
ship in the field and the latter for some lark data for the 1963 season. Drs. R. S.
Hoffmann and F. A. Pitelka read and criticized the manuscript for which I extend
my sincere thanks.
LITERATURE CITED
Beiile, W. H.
1943 Weights of some western subspecies of Horned Larks. Auk, 60:216-221.
Bent, A. C.
1942 Life histories of North American flycatchers, larks, swallows, and allies.
JJ.S. Natl. Mils. Bull., 179.
Drury, W. H.
1961 Studies of the breeding biology of Horned Lark, Water Pipit, Lapland Long-
spur, and Snow Bunting on Bylot Island, Northwest Territories, Canada.
Bird-Banding, 32:1-46.
DuBois, A. D.
1935 Nests of Horned Larks and longspurs on a Montana Prairie. Condor, 37:
56-72.
1936 Habits and nest life of the Desert Horned Lark. Condor, 38:49-56.
.Johnson, P. L., and W. D. Billings
1962 The alpine vegetation of the Beartooth Plateau in relation to cryopedogenic
processes and patterns. Ecol. Monog., 32:105-135.
Kelso, L. H.
1931 Some notes on young Desert Horned Larks. Condor 33:60-65.
MacDonald, H.
1916 Incubation period of the Horned Lark. Auk, 33:435.
Montagna, W.
1943 Weights and plumages of tbe Horned Larks of Central New ^ ork. Auk,
60:210 2L5.
218
THE WILSON BULLETIN
June 1967
Vol. 79. No. 2
PiCKWELL. G. B.
1931 The Prairie Horned Lark Trans. Acad. Sci. St. Louis. 27:1-160.
SiLLOWAY. P. M.
1903 Birds of Fergus County. Montana. Press of the Argus. Lewiston. Montana.
Fergus Co. Free High School Bull.. 1:1-77.
Si TTON. G. M.. AND D. F. Parmelee
1955 Nesting of the Horned Lark on Baffin Island. Bird-Banding. 26:1-18.
■^'etherbee. D. K.
1957 Natal plumages and downy pterylosis of passerine birds of North America.
Am. Mus. \at. Hist. Bull.. 113:343-436.
1958 New descriptions of natal pteiNlosis of various bird species. Bird-Banding.
29:232-236.
DEPARTMENT OF ZOOLOGY, UNIVERSITY OF MONTANA, MISSOULA, MONTANA
I PRESENT ADDRESS: MUSEUM OF VERTEBRATE ZOOLOGY, UNIVERSITY OF CALI-
FORNIA, BERKELEY, CALIFORNIA I 19 MARCH 1966
NEW LIFE MEMBER
Dr. Glen E. oolfenden has recently be-
come a Life Member of The \^'ilson Orni-
thological Society. Dr. "^’oolfenden is As-
sociate Professor of Zoology at The
Lniversity of South Florida. Tampa, and
holds degrees from Cornell Lniversity.
Lniversity of Kansas, and Lniversity of
Florida. His ornithological interests include
anatomy, ecology, systeniatics. and paleon-
tology. and he has published 25 papers in
these fields. He is a member of the Cooper
Society. Bird Banding Association. BOL.
Sigma Xi. Florida Academy of Sciences,
and an Elective member of the AOL . Dr.
oolfenden is married and has three chil-
dren.
OBSERVATIONS ON A LOCALIZED DUCK SICKNESS IN
THE DELTA MARSH; SUMMER, 1964
David A. Manuwal
The 33,000-acre Delta Marsh, in south-central Manitoba, lies at the
southern end of Lake Manitoba and is an important part of the water-
fowl breeding area of Manitoba. Between the lake and the marsh, some
nineteen miles of narrow, sandy, wooded ridge offers protection from strong
winds and wave action from the lake.
The marsh is a series of shallow bays and sloughs connected by small
waterways with only two outlets to the lake- a channel at Delta in the west
and Clandeboye Dam in the east. The water level of the marsh is greatly
affected by strong winds. Covering most of the marsh is a vast stand of
phragmites iPhra^mites communis] . This plant is rarely found in water
exceeding one-half meter in depth during the summer. Close to the phragmites,
and often growing on islands are bulrushes (Scirpus) and, occasionally,
cattails iTypha). In the deeper waters, sago pondweed, water milfoil, co-
ontail, and other aquatic plants form beds that sometimes make it difficult
to canoe.
In past years, serious outbreaks of duck sickness at Delta were, in most
cases, attributed to avian botulism. H. Albert Hochbaum, Director of the
Delta Waterfowl Research Station, notes that no major outbreaks occurred
there before 1957. However, in 1957 there was a serious outbreak in which
losses in the Lake Manitoba basin numbered about 500,000 ducks. Dying
birds were found everywhere there was exposed shoreline that was reflooded
by wind and rain. Since then, only small outbreaks have occurred.
On 3 August, 1964, an outbreak was reported at 22 Bay, a small body
of water above five miles east of Delta. It was evident from the decomposed
bird carcasses that the initial outbreak had occurred on about 20 July. The
lack of laboratory facilities made it impossible to determine that Clostridium
hotulinum (Type C) was indeed the lethal agent in the 1964 outbreak.
22 Bay is located about one-half mile south of Lake Manitoba, and is
approximately five-eighths of a mile across at its widest point. The vegeta-
tion is typical of the Delta Marsh, having a phragmites border, bulrush
islands, and floating aquatics in open water. The bay is fed by one ditch
and has outlets to a larger body of water ( Blackfox Lake) to the south and
a small bay to the east. The entire perimeter at the time of the study was
surrounded by exposed mudflats of varying size.
The bay was divided into five study units ( 1-V. Jable 2). each of which
was composed of approximately 150 to 175 yards of ex})osed mudflats, shore-
line, and islands. The units were checked in regular setpience as often as
219
220
THE WILSOX BULLETIN
June 1967
Vol. 79, No. 2
Sex.
Age, and
Condition
Table 1
OF Ducks Found
AT 22
Bay,
1964
Species
Ad.cf
Ad. 9
Juv.cf Juv. 9
Downy*
Und.**
Flight
less
Sick
Total
Pintail
89
33
15
11
2A, 2A
15
32
18
165
Blue-winged Teal
89
38
10
20
10
7
13
167
Mallard
67
12
6
2
15
9
14
102
Gadwall
28
3
1
lA, lA, 2A
3
19
3
38
Green-winged Teal
25
16
1
2
5
5
44
Shoveler
4
1
1
3
2
2
1
11
Am. Widgeon
18
4
14
22
Redhead
8
1
lA, lA
1
4
1
12
Canvasback
1
1
lA, lA
1
2
5
Black Duck
3
1
3
4
Ruddy Duck
2
2
Ring-necked Duck
1
2
Lesser Scaup
1
1
L^nidentified
92
Totals
337
105
37
38
9
54
94
58
666
* Refers to brood class. ( Gollop & Marshall, 1954. lA, downy young, no feathers visible; 2A,
partly feathered as view from side. )
** Unidentified as to sex and age.
possible, usually every day. Dead and sick birds were sexed. aged, and taken
back to the station for dissection and examination. The upper digestive tract
was immediately removed and preserved in 10 per cent formalin so that ani-
mal matter present would not be further digested. The report of this analysis
is not yet available.
The mechanism involved in the production and release of the bacterium
Clostridium hotulinum (Tvpe C) appears to be closely associated with fluc-
tuating water levels and the presence of large numbers of marsh flies
( Chironomidae I . Both of these conditions prevailed at 22 Bay. Strong winds
caused water level fluctuations up to eight feet throughout most of August.
The weather during August was quite variable. Most of the month was
rather cool. Early morning temperatures were usually in the high 40’s, and
day readings ranged in the 60’s and 70’s. The bay was checked from 4 to
25 August; on 12 of these days sick or dead birds were found. Occasionally,
it was impossible to check every day, so some of the dead birds reported on
certain dates may have been alive the day before. Tables 1 and 2 show the
findings.
Botulism deaths result from two main causes: (1) a massive dose of
toxin ingested while eating insect larval cases and ( 2 ) the ingestion of re-
peated sublethal doses of toxin plus food in water containing large amounts
of dissolved salts (Gooch, 1964). Clostridium botulinum (Type C) blocks
the parasympathetic nervous system and thereby affects gland function. Ob-
David A.
Manuwal
DUCK SICKNESS IN THE DELTA MARSH
221
Table 2
Birds Other Than Ducks Found at 22 Bay
AND
Blackfox
Lake, 1964
Species
Total
number
Sick
Study units
Blackfox L.
I
II
III
IV
V
Lesser Yellowlegs
54
10
18
3
6
5
5
17
Greater Yellowlegs
1
0
1
American Avocet
1
0
1
Dowitcher
8
4
2
1
1
2
2
Killdeer
1
1
1
Semipalmated Plover
3
3
1
1
1
Pectoral Sandpiper
43
6
2
5
4
17
1
14
Least Sandpiper
15
8
3
1
1
3
7
Semipal. Sandpiper
24
16
10
1
2
2
4
5
Stilt Sandpiper
8
6
1
3
1
1
2
Spotted Sandpiper
3
2
2
1
Wilson’s Phalarope
1
0
1
Ring-billed Gull
14
8
3
5
5
1
Franklin’s Gull
6
0
1
2
3
Bonaparte’s Gull
4
0
4
Black Tern
7
1
1
1
5
Forster’s Tern
1
0
1
Bl-crowned Night Heron
1
0
1
Am. Coot
18
2
4
5
1
1
8
Pied-billed Grebe
2
0
1
1
Eared Grebe
2
0
1
1
Red-necked Grebe
1
0
1
Marsh Hawk
1
1
1
Totals
219
58
52
21
25
37
20
65
served symptoms of sick birds at 22 Bay were the following: loss of ability
to fly; paralysis in legs; diarrhea; non-functioning nictitating membrane;
and complete collapse.
During the time of the outbreak, waterfowl usage of 22 Bay was quite
intensive. Pintails (Anas acuta). Blue-winged Teal [Anas discors). Mallards
(Anas platyrhynchos ) , American Widgeons iMareca americana). Gadwalls
(Anas strepera), and American Coots \Fulica americana) made up the bulk
of the waterfowl. Lesser Yellowlegs {Totanus flavipes), Dowitchers \ Limno-
dromus sp. ), Semipalmated Sandpipers [Ereunetes pusilliis), and Pectoral
Sandpipers ( Erolia melanotis I were the most common shorehirds. The peak
population on 22 Bay occurred around the first week in August when about
1 ()()() to 1500 birds were present. A few duck broods were still utilizing the
open water during the first 10 to I f days of August. Most of these were
Redheads ( Aythya americana). An increase in the numher of shorehirds
(more specifically, the “peeps”), gulls, and terns was noted. By the third
week of August, about 1 100 White Pelicans I Eelecanus erythrorhynchus I were
222
THE WILSON BULLETIN
June 1967
Vol. 79, No. 2
using the bay and Blackfox Lake as well as other parts of the marsh. Also
at this time, the number of ducks, especially Pintails, decreased. There was
a slight increase in Shovelers {Spatula clypeata) toward the end of the third
week. Herons, rails, and Marsh Hawks ( Circus cyaneus ) also used the area.
Evidence of muskrats, skunks, and raccoons was found along the mudflats.
Skunks and raccoons appeared to have eaten many of the dead birds and it
is likely that several sick birds were taken. On several occasions. Marsh
Hawks were observed eating both dead and freshly killed birds.
The numbers of birds affected by the sickness were directly proportional
to the numbers utilizing the area. The sickness was non-selective as to
sex and age. With the exception of rails, all the species in 22 Bay were af-
fected by the sickness. However, it is quite likely that some rails were killed.
Blue-winged Teals and Pintails were the birds most commonly seen feeding
along the edge of the bay and; as the data show, these two species accounted
for more than half the dead ducks (332 of 574). The Mallard was the third
most common species at the bay edges and also ranked third among the
birds affected by the sickness.
SUMMARY
An isolated outbreak of duck sickness was studied in the Delta Marsh, Manitoba.
Evidence suggests that the bacterium Clostridium hotulinum (Type C) was responsible
for the deaths of 885 birds found at 22 Bay. The deaths were closely associated with
fluctuating water levels. The ducks found most numerous in the kill were the Pintail,
Blue-winged Teal, Mallard. Among the ducks represented, a large proportion (76:24)
were drakes; however, for juvenile birds, a nearly perfect 50 : 50 ratio existed. Other
species, including shorebirds, gulls, terns, herons, grebes. Coots, and Marsh Hawks
were found sick.
ACKNOWLEDGMENTS
I wish to thank the staff of the Delta Waterfowl Research Station for their assistance
and especially Dr. H. A. Hochbaum for his advice. I am also indebted to Drs. D. L.
Allen, C, M. Kirkpatrick, and R. E. Mumford, Department of Forestry and Conserva-
tion, Purdue University for reviewing the manuscript.
LITERATURE CITED
CoocH, F. G.
1964 A preliminary study of the survival value of a functional salt gland in
prairie Anatidae. 4 w/c, 81 : 380-393.
Gollup, J. B., and W. H, Marshall
1954 A guide to aging duck broods in the field. Mississippi Flyway Council Tech.
Sect. Rept. ( Mimeo ) .
Hochbaum, H. A,
1944 The Canvasback on a prairie marsh. Stackpole Co., Harrisburg, Pa.
DELTA WATERFOWL RESEARCH STATION, DELTA, MANITOBA (PRESENT ADDRESS:
DEPARTMENT OF FORESTRY, UNIVERSITY OF MONTANA, MISSOULA, MONTANA)
ORIGINALLY RECEIVED 15 DECEMBER 1965.
MIGRATION IN THE LITTLE BLUE HERON
Julian L. Dusi
Migration in the Little Blue Heron {Florida caerulea) is a composite
of three distinct phases: 1) dispersal of the young and adults from
the colonial nesting sites; 2) the autumnal southward movement of adults
and of the young after their dispersal; and 3) the return to the breeding areas
in the north the following spring.
The writer started banding Little Blue Herons in 1953, at a colony south
of Tuskegee, Alabama, in an attempt to obtain the data necessary to describe
these migrations. Since then he has been banding them at a number of
colonies distributed over the state. Data other than the bandings done by the
writer were needed to explain North American migration outside of Alabama.
Reports in the literature, especially those of Ben B. Coffey, Jr. (1943,
1948), have been very helpful. A listing of bandings and recoveries for the
years 1926 to 1962, provided by Allen J. Duvall, from the Fish and Wildlife
Service Bird Banding Laboratory, have been an additional important source
of information.
PROCEDURES
Practically all of the banding of Little Blue Herons has taken place at
their colonial nesting sites and practically all of the birds banded have been
nestlings. Adults have been difficult to capture, whereas the nestlings have
been much more easily obtained in sufficient numbers to make banding them
attractive.
The banding of the nestlings has presented several problems mostly eoncerned with
the inaccessibility of the breeding colonies and nests. The majority of the colonies has
been located in small brushy ponds or swamps. The others have been in upland
situations, usually with ponds, swamps, or rivers nearby. In the colonies located over
water and in low bushes, the nests have l)een easy to reach and the young easily cap-
tured by hand or by the use of bamboo poles with wire hooks on the ends. In the
colonies with higher trees, nests were frequently 20-25 feet above the water. Longer
poles with hooks and baskets, or light weight extension ladders were needed in these
colonies. Our use of an extension ladder from a small boat has worked well in one
swamp. In upland colonies, trees were much taller and nests were frequently 35-50
feet high. This made the use of poles with hooks, from the ground, must less satis-
factory or impossible. If the young fall into water, little damage is done, hut if they
fall onto the land, before they can use their wings to break their fall, they are usually
fatally injured. Therefore, in upland colonies, the use of extension ladders was necessary
when the nests were more than 15 feet from the ground. In our work, the use of a
36-foot magnesium ladder has been very successful. The trees were usually tall and
spindly and would not support much weight. If the ladder was placed tightly against
the tree and tied to the tree every 10 feet, as it was ascended, it supported the tree
22.3
224
THE WILSON BULLETIN
June 1967
Vol. 79, No. 2
Table
Dispersal of
1
Young
Banding
Locality
Banding
Date
Recovery
Locality
Recovery
Date
Tuskegee, Ala.
6-12-53
Rising Fawn, Ga.
8-_-53
M H
5-27-55
Harperville, Miss.
7- 7-55
M M
1 1
Etowah, Tenn.
7- 2-55
M ft
M
Meridian, Miss.
8-12-55
It M
5-14-56
Eastman, Ga.
6-19-56
M M
n
Columbus, Ga.
8-25-56
Marvyn, Ala.
5-22-59
Thomaston, Ga.
7-_-59
Mt. Creek, Ala.
6-14-60
Oneonta, Ala.
8- 1-60
Opp, Ala.
5-22-61
Andalusia, Ala.
7-10-61
M If
It
II II
7- 3-61
II II
5-30-62
.. ..
9-18-62
Pansey, Ala.
5-13-64
Willacoochee, Ga.
8-_-64
Florala, Ala.
6- 1-64
Thomasville, Ga.
-_-64
St. Marks, Fla.
6- 6-26
Jacksonville, Fla.
9-_-26
II II
6- 3-61
Ashburn, Ga.
8-21-61
Glen Allan, Miss.
5-25-36
Dalton, Ga.
8-28-36
II II
II
Jena, La.
7- 6-36
11 II
5-24-36
Baton Rouge, La.
7-_-36
II II
Corning, Ark.
7-_-36
II II
Helena, Ark.
7- 6-36
II II
1 1
Watson, Ark.
7- 4-36
II II
1 1
Star City, Ark.
ll-_-36
II It
M
Delaplaine, Ark.
7-_-36
II II
1 1
Wellston, Ohio
8-_-36
Harperville, Miss.
1 1
Desha Co., Ark.
7-_-36
II II
5-31-36
Jennie, Ark.
7-12-36
II II
n
Merigold, Miss.
7- 3-36
II II
1 1
Louisville, Miss.
7-27-36
II II
1 1
Denmark, Miss.
7- 3-36
II II
Drew, Miss.
7- 6-36
It If
1 1
Isola, Miss.
8-20-36
Glen Allan, Aliss.
6- 7-36
Mayersville, Miss.
7-_-36
II II
1 1
Booneville, Miss.
8-_-36
II II
1 1
Tallula, Miss.
7-_-36
II II
1 1
Indianola, Miss.
8-_-36
II II
5-23-37
Rosedale, Miss.
8-_-37
II II
M
Holland, Mo.
7-22-37
II II
1 1
Vicksburg, Miss.
8- 3-37
II II
1 1
New Albany, Miss.
8-_-37
II II
1 1
Pollard, Ark.
8-_-37
II 11
1 1
Doniphan, Mo.
7-_-37
II n
1 1
Indian Bay, Ark.
7-12-37
M II
1 1
Marked Tree, Ark.
7- 8-37
11 II
"
Leland, Miss.
7-_-37
Julian L.
Dusi
LITTLE BLUE HERON MIGRATION
225
Table 1 [cont.)
Banding
Banding
Recovery
Recovery
Locality
Date
Locality
Date
M II
n
Alligator, Miss.
7-_-37
M M
M
Acworth, Ga.
8-_-37
M II
M
Crockett’s Bluff, Ark.
7-_-37
II II
6- 6-37
Batesville, Miss.
8-_-37
II II
II
Burr Ferry, La.
9- 7-37
II II
II
Crockett’s Bluff, Ark.
9-_-37
II II
„
Ruleville, Miss.
7-_-37
M II
1 1
Sikeston, Mo.
_-_-37
II II
1 1
Harrisburg, Ark.
7-20-37
II II
1 1
Lake Village, Ark.
7-_-37
II II
M
Carroll Parish, La.
9-_-37
II II
,,
Drew, Miss.
7-_-37
Moon Lake, Miss.
6- 3-40
Elaine, Ark.
7-21-40
II II
1 1
Gunnison, Miss.
7-_-40
II II
1 1
Crowville, La.
8- 9-40
II II
M
Abbeville, La.
8-_-40
II II
6- 1-41
Lucy, Tenn,
6-30-41
II II
n
Hogansville, Ga.
7-25-41
II II
1 1
Calhoun, Ala.
9-10-41
II II
6- 7-42
Uniontown, Ky.
9-19-42
Glen Allan, Miss.
5-25-47
New Iberia, La.
8-_-47
M M
II
Marked Tree, Ark.
7-_-47
Moon Lake, Miss.
6- 1-47
Kennett, Mo.
8-23-47
Glen Allan, Miss.
6-15-47
Marked Tree, Ark.
7-18-47
II II
1 1
Beaumont, Texas
10-_-47
II II
11
Moon Lake, Miss.
9-_-47
II II
6-13-48
Bastrop, La.
9-25-48
II II
II
Memphis, Tenn.
8-14-48
Norwood, Pa.
6- 2-41
Williamstown, N.J.
6- 7-41
Elizabethtown, N.C.
6- 1-43
Goldsboro, N.C.
7- 8-43
II II
n
Dillion, N.C.
7-15-43
II II
6- 3-43
Sanford, N.C.
8-_-43
II II
II
Salisbury, N.C.
7-_-43
II M
M
Spartansburg, S.C.
7-26-43
II 11
5-28-53
Danville, Va.
7- 4-53
Muskogee, Okla.
5-25-58
Warsaw, Mo.
9-_-58
II II
5-31-58
Vinita, Okla.
8-16-58
Arkoma, Okla.
5-23-59
Forest City, Ark.
7-_-59
Okla. City, Okla.
6- 7-59
Lebanon, Mo.
8-18-59
Webber Falls, Okla.
6-13-59
Waco, Texas
9-_-59
II II
II
Claremore, Okla.
8-_-59
Arkoma, Okla.
,,
Heavener, Okla.
8-21-59
Webber Falls, Okla.
6-14-59
Waco, Texas
9- _ -59
Muskogee, Okla.
6-12-60
Grove, Okla.
8-_-60
Charleston, S.C.
6- 9-31
Orktown, Va.
8-20-31
226
THE WILSON
BULLETIN
June 1967
Vol. 79, No. 2
Table 1 icont.)
Banding
Banding
Recovery
Recovery'
Locality
Date
Locality
Date
If n
8- 9-35
Moncks Corner, S.C.
10-14-35
Memphis, Tenn.
6- 7-42
Covington, Tenn.
7-12-42
II M
M
Monette, Ark.
7- 6-42
Dyersburg, Tenn.
6- 2-51
Madisonville, Ky.
7-22-51
Anahuac, Texas
5- 2-26
Fort Worth, Texas
9-11-26
II II
5-25-26
Baytown, Texas
7-17-26
It It
6- 3-26
Shelbyville, Ind.
8- 7-26
tl It
7-29-27
Alvin, Texas
9-19-27
It It
6- 3-30
Nacogdoches, Texas
7-_-30
M It
1 1
Tyler, Texas
7-15-30
Columbus, Texas
6- 4-38
Jennings, La.
7-29-38
Note: Banding and recovery localities are approximations determined from coordinates, except for
Alabama banding localities which are the writer’s.
from bending and was much more safe. If the climber tied himself to the tree, at the
top of his ascent, then caught the birds with his hands or a short pole with a wire
hook, and then lowered them in a plastic bucket to a helper on the ground who did
the banding and recorded the data, he could work much more efficiently.
The construction of the poles with hooks and baskets was simple. James E. Keeler,
Alabama Department of Conservation, introduced the writer to the use of the hooks in
a cooperative effort in banding White Ibises (Keeler, 1956). A bamboo pole of suitable
length was obtained. A piece of eight or nine gauge iron wire, about four feet long,
was attached to the upper two feet of the pole using several wrappings of adhesive
tape. The end of the wire was then bent so that about six or eight inches of the wire
was parallel to the rest of the wire and about one inch from it. The very end was bent
out slightly so that it was easier to guide the hook around the neck of a bird. The
basket was made with a similar pole and piece of wire. The wire was bent to form a
loop six to eight inches wide and about 18 inches long. A piece of one-inch mesh
chicken wire about 8 inches by 16 inches was slipped over the frame and the ends
of the frame were attached to the pole with adhesive tape. Keeler found that if the
Table 2
Dispersal of Adults
Banding
Locality
Banding
Date
Recovery
Locality
Recovery
Date
Tuskegee, Ala.
5-14-56
Wadesboro, N.C.
10-15-60
Glen Allan, Miss.
5-23-37
Oakland Mills, Iowa
10-27-41
It M
6- 6-37
New Orleans, La.
7-19-39
Moon Lake, Miss.
6- 3-40
It M
8- 5-40
It 1 1
6- 7-42
It It
8-_-44
Muskogee, Okla.
6- 6-59
Dyersburg, Tenn.
CO
Bay Town, Texas
5- 2-26
Baton Rouge, La.
7-31-27
Julian L.
I) usi
LITTLE BLUE HERON MIGRATION
227
Table 3
Southward Migration
Banding
Banding
Recovery
Recovery
Locality
Date
Locality
Date
Tuskegee, Ala.
5-27-55
British Guiana
3- 1-61
M II
It
Puerto Rico
10-31-55
II II
11
Venezuela
12-16-55
II II
1 1
British W. Indies
10-23-55
11 II
II
Honduras
1-29-56
II II
1 1
Cuba
1-15-60
II II
II
1 1
2-13-58
II II
1 1
Bahamas
3-_-56
II II
5-14-56
British Guiana
2- 3-60
II II
6-16-57
Venezuela
10-_-63
Marvyn, Ala.
6- 6-58
British W. Indies
10-15-61
II M
,,
British Guiana
6- 9-59
II II
5-22-59
British W. Indies
9-27-59
II 11
II
British Guiana
2-15-60
Faunsclale, Ala.
6- 1-59
Cuba
8-_-60
Opp, Ala.
6-22-60
Venezuela
10-12-60
n ..
6-12-61
Cuba
9-24-61
II II
5-10-62
Lake City, Fla.
6-17-64
Delaware
9-14-51
Haiti
l-_-52
St. Marks, Fla.
5-22-39
Panama
11- 1-39
M II
6-24-61
Jamaica
l-_-62
New Iberia, La.
7-17-37
Mexico
10- 2-37
Harpersville, Miss.
6-16-35
If
10-_-37
II II
6-16-35
British Honduras
7-20-36
Glen Allan, Miss.
5-25-36
Cuba
10-13-38
M It
1 1
Colombia
_-_-43
M M
5-24-36
Mexico
9-28-36
II II
,,
French W. Indies
9-_-36
Harpersville, Miss.
5-31-36
Mexico
1-23-38
Glen Allan, Miss.
5-23-37
Colombia
4-19-50
II II
M
Cuba
7-16-41
II II
M
Honduras
9-_-37
11 II
II
Mexico
9-30-37
II II
6- 6-37
Honduras
10- 8-37
II II
1 1
Panama
10-17-37
Moon Lake, Aliss.
6- 3-40
British Honduras
12- 6-40
II It
M
Mexico
12-13-40
II 11
6- 1-41
,,
2-_-54
II II
6-7-42
M
4- 2-46
Glen Allan, Miss.
5-25-47
Nicaragua
11-20-49
II II
II
Haiti
3-15-48
Moon Lake, Miss.
6- 1-47
Mexico
10- 4-47
M M
M
Cuba
2-22-48
Glen Allan, Miss.
6-15-47
Panama
3-10-51
228
THE WILSON BULLETIN
June 1967
Vol. 79, x\o. 2
Table 3. [cont.)
Banding
Locality
Banding
Date
Recovery
Locality
Recovery-
Date
1? tl
,,
Puerto Rico
4- 1-49
M M
,1
Mexico
2-_-49
Wildwood, N.J.
6- 8-41
British W. Indies
11- 6-41
fl It
5-29-49
II II II
12- 3-49
Clarkton, N.C.
6- 1-43
II II II
l-_-44
II II
5-25-54
Cuba
5- 6-55
II II
6-15-54
Bahamas
12- 7-54
Muskogee, Okla.
5-25-58
Mexico
ll-_-58
II II
1 1
II
ll-_-58
II II
5-23-59
Colombia
1-16-60
II II
5-24-59
Costa Rica
8-22-60
Greenwood, Okla.
5-23-59
Mexico
3-10-60
Okla. City, Okla.
6- 7-59
British Honduras
3- 7-60
II II
,1
Nicaragua
12-_-59
Okmulgee, Okla.
6-13-59
Mexico
10-13-60
M M
II
Costa Rica
11-26-59
M
II
Panama
11-26-59
Arkoma, Okla.
M
Nicaragua
3-_-60
Muskogee, Okla.
II
Costa Rica
5-_-60
II II
6-14-59
Mexico
9-15-59
11 II
II
II
2- 2-60
II II
1 1
1 1
8-15-60
Arkoma, Okla.
6- 4-60
1,
12-_-60
II II
II
Panama
9-24-60
II II
1 1
Costa Rica
9-30-60
11 II
6-18-60
Colombia
o
r
bs
o
Muskogee, Okla.
6-12-60
Panama
10-_-60
Charleston, S.C.
6-15-31
Louisiana
6-19-36
M II
6-11-32
Jamaica
10-30-34
II
6-24-32
British Honduras
9-25-32
II II
1.
Cuba
11-18-38
II II
6-12-33
Bahamas
10- 1-35
M II
II
Colombia
4-_-38
II II
1.
British W. Indies
1-16-34
II
6- 6-34
Venezuela
10-21-34
5-29-37
Haiti
2-_-43
II II
6- 5-38
Cuba
10-26-38
Dyersburg, Tenn.
6- 5-51
Colombia
3-21-53
II II
1 1
Mexico
12-_-51
Galveston, Texas
5-12-26
II
10- 1-26
II II
6-25-26
British Honduras
11-20-26
II II
6-14-26
Mexico
10-18-26
II II
6- 3-30
M
8-28-30
Note: Banding and recovery localities are approximations determined from coordinates, except
for the Alabama banding localities.
Julian L.
Du si
LITTLE BLUE HERON MIGRATION
229
Table 4
Northward Migration
Banding
Locality
Banding
Date
Recovery
Locality
Recovery
Date
Tuskegee, Ala
5-11-55
Wetumpka, Ala.
5-16-60
II M
M
Opp, Ala.
3-_-59
n M
5-20-55
Summit, Miss.
3-24-57
n M
5-27-55
Selma, Ala.
6-30-57
n M
5-14-56
Tuskegee, Ala.
8- 2-59=^
Opp, Ala.
5-30-62
Dothan, Ala.
4-20-63
Glen Allan, Miss.
5-25-36
Coushatta, La.
3-28-38
II II
5-24-36
Winnsboro, La.
5- 2-40
II M
II
Indianola, Miss.
4- 8-38
Harperville, Aliss.
5-31-36
Oxford, Miss.
7-26-38
II M
1 1
Natchez, Miss.
6- 1-40
Glen Allan, Miss.
5-23-37
Gonzales, Texas
3-26-39
II II
1 1
Indianola, Miss.
2-_-38
M It
6- 6-37
Bernie, Mo.
3-_-44
Moon Lake, Miss.
6- 3-40
Prichard, Miss.
2-_-46
.. ..
1 1
Batesville, Miss.
3-_-43
If It
M
Eudora, Miss.
3-14-41
II II
I 1
Swan Lake, Miss.
6-_-43
II II
6- 1-41
Clarksdale, Miss.
4-_-42
II II
6- 7-42
Crockett’s Bluff, Ark.
4- 8-47
Glen Allan, Miss.
6- 1-47
Memphis, Tenn.
l-_-54
Clarkton, N.C.
5-30-42
Boardman, N.C.
4-_-44
II II
6- 3-43
Clarkton, N.C.
4-26-50
Charleston, S.C.
5-29-37
Morehead City, N.C.
2-_-38
* A date this late does not necessarily indicate the destination of spring migration but may reflect
post-breeding dispersal before autumnal migration.
Note: Banding and recovery localities are approximations determined from coordinates, except
for Alabama banding localities.
birds were caught by the neck, they would release their toe-holds; if caught by the
leg, they usually held on and the leg would be broken. Little Blue Herons are quite
agile climbers and can frequently be returned to the nest by perching them on the
pole, below the hook, and raising them to their nests. Little Blue Heron nestlings that
cannot climb well and some of the other herons and ibises, are best returned to the
nests in the baskets.
The size of the nestlings banded varied greatly. The optimum size was
that attained at about two weeks of age, at which time the birds were able
to climb a little but not enough to evade the bander easily. At one week of
age, the birds are at tbe minimum size at which the proper size band will stay
on the tarsus. At about four weeks of age, the young are able to climb so
well that it is difficult to capture them. It was our practice to start banding
when the first group was about two weeks old and to return at periods of
230
THE WILSON BULLETIN
June 1967
79, No. 2
Fig. 1. Dispersal of Youn{>; From N(\stin«r (Colonies. Faeli numher represents a colony
(circled) and the hand recoveries from that y noting on the map the name
of the bird to which it belongs, hut not always. On page 152, for instance, the map
opposite the Least Auklet obviously belongs to the Marbled Murrelet, the bird below.
This is something that should certainly be corrected in future editions of the hook.
Another unique feature of the hook is the use of sonagrams for depicting songs and
calls. To my mind this is the least successful feature. While sonagrams have value in
scientific studies of bird calls, their usefulness as an aid to field identification is very
limited. To begin with, considerable practice is needed in order to he able to read
sonagrams; but even when some proficiency is acquired, I doubt if anyone can really
imagine or “hear” a new song simply by reading its sonagram. I challenge anyone who
has never heard the call of a Red-hellied or a Gila woodpecker to “hear” the difference
between their calls by reading the sonagrams on page 182. Admittedly it is interesting to
see what a call which you already know looks like as a sonagram, hut this is not the
point. A field guide should teach you to have an idea of a song before you hear it.
I maintain that you cannot learn bird songs from sonagrams. Bird songs are best
learned from records, of which there is a wide variety now available covering just about
every North American species. In a hook, they are best depicted by the time-honored
method of verbal description, and the authors have been wise to include many such
descriptions in the text. There is no sonagram for Coues’ Flycatcher; there is no need
for one. The authors’ description of its call as “a sad, whistled ‘ho-say mari-a’ ” is more
effective. We all know that the Olive-sided Flycatcher says “Q)uick, three beers,” (all,
that is, exeept the authors, who maintain it says “whip, three beers,” thereby turning
a memorable phrase into a more accurate hut meaningless one). There is no need to
add a sonagram of its song, as has been done; the verbal description is perfect.
There are a number of smaller points on which there is room for improvement in the
book. In a number of places the color is not true, and this may in part have occurred in
the printing. The Baird’s Sandpiper on page 128, for instance, shows a lot of yellow in
254
THE WILSON BULLETIN
June 1967
Vol. 79, No. 2
the plumage, and looks quite different from the same bird pictured on page 125. In a
number of illustrations, particularly those of flying terns and gulls, the painter has appar-
ently attempted to indicate shadow hy painting part of the underparts of these birds gray
or brownish where they should be white. This is extremely confusing, particularly in a
case like the Roseate Tern on page 143. The whole point about a Roseate Tern in summer
dress is that it is whiter below (even pinkish sometimes) than the similar Arctic and
Common terns, and yet here a Roseate labelled “summer” is pictured as gray below.
This is a case where artistic effect should definitely be passed up in favor of formal color
accuracy.
Something has gone wrong with the flight pictures of Least, Semipalmated, and
Western sandpipers on page 125; they are all far too dark. The flying Black Guillemot
on page 149 presents an anatomical puzzle as regards the position of the wings. The
head pictures of Ruff and Reeve on page 123 are useless for field identification, especially
as no two males are ever quite alike in spring dress. If there is no room for a full-length
or a flight picture, the birds are best left out. On the same page, I cannot understand
why the Sharp-tailed Sandpiper is shown in summer dress, when by the authors’ own
admission the bird is a fall visitor only, and the fall plumage is quite different. On page
94, we are left to assume that the unlabelled bird standing next to the Great Blue Heron
is an immature bird of that species. Or is it a female? Or in winter plumage? The
beginner needs to know.
It is a pity that only the head of Cory’s Shearwater is illustrated, on the grounds that,
as stated in the text, it has “plumage the same as the Pink-footed’s.” Not only is this
an unscientific remark, as the birds belong to quite different species, but it obscures a
piece of information vital for field identification, which is not mentioned anywhere in
the text. The upper tail coverts of Cory’s Shearwater can be very pale, almost whitish
at times, giving the effect of a narrow pale band above the dark tail tip, causing con-
fusion with the Greater Shearwater. The Pink-footed Shearwater as illustrated, on the
other hand, has the upper tail coverts even darker than the rest of the upperparts. The
text needs to be tightened up in this case, too, and it should be pointed out that the
best field mark for telling Cory’s and Greater shearwaters apart is not the pale band on
the tail but the contrast between dark cap and light cheeks in the Greater.
With regard to price, I think that $2.95 for the paper cover edition of this book
represents unparalleled value for money. It is incredible that a book with over 150
pages of colored illustrations should sell for under three dollars. Furthermore, the size
of the book is another selling point. Most field guides today are small, but still are too
large to fit into the pockets of many jackets without some squeezing. In this book, the
use of a soft cover reduces its dimensions all round, and its thickness is less than three
quarters of an inch. It thus fits comfortably into any but the smallest pockets.
In conclusion, in spite of some drawbacks, this is a really excellent book, and I
heartily commend it. It will not replace the older field guides, because they contain
additional features. Rather, it should be used to complement them, because it, likewise,
contains features which they lack. It is so cheap that everyone can afford to buy it in
addition to their other books. As to that inevitable, awkward question, “If you only had
room for one guide, which one would you take?,” I will sidestep it by saying that I
usually take more than one guide with me in any case. I suggest that every field birdman
makes sure that he has a spare pocket large enough for Birds of North America.
— Stuart Keith
June 1967
Vol. 79, No. 2
ORNITHOLOGICAL LITERATURE
255
The Birds of Shakespeare, By James Edmund Halting. Including Of Men and Birds:
Prolegomena to the Birds of Shakespeare. By Grundy Steiner. Argonaut Inc.,
Chicago, 1965: X 9M-> in., xxxviii -f 321 pp., 33 illus., 1 table. $7.50.
The re-issue of “The Birds of Shakespeare” by J. E. Harting is an important event for
all students of the poet. This book, first published in 1871 and long out of print, not only
was the first complete survey of the subject but also remains the best. In making
Harting’s study again accessible, the Argonaut Press has rendered a valuable service.
Emphasis in the book is placed upon the poet’s knowledge of falconry. This is sug-
gested in the frontispiece, where the fine figure of a Peregrine Falcon drawn by Wolf,
the famous German artist, has been superimposed upon the Chandos portrait. A wealth
of further engravings throughout the hook illustrates the subject at hand.
Nine chapters deal with birds in a natural grouping. Following passages containing
allusion to the eagle and other large birds, the author proceeds to what is perhaps his
most valuable chapter, “Hawks and Hawking.” Quotations accompany explanation of
the falconer’s jargon — tower, point, pitch, seel, watch, tire, and others, terms which came
naturally to the poet. Later, in Chapter 7, the author passes to the complementary theme,
“Game-birds and ‘Quarry’ flown at by Falconers.” Not least interesting here are quota-
tions from royal household accounts showing an astonishing variety of table birds with
the price paid for each.
In his prefatory essay, “Of Men and Birds,” Professor Steiner of Northwestern Uni-
versity reviews the role of birds among Greeks and Romans to emphasize the force of
tradition in Shakespeare’s time. He remarks the extent to which the poet leans toward
contemporary taste rather than to ornithological fact. He believes rightly that the plays
reflect “a preponderance of tradition over observation.” Mr. Harting is kinder to
Shakespeare than to his own contemporary, Alfred Tennyson. Allusions to birds by the
laureate, he writes elsewhere, tend to prove that he had “neither a good eye for colour
nor a good ear for bird music,” that in short, Tennyson was “inferior to many English
poets who have preceded him” {The Zoologist, 1883, p. 145). But whatever its faults, all
of them minor, Harting on Shakespeare’s birds is admirable throughout. Here is a
reprint that every lover of birds and poetry should own. — Thomas P. Harrison
Birds of Europe. Illustrations by John Gould. Text by A. Rutgers. Barnes & Noble,
New York (first published by Methuen & Company, London), 1966: 7M.> X 9% in.,
320 pp., 160 col. pis. $15.00.
This is not really a book in the usual sense but a well-reproduced selection of litho-
graphs that first appeared in Gould’s “The Birds of Europe” (1837) and “The Birds of
Great Britain” (1862-73). Opposite each plate is a page of brief text, written for this
volume, sometimes describing the species shown and giving a little information on habitat,
behavior, nesting habits, and vocalizations. Strangely lacking is a preface or any intro-
ductory material other than a table of contents. Nowhere is there one word about the
author of the text, the sources of his information and the objectives of his presentation;
and worse still, not one word about John Gould (1804-1881). Except for one dated
quotation (p. 1) from The Birds of Europe, the reader has no way of knowing how long
ago the lithographs were first published. The only information about Gould — and most
inadequate — is on the front flyleaf of the jacket. Here the publishers give a few laudatory
generalities about Gould’s work and mention the volumes from which the present litho-
graphs were taken, but give no dates and state that successive volumes will cover Gould’s
work on Asia, Australia, New Guinea, and South America. Hopefully they will he more
256
THE WILSON BULLETIN
June 1967
Vol. 79, No. 2
than “non-books” such as this one. Much as the plates from Gould’s works, all of them
rare, are welcome, they should he given historical perspective. — Olin Sewall Fettingill,
Jh.
ffuGS OH People? By Wheeler McMillen. Appleton-Century, New York, 1965: 5% X
8^/4 in., xi + 288 pp. $4.95.
The jacket of this hook includes the subtitle “A Reasoned Answer to Opponents of
Pesticides”; this should he enougli to forewarn the reader that a polemic is forthcoming.
The author is an experienced agricultural writer who has had a long and distinguished
eareer of service. He begins with an intimate hut somewhat clumsy description of the
antics of Timmy, the titmouse, on the author’s breakfast terrace. This gambit is appar-
ently designed to assure us of the author’s deep and abiding concern for wildlife. The
effect on me was somewhat uncertain and my unallayed suspicions were confirmed in
the third chapter when the real target of the hook is brought to focus: it is, of course,
Rachel Carson and “Silent Spring.” It is odd that an excellent and more recent review
( Rudd’s “Pesticides and the Living Landscape”) should he overlooked hy the author.
This is perhaps a good measure of the continuing effectiveness of Miss Carson’s role
as the protagonist to the pesticide industry.
In attempting to construct a rebuttal to Silent Spring, Mr. McMillen’s principal
stratagem is to balance the continued need for pesticides to sustain production of food,
fiber, and timber against the risks of damage to fish and wildlife. This position is
undeniably one of great inherent strength; however, the author misjudges his material.
To begin with, he fails to understand that threats to the robust success story of American
agriculture are not likely to catch our imagination with half the force of the continued
threats to an already depleted and beleaguered wildlife resource. Furthermore, the
success story is poorly told. The author attempts to pull in an impressive assortment of
specifics to set up his arguments. He is not deft in doing so and misses many excellent
opportunities (as on p. 46) in describing biological control of the Klamath weed. He
refers (p. 46) to the weed as “spread over several hundred thousand acres of once-good
native pastures in Oregon, Idaho, Montana, Washington, and Nevada . . .”. By failing to
check his sources carefully, the author has missed his mark by a fifteen-fold under-
estimate; actually, more than 5 million acres were affected by the Klamath weed! There
are many other examples where the author’s lack of precision destroys the impact of his
argument (as on p. 43) : “The predatory insects, which make their living hy destroying
other species . . .”.
Secondly, the author shows a startling lack of ecological perspective in his failure to
understand that the principal threat of pesticides to fish and wildlife is an indirect one,
namely, through the aetion of hio-accumulation. For example, in discussing the Missis-
sippi River fish kill ( p. 159) he asks “Could pollutions from higher up in the Mississippi
and Missouri Valleys have acquired deadly effect only after they had reached so near
to the big river’s mouth?”.
Lastly, the author fails to understand that, if the national challenge of the past
century was to attain an adequate standard of living for all, the challenge of the coming
century will be to preserve the quality of the environment. The author’s view of man’s
relationship to his environment is summed up in a concluding chapter on “What Needs
to Be Done.” His response is “We should proceed to master our environment.” One
cannot help but wonder what room would be left for “bugs” and other forms of wildlife
in a “mastered” environment. — Daniel Q. Thompson
This issue of The Wilson Bulletin was published on 5 June 1967
TfieWlsotiBulletin
PUBLISHED BY THE WILSON ORNITHOLOGICAL SOCIETY
WEST VIRGINIA U. • MORGANTOWN, W. VA.
VOL. 79, No. 3, SEPTEMBER 1967 PAGES 257-368
MUJ. COIvlP. ZOOL.
library
OCT 1 1 1967
HARVARD
UNIVERSITY
The Wilson Ornithological Society
Founded December 3, 1888
Named after ALEXANDER WILSON, the first American Ornithologist.
President — Aaron M. Bagg, Farm Street, Dover, Massachusetts.
First Vice-President — H. Lewis Batts, Jr., Dept, of Biology, Kalamazoo College,
Kalamazoo, Michigan.
Second Vice-President — William W. H. Gunn, Apt. 1605, 155 Balliol Street, Toronto,
Ontario.
Secretary — Jeff Swinebroad, Dept, of Botany & Zoology, Douglass College, Rutgers Univ.,
New Brunswick, New Jersey.
Treasurer — C. Chandler Ross, Academy of Natural Sciences, 19th and Parkway,
Philadelphia, Pennsylvania.
Elected Council Members — Pershing B. Hofslund (term expires 1968) ; Kenneth C.
Parkes (term expires 1969); Andrew J. Berger (term expires 1970).
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Allen Press, Inc., Lawrence, Kansas
LltjKAKY
OCT 1 1 1967
HARVARD
THE WILSON BULLETINs'^y
A QUARTERLY MAGAZINE OF ORNITHOLOGY
Published by The Wilson Ornithological Society
Vol. 79, No. 3 September 1967 Pages 257-368
CONTENTS
Ecology of the Nesting Birds of the McCurtain Game Preserve,
Oklahoma William A. Carter 259
Observations on Bird Distribution and Feeding Assemblages Along
THE Rio Callaria, Department of Loreto,
Peru Jared M. Diamond and John W. Terborgh 273
Reproductive Success of Red-Winged Blackbirds in North Central
Oklahoma Stephen V. Goddard and Veryl V. Board 283
Behavioral Stereotypy in Birds Peter H. Klopjer 290
Some Courtship Displays of the Golden-winged
Warbler James Baird 301
Food and Feeding Habits of Autumn Migrant Shorebirds at a
Small Midwestern Pond William S. Brooks 307
ClCONlA MALTHA AND GrUS AMERICAI^A FROM THE UpPER PlIOCENE
OF Idaho /. Alan Feduccia 316
Seed-size Preference in Chickadees and Titmice in Relation to
Ambient Temperature Becky A. Myton and Robert W. Ficken 319
Additional Observations on the Structure of Unusual Feather
Tips Alan H. Brush 322
The Influence of Vocal Behavior on the Performer’s Testicular
Activity in Budgerigars (Melopsittacus
UNDULATUS) Barbara F. Brockway 328
An Improved Cage Design for Fxperimentation with Passeriform
Birds Elden W. Martin 335
General Notes
flightle:ss gheen-winged teal in southeast MissoiiKi John P. Rogers 339
DISGORGING OF FOOD BY WOOD DUCKS — Paid A. Stewort 339
15UFF-BKEASTED SANDI’II’EK IN NOH'l II WESTERN OHIO
Richard S. Phillips 340
EGG TEETH AND HATCHING METHODS OF THE LONG-BILLED CURLEW
Dennis M. Forsythe 340
FOREIGN EGGS IN NESTS OF CALIFORNIA GULLS Kees Vermeer 341
bonararte’s gull feeding on walnut meat Robert C. Frohling 341
PREDATION BY CHUCK-WILl/s-WIDOW UPON MIGRATING WARBLERS
Oscar T. Owre 342
JOSSELYN VAN TYNe’s COMMON NIGHTHAWK NESTING RETURN
Andrew J. Berger 343
RETARDED OR ARRESTED CRANIAL DEVELOPMENT IN MYIORNIS ECAVDATUS
Raymond McNeil and Aida Martinez 343
THE GAl’ING RESPONSE OF NESTLING BANK SWALLOWS George W. Fllllc 344
SEASONAL VARIATION IN BILL LENGTH OF HOUSE SPARROWS Gary G. Packard 345
UNUSUAL ACTIVITIES OF A HOUSE SPARROW^ AND A BLUE JAY AT A TUFTED
TITMOUSE NEST Kenneth W. Prescott 346
EXTRALIMITAL BREEDING OF PAINTED BUNTINGS IN FLORIDA
John G. Ogden and Frank L. Ghapman 347
GOLDFINCH ACCEPT YOUNG AFTER LONG AND SHORT INCUBATION
Larry G. Holcomb 348
NEW STATUS FOR THE RUFOUS-CROWNED SPARROW IN UTAH .. Roland H. Waller 348
The President’s Page Aaron M. 350
Ornithological News 351
Ornithological Literature 352
Alfred M. Bailey and Robert J. Niedrach, The Birds of Golorado, reviewed
by Olin Sewall Pettingill, Jr.; Desmond Nethersole-Tliompson, The Snow
Bunting, reviewed by Margaret M, Nice; Robert S. Arbib, Jr., Olin Sewall
Pettingill, Jr., and Sally Hoyt Spofford, Enjoying Birds around New York Gity,
reviewed by Geoffrey Carleton; Sberwin Carlquist, Island Life: A Natural
History of the Islands of the World, reviewed by Robert I. Bowman; En-
vironmental Pollution Panel, Presidents Science Advisory Committee, Restoring
the Quality of Our Environment, reviewed by Daniel Q. Thompson.
Proceedings of the Forty-eighth annual meeting
Pershing B. Hojsluml 358
ECOLOGY OF THE NESTING BIRDS OF THE McCURTAIN
GAME PRESERVE, OKLAHOMA'
William A. Carter
This paper reports an ecological investigation of the nesting birds of a
virgin woodland area. Field studies during the summer of 1961 and
1962 were conducted in the McCurtain Game Preserve near Bethel, in south-
eastern Oklahoma. The purpose of this paper is to describe the breeding bird
populations of the major communities and to point to certain ecological
relationships between these populations and their communities. Attention is
directed to; (1) estimates of the breeding bird populations, (2) the type
of habitats which these populations occupy for breeding and foraging terri-
tories, (3) and the community structure at the western fringe of the oak-pine
forest.
This region is of particular interest since it represents a virgin forested
area and is near the western limits of this formation. It is to be regretted
that more detailed work has not been done in other biological fields within
the river-bottom forests of the Preserve, as this association will soon be
inundated by waters of the Broken Bow Reservoir. Construction of big dams,
lumbering practices, and over-utilization by cattle and hogs in the river
bottom areas of eastern Oklahoma are rapidly reducing the area of this
biotic association and leaving the remainder unsuitable for many types of
wildlife.
THE MCCURTAIN GAME PRESERVE
History of the Preserve.— The McCurtain Game Preserve includes 15,220 acres of
mountainous land in north-central McCurtain County, Oklahoma. It is the only Okla-
homa state-owned area of virgin oak-pine forest. According to P. R. Wheeler, director
ot the Southern Forest Experiment Station, New Orleans, Louisiana (in litt.) there is
... no comparable area of virgin timber in the Southeastern (Forest Service) Region."
Ins then, is a unique area for scientific research and one of high aesthetic value,
e Preserve was placed under the administration of the Oklahoma Game and Fish
Uepartment (now the Department of Wildlife Conservation) in 1927. Except for the
loun ary fence and maintenance roads, no cultural or management techniques were
undertaken on the Preserve until 1950. During that year, a block of 40 acres was
enced in the central area of the Preserve to provide a holding pen for a turky restocking
program. The Preserve has been protected from all forms of hunting and from fire
except for small burns, since 1926. Cattle penetrate the area from the surrounding open’
range when flooding or vandalism damages the fences, however, their nuniliers arc
small and they are promptly removed. No attempt is made to remove swine unless they
become too numerous.
^ Contribution No. 425 from the Department of Zoology, Oklahoma State University
259
260
THE WILSON BULLETIN
September 1967
Vol. 79, No. .3
Predator control, which has been maintained in the Preserve on a limited basis, has
been limited to trapping of bobcats, gray foxes, coyotes, and wolves (?). Dogs that
may stray into the Preserve are caught and returned to their owners.
The U.S. Army Corps of Engineers began survey work in the virgin river-hottom areas
of the Preserve for the Broken Bow Reservoir during the summer of 1963. The opening
of the Broken Bow Reservoir for public recreation will have a marked effect on the
remote Preserve. Inundation will destroy the most unique areas of the Preserve, the
virgin river-hottom hardwood forest. Enforcement of trespassing and hunting regula-
tions and wilderness protection for the remainder of the Preserve will he made difficult
as improvement of roads leading to the lake area increase the number of visitors.
Description of the Preserve. -^Jhe Preserve lies in the southern portion of the Ouachita
Uplift. The terrain varies from moderately rugged or rather steeply rolling, to precipi-
tous. Characteristically it is composed of rough ridges. Elevations vary from 561 feet
above sea level along the Mountain Fork of the Little River to 1,363 feet on Pine
Mountain in the east central part of the Preserve. Drainage of the Preserve is part of
the Mountain Fork River system.
The soil materials in the valleys consist of shales and fill material; the ridges are
composed of sandstones, shales, and slate. Streams of high gradient are actively cuUing
the narrow flood plains. Bottomland soils are leached, poorly drained, and relatively
infertile. There are small prairie openings and areas that support savannah on soils
with a higher clay content. Much of the mountain area is rough, stony land, with some
of the formations dipping 60 degrees or more from the horizontal. The exposed edges
of the rocks enable tree roots to grow between the layers. This, together with the high
precipitation, results in superior forest sites. By contrast, in areas where shallow soils
are on horizontally bedded rocks, very poor forest sites result. Ridges of the White Oak
and Little White Oak mountains fall into this classification. Shale hands across the
mountain slopes produce open or savannah areas with increased grass ground-cover.
The Ouachita Mountains of Oklahoma were first studied geologically by Honess
(1923) with more recent detailed work in Beavers Bend State Park (Pitt and Spradhng,
1963) a few miles south of the Preserve. Surface or near surface rocks which influence
the soil and vegetative associations within the Preserve include formations from the
Ordovician period to the Recent geologic epoch. These include: (1) Alluvium Forma-
tion of the Recent characterized by recent stream deposits of sand, silt and clay; (2)
Trinity Formation of the Cretaceous; (3) Stanley Shale Formation of the Mississipian ;
(4) Arkansas Novaculite Formation, of which the Upper Division is of the Mississippian
period, the Middle Division between the Mississippian and Devonian periods, the
Lower’ Division of the Devonian; (5) Missouri Mountain Shale Formation of the
Silurian; (6) Blaylock Sandstone Formation of the Silurian; (7) Polk Creek Shale
Formation of the Ordovician; and (8) Bigfork Chert Formation of the Ordovician.
The Stanley Shale Formation is the most extensive formation in the Preserve.
The Preserve is located in the area of Oklahoma which receives the highest annual
rainfall. Approximately 75 per cent of the rainfall occurs during the growing season.
Records for a 10-year (1954-1963) average monthly rainfall are shown in Table 1. Ex-
tremes for the 10-year period show a high of 12.42 inches in October 1954 and a low
of 0.31 inches in October 1963. Rivers and streams in the area may rise rapidly m
response to heavy rainfall during short periods of time, hut the run-off is rapid Ihe
10-year temperature records showed the highest monthly average maximum of 93 1 m
July and the lowest monthly average minimum of 28 F in January, as shown in Table .
A 24-year record showed an average annual frost-free period of about 233 days with
W illiam A.
Carter
NESTING BIRD
ECOLOGY
261
Table
1
Ten-Year
Average (1954-1963)
OF Climatological
Data
Precipitation
totals
Average Monthly
Temperature (°F)
Maximum
Minimum
January
2.80
51.48
27.78
February
2.99
57.31
33.19
March
3.96
63.55
38.03
April
4.36
74.02
49.26
May
5.35
81.60
57.75
June
3.08
87.46
64.06
July
4.88
92.66
68.59
August
4.33
92.45
67.17
September
4.29
86.28
60.78
October
4.38
76.13
51.07
November
3.48
63.43
38.10
December
3.36
54.66
32.56
the last killing frost usually occurring the third week in March, and the first killing
frost in the fall occurring about the second week in November. Published records of
the U.S. Department of Commerce (1954-63) were consulted for all climatic data.
The Austroriparian Biotic Province (Dice, 1943), characterized by subclimax pine
forests within the eastern deciduous forests, is found within this major climatic area.
The Preserve is located in the western limits of this Province. The vegetative units
within the Preserve may be delimited according to the topographic and soil character-
istics of the site. Lindzey, studying the deer in the Preserve (1950), recognized six
game (habitat) types within the Preserve. The steep north slopes and the protected
ravines are characterized by white oak iQuercus alba), red oak iQuercus rubra), and
flowering dogwood iCornus florida) . The ridges are characterized by mature stands
principally of short-leaf pine iPinus echinata) , hut include post oak iQuercus stellata) ,
white oak iQuercus alba), and blackjack oak iQuercus marilandica) . The south slopes
have essentially the same composition as the ridges. A large portion of the Preserve
manifests an intermediate condition, with variable sites which show a composite of
other upland areas. The virgin river bottom hardwood forests are dominated by holly
illex opaca) , white oak iQuercus alba), sweetgum i Liquidambar styraciflua) , hickory
iCarya sp.), ash (Fraxinus sp.), and baldcypress iTaxodium distich um) , with cane
i Arundinaria gigantea) , spicebush iLindera benzoin), and some panic grasses iPanicum
spp.), for ground cover. The stream bottom woodlands typically have a composition
similar to that of the north slopes. It is of major importantce to recall that the avian
habitats are essentially of the same life-form in all areas of the Ouachita Uplift. Out-
side of the Preserve, however, mature virgin stands are found in very limited areas.
METHODS
The present study is an attempt to obtain the absolute abundance or the
actual avian breeding populations of sample areas and to project these figures
for an estimate of the total breeding bird populations for the Preserve. As
262
THE WILSON BULLETIN
Sc|itcml)er 1967
Vol. 79, .No. :i
Table 2
Dominants and Codominants of tup: Rived Bottom Forest*
Species
Frequency of
occurrence
( per cent )
Basal area
(sq. ft.)
(per cent)
American holly (//ex opaca)
34
12.4
19.7
White oak {Quercus alba)
19
11.7
18.5
Sweetgum i Liquidamhar styracijiua)
9
13.2
20.9
Mockernut Hickory iCarya tomentosa)
8
3.7
5.9
Sourgum iNyssa sylvatica)
5
6.1
9.6
A.'ih \Fraxmus sp.)
5
0.9
1.4
Baldcypress (Taxodium distichum)
4
6.8
10.8
Hornheam iOstrya virginiana)
3
-
-
Ironwood (Carpinus caroliniana)
3
0.6
0.9
Total
63.1
* Plant nomenclature taken from Petrides, 1958.
this study was primarily concerned with obtaining the most dependable re-
sults possible, a combination of various census techniques was employed.
On the basis of field reconnaissance and a review of aerial photos and
topographic maps, three areas were selected for intensive study. This selec-
tion was based on the following points: areas were (1) representative of
the three major plant communities in the Preserve; (2) not disturbed by
roads, fence lines, or other maintenance improvements of the Preserve; (3)
of uniform life-form and were surrounded by identical community type in
order to eliminate edge effect; and (4) of adequate size for uniform plots.
The boundaries of these areas were marked. The size of each plot was de-
termined by use of steel tape, compass, and aerial photographs. A sketch
map of each plot was used each time an area was censused. These maps in-
cluded any distinctive landmark which helped pinpoint the exact locality.
Field data were noted on the maps to show approximate locations of singing
males, active nest sites, young out of the nest, adults carrying food, family
groups, or any other behavioral activities or signs that would indieate nesting.
The areas were censused from 5 am to about 8 am. I found that the activity
of singing males for most species had decreased by 7:30 am to 8:30 AM to
the point that counts were invalid. However, observations on other activities
associated with breeding could be made after that time.
The belt transect sampling method (Weaver and Clements, 1929; Lutz,
1930 ) was used to determine species composition of trees and shrubs in the
sample plots. The width of the transect lines was 20 meters for trees and two
meters for shrubs. In the upland samples with a large area of uniform com-
munity type, the length of the transect line was inereased until the percentage
composition was not varied when the last segment was added. The river
W illiai
Carter
A.
NESTING BIRD ECOLOGY
263
Table 3
Undekstoky Plants of the River Bottom Forest*
Frequency of
occurrence
Species (per cent)
Ironwood iCarpinus Carolinian a) 16
Ward willow {Salix caroliniana) 14
Mockernut hickory iCarya tomentosa) 9
Hornbeam iOstrya virginiana) 9
Buttonbush {Cephalanthus occidentalis) 6
Grape iVitis sp.) 5
Flowering dogwood (Cornus florida) 3
Sweetgum (Liquidambar styraciflua) 2
Red oak {Quercus rubra) 2
Baldcypress {Taxodium distichiim) 2
* d.b.h. less than 4"; 1 m high.
bottom and stream bottom plots were sampled by three transect lines running
at right angles to the plots.
BIRD POPULATIONS AND THE PLANT COMMUNITIES
The avian habitats of the Preserve reflect the basic structure of the domi-
nant vegetation, rather than the species composition of individual plant as-
sociations— a point well demonstrated by Pitelka ( 1941 ) lor the North
American bird fauna. Considering the distribution of local bird species, the
predominant habitats, preferred for breeding activities, are upland forests,
river bottom forests, and stream bottom woodland.
The river bottom community. — The study area of this habitat type in-
cluded that portion of the river bottom east of the Mountain Fork River from
the low-water bridge north to the Preserve fence. The 35-acre study area was
located in Section 4, R25E, T3S. Elevation was 560 feet above sea level.
One-half mile of edge occurs along the river. The closure of the forest crown
cover of this community varies from 50 to 100 per cent. The frequency of
occurrence and basal area of the dominant and codominant trees is given
in Table 2. The frequency of occurrence of the common understory plants
is given in Table 3. The ground cover is sparse, composed chiefly of: Panicurn
sp., Smilax spp., spicebush [Liiidera benzoin), and cane { Arundinaria
gigantea ) . A high percentage of the river bottom forest floor is open, bare
ground, or covered with river drift materials.
The river bottom community is the most important one of the Preserve
for the study of bird ecology as it supports the greatest total biomass. The
floral and faunal composition make this a unique feature of the Preserve.
264
THE WILSON BULLETIN
September 1967
Vol. 79, No. 3
Nesting Birds
Table 4
OF THE River
Bottom
Forests
Species
Pairs/100
acres
1961
Pairs/ 100
acres
1962
Average
Projected
estimate
( 200 acres )
Turkey Vulture
+
+
+
Wood Duck
1
1
1.0
Red-shouldered Hawk
Bobwhite
1
+
1
1
2.0
+
Turkey
+
+
+
Yellow-hilled Cuckoo
5.7
5.7
5.7
11.4
Barred Owl
8.6
2.9
5.7
11.4
Chuck-will’s-widow
8.6
2.9
5.7
11.4
Chimney Swift
+
+
+
Ruhy-throated Hummingbird
2.9
2.9
5.8
Belted Kingfisher
+
+
+
Pileated Woodpecker
2.9
2.9
2.9
5.8
Red-hellied Woodpecker
5.7
5.7
5.7
11.4
Hairy Woodpecker
5.7
2.9
4.3
8.6
Downy Woodpecker
2.9
2.9
2.9
5.8
Great Crested Flycatcher
8.6
2.9
5.8
11.6
Acadian Flycatcher
14.3
11.4
12.9
25.8
Eastern Wood Pewee
5.7
5.7
5.7
11.4
Blue Jay
+
+
+
Common Crow
1
1
1
2.0
Carolina Chickadee
11.4
11.4
11.4
22.8
Tufted Titmouse
5.7
8.6
7.2
14.4
White-breasted Nuthatch
8.6
2.9
5.7
11.4
Carolina Wren
8.6
8.6
8.6
17.2
Wood Thrush
2.9
2.9
2.9
5.8
Blue-gray Gnatcatcher
11.4
2.9
7.2
14.4
White-eyed Vireo
25.7
17.1
21.4
42.8
Red-eyed Vireo
28.5
25.7
27.1
54.2
Blaek-and-white Warbler
8.6
8.6
8.6
17.2
Prothonotary Warbler
1
1
1
2.0
Swainson’s Warbler
1
1
1
2.0
Worm-eating Warbler
3
2
2.5
5.0
Parula Warbler
8.6
11.4
10.0
20.0
Cerulean Warbler
2.9
2.9
2.9
5.8
Ovenbird
5.7
2.9
4.3
8.6
Louisiana W'aterthrush
8.6
8.6
8.6
17.2
Kentucky Warbler
11.4
8.6
10.0
20.0
Yellow-breasted Chat
2
2
2
4.0
Hooded Warbler
14.3
17.1
15.7
31.4
American Redstart
20.0
14.3
17.2
34.4
Cardinal
8.6
5.7
7.2
14.4
Indigo Bunting
2.9
2.9
2.9
4.8
Totals (36 species, +6)
279
219
248
502
William A.
Carter
NESTING BIRD ECOLOGY
265
Table
Dominants and Codominants of
5
THE Stream Bottom Forest
Species
Frequency of
occurrence
( per cent )
Basal area
(sq. ft.)
( per cent )
White oak {Quercus alba)
17
11.0
14.1
Shortleaf pine i Pinas echinata)
17
23.1
29.6
Mockernut hickory iCarya tomentosa)
16
11.4
14.6
Sweetgum ( Liquidambar styraciflua)
14
13.0
16.7
Ironwood iCarpinus caroliniana)
7
2.7
3.4
Sourgum (Nyssa sylvatica)
6
4.9
6.3
Red oak (Quercus rubra)
4
2.8
3.6
Red maple (Acer rubrum)
4
1.2
1.6
Hornbeam (Ostrya virginiana)
4
0.7
0.9
Swamp oak (Quercus bicolor)
2
0.7
0.9
Pignut hickory iCarya glabra)
2
1.0
1.3
Winged elm (Ulmus alata)
2
1.5
1.9
Sycamore (Platanus occidentalis)
2
2.9
3.7
Red mulberry (Morus rubra)
2
1.0
1.3
Ash (Fraxinus sp.)
2
0.6
0.7
Red cedar (Juniperus virginiana)
1
0.5
0.6
Total
78.0
Studies in various areas of this community other than the study area show
remarkable uniformity in proportions of species. There is very little dis-
parity between the counts made during the two summers. The estimates of
species in the study area and the projected estimates for the 200 acres of
this community are given in Table 4. A plus sign ( + ) is used to indicate
species which nested outside the study area in this habitat and species fre-
quently observed but not definitely known to breed in the habitat. The figures
for the average number of pairs are derived from the populations in the study
areas and augmented by data from observations in the same habitat but
outside the study area.
The stream bottom community. — The stream bottom community study
area consisted of a 32-acre plot along Panther Branch in Sections 4 and 5,
R25E, T3S. The area averaged 130 yards wide with the stream bed in
the center and the outer boundaries more or less paralleling the stream bed.
Sufficient width was allowed between these outer boundaries and the slopes
to avoid edge effect.
The closure of the forest cover ranged from 50 to 75 per cent and was
generally uniform. The frequency of occurrence and basal area of the
dominant and codominant trees is given in Table 5. The frequency of oc-
currence of the common understory plants is given in liable 6. This community
266
I HE WILS()\ BULLETIN
Septemher 1967
Vol. 79, No. 3
Table 6
Unuekstoky Plants of tup: Sthp:am IJottom Forest*
Frequency of
occurrence
Species ( per cent )
Ironwood {Carpinus caroliniana) 31
Red cedar (Juniperus virginiana) 16
Sweetgum ( Liquidambar styraciflua) 11
Witch-hazel ( Hamamelis virginiana) 10
Flowering dogwood (Cornus jlorida) 9
Hornbeam iOstrya virginiana) 1
Red oak iQuercus rubra) 3
White oak iQuercus alba) 3
Shortleaf pine iPinus echinata) 2
Sourgum (Nyssa sylvatica) 1
Mockernut hickory iCarya tomentosa) 1
Common spicebush (Lindera benzoin) 1
Winged elm iUlmus alata) 1
* d.b.h. less than 4"; 1 m high.
had the best ground cover of the three major habitats of the Preserve.
Andropo^on spp. formed about 75 per cent of the non-woody ground cover.
Paniciirn spp. and seedlings of the various woody species formed most of
the remaining living ground cover. Heavy litter covered most of the space
between plants so that very little bare ground was exposed.
The nesting bird populations showed a species composition intermediate
between those of the moist river bottom and the drier uplands. No birds were
restricted to this habitat. The estimate of species in the study area and the
projected estimate for the 1,100 acres of this community in the Preserve are
given in Table 7.
The upland community. — The upland Oak-Pine community study area
was located in Sections 2 and 11, R25E, T3S. The 30-acre area was
along the section line on the east side of the given sections. Crown
closure of this area was from 70 to 100 per cent. The area is typical
of the intermediate areas of the Preserve, that is, those with moderate slopes.
Lindzey (1950) recognized four game types in the upland community. How-
ever, field observations showed no significant variations in the avian species
distribution in these four types. Significant divergence of species composition
did occur on White Oak and Little White Oak mountains, but the remoteness
of these areas made it impossible to adequately sample the bird populations
there. The frequency of occurrence and basal area of the dominant and
codominant trees are given in Table 8. The frequency of occurrence of the
common understory plants is given in Table 9. The ground cover varied
Williai
Carter
A.
NESTING BIRD ECOLOGY
267
Nesting Birds
Table 7
1 OF THE Stream
Bottom
Forests
Species
Pairs/ 100
acres
1961
Pairs/ 100
acres
1962
Average
Projected
estimate
(1,100 acres )
Turkey Vulture
+
+
+
Broad-winged Hawk
3.1
+
1
11
Sparrow Hawk
+
3.1
1
11
Bobwhite
3.1
+
3.1
34
Yellow-billed Cuckoo
3.1
3.1
3.1
34
Screech Owl
3.1
+
1
11
Chuck-will’s-widow
+
+
+
Chimney Swift
+
+
+
Ruby-throated Hummingbird
1
1
11
Pileated Woodpecker
1
1
1
11
Red-bellied Woodpecker
+
+
Hairy Woodpecker
3.1
3.1
3.1
34
Downy Woodpecker
3.1
3.1
3.1
34
Great Crested Flycatcher
3.1
3.1
3.1
34
Acadian Flycatcher
9.4
6.3
7.9
87
Eastern Wood Pewee
9.4
9.4
9.4
103
Blue Jay
6.3
3.1
4.7
52
Common Crow
+
+
+
Carolina Chickadee
12.5
9.4
10.5
116
Tufted Titmouse
3.1
6.3
4.7
52
White-breasted Nuthatch
6.3
6.3
6.3
69
Carolina Wren
9.4
9.4
9.4
103
Wood Thrush
+
+
Blue-gray Gnatcatcher
6.3
3.1
4.7
52
White-eyed Vireo
3.1
3.1
3.1
34
Red-eyed Vireo
18.8
18.8
18.8
207
Black-and-white Warbler
3.1
3.1
3.1
34
Parula Warbler
9.4
12.5
10.5
116
Pine Warbler
9.4
6.3
7.9
87
Ovenbird
3.1
3.1
3.1
34
Louisiana Waterthrush
3.1
6.3
4.7
52
Kentucky Warbler
3.1
+
3.1
34
Indigo Bunting
+
3.1
3.1
34
Totals (27 species, +6)
140
126
136
1,491
from sparse Andropogon in the more open areas to exclusively pine needle
and leaf litter in areas with dense crown cover.
The virgin stands of mature short-leaf pine are the habitat of the Preserve’s
two most unique permanent avian residents, the Red-cockaded Wood})ecker
and the Brown-headed Nuthatch. Nice (1931) reported Red-cockaded Wood-
peckers in 1925. This species was not recorded from the state again until
268
THE WILSON BULLETIN
Septfiiil)er 1967
\ ol. 79, No. ;j
4\ble
Dominants and Cooominants
8
OF THE UpLANIJ
Forests
Frequency of
Basal
area
occurrence
Species
( per cent )
(sq. ft.)
(per cent)
Sliortleaf pine iPinus echinata)
81
69.6
87.0
White oak ( Quercus alba)
10
2.9
3.6
Post oak (Quercus stellata)
7
6.6
8.4
Blackjack oak (Quercus marilandica)
2
0.2
0.25
Total
79.3
1954 (Baumgartner, 1954). The Recl-cockaded Woodpeckers were limited
in distribution in the Preserve to areas with stands of large mature pine—
d.b.h. 15 inches or more. Nest trees which I was able to locate averaged 17
inches d.b.h. Their habit of scaling the bark from the living pine for two
feet above and below the entrance of the nest cavity and of puncturing a
series of small holes to allow the pine pitch to ooze to the surface allows the
nests to be located easily. The only nesting record for Oklahoma outside of
the Preserve was reported in Robber’s Cave State Park near Wilburton in
1961 (Baumgartner, 1961). The Brown-headed Nuthatch was observed in
Pushmataha County in 1920 (Nice, 1921) and was not recorded in Oklahoma
again until 1953 (Baumgartner, 1954). Tom lessee, then the Preserve man-
ager, reported this species nesting in a fence post on the Preserve on 11 March
1954 with young noted in late April. Other species found in the upland habi-
tat are considered typical for the region. The estimates of species in the
study area and the projected estimate for the 12,000 acres of this community
type are given in Table 10.
DISCUSSION
Eleven species were nesting only in the river bottom habitat within the
Preserve. No species were found using the stream bottom habitat exclusively
for nesting. However, seven species were limited to the stream bottom and
the river bottom — the more moist habitats within the Preserve. A total of
eighteen species were limited to the two riparian woodland formations within
the Preserve — the river bottom and the stream bottom communities. Of
these eighteen species, seven are approaching their western limits of distribu-
tion (AOU, 1957). The Wood Duck, Prothonotary Warbler, Louisiana
Waterthrush, Swainson’s Warbler, and Cerulean Warbler are typical nesting
species of the riparian habitats over their entire breeding ranges. The Oven-
bird and the Worm-eating Warbler are typical woodland nesting forms over
most of their range and are restricted to the riparian woodlands only in the
William A.
Carter
NESTING BIRD ECOLOGY
269
Table 9
Understory Plants of the Upland
Forests*
Species
Frequency of
occurrence
( per cent )
Mockernut hickory (Carya tomentosa)
29
Post oak (Quercus stellata)
20
Blackjack oak {Quercus marilundica)
14
Flowering dogwood (Cornus floridu)
14
White oak (Quercus alba)
6
Shortleaf pine {Pinus echinata)
3
Common spicehush (Lindera benzoin)
2
Red oak (Quercus rubra)
2
* d.b.h. less than 4"; 1 m high.
southwestern limits of their nesting distribution (AOU, 1957). Eour species
were limited to the stream bottom and upland forests for their nesting
activities within the Preserve. The intermediate character of the stream
bottom communities was therefore emphasized by the nesting distribution
pattern which showed an overlap of species from both the river bottom and
the upland forests, as well as a mixed floral composition. The upland
habitat was utilized by seven species exclusively for their nesting activities.
Twenty-three species utilized all three of the major habitats in the Preserve
for nesting activities. This pointed out the fact that a woodland habitat —
regardless of its composition — was the only requirement for certain species
with less specialized nesting niches. It was also noted that some of these
species reached greater densities in one habitat than in the other.
Nine species were considered to be rare within the Preserve. The follow-
ing reasons are suggested to explain the limited occurrence of these nine
species: The Wood Duck and Prothonotary Warbler populations were limited
due to the lack of proper nesting cavities in trees along the river; the minimal
numbers of Red-shouldered Hawks are attributed to their large territorial
requirements and the limited area of suitable river bottom habitat; the
Roadrunner, having recently invaded this region (Lowery, 1955), is reach-
ing its eastern limits of distribution (AOU, 1957) ; the Red-cockaded Wood-
pecker, being intimately associated with mature stands of pines, is limited
by their distribution; the Brown-headed Nuthatch, Prothonotary Warbler,
Swainson’s Warbler, Worm-eating Warbler, and Cerulean Warbler are ap-
proaching the western limits of their nesting range (Griscom and Sprunt.
1957); and the Turkey populations, once extirpated from this area, have
been reintroduced.
270
THE WILSON BULLETIN
Sc[)tpnil»er 1967
Vol. 79, No. .1
Nesting
Table 10
Birds of the Upland Forests
Species
Pairs/ 100
acres
1961
Pairs / 100
acres
1962
Average
Projected
estimate
(12,000 acres)
Turkey Vulture
+
+
+
Sparrow Hawk
1
1
1
20
Bobwhite
+
+
Turkey
+
+
+
Yellow-billed Cuckoo
6/)
6.6
6.6
792
Roadrunner
+
+
4
Screech Owl
+
+
+
Chuck-will’s-widow
+
+
Chimney Swift
+
+
+
Yellow-shafted Flicker
+
+
Red-bellied Woodpecker
3.3
3.3
3.3
396
Red-headed Woodpecker
6.6
6.6
6.6
792
Hairy Woodpecker
3.3
+
3.3
396
Downy Woodpecker
+
3.3
3.3
396
Red-cockaded Woodpecker
+
+
7-10
Great Crested Flycatcher
6.6
6.6
6.6
792
Eastern Wood Pewee
9.9
9.9
9.9
1,188
Blue Jay
3.3
6.6
5.0
600
Common Crow
+
+
+
Carolina Chickadee
6.6
6.6
6.6
792
Tufted Titmouse
6.6
6.6
6.6
792
White-breasted Nuthatch
9.9
6.6
8.3
996
Brown-headed Nuthatch
+
+
+
Carolina Wren
3.3
6.6
5.0
600
Wood Thrush
+
6.6
6.6
792
Blue-gray Gnatcatcher
3.3
6.6
5.0
600
Red-eyed Vireo
9.9
19.9
14.5
1,740
Black-and-white Warbler
3.3
+
3.3
396
Parula Warbler
+
+
+
Yellow-throated Warbler
+
+
+
Pine Warbler
9.9
13.2
11.5
1,380
Prairie Warbler
+
+
Ovenhird
3.3
3.3
3.3
396
Scarlet Tanager
3.3
3.3
3.3
396
Summer Tanager
3.3
6.6
5.0
600
Indigo Bunting
3.3
+
3.3
396
Chipping Sparrow
+
+
+
Total (35 species, +2)
107
130
128
15,262
William A.
Carter
NESTING BIRD ECOLOGY
271
The densities of a few species within the Preserve were lower than those
outside of the Preserve. Among these, personal observations indicated that
the Chipping Sparrow, Bobwhite, Cardinal, Blue Jay, and Common Crow
were more tolerant of the open areas created by the activities of man. Al-
though common outside, the Mourning Dove, House Sparrow, Orchard Oriole,
Brown-headed Cowbird, Eastern Bluebird, and Starling were found only in
limited numbers in the small disturbed areas around the manager’s home
and barns. These species were never recorded in any other part of the Pre-
serve. The population of ground nesting species was suppressed by the de-
struction of the ground cover, nests, and young by the activities of swine.
SUMMARY
Field studies of the nesting birds of the McCurtain Game Preserve, McCurtain County,
Oklahoma, were conducted during the summers of 1961 and 1962 in the months of
June, July, and early August. Intensive studies were made in three areas representative
of the major habitats of the Preserve. Data derived from these study areas were aug-
mented by less intensive surveys within each of the habitats at various locations over
the Preserve.
The river bottom community supported the highest population of nesting birds (248
pairs per 100 acres) and the greatest number of species (36, plus six others possible).
Eleven species utilized the river bottom habitat exclusively for nesting activities. The
stream bottom community supported 136 pairs per 100 acres with 27 species (plus six
others possible). The upland community supported 128 pairs per 100 acres with 35
species (plus two others possible). The total projected breeding bird population for
the 13,300 acre virgin woodlands of the Preserve was 17,255 pairs composed of 56 species.
Two of these species, the Red-cockaded Woodpecker and the Brown-headed Nuthatch
are limited to the mature virgin pine areas of the Preserve in Oklahoma. The activities
of swine suppress the population of ground nesting birds in the Preserve. The unique
attributes of the virgin hardwood forest of the river bottom will be destroyed by waters
of the Broken Bow Reservior now under construction. Steps should be taken to assure
adequate protection for the remaining virgin woodland areas of the Preserve.
ACKNOWLEDGMENTS
Appreciation is expressed to my major adviser. Dr. F. M. Baumgartner, who has
freely given his time and counsel during the course of this research project. The results
reported here represent part of a dissertation submitted in partial fulfillment of the
requirements for the Ph.D. at Oklahoma State University. I wish to thank the admin-
istration of the Oklahoma Department of Wildlife Conservation for permission to carry
out the field study and use the facilities in the Preserve. Special thanks are due Mr.
Eugene Woods, Preserve manager, and Mr. Glen Scott, former assistant, and their
families for cooperation and courtesies extended during my stay in the Preserve, 1
am indebted to Drs. G. A. Moore and H. W. Reno for reading early drafts of the manu-
script.
LITERATURE CITED
Amkrican Ornithologist’s Union
1957 Check-list of North American birds. 5tb Ed. Baltimore, Maryland.
272
THE WILSON BULLETIN
Se])temher 1967
Vol. 79, No. 3
lUuMGAKTNEH, F, M.
1954 Southern Great Plains Region. Audubon Field Notes, 8:260.
1961 Southern Great l^lains Region. Audubon Field Notes, 15:478.
Dice, L. R.
1943 The liiotic provinces of North America. Univ. of Michigan J^ress, Ann Arlior.
Gkiscom, L., and a. Sprunt, Jr.
1957 The warhlers of America. Devin-Adair Go., New York.
Honess, C. W.
1923 Geology of the Southern Ouachita Mountains of Oklahoma. Okla. Geological
Survey, Bull. 32, Parts 1 and II.
Lindzey, J. S.
1950 The white-tailed deer in Oklahoma. Okla. Game and Fish Dept., Oklahoma
City.
Lowery, G. H., Jr.
1955 Louisiana birds. Louisiana State University Press, Baton Rouge, Louisiana.
Lutz, H. J.
1930 The vegetation of Heart’s Content, a virgin forest in northwestern Pennsyl-
vania. Ecology, 11:1-29.
Nice, M. M.
1921 The Brown-headed Nuthatch in Oklahoma. Condor, 23:131.
1931 The birds of Oklahoma. Rev. ed. Univ. of Oklahoma Biol. Survey 3:1-224.
Petrides, G. a.
1958 A field guide to trees and shrubs. Houghton Mifflin Co., Boston.
PiTELKA, F. A.
1941 Distribution of liirds in relation to major biotic communities. Amer. Midland
Nat., 25:113-137.
Pitt, W. D., and C. B. Spradling
1963 Geology of Beavers Bend .State Park. In Beavers Bend .State Park. Okla.
Geological Survey Guide Book XI.
U.S. Dept, of Commerce
1954-1963 Climatological Data. Oklahoma Sections. U.S. Gov’t. Printing Office,
Washington, D.C.
Weaver, J. E., and F. E. Clements
1929 Plant ecology. McGraw-Hill, New York.
DEPARTMENT OF BIOLOGY, EAST CENTRAL STATE COLLEGE, ADA, OKLAHOMA,
7 FEBRUARY 1966.
OBSERVATIONS ON BIRD DISTRIBUTION AND FEEDING
ASSEMBLAGES ALONG THE RIO CALLARIA, DEPARTMENT
OF LORETO, PERU
Jared M. Diamond and John W. Terborgii
This paper presents a summary of bird observations made in late July
and early August. 1963, along the Rio Callaria, a small tributary of the
Ucayali in the Department of Loreto, Peru. The Rio Callaria flows westward
from the Brazilian border region to its confluence with the Ucayali at ap-
proximately o°o'S and 74°38'W. From this point we travelled by dugout
canoe some 20-30 miles upstream and returned. Observations of birds were
made from the river and its banks and on excursions into the flanking forests.
The relative abundance of 88 species in each of three distinct vegetational
zones is given along with incidental notes and a description of two mixed
assemblages of birds observed in feeding trees.
ECOLOGICAL ZONATION OF BIRDLIFE
So far as we were able to ascertain, the terrain in the vicinity of the Cal-
laria had suffered relatively little from the effects of human incursion. Three
small Indian villages with their adjacent plantations of bananas and yucca
occupied high sections of the bank, thus creating small enclaves of secondary
habitat. In addition we were informed by a missionary, who had lived a
number of years in one of these villages, that some selective logging for
'‘cedar” had taken place in the forests upstream during periods of high water.
As “cedar” trees occur uncommonly and singly, the effects of this logging
were not apparent. Thus the observations reported here, to a close approxi-
mation, should reflect the status of birdlife in an undisturbed primary region.
The distinctive feature of the Callaria is that natural habitats replace one
another in a succession as one passes upstream. Thus, within a relatively
short distance we had the opportunity to relate changes in bird distribution
to an evident ecological zonation along the river.
In the course of its lower 20 miles, the Callaria flows through three distinct
vegetational zones. The first of these is a low-lying flood-plain or matorral
formation ( MacBride, 1936 ) which extends upstream from the mouth for
about 3 miles. The river runs nearly straight here and at the time of our
visit was confined to a shallow channel about 100 feet in width. There was
no forest within sight of the river in this stretch, the vegetation along its
banks consisting of a dense growth of rangy bushes and tall grass.
The second, middle zone, a transitional region, extends for 5-8 miles above
the flood-plain. Along this section the river becomes gradually narrower.
273
274
THE WILSON BULLETIN
S(‘i)ternl)er 1967
Vol. 79, No. 3
turns more frequently, and flows between progressively steeper banks as one
])roceeds upstream. Concommitantly, the character of the vegetation changes
from that of the lower reaches to the high overhanging canopied forest
typical of the upper river. In most of this transitional section the forest does
not impinge on the banks but lies back somewhat. A bordering strip, up to
50 yards in width, of tall grass and or dense shrubbery and bushes fills the
intervening area.
In the third zone, further upstream, the forest closes in on the banks of tbe
river, the channel becomes reduced to a width of 40-70 feet, and the stream
flows rapidly. The overhanging trees are sufficiently tall to shade the water
for much of the day. Numerous fallen trunks lying in the channel provide
perches for hawks, kingfishers, swallows, and flycatchers.
By early August the dry season in eastern Peru is well advanced. Conse-
(juently, during our visit the river’s flow was near the minimum for the year.
Extensive sandy banks were exposed along most of its course, and in the lower
section particularly there were many bars and shoals in mid-stream. During
the rainy season, which extends from November to May, the Ucayali and
its tributaries fill with water, the annual fluctuation in river level approach-
ing forty feet in many places. Although we were told that there had been no
rain for more than two months, the vegetation, except for a few species of
deciduous trees, showed few signs of desiccation either close to the river or
on higher ground. The high humidity, heavy dew each night, and low evapo-
ration from the shaded forest floor are probably all important in maintaining
the verdant aspects of this region throughout the dry season.
Table 1 summarizes our observations on the distribution of birds in the
three vegetational zones. The relative abundance in each zone is given for 88
species of birds. Nomenclature follows that of de Schauensee ( 1966 I . Spe-
cies that were regularly seen in pairs are denoted by a “p” in parentheses
after the name. The only positive evidence of breeding activity that we ob-
tained was a nest burrow containing a single white egg attributed to Mouasa
ni^rijrons by our Indian guides.
A summary of the zonal distribution of the 88 species is presented in Table
2. The species in each zone have been classified according to whether they
occurred in all three zones, in two, or only in the zone in question. Those
found in all three must occupy niches that all three zones share in common,
for example, the air space over the river.
The data in Table 2 suggest the following statements regarding the en-
vironmental factors controlling bird distribution on the Rio Callaria.
(1) The avifauna of the lower zone is by far the poorest in species but
nevertheless is distinct to a high degree. Apart from the 11 wide-ranging
forms ( two storks, one vulture, one kingfisher, one puffbird, two flycatchers.
Diamond and
Tert.orgh
PERUVIAN BIRD DISTRIBUTION
275
Table 1
List of Bird Species Observed along the Rio Callaria.
(Tlie relative aliundance of each species in the three vegetational zones is
follows: +5 observations; + + , 4-10 observations; + ++, more
10 observations)
indicated as
than
Zone
Lower
Middle
Upper
Ardeidae
Pilherodius pileatus
+
Bii tor ides striatus
+ +
Casmerodius albus
+
Tigrisoma sp. (p)
+
Ciconiidae
Mycteria americana
+
+
+
Jabiru mycteria
+
+ +
+ +
Threskiornithidae
Mesembrinibis cayennensis
+
Anhimidae
Anhima cornuta (p)
+ + +
+ +
Cathartidae
Sarcorhamphus papa
+
Coragyps atratus
+ + +
+ + +
+ + +
Cathartes aura
+ +
+ +
Cathartes melambrotus
+
Accipitridae
Elanoides forficatiis
+
Buteo magnirostris (p)
+ + +
+ + +
Buteogallus urubitinga
+
Busarellus nigricollis
+ +
+ +
Falconidae
Daptrius ater (p)
+ +
+ +
Daptrius americanus (p)
+
Milvago chimachima
+ +
Falco rufigularis (p)
+
Cracidae
Ortalis guttata
+ +
+ +
Rallidae
Aramides cajanea
+
Eurypygidae
Eurypyga h el ias ( p )
+
+
Jacanidae
Jacana jacana
+ +
+
Charadriidae
Charadrius collaris
+
Scolopacidae
Tringa flavipes
+ +
276
THE WILSON BULLETIN
September 1967
Vol. 79, No. .3
Table 1 icont.)
Zone
Lower Middle Upper
Trill ga so/itaria +
Act it is macularia +
Laridae
Phaetusa simplex
Sterna siiperciliaris
(A)lumhidae
Cola m bi gal I i n a tal pa coti
Psittacidae
Ara ararauna (p)
Brotogeris versicolorus
Am a zona sp.
Cuculidae
Piaya cay ana
Crotophaga major (p)
Crotophaga ani
Strigidae
Otus choliba
Caprimulgidae
Nyctidromus albicollis
Trogonidae
T logon viridis
Trogon collar is
Alcedinidae
Ceryle torquata
Chloroceryle amazona
Chloroceryle americana (p)
Momotidae
Mo mot us momota
Galhulidae
Galbalcyrhynchus leucotis
Galbula cyanescens
Bucconidae
M on asa n i gri jron s
Cheiidoptera tenebrosa (p)
Capitonidae
Eubucco richardsoni
Ramphastidae
Ramphastos tucaniis
Pteroglossus castanotis
Pteroglossus inscriptus
Picidae
Melanerpes cruentatus
Phloeoceastes melanoleucos
+ +
+
+
+
+++ +++
+++ +++
+ + + +
+ + + +
+++ +++
+
+ + + +
+
+ + + +
+++ +++
++ +++ ++
+ + +
+
+ + +
+ + + +
+ + +
+ +++ +++
+
+ + + + +
+ + + + +
+
+ +
+
Diamond and
Terl.oigli
PERUVIAN BIRD DISTRIBUTION
277
Table 1 [cont.)
Zone
Lower Middle Upper
Dendrocolaptidae
Xiphorhynchiis sp.
Furnariidae
Furnarius leucopus
Formicariidae
Pygiptila stellaris
Cotingidae
Cotinga sp.
Tityra sp.
Tyrannidae
Colonia colonus
Arundinicola leucocephula
Pyrocephalus rubinus
Ochthornis littoralis
Tyrannus melanocho/icus (p)
Pitangus sulphuratus (p)
Hirundinidae
Tachycineta al biventer
Atticora fasciata
Stelgidopteryx ruficollis
Corvidae
Cyanocorax violaceus
Troglodytidae
Thryothorus cor ay a
Mimidae
Donacobius atricupillus (p)
Coerebidae
Coereba flaveola
Dacnis cay ana
Dacnis lineata
Thraupidae
Chlorophonia cyanea
Tanagra laniirostris
Tangara chi/ensis
Ramphocelus carbo
Cissopis leveriana
Icteridae
Psarocolius sp.
Cacicus cela
Icterus icterus
Agelaius icterocephalus
Fringillidae
Saltator coerulescens
Paroaria gularis (p)
+ +
++
+ + +
+
+
+
+
++
++
+++
+ + +
++
+++
+++
++
++
+++
+ + +
+++
+++
+ + +
++
++
+ +
+++
++
+
+ +
+++
+ +
+++
+ +
4-
+
+
+
+
+
+ +
++
+ +
+
+
++
++
++
+
++
+++
+ + +
I
278
THE WILSON BULLETIN
September 1967
Vol. 79, No. 3
Table 1 icont.)
Zone
Lower
.Middle
Upper
Sporophita castaneiventris
+ +
Myospiza aurifrons
+
Total
26
57
58
Combined Total
88
three swallow s, and one tanager ) w hose distribution was largely independent
of the character of the vegetation, the lower zone was found to share rela-
tive few species with the middle zone and none at all with the upper zone.
It was apparent moreover that the waters of the lower Callaria are ecologi-
cally distinct from those of the nearby Ucayali. The most striking evidence
for this distinction was provided by the distribution of the river cormorant,
Fholacrocorax olivaceus. which occurred on the Ucayali in flocks of thou-
sands but was altogether absent from the Callaria. Three other common
species of the Ucayali. Casmerodiiis alba, Phaetusa simplex, and Sterna
superciliaris, appeared on the Callaria only in the immediate vicinity of its
mouth, and there in sparing numbers.
12) As could be expected, the middle zone is faunistically the least distinct
of the three. It showed the lowest proportion of characteristic species I 26
per cent ) . Thus our impression that the middle zone is a region of vegeta-
tional transition between the flood plain scrub habitat and the upstream
forests is confirmed by the distribution of bird species in the three regions.
It will be noted in Table I that the middle zone was the only one in which
all three species of kingfishers were found. Ceryle torquata, Chloroceryle
amazona, and C. americana form a graduated series from large to small,
respectively. The distribution of the three species was closely correlated with
the width and swiftness of flow of the Callaria. Ceryle torquata was the most
abundant form along the lower section, while Chloroceryle amazona was more
common in the middle zone where the river is narrower and faster. The
smallest kingfisher, Chloroceryle americana, was infrequent in the middle
zone but was found with C. amazona in equal numbers on the sheltered and
rapidly flowing water of the upper zone.
(3) The upper zone, though sharing 43 per cent of its avifauna with the
middle zone, nevertheless had the highest proportion ( 38 per cent I of char-
acteristic species. Thus, as a natural habitat the forest can be shown to offer
more opportunities for ecological specialization than the habitats in the two
downstream zones. In fact, apart from the wide-ranging species found over
the river the fauna of the upper zone appears to be entirely distinct from that
of the lower zone.
Diaiiioiiil uiul
Torl.orgh
PERUVIAN BIRD DISTRIBUTION
279
Zonal Distribution
Table 2
OF Bird Species on
THE Rio
Callaria.
Zonal distribution
of species
Lower zone
Middle zone
Upper
zone
No. of
species
Per cent
of total
No. of
species
Per cent
of total
No. of
species
Per cent
of total
Observed in all zones
11
42
11
19
11
19
Only in upper and middle
—
—
25
44
25
43
Only in middle and lower
6
23
6
11
—
—
Only in upper and lower
0
0
—
—
0
0
Only in one zone
9
35
15
26
22
38
Total
26
100
57
100
58
100
(4) It is evident that overall species diversity is promoted to a much
greater extent by the more complex multi-storied vegetational structure of
the upper and transitional zones than by the flood-plain scrub of the lower zone.
(5) The fact that the three zones shared in common only 11 species of
birds suggests that ecological specialization may have played a major role
in the development of the strikingly rich neotropical avifauna.
Our list of 88 bird species undoubtedly represents no more than 30 per cent
of the total number that occur in the vicinity of the Rio Callaria. However,
our observation time was fairly evenly divided among the three zones, and
there are no outstanding reasons for supposing that any of the faunal samples
we obtained are not representative. Thus it seems safe to assume that a more
thorough-going study would only strengthen our conclusions, though at the
quantitative level alteration of the results would be expected.
FEEDING ASSEMBLAGES
While on the Callaria we located two fruiting trees in which large and
heterogeneous groups of birds had assembled for the purpose of feeding. The
birds using each of these trees were observed for several periods of 1-2 hours.
The first tree (see Table 3 for list of bird species observed in it) was located
about 100 yards from the Rio Callaria in second growth near an Indian
village and bore many brown plum-sized fruits. The second tree (see Table
4 for species list) overhung the Rio Callaria from the edge of tall upper-zone
forest, and was heavily laden with orange cherry-sized fruits. A striking fact
evident from the tables is that these two feeding trees contained no species
in common. The first tree (Table 3) had a broad crown about 40 feet high
and stood in dense second growth in the transitional zone near an Indian
village. A much taller primary forest was less than 100 yards away, however.
The second tree (Table 4) was located on the river hank in the primary forest
upstream and was more than twice as tall as the first.
280
THE WILSON BULLETIN
SojitPiiiber 19()7
\ ol. 7'). No. 3
Table
List of Birds ()bseiut:i) in
3
First
Fruiting Tree.
Ihotogeris versicoloriis
Goereha jiaveola
l^iaya cay ana
Psarocolius sp.
G a! ha! cyrh yn ch as leu cot is
Gacicus cel a
Melanerpes cruentatus
Icterus icterus
Demlrocolaptidae sp.
Tityra sp.
S poroph ila cast an ei ventris
A second fact apparent from the tables is the large number of families
represented in both feeding assemblages. The 11 species found in the first
tree represent nine families, while the 17 from the second tree include 10
families. Similarly, Land ( 1963 > recorded members of 11 families of birds
taking fruit from a tree in Guatemala. The association of diverse species
possessing a wide variety of sizes and bill shapes in feeding trees suggests
extensive niche overlap among carpophagous birds in the neotropical forests.
It is evident that birds so conspicuously different from one another as cha-
chalacas, parrots, toucans, and honeycreepers at least occasionally utilize the
same food sources. Though tropical species are usually assumed to be more
specialized and less versatile than their counterparts in higher latitudes
( Klopfer, 1962; Margalef, 1963), the congregation of large numbers of
disparate species at ephemeral food sources suggests that many of them may
have rather flexible feeding habits.
In observing the second tree (Table 4), we noticed that the individuals of
certain species were distributed in a non-random fashion. Trogons \Trog,on
collaris and T. viridis ) kept to the lower branches, while the toucan. Ram-
phastos tiicanus. the honeycreeper, Dacnis cayana. and the tanager, Tangara
chilensis. were seen only in the upper branches. Other species, e.g., the
chachalaca, Ortalis guttata, and the Ptero^Iossus toucans, appeared to feed
indiscriminately in the lower, middle, and upper branches of the crown. As
MacArthur (1958) has so carefully shown for 5 species of Dendroica war-
blers in a Maine spruce forest, interspecific competition for food is greatly
reduced in species having pronounced preferences for different locations in
the canopy.
In general, birds arrived at and left both fruiting trees as individuals or
else as groups of several individuals belonging to one species. The majority
of species was seen to come and go in this manner. Although the species
composition of these assemblages changed gradually with time, the total
number of birds in a given tree did not vary by more than a factor of two
during the observation periods. The largest movements were the arrivals
and departures of small groups of parrots or toucans. Thus the congregation
Diamotul and
Tcrl)orf;li
PERUVIAN BIRD DISTRIBUTION
281
Table 4
List of Birds Observed in Second
Fruiting Tree.
Orta/is guttata
Phloeoceastes melanoleucos
Amazona sp.
Cotinga may nan a
Trogon co/laris
Cotinga cayana
Trogon. viridis
Cyanocorax violaceus
Capita sp.
Dacnis lineata
Ramphastos tucanus
Dacnis cayana
Pteroglossus castauotis
T an gar a ch il ensis
Rteroglossus inscriptus
Ramphocelus car bo
Cissopis leveriana
of birds that are attracted to fruit trees for feeding cannot be regarded as
flocks in that they do not appear to have any social or temporal integrity.
Rather, they may be considered as transient and more or less chance as-
semblages of small flocks of several species plus scattered individuals of
others. Socially organized itinerant feeding flocks of the kind extensively
described by Davis (1916), Short (1961), and Moynihan (1962) are of
widespread and common occurrence in neotropical forests. Such true flocks
differ from feeding assemblages in the following respects. ( 1 ) They are
characterized by interspecific social interactions rather than by the lack of
them. ( 2 ) They retain their integrity as social units while progressing
through the forest. Feeding assemblages of necessity are stationary. (3)
Members of a feeding flock pursue a variety of food sources, both plant and
animal, while in a feeding assemblage all individuals are consuming the same
food.
It can be expected that members of feeding flocks may temporarily join
feeding assemblages and that birds initially in feeding assemblages in turn
may leave to join feeding flocks. Such exchanges could have taken place in
the second feeding tree during our observations, as birds of the genera Daciiis
and Tangara are known (Moynihan, 1962) to join feeding flocks.
SUMMARY
1. The distribution of liirdlife along a 20-30 mile section of the Rio Callaria (De-
partment of Loreto, Peru) has been tabulated with reference to three conspicuously
distinct ecological zones, through which one passes in succession when travelling up-
stream from the mouth. They are characterized by differences in the width and rate
of flow of the stream and by the principal features of the vegetation on the hanks. The
ecological character of the zones has been analyzed by considering the proportions of
the fauna of each which occurred in only that zone and in the two other zones. The
degree of faunal distinctness and the pattern of faunal overlap with other zones was
different for each zone. As expected, greater species diversity was found in the zones of
greater vegetational complexity.
282
TIIK WILSON nULLLTIN
Sciitemhci- 1907
Vol. 79, Ni). 3
2. 1'wo fruiting trees wliieli w(‘re lieing used for feeding by representatives of nine
and ten bird families, respectively, have lieen described. The significance of the high
diversity of bird sj)ecies using these fe(“ding trees has he<*n discussed. Acconij)anying
hehavioral ohservations liave been considered in relation to the problem of interspecific
competition. Assemblages of birds using sucli feeding trees have been operationally
distinguished, on the basis of three behavioral criteria, from the itinerant feeding flocks,
so jirevahmt in neotropical forests, that recently have received much attention from other
authors.
ACKNOWLEDGMENT
We are greatly indebted to Dr. Maria Koepcke of the Museo de Historia Natural in
Lima for aid in identifying from our field notes many of the species listed in this
report and to Dr. K. A. Paynter, Jr. for (omments on the manuscript. The identific-ations
of all species cited here have been checked against specimens in the Museo de Historia
Natural in Lima, the Museum of Comparative Zoology of Harvard University, and the
American Museum of Natural History.
LITERATURE CITED
Davis, D. E.
1946 A seasonal analysis of mixed flocks of birds in Brazil. Ecology, 27:168-181.
DE SciIAUENSEE, R. M.
1966 The species of birds of South America and their distribution. Acad. Nat.
Sci., Philadelphia, Pennsylvania.
Kloi’Fek, P. H.
1962 Behavioral aspects of ecology. Prentice-Hall, Inc., Englewood Cliffs, N. J.
Land, H. C.
1963 A tropical feeding tree. Wilson Bull., 75:199-200.
MacAhthuh, R. H.
1958 Population ecology of some warhlers of northeastern coniferous forests.
Ecology, 39:599-619.
MacBhide, J. E.
1936 Elora of Peru. PuhL Field Mas. Nat. Hist., Bot. Ser., 13, Part I, No. 1.
Mahgalef, R.
1963 On certain unifying principles in ecology. Amer. Nat., 97:357-374.
Moynihan, M.
1962 The organization and probable evolution of some mixed species flocks of
neotropical birds. Sj?iithsonian Misc. PuhL, 143:1-140.
Short, L. L., Jr.
1961 Interspecies flocking of birds of montane forest in Oaxaca, Mexico. Wilson
Bull., 73:341-347.
DEPARTMENT OF PHYSIOLOGY, UNIVERSITY OF CALIFORNIA MEDICAL CENTER,
LOS ANGELES, CALIFORNIA (.J.M.D. ), AND DEPARTMENT OF BOTANY, UNIVERSITY
OF MARYLAND, COLLEGE PARK, MARYLAND ( J.W.T. I , 13 JUNE 1966.
REPRODUCTIVE SUCCESS OF RED-WINGED BLACKBIRDS
IN NORTH CENTRAL OKLAHOMA
Stephen V. Goddard and Veryl V. Board
The general upward trend in the number of Red-winged Blackbirds
{Agelaius phoeniceus ) nesting in Oklahoma can probably be attributed
to the large number of farm ponds, flood detention, and flood control dams
which have beeen constructed in the last 23 years. During this period an
estimated 161,000 farm ponds, flood detention, and flood control dams have
been built in Oklahoma, and an additional 1,500 are being constructed every
year ( Anon, 1963 ) . Presently, there are more than 4,500 farm ponds and
flood control structures in the two north-central counties (Payne and Noble)
selected for this study. Many of these do not have good redwing nesting
habitat. However, ponds with good growths of cattails { Typha sp. ) have
high densities of nesting birds.
The major objectives of this study were to examine the phenology of red-
wing nesting and to determine their reproductive success in these new habitat
situations. The effect on reproductive success of early versus late nesting,
type of nesting cover, height of the nest above the surface of the ground or
water, and water depth below the nest were considered.
METHODS AND GENERAL DESCRIPTION OF AREAS
Observations were conducted throughout the breeding season on ten study
areas selected on eight ponds and two lakes. Only the larger nesting colonies
were studied on the two lakes (Boomer and Yost).
Nests were numbered using a “Sanford’s Marker Compact.” The number was written
on two or three stems or limbs supporting the nest. Blue was found to be the best
color and remained readily visible for two or three weeks, at which time the nest could
be re-marked, if necessary.
Initially, the following data were recorded: date, area, general weather conditions,
time, number of redwings and nests in the area, and type of nesting vegetation. The
height of the nest above the surface and the water depth were measured. The number
of eggs and/or young were noted when present, and the ages of the nestlings were
recorded. The nestlings were aged by the criteria used by Allen (1914). The subse-
quent history of each nest was recorded during a series of visits.
The number of active nests, those which contained at least one egg and which subse-
quent observations indicated were not abandoned, was used to determine the number of
females using an area. This was necessary because usually fewer females than active
nests were observed around a pond. Occasionally, more females were observed than there
were active nests and in these cases, the actual number of females observed was used as
a measure of the female population size.
The study areas varied in size from 0.2.5 to 7.3 acres (Table 1). 4'he cattails growing
around the borders of the ponds varied in stand density and area of cov('ragc. All of
283
284
THE WILSON BULLETIN
S<‘|.lcnil)cr 1%7
V(.l. 7<), No. 3
Table
1
Size, Cattail
Nesting Covek,
AND TeHIUTOHIAL
Males
Area
Area
( acres )
Cattails
( acres )
Average number
territorial males
Pond 9
0.60
0.03
3
Pond 30
0.60
0.08
2
Pond 51
0.25
0.12
2
Pond 52
1.00
0.90
7
Pond 53
0.40
0.10
5
Pond 63
0.50
0.08
4
Ihnid 64
0.30
0.15
5
Pond 66
0.25
0.25
3
Boomer Lake
4.50
1.00
9
Yost Lake
7.30
1.65
10
Total
15.70
4.36
50
the ponds, except Pond 53, had tall perches available on or adjacent to the pond. Male
redwings used the tallest cattails and nearby fence posts for song perches in this area.
RESULTS
The average amount of cattails available per male varied from 0.01 acres
(435 square feet) on Pond 9, which had the smallest amount of nesting cover,
to 0.165 acres per male (7,187 square feet) on Yost Lake, which had the
largest block of nesting cover (Table 1).
A few males already had established territories when the observations were
first initiated on 8 April. Their number reached a peak during early May
and then slowly declined. One male was still on territory on 29 July. How-
ever, it was not in the area on 31 July when observations were terminated.
The nesting cycle sequence continues with the arrival of the resident fe-
males and pairing behavior. Nero ( 1956 ) reported that the first female
arrived at a nesting colony on a marsh in Wisconsin on 8 April. He also
indicated that pair formation begins or actually occurs when a female enters
a male’s territory. Meanley and Webb ( 1963 ) stated “females usually move
into territories and begin pairing after April 1 in Maryland.” By the middle
of April in New York, most of the females were paired (Case and Hewitt,
1963 ) . Small flocks of female redwings were observed at various times on
the study areas throughout April, which indicated that all females were not
paired. There were four known pairs on the study areas by 17 April.
The tendency of male redwings to pair with more than one female has
been reported by many authors: Wright (1907), Allen (1914), Linsdale
( 1938 ) , Nero ( 1956 ) , Case and Hewitt ( 1963 ) , and Meanley and Webb
( 1963 ) . Similarly, redwings were found to be polygynous in this study.
(Mxlilanl arid
Boai (I
REPRODUCTIVE SUCCESS OE REDWINGS
285
Table 2
Number
OF Nests,
Active Nests, Eggs
Laid, Clutch
Size, Eggs Hatched, Young
Fledged, and
Per Cent
Successful Nests for
THE Ten
Study
Areas
Number
Active
Esgs
Clutch
Ekss
Youns
Per cent suc-
Area
of nests
nests
laid
size
hatched
fled5^ed
cessfid nests
Pond 9
9
9
28
3.1
8
5
22.2
Pond 30
8
7
23
3.3
1
0
0.0
Pond 51
13
7
25
3.6
10
6
28.6
Pond 52
79
61
207
3.4
71
29
14.8
Pond 53
47
44
153
3.5
68
50
38.6
Pond 63
29
26
92
3.6
42
22
26.9
Pond 64
30
29
105
3.6
69
50
58.6
Pond 66
6
5
19
3.8
14
7
60.0
Boomer Lake 23
15
45
3.0
4
4
6.7
Yost Lake
62
40
124
3.1
42
23
17.5
Total
306
243
821
3.4
329
196
26.7
There were only 0.68 females per male early in the nesting season. This ratio
increased to 1.95 by the peak period of nesting, which was in the third week
of May. The sex ratio declined homewhat during the next three weeks and
then increased to 2.19 during early July, when several females were renesting
or attempting to raise a second brood. The average sex ratio for the period
from 16 April to the end of July was 1.57 females per male.
The first nest, which contained two eggs, was located on 22 April. This
coincides with the findings of Allen (1914 ) and Meanley and Webb (1963).
Beer and Tibbits (1950) recorded their earliest nests on 25 April and 1 May
in their two-year study in Wisconsin.
Some females built several nests before starting a clutch. This is illustrated
by the fact that although 306 nests were fully completed and lined, only 243
of them were known to have been actively used by the female (Table 2).
Early in the breeding season, female redwings appeared to be intolerant of
disturbance and readily abandoned their nests. The rate of desertion was
low (1.2 per cent) once the female had initiated a clutch or if nestlings were
present.
Redwings were persistent renesters. Some females on ponds with high
predator populations initiated nest after nest only to have them broken up.
Generally, females will build a new nest when renesting or attempting a
second brood. However, there were five instances where a female laid eggs in
a nest in which the original clutch had been destroyed. This was observed
early in the nesting season and only occurred once on any pond. No nest
was used more than twice. Only one of the five nests mentioned above was
successful.
286
THE WILSON RULLEIIN
September 1967
Vol. 79, No. 3
Table 3
CoMi*AHis()N OF Numbkh, Clutcii Size, Young Fledged, and Nesting Success
BETWEEN EaBLY AND LaTE NeSTS
Time of
Active
Clutch
Young
Successfid
Per cent suc-
nesting
nests
size
fledged
nests
cessful nests
Before June 1
155
3.6
135
45
29.0
After June 1
88
3.2
61
20
22.7
There were 821 eggs laid in the active nests for an average clutch size of
3.4. The range was from one to five eggs with four being the most common
number.
Allen 1 1914 ) reported that incubation began after the third egg and
usually 11 days were required for the eggs to hatch. Using this information,
incubation time determined during the present study varied from 10-13 days.
Three hundred and twenty-nine of the 821 eggs hatched, giving a hatching
success of 38.9 per cent. One hundred and ninety-six young were fledged or
23.9 per cent of the total eggs resulted in fledged young. The results of many
studies, Perkins (1928), Wood (1928), Wood (1938), Smith (1943), Beer
and Tibbits (1950), and Williams (1960) have indicated that young were
fledged from 48 per cent or more of the eggs.
Nesting success is another measure of reproductive success. A successful
nest was one that fledged one or more young. Young fledged from 65 of
the 243 active nests, which gave a nesting success of 26.7 per cent. This
success was considerably lower than the 42 per cent reported by Wood
Nesting Success in
Table 4
Relation to Kind of Cover
Nesting cover
Active nests
Number Per cent
Nesting success
Old Cattails iTypha)
52
21.4
38.5
Old and new Cattails
83
34.2
19.3
New Cattails
89
36.6
29.2
Willows (Salix)
10
4.1
10.0
Dogwood iCornus)
2
0.8
0.0
Buckbrush ( Symphoncarpus)
2
0.8
50.0
Bulrush (Scirpus)
2
0.8
50.0
Lead Plant ( Amorpha)
2
0.8
0.0
Buttonbusli ( Ceph (dan thus)
1
0.4
0.0
Total
243
99.9
26.7
(Mul.lanI an.l
Board
REPRODUCTIVE SUCCESS OF REDWINGS
287
Table 5
Nesting Success in Relation
TO Nest
Height above Surface
OF Ground or Water
Nest
height
( inches )
Active nests
Nunil)er
Per cent
Nesting success
0-12
34
14.0
38.2
13-24
125
51.4
27.2
25-36
53
21.8
22.6
Over 36
31
12.8
19.4
Total
243
100.0
26.7
(193o ) and the 57 per cent obtained by Meanley and Webb (1963). How-
ever, Young (1963), in a two-year study in Wisconsin, obtained a nesting
success of 35 and 24 per cent for 1959 and 1960 respectively.
The major losses of eggs and nestlings were due to egg and young removal,
probably as a result of nest predation in most cases, and to nests tipping over
and the eggs or young falling out. Of 243 active nests, eggs were removed
from 105, young from 25; 36 nests containing eggs and eight nests containing
young were destroyed when the vegetation or wind tipped the nest. Three
nests were abandoned and one was lost to flooding.
Similarly, Smith (1943) and Beer and Tibbitts (1950) obtained results
indicating that there was a greater loss of eggs than of nestlings. However,
Peterson and Young (1950) for Common Crackles {Quiscalus quiscula) ^ and
Young (1963 ) for Red-winged and Yellow-headed blackbirds { Xauthocepha-
lus xanthocephalus) found that losses of nestlings exceeded those of eggs.
In Oklahoma, early nests tended to be more successful than nests started
after 1 June (late nests). This date was used as a separation criterion be-
cause it fell at the end of the first nesting period and before the initiation of
most renesting. On nine of the ten ponds, early nests were more successful.
The one exception, Pond 64, had a nesting success of 50 per cent for early
nests compared to 85.7 per cent for late nests. Overall nesting success for
early nests was 29.0 per cent compared to 22.7 per cent for late nests (Table
Table 6
Nesting Success in Relation to Water Depth
Water
depth
( inches )
Active nests
Number
Per cent
Nesting success
0-10
155
63.8
23.2
11-20
65
26.7
29.2
Over 20
23
9.5
43.5
Total
243
100.0
26.7
288
THE WILSON BULLETIN
S<‘|>ternl)er 1967
Vol. 79, No. .3
3). Nesting success among the study areas varied from zero to 62.5 per
cent for early nests and from zero to o5.7 per cent for late nests. Lor the
entire nesting season, nesting success varied among areas from zero to 60
])er cent.
3 he average clutch size was larger for early nests (3.6 eggs) than for late
nests ( 3.2 eggs ) . 1 here were 0.o7 young fledged per early nest compared to
0.69 young per nest for the later nests, another indication that early nests
tended to he more productive.
The number of nests found in each type of nesting cover is presented in
Table 4. The percentage of the total nests and active nests was independent
of the type of supporting vegetation. Lor vegetation types containing at least
10 nests, nesting success was highest (38.5 per cent I in old cattails. This
higher nesting success may have been due to old cattails being virtually the
only nesting cover available early in the nesting season when nesting efforts
were more successful.
A summary of the nest height above the surface of each pond is presented
in Table 5. Ihe highest nesting success (38.2 per cent) occurred among
nests in lower situations. Nesting success decreased as the height of the nest
increased. This decrease may be attributed to a majority of the nests’ being
constructed in cattails; the higher the nest the greater became the possibility
of its tipping over and losing the contents.
rhe number of nests constructed above each of the three water depth cate-
gories is presented in Table 6. Nesting success increased directly with the
depth of the water.
SUMMARY
During the 1965 breeding season the reproduetive suecess of Red-winged Blackl)irds
was studied on eight ponds and two small lakes loeated in two north-eentral Oklahoma
eounties.
A few males were already on territory when observations were initiated on 8 April.
Density of males on the study areas generally varied inversely with the size of the cat-
tail nesting cover.
Four females were known to he paired by 17 April. The nesting peak occurred during
the third week of May. Cattails furnished sites for over 90 per cent of the nests.
Generally, redwings built a new nest when they attempted to renest. However, on five
occasions, a nest was used for two nesting attempts. This occurred early in the nesting
season and only once on any pond.
Eight hundred and twenty-one eggs were laid in 243 active nests for an average clutch
size of 3.4. Hatching success was 38.9 and young were fledged from 24 per cent of the
eggs. Sixty-five nests fledged one or more young, giving a nesting success of 26.7 per
cent.
Egg or young removal and nests tipping over were the major reasons for nest failure.
Egg loss exceeded mortality of the young. The high nest densities in a limited area
would make it possible for a single factor to destroy a large number of nests.
Nesting success was higher for nests initiated prior to 1 June. Average clutch size
(;...l.h.nl and
Hoard
REPKODUCTIVE SUCCESS OE REDWINGS
289
was greater in early nests. Nests in old cattails were more successful. Over 50 per cent
of the nests were constructed less than two feet above the ground or water. Nesting
success was higher for nests in lower situations and decreased as nest height increased.
Approximately two-thirds of the nests were constructed above ground or aho\e water
that was less than 10 inches deep. Nesting success was greater as the depth of the
water below the nest increased.
LITERATURE CITED
Alt.kn, a. a.
1914 The Red-winged Blackbird: A study in the ecology of a cat-tail marsh. /''roc.
Linnean Soc. New York, 24-25:43-128.
Anonymous
1963 This is Oklahoma. Daily Oklahoman, p. 1-24. 20 October.
Bkek, .1. R., AND D. Tihhitts
1950 Nesting behavior of the Red-winged Blackbird. Flicker, 22:61-77.
Case, N. A., and 0. H. Hewitt
1963 Nesting and productivity of the Red-winged Blackbird in relation to habitat.
Living Bird, 2:7-20.
Linsdale, J. M.
1938 Environmental responses of vertebrates in the Great Basin. Amer. Midland
Nat., 19:1-206.
Meanley, B., and J. S. Webb
1963 Nesting ecology and reproductive rate of the Red-winged Blackbird in tidal
marshes of the upper Chesapeake Bay region. Chesapeake Sci., 4:90 100.
Nero, R. W.
1956 A behavior study of the Red-winged Blackbird. 1. Mating and nesting ac-
tivities. WAIson Bull., 68:4-37.
Perkins, S. E., Ill
1928 City park nests of Red-winged Blackbirds. Bird Lore, 30:393-394.
Peterson, A., and H. Young
1950 A nesting study of the Bronzed Crackle. Auk, 67:466-476.
Smith, H. M.
1943 Size of lireeding populations in relation to egglaying and reproductive success
in the eastern red-wing. (Agelaius phoeniceus) . Ecology, 24:183-207.
Williams, J. F.
1940 The sex ratio in nestling eastern red-wings. Wilson Bull., 52:267-277.
Wood, H. B.
1938 Nesting of Red-winged Blackbirds. Wilson Bulk, 50:143-144.
Wood, M.
1928 Mortality of young Red-winged Blackbirds. Bird Lore, 30:262.
Wright, M. O.
1907 The Red-winged Blackbird. Bird Lore, 9:93-96.
Young, H.
1963 Age-specific mortality in the eggs and nestlings of blackbirds. Auk, 80:
145-155.
DEPARTMENT OF ZOOLOGY, OKLAHOMA STATE UNIVERSITY, STILLWATER, OKLA-
HOMA. (PRESENT ADDRESSES: DEPARTMENT OF BIOLOGY, WISCONSIN STATE
UNIVERSITY, RIVER FALLS, WIS., AND DEPARTMENT OF BIOLOGY, ARKANSAS
COLLEGE, BATESVILLE, ARK.), 7 MARCH 1966.
BEHAVIORAL STEREOTYPY IN BIRDS
Peter H. Klopfer
IT has previously been argued that the climatic stability provided by the
tropics allows animals to specialize to an extent not possible where cli-
matic conditions and the sources of food and other necessities change season-
ally, if not daily (see Klopfer, 1962 for bibliography). This permits the
coexistence of more species than would be true in a population of “jacks-of-
all-trades,” and partially explains the greater faunal diversity of the tropics
as compared with temperate zones.
I have sought to put this notion to an experimental test by comparing the
degree of behavioral stereotypy (which is, in effect, a measure of niche size:
the larger the niche the less stereotyped the animal ) in selected representa-
tives from the temperate and tropical avifaunas. The demonstration of
stereotypy, of course, does not necessarily prove that constancy of available
sources of energy explains species diversity. Greater stereotypy in tropical
forms would provide collateral evidence for the constancy-diversity relation-
ship, however.
Specifically, I have sought to measure degrees of stereotypy in foliage
preference and motor pattern of individuals of several species of birds. (The
ultimate aim, it should be added, is to include several dozen species, repre-
senting many families, in this survey, and to include measures other than
foliage preferences and movement patterns.)
Regarding the relevance of measures of foliage preference, consider the
work of MacArthur, MacArthur, and Freer (1963) who studied early serai
stages in North America. They predicted the bird species diversity as well
as the actual species which would he present in a given area from measure-
ments of diversity in foliage height density. They showed that each bird
species occurred in habitats with a characteristic proportion of foliage in
each of three arbitrarily designated layers. These preferences can reasonably
he assumed to be based upon either leaf number, leaf size, or leaf shape, or
some correlate of these variables, since they alone determine foliage density.
Thus, the work of MacArthur, et al. justifies the use of leaf shape and size
as the principal discriminanda in studying perceptual preferences. Of course,
there are bird species for whom some other and very particular element of
the environment such as an unique nest site or particular food will be more
important than the characteristics of the foliage density. In most instances
these exceptions can be noted. Nor does the importance of foliage char-
acteristics mean that other components of the environment are irrelevant.
However, we can at least assert that foliage characters are an important factor
in habitat selection.
290
IVUM H.
k lopfer
BEHAVIORAL STEROTYPY IN BIRDS
291
Other factors than constancy of energy source may influence the degree of
stereotypy. Most conspicuous among these is the role of competition, e.g.,
the numher of potentially competing species. On islands or other geograph-
ically or topographically isolated areas the species diversity may he well
helow that of comparable areas of large continental land-masses ( see Mac-
Arthur, 1965). In the absence of competitors, the ecology of many species
is known to change (Crowell, in press, and see van Valen, 1965) generally
in the direction of increased plasticity (van Valen, 1965). This increased
plasticity may have two different manifestations: each individual of the
species concerned may become more plastic, i.e., do more different things,
or, the individuals may remain as stereotyped as ever, hut with different
individuals specializing for different ways of life, or a combination. This
would represent decreased specific ( as opposed to individual ) stereotypy,
and might well be regarded as a first stage in the formation of subspecies.
It is as interesting to assess the interaction between degree of isolation ( or
competition) and climatic stability as to study the latter alone. Thus, our
design calls for comparisons between insular and continental birds of the
tropics and temperate regions, as diagrammed below:
Islands
vs
Continents
temperate
Bermuda
Eastern U.S.
vs
tropical
West Indies
Panama
DEFINITIONS AND METHODS
“Behavioral stereotypy” refers both to perceptual and motor stereotypy.
On the perceptual side, the stereotypy involves a sensitivity to, or an aware-
ness of, or preference for, a limited range of a larger complex of stimuli.
An animal that responds only to a narrow band of wavelengths, for instance,
would be considered perceptually more stereotyped than one responding to
a wider band. On the motor side, stereotypy refers to the availability of only
a small variety of movements by means of which an animal can accomplish
a given act. It reflects an inability to adjust movements in accordance with
changes in the form of the substrate. In either instance, the constraints may
be peripheral (in terms of muscle attachments or shapes, or sensory filters),
or due to central nervous mechanisms. While it is of interest to study the
nature of the constraints and to determine whether they differ systematically,
this is not considered here.
To measure stereotypy in preferences for particular types of foliage the
birds were tested in rooms divided by netting into two chambers, alike ex-
cept for the foliage with which they were decorated. This foliage was made
of a green plastic and consisted of one of I kinds of “leaves” that differed
292
THE WILSON BULLETIN
S('|itcml)ei- 1967
Vol. 79, No. 3
Fig. 1. IMiotooraph of artificial leaves.
in size or shape or density ( a large and small ”Oak“ and “Elm’* type I ( Fig.
1 I . Movement of the bird from one chamber to the other, and thus the time
spent in each chamber, was monitored by a series of photo-cells in the sole
connecting passage between the two chambers, which also served as a feeding
place. The three test rooms averaged 3 by 3 by 4 meters. Details of the
procedure and controls for position preferences have previously been pub-
lished ( Klopfer, 1965 i .
The four foliage types employed were offered in all possible pairs, though
because of escapes or mortality, every bird was not tested with every pair.
For each pair of foliage types, the portion of time spent amidst one or the
other was calculated and converted to a discrimination index, H. The
rationale for the use of the index has been summarized as follows
( Klopfer, 1965 ) : the more stereotyped the preferences of an organism, the
more marked will be its preferences among an array of discriminanda. If
the discriminanda are paired, a non-stereotyped or plastic individual should
select each member of each pair. 50 per cent of that time. A highly stereo-
typed individual will tend to select one member of many pairs to the exclusion
of the other. The greater the stereotypy the higher the proportion of pairs
BEHAVIORAL STEROTYPY IN BIRDS
293
i>.
K
<-f H.
.|.[cr
Table
1
Species
Rearing conditions
11 of individual birds
(11 values are means for tests with
4 pairs of foliage; H are the
means of the individual H values)
Panamanian tanagers
Hand-reared:
(Thraupis cana.
without sight
of foliage
0.06, 0.08, 0.09, 0.14, 0.28
(H =
0.13)
and Ramphocelus
Hand-reared :
(Umidiatus )
with pine needles
0.08, 0.12, 0.28, 0.31
(H =
0.20)
Wild-trapped :
0.16,0.17, 0.19, 0.19, 0.20
0.20, 0.21, 0.25, 0.25, 0.28
0.30, 0.32, 0.36
(Tl=:
0.24)
Dominican Rananaquits
( Coereba flaveola )
Wild-trapped :
0.12, 0.12, 0.18,0.21,0.27,0.31
(H =
0.20)
for which the choice should deviate from 50 per cent. The stereotypy index,
//, represents the proportion of choices that deviates from 50 per cent. Of
course, if a bird selects its habitat using one clue only, for instance light
intensity, it would in fact be stereotyped but not so labelled on the basis of
tests with irrelevant discriminanda. Thus far, the extremes of H values
recorded have been 0 and 0.8 ( see below ) .
Motor stereotypy was assessed in two different ways. First, by slow motion
analysis of movie film of foraging movements of birds in their natural habi-
tat, taken at varying times throughout the day. Secondly, by observation of
the movements of captive birds on artificial “trees.” These “trees,” ca. 2 m
high and varying from ca. % m to 2 m in diameter from top to bottom, were
constructed of 0.5 cm steel reinforcement rods so as to allow the bird to fly
in either a radial, vertical, or horizontal direction without hindrance. ( By
radial flight is meant flight along a branch, by vertical movement, across
branches and in the vertical plane, and similarly, across the horizontal plane
for horizontal or oblique flight. ) Thus, the environmental constraints upon
certain kinds of flight that are posed, for instance, by the thick horizontal
strata of foliage or an absence of horizontal branches on some large cacti,
were eliminated. The degree of motor plasticity of the subjects could be
assessed (even though arbitrarily) under conditions where all three com-
ponents of the normal flight directions of birds were equally possible. A
stereotyped individual, then, would he one which failed to adapt its pattern
of flight to this relative absence of physical constraints. Scoring was achieved
by simply calculating the proportion of time spent flying in one or other of
these planes.
The laboratory and some of the field data were obtained from three tro])i-
cal species. Blue and Crimsoii-hacked tanagers (Thraupis cana and Rampho-
294
THE \MLSO\ BULLETLN
Septemlier 1967
Vol. 79, No. 3
Fig. 2. Habitats in Puerto Rico in Avhich Bananaiiuits are among tlie three most
common species (after MacArthur).
celus dimidiatus\. and the Bananaquit \Coereba flaveola). Some of these
birds were wild-trapped as adults, others were hand-reared, either without
sight of foliage or with a particular kind of foliage. ( Comparable data have
been previously published for groups of hand-reared and wild-trapped
Chipping Sparrows iSpizella passerina) and others, Klopfer, 1962, 1965.)
The Bermuda field data are taken from the work of Crowell (1962) on the
feeding and behavior of Cardinals \ Richmondena cardinalis ) and Catbirds
( Dumetella carolinensis) and vireos ^Vireo griseus) .
The inadequacy of the sampling and our frequent inability to apply statis-
tical measures of significance, will be apparent. It is the result of the exces-
sive amount of time required for hand-rearing birds from an early age to
maturity. The justification for presenting such incomplete data lies (1) in
the importance of the general problem and (2) in the desire that this ap-
proach may become known to and explored by others.
DATA AND CONCLUSIONS
Perceptual preferences of tropical mainland (Panama) species. — The data
of Table 1 suggest that these tropical birds are not innately stereotyped. If
reared for the first 8 weeks of life in a particular type of foliage they become
more stereotyped. Wild-trapped adults are yet more stereotyped. Of the
hand-reared birds, only three out of nine of the tanagers showed scores
overlapping with those of any of the 13 wild-trapped tanagers. 51ost of the
hand-reared birds had scores very much below those of the wild birds (i.e.,
they were less discriminating in their foliage choices ) .
BEHAVIORAL STEROTYPY IN BIRDS
295
IVtcr H.
K lopfer
I007o-|
o
A
X
A
507o-
RADIAL
above limb
o = University Park
• = La Paquera
°= Mangrove Swamps
■ = Casuarina Groves
g A
J JL
below limb
A
X
■
_Q
HORIZONTAL
A= Coconut Palms
A= Maricao
x= El Yunque
• °
Q
VERTICAL
Fig. 3. Movement stereotypy of Puerto Riean Bananaquits.
Perceptual preferences of tropical island (West Indies) species. — Eigure
2 indicates the character of the habitats of Puerto Rico in which Bananaquits
are among the three commonest birds (the data for this figure were gener-
ously provided by R. H. MacArthur ) . Erom the variety of habitats in which
they occur, it will be apparent that, if Bananaquits can in any way be
considered “stereotyped,” this is not manifested by their restricting them-
selves to any particular plant formation. Is it possible that they are re-
sponding to some feature common to all of the habitats in whieh they are
found, and lacking in those habitats where Bananaquits do not occur? Table
1, which provides the data from foliage preference experiments with Do-
miniean, wild-trapped Bananaquits (on Dominica, Bananaquits are also
found at all altitudes and in most habitats, as on Puerto Rico) shows a
rather low discrimination index (ranging from 0.12 to 0.31). Particular
leaf shapes or sizes are apparently no more rigidly preferred than is the case
with the relatively “plastic” hand-reared isolates of the other species tested,
whether from tropical or temperate zones. In an experiment where the
ehoice was between two different densities of the same foliage (artificial
bamboo), a similarly low index obtained (0, 0.03, 0.1 I, 0.30, and 0.3<3 1 .
indicating that leaf density, per se, was not by itself important for three out
of the five birds. Another experiment in which the Bananaijuits could choose
296
THE WILSON BULLETIN
Septcmher 1967
Voi. 79, No.
1007o-i
507o-
RADIAL HORIZONTAL VERTICAL
above limb below limb
Fig. 4. Movement stereotypy of Panamanian Ijananaciuits.
between articial bamboo and squares of cardboard, arranged so as to afford
a similar range of light intensities and “hiding places” yielded scores of 0.06,
O.Oo, 0.16, 0.71, 0.71, and 0.80. Thus, for half of the individuals, the pres-
ence of leaves was clearly important (scores of 0.71, 0.71, and 0.80) though
strong preferences for any given configuration were, as indicated earlier,
not evident. Comparable data for Bananaquits from the mainland are not
available, though we should note our impression that, in Panama, Banana-
(juits are far less ubiquitous than they are in the West Indies. In Panama
they appear to be restricted to the forest edge and home gardens. MacArthur
(1965) has also suggested this in pointing to the increased “between-habitat”
differences on the mainland as compared with nearby islands.
Motor patterns of tropical mainland and island species. — Figures 3 and T
indicate variations in motor patterns of the Puerto Rican and Panamanian
Bananaquits. Despite the variety of habitats in which the former is found,
the similarity in its patterning of movements within all these habitats is strik-
ing. The timing of movements, however, is less stereotyped, as is seen in
Figures 5 and 6, in which are graphed the duration of feeding bouts in dif-
ferent habitats. ( By “feeding bout” is meant the period from one flight to
the next, during which period feeding occurs more or less continuously. )
IVter H.
Klui-fer
BEHAVIORAL STEROTYPY IN BIRDS
297
University
Park
La
Paquera
Mangrove
Swamps
• •• • • • • • •
• •
Casuarina
Groves
:<:••• •••
Coconut
Palms
Maricao
•••
••-v./.v:
* •
El Yunque
0 100 200 300 400 500 600
Fig. 5. Duration of feeding l)outs of Puerto Rican Bananaquits.
There are some significant inter-habitat variations in this measure ( spe-
cifically, Maricao vs. La Paguera, Median test, Tate and Clelland, 1957),
presumably reflecting differences in the kind and amount of food available.
Thus, these birds do make certain adjustments to the nature of their habitat.
The data for the mainland Bananaquit show a basically similarity to Banana-
quits at Maricao, P. R., both with regard to movements and duration of
feeding bouts. The Maricao habitat appears, at least superficially, the most
similar of any of those on Puerto Rico to the Bananacjuit habitat in Panama.
On the artificial trees, neither wild-trapped Bananaquits (Dominica) or
Blue Tanagers ( Panama ) adhered to the pattern of movements characteristic
in nature. Radial movements were virtually nonexistent; Bananaquits’ move-
ments were principally in the horizontal plane ( 68 per cent ) ; those of the
tanagers almost evenly divided between horizontal and vertical (54-16 per
298
THE WILSON BULLETIN
.S<‘pt<*nil)cr 1967
Vol. 79, No. 3
Bananaquits
• ••••• /•• •
• ••«•••••• • •• •• •• • ••
•• •••• •• •• • • •
Blue
Tanagers
......
... .
. . . •
0 100 200 300 400 500 600 700
Fig. 6. Duration of feeding bouts of Panamanian liirds.
cent). This does not support the notion that these birds are incapable of
modifying the pattern of their movements.
Motor patterns of temperate mainland and island species. — Ligure 7, taken
from Crowell, illustrates in a somewhat different manner, the feeding methods
of three species of passerines common both to the eastern U.S. and the island
of Bermuda. The differences between island and mainland populations were
significant ( Chi square, P < 0.001 ) . Mainland Cardinals and Catbirds
showed a greater diversity of feeding methods than did their island counter-
parts; the reverse was true for the vireo. It is not yet known whether the
increased feeding diversity reflects changes in the behavior of single indi-
viduals or different degrees of polymorphism (more strictly, polyethism)
in the population as a whole. Since Crowell’s mainland observations were
not limited to a small area, this is a point that must be examined.
It is premature to interpret these results as either favoring or invalidating
our hypothesis concerning the causes of tropical diversity. Samples including
far more individuals and species will first be needed to fill gaps in the ex-
perimental design. However, a number of interesting, if tentative, conclusions
can be drawn from these data.
To begin with, given a situation in which the number of potentially com-
peting species is reduced, as occurs on islands with an impoverished fauna,
at least one tropical species ( specifically, the Bananaquit I apparently has no
difficulty expanding into habitats in which, on adjacent mainland, it does
not occur. By “habitat” we mean morphologieally defined ( generally in
terms of foliage-height diversity ) plant assemblages. On continental land
masses such assemblages have particular bird species associated with them
DISCUSSION
Peter H.
Klopfer
BEHAVIORAL STEROTYPY IN BIRDS
299
CATBIRD
CARDINAL WHITE-EYED VIREO
425
629
Fig. 7. Crowell’s (1962) comparison of the feeding methods (pecking off ground,
foliage-gleaning, bark-gleaning, feeding while hovering, hawking) of Catbirds, Cardinals,
and White-eyed Vireos in North America and on Bermuda. The numliers show the
frequency of the feeding method as observed at 10-second intervals; H is the measure
of diversity in feeding methods.
( MacArthur, pers. comm, and 1965). Either these island birds show less
selectivity in their choice of habitat or else the features of different habi-
tats relevant to them are not associated with foliage-height diversity, as
on the mainland. The data here presented ( and those of Crowell, 1962 and
MacArthur, 1965) suggest the former to be more likely. Thus, while as a
consequence of early learning experiences, tropical birds may in fact prove
more “stereotyped” in their actual behavior than temperate zone species
(Klopfer, 1965), the responses of these same tropical birds on islands indi-
cates they have a tremendous capacity for “plasticity.” That this is a true
ontogenetic plasticity is evident from the catholicity shown by the hand-
reared birds. Thus, it would appear that while tropical species on tropical
mainlands are in fact “stereotyped,” this is more likely an effect rather than
a cause of their greater diversity.
SUMMARY
The foliage preferences of hand-reared tropical birds are relatively broad. Exposure
to a particular type of foliage narrows these preferences. Previous experiments ( Klopfer,
1%5) had shown that certain temperate zone birds had narrower preferences whether
wild-trapped or hand-reared.
The motor patterns of tropical species were shown capable of considtuahh* modification.
300
THK WILSON BULLETIN
Scptciiilicr 1967
\ 79, No. 3
ACKNOWLEDGMENTS
'I'liis work was supported in part hy an NIH career Development Award and NIH
(irant #04453. Travel supjiort was also provided hy the Chapman Fund of the American
Museum. 1 am indebted to J. Potter and j. Reiss for their assistance, and to .). J. Hatch
for critical comments. Able assistance in the field was rendered hy Barrie (iilhert and
Dr. Wolfgang Schleidt.
LITEExATURE CITED
CltOVVELL, K.
1962 Reduced interspecific competition among the birds of Bermuda. Ecology.
43:75 87.
In press Changes in the ecology of Bermuda birds.
Kl()i>feh, P. H.
1962 Behavioral Aspects of Ecology. Prentice-Hall, Inc., Englewood Cliffs, New
Jersey.
1965 Behavioral aspects of habitat selection; a preliminary report on stereotypy
in foliage preferences of birds. Wilson Bull., 77:376-381.
MacAkthuh, R. H.
1965 Patterns of species diversity. Biol. Rev., 40:510 533.
MacAhtiilih, R. H., j. MacAuthuh, and J. Pheeh
1963 On bird species diversity; prediction of bird census from habitat measure-
ments. Amer. Nat., 96:167-174.
Tate, M. W., and R. C. Clelland
1957 Nonparametric and shortcut statistics. Interstate Pub., Inc., Danville, 111.
VAN VaLEN, L.
1965 Morphological variation and width of ecologic niche. Amer. Nat., 99:377-390.
DEPARTMENT OF ZOOLOGY, DUKE UNIVERSITY, DURHAM, NORTH CAROLINA, 31
MAY 1966.
SOME COURTSHIP DISPLAYS OF THE
GOLDEN-WINGED WARBLER
James Baird
Despite the fact that the Golden-winged Warbler ( V errnivora chrysoptera)
has been of exceptional ornithological interest for more than 75 years
because of its interbreeding with the Blue-winged Warbler (V. pinus), re-
markably few ethological observations have been published ( see Ficken and
Ficken, 1962 ) . In view of this general lack of behavioral information, it
seems worthwhile to publish the following observations on Golden-winged
Warbler displays. The terminology, where applicable, follows that of Ficken
( 1963 ) .
DISPLAYS
Gliding. — On 15 May 1962 a male Golden-wing was observed Gliding at
the Cambridge Reservoir, Lexington, Middlesex County, Massachusetts. The
context of the Glide was not determined, but briefly what was observed was
that the male, which had been singing steadily for a half hour, flew to the
top of a tall dead tree, took off, set his wings and Glided to a nearby tree
from which he immediately Glided again ( Fig. 1 ) , No other bird was visible.
Unlike the Redstart ( Ficken, 1962 ) , the male did not spread his tail during
the Glide.
Courtship feeding. — In the late afternoon of 14 May 1964 in Lincoln,
Middlesex County, Massachusetts, a female Golden-wing was found feeding
halfway up a white pine {Pinus slrobus). In order to obtain a closer look,
I started “squeaking” and immediately a male Golden-wing appeared in a
maple adjacent to the pine, chipped a few times, and flew down to sit about
6 inches away on the same branch as the female. At once the female raised
her bill and fanned her tail so that the white flashed conspicuously ( Fig. 2a ) .
She then thrust her head towards the male and gaped ( Fig. 2b I . The male.
Fic. 1. Male Lolden-winjred War!)ler (diding.
301
302
THE WILSON BULLETIN
Sei)teml)er 1967
Vol. 79, No.
Fig. 2. Agonistic displays of Golden-winged Warblers,
either simultaneously or shortly thereafter, sleeked his plumage and raised
his head and pointed his hill upwards at a 45 degree angle ( Lig. 2c I . As far
as could be seen, he did not fan his tail. The female flew and the male fol-
lowed at once; they then separated, the female foraging low and the male
feeding high in an oak.
A few minutes later the male flew down to the female, which was perched
on a low dead shrub, and fed her a caterpillar. In feeding the female, the
male perched beside her with his body and head held high and his bill point-
ing down. As the male alighted, the female crouched, turned her head
towards him and raised her bill and accepted the caterpillar ( Lig. 3 ) . It was
not noted whether she wing-quivered.
Fig. 3. Courtship Feeding by male Golden-winged Warbler.
James
Baird
GOLDEN-WINGED WARBLER DISPLAYS
303
Fig. 4. Courtship Display of male Golden-wiiiged Warbler: fluffed display given while
following the female.
Although a male had been heard singing in this locale earlier in the day,
this male did not sing during any of these displays. The female did quite a
hit of chipping ( largely in response to my “squeaking” ) ; her most frequent
note was a very short tchip and occasionally a dry rattle.
During this half-hour observation period, the male Golden-wing was seen
to chase a male Prairie Warbler {Dendroica discolor), a male Magnolia
Warbler ( Dendroica magnolia ) , a Parula Warbler ( Panda americana ) and
a Nashville Warbler {V ermivora rujicapilla) .
Courtship display. — On the afternoon of 17 May 1965 in Lincoln, Middle-
sex County, Massachusetts, 1 observed a female Golden-wing foraging along
the edge of an alder thicket that bordered the road. A male Golden-wing was
persistently following her and continually orienting his head towards her
304
THE WILSON BULLETIN
Sp|)tonihcr 1967
\ Ol. 79. No. .1
Fig. 5. Courtship Display of male Golden-winged \'i'arl)ler: hovering flight display.
(when beneath her, he looked up; when above her, he looked down, when
to one side, he looked towards her I . During this following, his crown feathers
were raised and his cheek and throat feathers were fluffed. His tail was
continually being fanned ( opened and shut ) , thus showing the white mark-
ings, and occasionally waved from side to side ( Eig. 4l. The male followed
the female in this fashion for a full five minutes. Then he suddenly crouched,
raised and spread his tail, raised his wings and started to vibrate them very
rapidly, while lifting his head high, and raising his crown feathers ( Eig. 5 I .
He then assumed a more normal posture, hopped towards, and resumed fol-
lowing the female. Again he raised his tail, spread it, raised his wings, vi-
brated them, and this time actually flew to within eight inches of the female,
where he hovered briefly, and then, with his wings still upraised and vibrat-
ing, made a rapid, sideways flight around the female in an arc of about two
feet. He attempted to land either on or near the female but she pecked at
James
Baird
GOLDEN-WINGED WARBLER DISPLAYS
305
him and he flew away in a normal flight. This was repeated again. Although
my attention was focussed on the male, I am reasonably certain that the fe-
male maintained a “normal” posture during these displays.
Because of the fragmentary nature of the above observations, detailed dis-
cussion of their ethological significance is not possible, however, since ap-
parently none of these displays have been reported in the literature, some
comment seems justified.
DISCUSSION
Although Gliding in warblers has been shown to be an expression of both
agonistic and sexual behavior ( Eicken and Eicken, op. cit. ) , it seems likely
that the Gliding I observed was a sexual display ( despite the fact that a sec-
ond bird was not seen ) , since M. S. Eicken informs me ( pers. comm. ) that
she has seen “. . . . Gliding several times in both Golden-wings and Blue-
wings,” and that it “definitely seem part of the courtship ceremony (rather
than agonistic ) .”
The observation on Courtship Eeeding was preceded by displays by both
sexes, which were apparently initiated by the male violating the female’s
individual distance. The female reacted to the male’s intrusion by Bill Rais-
ing, Tail Banning, and then giving a Head Eorward display (including Gap-
ing) ; the male responded by Bill Raising and sleeking his plumage. The
most unusual aspect of these essentially agonistic displays was the Bill Raising
by both the male and the female. Eicken and Eicken ( op. cit. ) considered
that Bill Raising is “apparently lacking in warblers (except the Ovenbird
(Seiurus aurocapillus ) ) .”
Equally interesting was the Courtship Eeeding which was observed witbin
minutes after the previous displays. Courtship Eeeding has not been reported
for the Golden-wing and is apparently rare among warblers; Nolan (1958)
found evidence of Courtship Eeeding in only “three or four” of 21 parulids
reviewed. However, incubation feeding has been reported for many warbler
species (Nolan, op. cit.), and a male Brewster’s Warbler has been seen to
feed his mate, an incubating female Golden-wing, on the nest (Carter, 1941).
The actions and the feather postures adopted by the male during the Court-
ship display were similar to those reported for other warblers ( Eicken and
Eicken, op. cit. — see especially Table IV, p. 115). Particularly noteworthy
were the persistent following movements by tbe male during which the head
with its striking markings was directed towards the female, and the display
flight, whieh emphasized the golden wing bars, and the white in the tail.
As Eicken and Eicken (op. cit.) point out such displays as fluffing the
])lumage and moving the wings tend to accentuate the species-typical markings.
306
THE WILSON BULLETIN
Se[)teinl)er 1967
Vol. 79, No. .1
SUMMARY
Tliree sexual displays previously unreported for the Golden-winged Warbler are
described: Gliding, Court.sbip Feeding, and a Gourtship display. The behavior of the
male during the Gourt.sbip dis()lay was similar to that of other parulids, involving such
(lisjilay components as plumage fluffing, crown raising, wing movements, etc.
ACKNOWLEDGMENTS
I would like to thank Dr. Millicent S. and Dr. Robert W. Ficken for reading the
manuscript and making several helpful suggestions.
LITERATURE CITED
Garter, T. D.
1944 Six years with a Brewster’s Warbler. Auk, 61 :48-61.
Ficken, M. S.
1962 Agonistic behavior and territory in the American Redstart. Auk, 79:607-632.
1963 Courtship of the American Redstart. Auk, 80:307-317.
Ficken, M. S., and R. W. Ficken
1962 The comparative ethology of the wood warblers (Parulidae): a review. Liv-
ing Bird, 1:103-122.
Nolan, V., Jr.
1958 Anticipatory food-bringing in the Prairie Warbler. Auk, 75:263-278.
MASSACHUSETTS AUDUBON SOCIETY, LINCOLN, MASSACHUSETTS, 22 APRIL 1966.
NEW LIFE MEMBER
Mr. Clive Goodwin, of Weston, Ontario,
has recently become a Life Member of
Tlie Wilson Ornithological Society. A
graduate of the University of Toronto,
Mr. Goodwin is Executive Director of the
Conservation Council of Ontario. He is a
member of the AOU, BOU, and British
Trust for Ornithology, as well as The
Federation of Ontario Naturalists, for
which he served as editor of Ontario Natu-
ralist and Young Naturalist. He has also
served as Regional Editor for Audubon
Field Notes. He has published numerous
papers in local journals on his principal
ornithological interests, bird populations
and migrations. Mr. Goodwin’s other in-
terests include photography, biophilately,
and music.
FOOD AND FEEDING HABITS OF AUTUMN MIGRANT
SHOREBIRDS AT A SMALL MIDWESTERN POND
William S. Brooks
Most shorel)ircls in migration traverse so great a distance and so many
ecologically different areas that it is improbable that they are able
to maintain a very specific diet. Whereas they might feed, for example,
mainly on certain dipteran larvae on the breeding grounds, they may not
find these available during migration. Thus they must turn to other types of
food and broaden their feeding niches. This may cause greater dietary over-
lap and competition between species.
Although some overlap is to be expected, there are differences in the basic
feeding patterns and size differences which preclude total overlap between
species. It is the purpose of this study, besides adding to the sparse knowledge
of foods of migrating birds, to demonstrate that while there is considerable
overlap in the diets of several species of shorebirds during autumn migration,
there are differences which indicate at least partial segregation into different
feeding niches.
The data were gathered in conjunction with a migration study done in 1960
and 1961. Observations were made and sampling was done at a shallow mud-
bottom pond approximately % mile north of Champaign, Illinois. This was
apparently the only suitable feeding place for shorebirds in the area, and it
is probable that the birds collected had consumed their food there.
METHODS
Varying numbers of nine of the 20 species under observation were col-
lected with a shotgun for stomach analysis during the autumn migration:
Common Snipe (Capella gallinago) , 5 in October, 1961; Greater Yellowlegs
iTotanus melanoleucus) , 2 in October, 1960, one in November, 1961; Lesser
Yellowlegs iTotanus flavipes), 4 in September and 2 in October, 1960, 3
in October, 1961; Pectoral Sandpiper [Erolia melanotos ) , 2 in October, 1960,
and 1 in October, 1961, 4 in July, 1961; Least Sandpiper [Erolia miniitilla) ,
1 in October, 1960, 3 in July, 1961; Dunlin {Erolia alpina) , 2 in October,
1961; Stilt Sandpiper (Micropalama hiinantopus ) , 2 in October, 1960; Semi-
palmated Sandpiper (Ereunetes pusilliis), 2 in August, 1961; Wilson’s
Phalarope (Steganopus tricolor)^ 1 in July, 1961.
The digestive tract was removed no later than one hour after death and
preserved in 70 per cent ethanol. The contents of esophagus, proventriculus,
and ventriculus were later emptied into a shallow dish and the parts of each
type of food organism separated into groups using a binocular dissecting
307
308
THE WILSON BULLETIN
Septenil)er 1967
Vol. 79, No. .3
microscope. The number of organisms making up each group and the per-
centage that these made up of the total number of organisms in the stomach
was then determined. In the cases where it was considered that plant material
was jmrposefully ingested the jiercentage by bulk of this material was esti-
mated, and the percentage of other organisms calculated on the remainder,
as above.
The pond bottom was sampled throughout the year to determine the kinds
and numbers of benthic organisms available to the birds by pushing a brass
cylinder of 0.0077 m“ area into the substrate to a depth of 10-15 cm, washing
the contents through a 1.5 mm mesh sieve, and counting the organisms.
Sampling locations were randomly selected in water 15 cm or less deep in
the general areas where the birds fed. Varying numbers of samples were
taken 2 to 4 times a month during migrations, and once a month at other
times of the year.
Mats of filamentous algae formed over much of the pond’s surface in late
summer and autumn, creating a new feeding substrate for the smaller shore-
birds in particular. Lree-swimming, algal-mat, and shoreline food organisms
were not sampled quantitatively hut relative numbers were established by
observation on the days when bottom samples were taken.
RESULTS AND DISCUSSION
In addition to the benthic organisms (Table 1 ), northern fathead minnows
( Pimephales prornelas: Cyprinidae ) and numerous free-swimming adult
aquatic beetles were present. Relative numbers of the fish could not be de-
termined but, of the insects, Dytiscidae made up approximately 50 per cent,
Haliplidae ( crawling water beetles ) , 30 per cent, and Hydrophilidae, 20 per
cent. Their relative numbers did not appear to change significantly during
the migration period. Other aquatic insects were present but in very small
numbers. Non-aquatic insects made up about 60 per cent of the available
shoreline and algal-mat organisms during the entire migration period, stratio-
myid (soldier fly) larvae, 30 per cent, and haliplid larvae, 10 per cent.
Terrestrial insects of various species were commonly found trapped on the
water surface, and wind-blown concentrations were often found against and
on the algal mats.
Specificity of diet concerns the number of different food items consumed
by a species. By these terms the Lesser Yellowlegs would be least, and the
Stilt Sandpiper most specific (Tables 2 and 3), but the small and unequal
sample sizes do not permit any conclusion here. It is probable that the larger
species are less specific than the smaller ones, since they are not as restricted
to the shoreline or to relatively smaller organisms.
William S.
Mrouks
SHOREBIRI) FEEDING HABITS
309
Table 1
Dknsitiks^ of Benthic Organisms
Jau.
Feb.
Mar.
Apr.
May
June
July
Aug.
Sept.
Oct.
Nov.
Dec.
Oryaiiism
(3)^
(2)
(4)
(7)
(4)
(3)
(7)
(11)
(15)
(8)
(4)
(2)
Pliysidae
(snails)
130
65
130
334
1,203
650
1,021
1,076
966
748
390
130
Chironomidae
(midge flies)
larvae, pupae
173
195
111
293
130
111
166
337
211
98
65
Diptera (flies)
larvae, pupae
87
228
74
163
216
74
142
57
33
131
65
Corixidae (water
boatmen)
163
56
98
43
37
154
61
98
98
Baetidae ( may-
flies) naiads
33
43
56
59
132
65
Hydropliilidae
( water scav-
enger beetles)
larvae
65
43
56
24
20
16
Anisoptera
( dragonflies)
naiads
19
65
43
12
1
16
Coenagrionidae
( damselflies)
naiads
33
43
12
Dystiscidae
( predaceous
diving beetles)
larvae
43
24
16
1 Individuals per m^.
2 Number of samples.
Selectivity of diet concerns the relation between the quantity of a certain
food item available and the quantity consumed. The forage ratio of Hess and
Swartz ( 1941 ) , calculated by dividing tbe per cent of a food item in the
stomach by the per cent of that item in the fauna, gives a measure of the
selectivity of an animal for the components of its diet. A value of less than
unity denotes that the item is not selected in relation to its abundance; unity,
that it is selected in direct relation to its abundance; greater than unity, that
it is selected out of proportion to its abundance or that it is a preferred
item. The forage ratios (Tables 2 and 3) show that most of the species were
apparently selective for several items in their diets but had at least one item
of high preference peculiar to each.
Lack (1945) concluded that closely related species differ in one or more
of the following: habitat, region, or diet. Two closely related phalacrocora-
310
THE WILSON BULLETIN
Sp|itcml)('r 19f)7
Vol. 79, No. 3
cicis, very similar in appearance, habitat, and region “differ markedly in
both nesting sites and food.” Dietary selectivity is the major differing factor
in the niches of these species which can account for their coexistence without
contradicting Cause’s rule. He found ( 1914 ) that in many closely related
sympatric passerines dietary differences were important in their ability to
coexist. This is now a rather well-known ecological fact, but his and others’
observations have concerned only breeding or permanent resident birds.
Lack stated (1944:276) that “closely related species are potential food com-
petitors in winter, and so have evolved geographical isolation at this sea-
son . . . ,” and suggested that off the breeding grounds ( during migration
and on the wintering grounds ) their food may become more similar. The
results of the present study, however, indicate that the identities of separate
feeding niches may be maintained through migration, or, in light of Holmes’
(1964) finding, that the feeding niches of congeneric species of sandpipers
almost completely overlapped during the breeding season, the niches may
even become more divergent.
Competition should be greater for preferred food items than for others.
In cases where two or more species shared a high preference, they usually
did not compete, because their feeding areas were different. However, during
the peak of migration, in early September both years, competition should have
been and apparently was keenest between species which had common pre-
ferred food items and common feeding areas. Lesser Yellowlegs and Pectoral
Sandpipers (the first and second ranked species at the pond with respective
4-month averages of 14 and 12 birds seen per trip to the area and peak num-
bers of 125 and 50) both selected hydrophilid larvae, and aggressive en-
counters between these two species were the only ones seen, being most
noticeable in early September. Close study was not made of this behavior,
and although Hamilton’s (1959) “crouch” and “supplanting” displays by
Pectoral Sandpipers were the only ones noticed, there were no doubt other
aggressive displays that I did not recognize. This behavior was shown usually
between Pectoral Sandpiper individuals, less often between these and Lesser
Yellowlegs, with the former being the apparent aggressor. The Least Sand-
piper also selected hydrophilid larvae but no aggressive displays were noted
involving this species, although less obvious displays, sufficient to cause the
smaller species to move away without apparent conflict, could have been em-
ployed by the larger sandpipers.
No encounters between Stilt Sandpipers and Lesser Yellowlegs were ob-
served, although they both selected chironomid larvae and corixids. Either
the supply was sufficient or the fact that the former habitually fed in deeper
water may have eliminated competition. There was no competition for
chironomids between Lesser Yellowlegs and Least Sandpipers, since the
Food Habits of the Shoreline-frequenting Shorebirds
W illiai
Brooks
SHOREBIRI) FEEDING HABITS
311
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Frequency, per cent of stomachs containing item. 4 Forage ratio, values > 1 in boldface.
Table 3
Food Habits of the Shorebirds feeding away from Shore
312
THE WILSON BULLETIN
September 1967
Vol. 79, No. 3
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SHOREBIKI) FEEDING HABITS 313
former generally probed the bottom and the latter took only pupae which had
come to the surface and were washed ashore or against the algal mats.
It is possible that the aggressive behavior described above was not due to
active competition for a food item but to the preservation by the birds of their
“individual distances.” Hamilton (1959) reports that when this distance is
reached, threatening usually occurs among Pectoral Sandpipers. However,
he did not mention that this occurred interspecifically in the general feeding
area, and for this reason active competition cannot be excluded as being re-
sponsible for the aggressive behavior shown between species in the present
study.
Several species examined had eaten considerable plant material. Forage
ratios could not be calculated for this type of food but the high frequencies
and percentages of seeds taken by the Common Snipe and Pectoral Sand-
piper, and of algae by the snipe and Semipalmated Sandpiper indicate that
they were selecting this over animal food in some instances. Plant material
was present in almost all stomachs examined but was usually in very small
amounts and was considered to have been taken incidentally with animal
food by all except the species mentioned above.
Of interest is that while adult haliplid beetles composed about 30 per cent
of the free-swimming fauna, not one was found in the stomachs. The reason
for their apparent unpalatability may be that they have an extremely thick
and hard external covering and are very resistent to crushing. If they can-
not be crushed they obviously have little food value.
Little correlation can be made between temporal changes in densities of
food organisms, number of birds present, and dietary changes of the birds,
due to the relatively small number of stomachs examined. Forage ratios
should reflect a change of any sort (or no change) when comparing a species
of shorebird at different times. The Lesser Yellowlegs, for which the most
samples are available, is taken as an example. Of those food items for which
the ratio was greater than unity in either September or October (see Table
3) the density of hydrophilid larvae decreased about 20 per cent, mayfly
naiads, 50 per cent, and chironomid larvae and pupae, 33 per cent, while
corixids increased about 33 per cent. The respective forage ratios decreased
about 50 per cent, increased 20 per cent, decreased 100 per cent, and in-
creased about 33 per cent. Although the data do not permit a conclusion, it
is attractive to speculate that as the density of one preferred organism de-
creases, the birds feed more intensively on another preferred organism for
which the density has increased. This, of course, follows the established
ecological principle that as a population decreases or increases, external pres-
sures such as predation tend to decrease or increase with it.
The size of the bird, or more accurately, the leg-length, appeared to in-
314
THE WILSON BULLETIN
Seplf’ii'l'fr 1967
Vol. 79, No. 3
fluerice the food of the different speeies. The smaller or short-legged species
usually did not feed in deeper water, taking organisms available on the shore,
the algal mats, or in very shallow water. Greater numbers of free-swimming
and terrestrial forms were consumed by them, in contrast to the larger
speeies, which took more benthic organisms (see Tables 2 and 3 respectively).
It should be mentioned here that the Least Sandpiper collected in October
and the Wilson’s Phalarope in July, omitted in the tables, had eaten only non-
aquatic insects.
On the basis of the food habits, general size of the birds, main feeding
sites, and tendency to feed together, the 20 species present at the pond during
the study can be placed into three feeding groups:
Group I. Larger species which fed exclusively on the shore:
Killdeer iCharadrius vocijerus) . American Golden Plover { Pluvialis
dominica) , Black-bellied Plover {Squatarola squatarola) ^ Buff-breasted
Sandpiper ( T ryngites su hru ficollis ) .
Group II. Smaller or short-legged species which fed on or near the shore
or on the algal mats:
Semipalmated Plover i Charadrius semipalmatus) , Gommon Snipe,
Spotted Sandpiper i Actitis macularia) , Pectoral Sandpiper, Baird’s
Sandpiper iErolia bairdii) , Least Sandpiper, Dunlin, Semipalmated
Sandpiper, Western Sandpiper (Ereunetes mauri), Sanderling (Cro-
ce thia alba) .
Group III. Larger species which fed most commonly in water up to belly-
deep:
Solitary Sandpiper [Trin^a solitaria) , Greater Yellowlegs, Lesser Yel-
lowlegs. Short-billed Dowitcher { Limnodromiis griseus). Stilt Sandpiper,
Wilson’s Phalarope.
There were individual exceptions, but as a rule these groups were distin-
guishable in the field. A zonation was evident, with Group I at the periphery,
Group II near the water’s edge, and Group III located out in the water. The
Lesser Yellowlegs was ubiquitous but more often fed in deeper water away
from shore. It has been somewhat arbitrarily placed in Group III rather than
in Group II.
The Wilson’s Phalarope possibly should be grouped by itself. Although it
fed with the others of Group III, the specimen collected had consumed 100
per cent non-aquatic insects, as mentioned above. Apparently it took float-
ing insects from the surface of the water and from algal mats, unlike the
others.
SUMMARY
The general feeding habits of 20 species of shorehirds at a small pond near Cham-
paign, Illinois, were observed and stomach analyses of nine of these species were made
William S.
llrooks
SHOKEBIKI) FEEDING HABITS
315
(luring the autumn migrations of 1960 and 1961. The numbers and kinds of availal)le
food organisms at the pond were estal)lished l)y (juantitative sampling of henthic in-
vertebrates and estimation of relative numbers of free-swimming and shoreline orga-
nisms.
Although most species did not show dietary specificity, consuming a rather wide array
of organisms, all showed dietary selectivity, in that one or a few of the food items were
sought out over the others and out of proportion to their abundance. Competition was
probably reduced by this selectivity, and where two species shared high preference for
the same item, competition was alleviated by the fact that they usually fed at different
sites.
Aggressive behavior was observed intraspecifically with the Pectoral Sandpiper, and
at the peak of migration, interspecifically between these and Lesser Yellowlegs. They
may have been actively competing for a preferred food item common to both.
The Common Snipe, Pectoral Sandpiper, and Semipalmated Sandpiper appeared to
consume considerable amounts of plant material intentionally. The other species prob-
ably took it incidentally with animal food.
The size or leg-length of the bird partially determined its diet. Small species were
apparently unable to forage in deeper water or ingest large organisms.
The 20 species were placed into three groups on the basis of their food, general size,
main feeding sites, and tendency to feed together. These groups, when feeding, were
distinguishable in the field because of iheir evident zonation.
ACKNOWLEDGMENTS
I greatly appreciate the help and advice given me by S. Charles Kendeigh during
the study. Thanks are due John E. Williams for his aid in obtaining specimens for
stomach analysis. For identifications of various food organisms I am indebted to Mrs.
Leonora K. Gloyd, John M. Kingsolver, Milton W. Sanderson, and Philip W. Smith
of the Illinois Natural History Survey. This report is based on a portion of a master’s
thesis in the Department of Zoology, University of Illinois.
LITERATURE CITED
Hamilton, W. J.
1959 Aggressive behavior in migrant Pectoral Sandpipers. Condor, 61:161-179.
Hess, A. D., and A. Swartz
1941 The forage ratio and its use in determining the food grade of streams. Trans.
Fifth North Amer. Wildl. Conf., 1940:162-164.
Holmes, R. T.
1964 Food overlap in breeding sandpipers in northern Alaska (Abstract). Proc.
14th Alaskan Sci. Conf., Anchorage, 1963:66.
Lack, D.
1944 Ecological aspects of species-formation in passerine birds. Ibis, 86:260-285.
1945 The ecology of closely related species with special reference to Cormorant
{Phalacrocorax carbo) and Shag (P. aristotelis) . J. Animal EcoL, 14:12-16.
DEPARTMENT OF ZOOLOGY, UNIVERSITY OF ILLINOIS, URBANA, ILLINOIS (PRES-
ENT ADDRESS: DEPARTMENT OF BIOLOGY, RIPON COLLEGE, RIPON, WISCONSIN
54971), 21 MARCH 1966.
CICO.MA MALTHA AND GRIS AMERICAS A FROM THE
UPPER PLIOCENE OE IDAHO
J. Alan Feduccia
Recent paleontological collecting by Claude . Hibbard and his field
assistants has yielded a large array of avian fossils from Idaho. The
specimens reported herein were collected from the Glenns Ferry Formation.
Twin Falls County. Idaho, and constitute part of the Hagerman Local Fauna,
which has been assigned to the Upper Pliocene ( Hibbard et al.. 1965 ). The
best estimate of the age of this fauna on the basis of potassium-argon dating
is considered to be 3.48 = 0.27 million years ( Evernden et al.. 1964. p. 191).
Ciconia maltha has been reported previously from the Lpper Pliocene of
Idaho I Miller. 1944 » . but the locality from which the specimens were taken,
the Bruneau Eormation. has more recently been assigned to the Middle
Pleistocene i see 5Ialde and Powers. 1962 1 . This species has also been re-
ported from numerous Lpper Pleistocene localities (see Brodkorb. 1963).
Grus americana has been reported from the Glenns Eerry Eormation (13
miles NA^ of Grandview. Idaho) on the basis of a tibial fragment (Miller,
op. cit. ). and from several Pleistocene localities i see A etmore, 1956 ).
In the course of this study I examined Recent specimens of Jahirii mycteria,
Eiixenura ma^iiari, Ciconia ciconia, Grus americana, and Grus canadensis
in the skeletal collection of the Lniversity of Michigan ^Museum of Zoology.
A scapula of Ciconia maltha from the type locality of Rancho La Brea, and
skeletal elements of Recent Grus americana were kindly loaned by Theodore
Downs of the Los Angeles County Museum of Natural History and Clayton
M. A hite of the Lniversity of Kansas Museum of Natural History, respec-
tively. All of the specimen numbers refer to the Lniversity of Michigan
5Iuseum of Paleontologv unless otherwise indicated.
DESCRIPTION OF M ATERIAL
Ciconia maltha.
Specimen: Proximal 69 mm of right scapula (4MMP 52540 », from the Hagerman
quadrangle, SE ^4 sec. 29. T7S, RISE, 1.850 feet and 1.100 feet A of SE corner
of sec. 29. elevation 3.125 feet. Measurement: maximum breadth of head. 26.1 mm.
There has been considerable uncertainty in the past regarding the number of species
of fossil storks (excluding the Mycteriinae) recorded from Aorth America. Howard
( 1942 > examined all of the then known specimens and concluded that all represented
one highly variable species. C. maltha. I have examined scapulae from four sp)ecimens
of Jahiru mycteria. a form that closely approximates C. maltha in size and in osteological
characters, and have found not only variation in size, but also in osteological characters
of the scapulae. It is therefore not surprising to find individual bones that do not
conform in all details to the presently known specimens of C. maltha. The fossil re-
ported herein differs from the scapula of C. maltha (Los Angeles County Museum of
316
,1. Alan
Fcdiiccia
PLIOCENE STORK AND CRANE
317
Natural History B8120) that I examined and from the description of scapulae of C.
maltha (Howard, 1942, p. 196) in the following characters: concavity hetween acromion
and glenoid facet slightly deeper, and the depression at the base of the dorsal surface
of the coracoid articulation somewhat more depressed. However, both of these char-
acters vary somewhat in the specimens of Jabiru that I examined. The Hagerman fossil
agrees with the scapula of C. maltha in general form, the region of the base of the
scapula mesial to the coracoid articulation being straight (in Jabiru the same region
is well rounded) and coming to an abrupt end at the furcula articulation. This region
of the base in the Hagerman fossil and in C. maltha is perforated by pneumatic foramina.
Scapulae of Ciconia ciconia and Euxenura maguari are similar to those of the Hagerman
fossil and the specimen C. maltha in general contour of the basal region, hut the de-
pression under the coracoid articulation is absent in Euxenura and only slightly de-
pressed in C. ciconia. In size, the Hagerman scapula and that of C. maltha overlap with
Jabiru mycteria and are larger than either Euxenura maguari or C. ciconia. The differ-
ences in osteological characters hetween this fossil and C. maltha are not, in my
opinion, sufficient to warrant recognition of a new species.
Grus americana.
Specimens: (1) Fragment of proximal 53 mm of left coracoid (UMMP 48927), from
the Hagerman quadrangle, SW ^ NW sec. 16, T7S, RISE, elevation 3,025 to 3,100
feet. Measurements: least width of shaft, 13.8 mm; least depth of shaft, 9.4 mm.
(2) Left quadrate minus orbital process (UMMP 52249), from the Hagerman quad-
rangle, SE 1/4 SW lA sec. 5, T8S, RISE, 1,400 feet E and 250 feet N of SW corner
of sec. 5. Measurement: greatest distance from squamosal articulation to mandibular
articulation, 18.2 mm.
(3) Distal 93 mm of left tihiotarsus (UMMP 52541), from the Hagerman quadrangle,
NE lA NE 1/4 sec. 32, T7S, RISE, 850 feet S and 1,100 feet W of NE corner of sec.
32, elevation 3,050 feet. Measurements: depth through condyles, 23.2 mm; width of
condyles, 23.0 mm.
(4) Fragment of distal end of right tihiotarsus (UMMP 52288), from the Hagerman
quadrangle, NW lA NE lA sec. 16, T7S, RISE, 800 feet S and 2,600 feet W of NE
corner of sec. 16, elevation 3,010 feet. This bone appears to be that of a large crane
hut is so fragmentary that specific designation seems inadvisable.
(5) Fragment (155 mm) of proximal end of right tarsometatarsus (UMMP 52242),
from the Hagerman quadrangle, SE % NE lA sec. 17, T7S, RISE, elevation about 3,225
feet. No useful measurements could he taken from this fragment.
(6) Distal 51 mm of right tarsometatarsus minus trochleae for digits HI and IV (UMMP
52243), from the same locality as UMMP 52242. Measurement: greatest antero-
posterior distance through trochlea for digit II, 12.7 mm.
I have examined the following hones of the Recent form: four coracoids, quadrates
from one skull, five tarsometatarsi from four specimens, seven tihiotarsi from four speci-
mens, plus six complete skeletons of Grus canadensis. Grus americana, like Ciconia
maltha, varies both in size and in osteological characters of hones. All of the specimens
reported herein are intermediate in size hetween the largest and smallest of the Recent
Cr. americana that I examined, and are well accommodated into the range of variability
of osteological characters. Although the possibility exists that the fossils reported herein
do not actually represent the same biological species as Recent G. americana, the hones
appear to he inseparable from those of the Recamt form.
318
THE WILSON BULLETIN
September 1907
Vol. 79, No.
ACKNOWLEDGMENTS
I am indeltted to Dr. Claude W. Hiltltard for permission to study the fossils and for
supervision throughout this study, and to Dr. Robert W. Storer for criticizing the
manuscript. Mr. B. G. Murray, .Ir., did considerable work in sorting the Hagerman
fossils.
LITERATURE CITED
Brodkorb, P.
1963 Catalogue of fossil birds. Part 1 ( Archaeopterygiformes through Ardei-
formes). Bull. Florida State Mus., 7:180 293.
Evernden, J. F., D. E. Savage, G. H. Curtis, and G. T. James
1964 Potassium-argon dates and the Cenozoic mammalian chronology of North
America. Amer. J. Sci., 262:145-198.
Hibbard, C. W.
1965 Quaternary mammals of North America hi The Quaternary of the United
States ( H. E. Wright, Jr., and 1). G. Frey, Eds.), Princeton Univ. Press,
Princeton, N.J., pp. 509-525.
Howard, H.
1942 A review of the American fossil storks. Carnegie Inst. Wash., Puhl. 530:
187-203.
Maude, H. E., and H. A. Powers
1962 Upper Cenozoic stratigraphy of Western Snake River Plain, Idaho. Geol.
Soc. Amer. Bull., 73:1197-1220.
Miller, L.
1944 Some Pliocene birds from Oregon and Idaho. Condor, 46:25-32.
Wetmore, a.
1956 A check-list of the fossil and prehistoric birds of North America and the
West Indies. Smithsonian Misc. Coll., 131:1-105.
MUSEUM OF ZOOLOGY, THE UNIVERSITY OF MICHIGAN, ANN ARBOR, MICHIGAN,
11 MAY 1966.
SEED-SIZE PREEERENCE IN CHICKADEES AND TITMICE
IN RELATION TO AMBIENT TEMPERATURE
Becky A. Myton and Robert W. Ficken
COMPETITION for food between two closely related, sympatric species can
be assayed in four ways — differences in feeding habits, feeding loca-
tions, nature of food, and size of food ( Hinde, 1959).
The original object of this study was to test the seed-size preference of
two sympatric species, the Carolina Chickadee ( Parus carolinensis ) and the
Tufted Titmouse {P. bicolor). A direct correlation has often been observed
between the size of food taken and the size of the bill of the bird ( Lack,
1947; Snow, 1954; Betts, 1955; Morris, 1955) ; hence, we hypothesized that
chickadees would prefer smaller seeds while the larger-billed titmice would
prefer larger ones. Further, we predicted that both species would be most
efficient at husking and eating the size they preferred. It became apparent
soon after observations began that the chickadees took more of the larger
seeds on colder days. The objective was therefore expanded to test for corre-
lation between temperature and seed-size preference.
MATERIALS AND METHODS
Feeders were attached four feet up on large trees at four well-separated
locations in deciduous woods near College Park, Maryland. The feeders
were flat plastic trays measuring 12 X 30 inches with a 1 inch rim. Observa-
tions were begun on 17 November 1964, and continued through 22 February
1965.
Two size groups of sunflower seeds, dyed black with India Ink, were
placed on one or the other side of each feeder; the large-seed group was
0.12-0.17 g and the small-seed group was 0.03-0.07 g. The two size groups
were shifted randomly in order to minimize the effect of position. To test
for randomness of choice on each side of the feeder, observations were ob-
tained on mixtures of both sizes.
Data taken included seed size (large or small) chosen, the amount of time
spent husking and eating, and ambient temperature.
RESULTS
Control for position effect. — Virtually the same number of seeds of mixed
size was chosen from the right side of the feeder (78) as from the left (75)
by a flock including several birds of both species, thus indicating no prefer-
ence for a particular side.
Time spent husking and eating. — The relative efficiency of the two species
in dealing with each seed size is presented in Table 1. Chickadees ate the
319
320
THE WILSON BULLETIN
Septcml)er 1967
Vol. 79, No. .3
Mean Times
Table 1
FOR Chickadees and Titmice to
Small Sunflower Seeds (in
Husk and Eat
Seconds )
Large and
Species
Seed size
Husk
Eat
Husk plus Eat
Chickadees
large
14.6
69.0
76.4
Chickadees
small
10.1
29.6
39.7
Titmice
large
5.3
28.5
33.8
Titmice
small
3.3
23.3
26.9
smaller seeds faster than the larger [P < 0.05. Student’s test ) and titmice
husked the smaller seeds faster than the larger ( P < 0.05, Student’s test I .
A comparison of husking, eating, and husking plus eating in both species
shows that titmice were significantly faster with both seed types, except in
eating the small seeds.
Effect of temperature on size preference. — The observations on size choice
were divided into two periods based on temperature ( 32 L and below, “cold,”
and above 32 L, “warm” ) .
Chickadees showed a very strong preference for small seeds on warm days
and a marked shift in preference toward large seeds on cold days ( P < 0.0001,
Chi Square for contingency I . The titmice always preferred large seeds and
chose a slightly greater proportion of them on the warm days than on the
cold days I P < 0.05, Chi Square for contingency) (Table 2).
DISCUSSION
In general, the titmice preferred larger seeds than the chickadees. This
supports the original hypothesis; namely, that the larger-billed titmice would
])refer larger seeds and the smaller-billed chickadees would prefer smaller
seeds. The titmice were more efficient than the chickadees as judged by the
time spent husking plus eating both seed sizes, indicating an absolute ad-
vantage to a larger bill in utilizing sunflower seeds.
Table 2
The Numbej^ of Large and Small Sunflower Seeds Taken by Chickadees and
Titmice on Warm and Cold Days
Chickadees Titmice
Temperature
Large
Small
Large
Small
Above 32 F
98
346
301
83
32 F and below*
333
352
785
331
Total
431
698
1,086
- 414
SEED-SIZE PREFERENCE IN TITMICE
321
Mytoi. aiul
Kickon
The change in size preference by the chickadees on cold days might he
explained by the increased amount of food obtained per unit effort when
large seeds were taken. Although there was slightly more than twice as
much endoplasm in a large sunflower seed as in a small one, it also took the
chickadee approximately twice as long to husk and eat a large seed as a small
one (Table 1). However, the chickadee had to make two trips to the feeder
to obtain the same amount of food when it chose small seeds, and it would
he more efficient for the chickadees to take the large seeds. Because of the
stress of cold placed on the chickadees in the cold weather ( Brewer, 1963 )
and the need for greater energy on cold days, it follows that chickadees would
benefit by being more efficient on cold days. Thus, it seems that there are
two mechanisms in operation. First the chickadee shows a natural preference
for smaller seeds; and, second, this preference is modified under conditions
of cold stress when efficiency is of overriding importance.
SUMMARY
Field experiments on seed-size ehoiee revealed that Tufted Titmice preferred larger
sunflower seeds and Carolina Chickadees preferred smaller sunflower seeds as pre-
dicted from their difference in hill size. However, the chickadees showed a marked
shift toward large seeds when the temperature was 32 F or below. Two mechanisms
seemed to operate in this species: 1) a natural preference for small seeds, and 2) the
modification of this preference toward one of increased efficiency under cold stress.
ACKNOWLEDGAIENTS
We are grateful to Edward C. Keller for his help with the statistical analyses, and to
him and Millicent S. Ficken for their critical reading of the manuscript. This research
was supported hy the National Science Foundation (GB-891 and GB-3226).
LITERATURE CITED
Betts, \I. NI.
1955 The food of titmice in an oak woodland. J. Animal Ecol., 24:282-323.
Brewer, R.
1963 Ecological and reproductive relationships of Black-capped and Carolina
Chickadees. Auk, 80:9-47.
Hinde, R. a.
1959 Behaviour and speciation in birds and lower vertebrates. Biol. Rev., 34:85-128.
Lack, 1).
1947 Darwin’s finches. Cambridge Univ. Press, Cambridge.
Morris, I).
1955 The seed preferences of certain finches under controlled conditions. Aricul-
tural Mag., 61:271-287.
Snow, D. W,
1954 The habitats of Eurasian tits ( Parus spp. ) . Ibis, 96:565-585.
DEPARTMENT OF ZOOLOGY, UNIVERSITY OF MARYLAND, COLLEGE PARK, MARY-
LAND (PRESENT ADDRESS ( R.W.F. ) . UNIVERSITY OF WISCONSIN-MIIAVAUKEE,
MILWAUKEE, WISCONSIN). 3 MARCH 1966.
ADDITIONAT. OP>SEKVATIONS ON THE STRUCTURE OF
UNUSUAI. FEATHER TIPS
Alan H. Bkusit
IN spile of their obvious importance in almost all phases of avian biology
there are still some asjjects of feathers which are poorly known structur-
ally. Accordingly, interest in feather morphology persists among ornitholo-
gists ( Portmann, 1963 ) . One such area is the internal morphology of tipped
elements which occur on feathers of widely diverse taxonomic groups of
birds. Recently, for example, the relationship between pigment and feather
tip structure has been described in the Cedar Waxwing ( Bornbycilla cedro-
rum] (Brush and Allen, 1963), and in the Scaled Cuckoo { Lepido }>:r animus
cumin^i) (Brush, 1965). These investigations have indicated the existence
of at least two different structural arrangements involved in the formation of
such tips. The first, as found in the waxwing, involves the expansion and
flattening of the terminal portion of the rachis. In these structures, the
structured medulla lies between unequal thicknesses of the surrounding
amorphous cortex. The carotenoid pigment is deposited in the cortex. This
uneven cover produces the shiny ventral and duller dorsal aspect character-
istic of these tips. The second mechanism, as found in the cuckoo, involves
the fusion of the rachis with a number of barbs and minor structural ele-
ments. This produces a flattened structure with an internally segmented
appearance. Individual segments are compressed laterally and may fuse.
There is a heavy pigment ( melanin ) concentration in the center of the tip.
There are no external differences in the appearance of the surfaces in such
tips.
The latter mechanism is more common than the former. Indeed, Chandler
(1916) suggested that the structure in the waxwing may be unique among
birds. It should also he noted that there is a weak correlation of one mecha-
nism with melanin pigments and of the other with carotenoids. In no case
described thus far is the functional aspect of these structures completely clear.
It was the objective of the study reported here to investigate further the
structural and chemical nature of various unique feather tips not reported
previously. Included in this investigation were feathers from the Curl-crested
Aracari ( Pteroglossiis beauharnaesii ) ( family Ramphastidae ) . and several
species of the genus Rallus.
METHODS AND RESULTS
Pigmentation. — The coloration of the tips in all feathers described in this
study was due to melanin pigments. The techniques of bleaching with hydro-
322
Alan H.
Brush
FEATHER TIP STRUCTURE
323
RqIIus elegons
Fig. 1. Tipped feather from the crest of the Curl-crested Aragari { Pteroglossus
heaiiharnaesii) . Actual length, 20 mm.
Tipped feathers from several Rails. Lengths range from 7.2 mm iR. elegons)
to 1.1 mm iR. longirostris) .
gen peroxide or peracetic acid and reduction of ammonical silver nitrate
were used for melanin analysis (Brush, 1965).
Structure. — Whole mounts of feathers were made with Canada halsam
( Fig. 1 ) .
Cross-sections were made by mounting tissues in methacrylate and section-
ing with a glass knife. Several other techniques which included embedding
and sectioning in high melting point paraffin (Dr. P. Stetlenheim. pers.
comm.), diethylene glycol distearate, or gelatin were tried, hut met with less
success.
324
TIIK WILSON BULl.KTIiN
ScptcmlxT 1967
\ ul. 79. N...
Fig. 2. Cross-section of feather tip from R. indicus. Note relatively unstructured
cortical layer.
Ill cross-section the tips of the feathers from the crest of the Curl-crested
Aracari appeared similar in morphology to that of the Scaled Cuckoo, in
that the tip consisted of an internal medullary area which was heavily pig-
mented and which was surrounded by a relatively clear cortex. The highly
keratinaceous cortex when seen in serial section supports the notion that it
has developed from the fusion of several barbs or barb-like structures.
Cross-sections of the feather tips from members of the genus Rallus ( R.
ac/uaticus, R. elec^ans. and R. lon^iroslris I presented a pattern quite different
from that described above. Tips generally tended to be oval rather than
flattened and the internal structure (Fig. 2) suggested that only the rachis
was involved in the formation of the tip. The tips of the rail feathers lacked
the regular, repetitive structural units characteristic of the Pteroglossus tip.
The cuticle appeared unsegmented and the inner pulp contained pigment
FEATHER TIP STRUCTURE
325
Alan H.
Bnish
X-Section of Tip
f
Lepidoqrammus. Pteroqlossus
X-Section of C£3
Rach i s and Barbs
C®3 ® ®
Fig. 3. Suggested relationships among various tipped feathers. The generalized
structure of the rachis can he modified to produce tip structures of divergent morphology.
granules and various structural elements characteristic of the rachis. Gen-
erally, the tips of Rallus were considerably smaller than any of those investi-
gated previously. Feathers similar to those in Rallus were also observed on
the forehead of the Pied-billed Grebe { Podilymbus podiceps).
DISCUSSION
As was suggested earlier, at least two mechanisms may exist for the pro-
duction of feather tips. Both types are found in widely divergent taxonomic
groups and are therefore the result of convergent evolution within these group.
Bonhote (1912) observed that the external structure of the feather tip of
the rails resembled those of the waxwing. There are. however, differences. 1 he
waxwing tip contains carotenoid rather than melanin pigments and it is
326
THE WILSON BULLETIN
Septi-inluM- iy()T
Vol. 79, No. 3
considerably more flattened than is the rail tip. Carotenoid pigments are
deposited in the relatively clear, unstructured cortex while the melanin pig-
ment of the rails is deposited in the medullular areas. In spite of these dif-
ferences in the location and type of pigments it appears the basic internal
structure is similar in both forms. Therefore the waxwing tip can no longer
he considered an entirely unique structure.
The function of the feather tips described here is still somewhat obscure.
Bonhote suggested that the tipped feathers on the head of the rails may serve
a protective function in preventing the abrasion of the feathers as the bird
moved through the underbrush. The small size and the fact that relatively
few feathers actually have tips cast some doubt on this interpretation. How-
ever, the similarity of the size, structure, and location of the tipped feathers
in the rails and the grebe may be a convergent response to similar selective
pressures. The larger tips of the aragari and cuckoo may serve a signal func-
tion. However, they are dark and their visibility, and thus potential use-
fulness, in the animal’s habitat is unknown. The absence of a satisfactory
functional analysis of tbe tips in the waxwings has been discussed ( Brush
and Allen, 1962) .
Regardless of differences in their internal structure and function, the
feather tips presumably share a common origin ( Lig. 3 ) . The structural ele-
ments of the tips are derived ultimately from modifications of structural
elements already present in feathers. The formation of feathers may be one
of the most complex developmental processes in vertebrate skin as it involves
the alignment of rows of cells which form the shaft, barbs, and barbules
1 Spearman, 1966). Additional studies on the control of development of these
structures promise to be of interest.
ACKNOWLEDGMENTS
I thank Avis Sylvia for technical assistance and Dr. Allen Wachtel for the generous
loan of equipment. This investigation was supported in part by a grant from the
University of Connecticut Research Foundation.
LITERATURE CITED
Bonhote, J, L.
1912 On a peculiar type of feather in the Water-rail. Brit. Birds, 5:42-44.
BFtusH, A. H.
1965 The structure and pigmentation of the feather tips of the Scaled Cuckoo
( Lepidogrammus cumingi). Auk, 82:155-160.
Bhusii, a. H., and K. Allen
1963 Astaxanthin in the Cedar Waxwing. Science, 142:47-48.
Chandler, A. C.
1916 A study of the structure of feathers, with reference to their taxonomic sig-
nificance. Univ. California Publ. Zook, 13:243-446.
FEATHER TIP STRUCTURE
327
Alan H.
Brush
PoHTMANN, A.
1%3 Die Vogelfeder als inurphologisclies I^rohlem. Verhandl. Nalitrf. Ges. Basel,
74:106-132.
Spearman, R. I. C.
1966 The keratinization of epidermal scales, feathers and hair. Biol. Rev., 41:59-96.
DEPARTMENT OF ZOOLOGY AND ENTOMOLOGY, UNIVERSITY OF CONNECTICUT,
STORRS, CONNECTICUT, 25 APRIL 1966.
NEW LIEE MEMBER
Dr. William A. Carter, Associate Pro-
fessor of Biology at East Central State
College, Ada, Oklahoma, is a new Life
Member of The Wilson Ornithological So-
ciety. Dr. Carter holds a bachelor’s de-
gree from East Central State, and a Ph.D.
from Oklahoma State University. His
doctoral research involved an ecological
study of the nesting birds of the McCur-
tain Game Preserve. Some of the results
of this project appear in the paper on
page 259 of this issue of The Bulletin.
He is a member of the AOU, Cooper
Society, National Audubon Society, Okla-
homa Ornithological Society, American
Society of Ichthyologists and Herpetolo-
gists, as well as other scientific societies.
His principal ornithological interests are
in the fields of ecology and niche posi-
tions, and bird populations, and he has
pul)lished several papers in this field, as
well as in the field of herpetology.
THE IXFEUENCE OF VOCAL BEHAVIOR ON THE
PERFORMER'S TESTICI EAR ACTIVITY IN BUDGERIGARS
( MEJAJPSITTACI S UM)l LATi S )
B\rbara V. Brockway
Astrikinji feature of an aviary containing the Budgerigar is the seem-
ingly constant ‘'chatter'' or "singing" which results from many indi-
viduals simultaneously performing Loud and Soft Warble. Both of these
‘‘songs'' ( sensu Borror. 19611 contain several components performed in
varving sequences and are the most elaborate of all Budgerigar vocal patterns
I for description of all vocalizations, see Brockway. 1964a and 196-46 I .
It is common avicultural knowledge that Budgerigars ( commonly called
parakeets in the U.S.A. ) typically do not breed unless pairs can hear each
other. This has been experimentally substantiated by Ficken et al. 1 1960)
and Brockwav 1 1964c i . W hen males are able to hear others, individuals
commonly spend up to one-quarter of their waking hours performing Loud
W arble as a result of inductive mimesis ( Brockway, 19646 and unpublished
data ) . If permitted to interact with a homo- or heterosexual partner, such
males will also perform three precopulatory vocalizations, namely Soft
Warble. Tuks, and W hedelees. These three vocal patterns function in part
to stimulate ovarian activity ( Brockway, 1965 ) . Even without a sexual
partner, males that are able to hear others maintain their year-long typically
high levels of testicular activity and can be milked for motile, unstainable
spermatozoa (see Table 1). Males, which are prevented from hearing each
other, perform such vocalizations as alarm and location calls in quantities
similar to those of males able to hear others. Such isolated males, however,
perform significantly little or no Loud W arble or precopulatory sounds,
cannot be milked for seminal fluid containing spermatozoa, and possess
markedly regressed testes and vasa deferentia after 3 to 5 weeks of isolation
( Brockway, 1964c and Ficken et al.. 1960 ) .
To investigate whether it is the hearing of Loud W arble with or without
precopulatory vocalizations performed bv other males and/or some factor
arising from the performance of these by an individual which stimulates a
male's testicular activity, the gonadal conditions of both “devocalized" and
sham-operated males able to hear others was studied.
MATERIALS AND METHODS
Seven males were rendered incapable of performing recognizable budgeri-
gar sounds by surgically severing their right and left sternotrachialis muscles
and removing a half-inch segment from both the right and left hypoglossal
328
Harhara F.
Brockway
VOCAL BEHAVIOR AND TESTICULAR ACTIVITY
329
nerves adjacent to these muscles. Such “devocalized’’ birds utter only hoarse
mono- and polysyllabic “burp’' or “keek” sounds. Sham operation on seven
control birds involved procedures identical to those used in “devocalization
except the sternotrachialis muscle and hypoglossal nerves were only gently
touched with forceps. For further control, “devocalization” surgery was
performed on only the left side of two additional males.
At the time of surgery (day 0) and at 21 and 36 days later, all of the
sexually mature 9 month old virgin males used for this study were milked
for spermatozoa and laparotomized so that their reproductive organs could
be measured. Following the initial surgery, all males were returned to the
aviary environment in which they had previously lived and where they could
hear all budgerigar sounds including the almost continual daily Loud Warble
performed by some 60 males in stock cages and 14 males of pairs in breeding
cages.
Control and experimental males were placed in adjacent cages so that both
groups could hear the abnormal utterances of “devocalized” males. The
sounds produced by each “devocalized” or control male were qualitatively
and quantitatively recorded during 45 minute observation periods three to
six times a week for 35 days. Maintenance (e.g. ; preening, eating, etc.) and
sexual behavior were noted during these observations and also at other times
during the study.
French’s Parakeet Seed, French’s Conditioning Food, cuttlebone, quartz
gravel, and water were provided ad libitum.
RESULTS AND DISCUSSION
After three days, all control birds resumed their typical performance of
budgerigar sounds including large quantities of Loud Warble. The seven
“devocalized” males continued to perform only low-pitched “burp” or higher-
pitched “keek” sounds throughout the study. The results, presented in Table
2, show that high levels of testicular activity are maintained only by males
performing typical budgerigar sounds. Hearing the vocalizations of other
males is not sufficient. No finer correlation was found between the recorded
amounts of any vocalization performed by an individual and the size of his
reproductive organs within either the control or experimental groups. That
surgical trauma did not produce the decreased testicular activity of the
“devocalized” males can be seen from data on controls, especially those “half-
devocalized” birds which showed no significant changes in testicular ac-
tivity and performed Loud Warble and all typical adult non-sexual vocaliza-
tions.
“Devocalized birds experience two phenomena which control birds do
not. I hey suddenh (ll are unal)le to perform normal species-t\ pical vocal
330
Till-; WILSON BLLLE'IIN
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Vol. 79, No. 3
Table 2
Stimulation of Testicular Activity by Factors Involved in Performing Vocal Behavior.’
Barliara F.
Biockway
VOCAL BEHAVIOR AND TESTICULAR ACTIVITY
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square and analysis of variance tests.
** The day of surgery, 1 day before the start of this study.
*** Comparisons between values for day 0 and 36.
**** These values are not included in the statistical comparisons between devocalized and control sham-operated males.
332
TIIK WJLSON BULI;ET1^
il.iT 1907
■9, No. ;i
ScpIlMlI
\ ol. 7
i)ehavior and (2) produce sounds dissimilar to any they had ])reviously made,
rhese experiences cannot, as yet, be separated from each other. Furthermore
either, in itself, might he a stress sufficient to prompt the decreased testicular
activity observed for “devocalized” males. This possibility might be mini-
mized by “devocalizing” young birds well before they ordinarily would
perform the elaborate Loud Warble and precopulatory vocalizations and
studying their subsequent gonadal development. High blood levels of adrenal
hormones (e.g., corticosteroids) are commonly associated with stress, re-
sulting in gonadal regression. Unfortunately, methods do not yet exist for
measuring these levels in the limited blood volumes of small birds. Accord-
ingly, birds were examined for other, grosser indications of stress. The
following data suggest that the “devocalized” males were not undergoing
reactions to stress as a result of their inability to perform anything but ab-
normal vocalizations: (1) the amounts of food and water they consumed
did not differ from the amounts consumed by the control group; (2) their
body weights were insignificantly different from those of the controls; (3)
they showed no abnormal persistently ruffled or sleeked body feather pos-
tures; (4) they performed no aberrant visible behavior patterns; (5) some
males performed visible precopulatory displays oriented to other males ( a
typical event among unisexually caged Budgerigars) ; and (6) 70 days after
devocalization, their reproductive organs were in the same conditions as
noted 35 days after “devocalization.”
Of all the vocalizations in the repertoire of Melopsktacus, only Loud
Warble, Soft Warble, Tuks, and Whedelees appear to be associated with
gonadal activity ( Brockway, 1964c ) . Not all control birds were heard to
perform the three precopulatory vocalizations and yet all non-performers
showed spermatozoa when milked and there was no distinguishable difference
in their testes and vasa deferentia measurements and those of control males
which did perform these vocalizations. Furthermore, the circumstances dur-
ing which these three vocalizations are predominantly performed, i.e., pre-
copulatory interactions, are not necessary for the full gonadal development
or function of either sex ( Brockway, 1962 and 1965 ) . These observations
strongly suggest that the performance of Loud Warble promotes the main-
tenance of high levels of testicular activity.
Whilst hearing the vocalizations of other males appears insufficient, in
itself, to maintain full testicular activity, a male’s performance of Loud
Warble stimulates and in turn is stimulated by the Loud Warble of others.
By so stimulating individual vocal performances, social vocal activity would
play an important role in promoting the testicular activity of the flock. This
would also help to explain why a male which is isolated from the sounds of
others typically shows low levels of androgen secretion and spermatogenesis
Ilarl.ata F.
Hiockwav
VOCAL BEHAVIOR AND TESTICULAR ACTIVITY
333
and why pairs of Budgerigars isolated from the sounds of others typically
fail to breed.
Other known instances in which the performance of specific behavior
patterns stimulates or is required for anterior pituitary gonadotrophin or
gonadal hormone secretions in the perjonner seems mainly restricted to
parental behaviors (for review, see Lehrman, 1961). Other known examples
of a behavior’s stimulation of anterior pituitary or gonadal activity involve
sexual or courtship interactions between 2 individuals. In these, the behavior
of one influences the endocrine activity of the other (e.g., Brockway, 1965;
Burger, 1942 and 1953; Polikarpova, 1940; Matthews, 1939; Shoemaker,
1939; Lehrman et al., 1961, and Warren and Hinde, 1961). Thus, this study
on Budgerigars may be the first experiment indicating a self-stimulation of
an individual’s gonadotrophin secretion or gonadal activity by the perform-
ance of a non-parental behavior. It would be interesting to know if any
"‘songs” of other avian species might have, in part, a similar function.
Another point of interest stems from the ethological designation of all
vocal behaviors as displays. Displays are commonly regarded as those
species-typical behavior patterns primarily functioning to provide signals
which alter the activity of the nervous or endocrine systems of other indi-
viduals (Tinbergen, 1964; and Hinde and Tinbergen, 1958). Budgerigars
may possess at least one display which functions not only to stimulate other
males to perform it but also stimulates the endocrine activity of the performer.
SUMMARY
Data on surgically “devocalized’' and sham-operated controls indicates that the
gonadal activity of male Budgerigars may he stimulated as a result of their performance
of vocal display (s) rather than as a result of hearing such behavior hy others. This
may he the first demonstration of the self-stimulation of an individual’s endocrine ac-
tivity hy his performance of a species-typical behavior which involves gonadotrophins
and non-parental behavior. Since vocalizations are ethologically regarded as displays,
the current thinking about the functions of displays may need expansion,
ACKNOWLEDGMENTS
This study was supported hy Researeh Grant CB-3191 from the National Science
Foundation and the generous provision of seed hy the R. T. French Company of
Rochester, N.Y. The author also wishes to thank Dr. Alan P. Brockway and Mrs.
Marilyn Goodrich for their invaluable help during this study.
LITERATURE CITED
Bohhoh, 1). J.
1961 Songs of finches ( Fringillidae t of eastern North America. Ohio Jour. Sci.,
61:161-174.
IhtOCKWAY, B. F.
1962 The effects of nest-entrance, positions and male vocalizations on reproduction
in Budgerigars. Living Bird, 1 :93-101.
334
THE WILSON RULLETm
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Vol. 79, No. .3
l%4r/ Etholojiical studies of the Ifudgerigar ( Melopsittacus andulatus) : non-
reproduct ive heliavior. Behaviour, 22:193-222.
VXAh Etliologieal studies of the Budgerigar (Melopsittacus undulatus) : reproduc-
tive heliavior. Behaviour, 23:294 324.
1964c Social influences on reproductive physiology and ethology of Budgerigars
i Melopsittacus undulatus) . Animal Behaviour, 12:493-501.
1965 Stimulation of ovarian development and egg laying hy male courtship vocali-
tion in Budgerigars (Melopsittacus undulatus). Aninad Behaviour, 13:
575 578.
Buhgkk, .1. W.
1942 The influence of some external factors on the ovarian cycle of the female
starling. Anat. Rec., 84:518.
1953 The effect of photic and psychic stimuli on the reproductive cycle of the male
starling, Sturnus vulgaris. J. Exp. Zool., 124:227-239.
EiCKr:N, R. W., A. van Tikniioven, M. S. Fk.ken, and Y. C. Sibley
1960 Effect of visual and vocal stimuli on breeding in the Budgerigar ( Melopsitacus
undulatus). Animal Rc/icc/oi/r, 8:104-106.
Hinde, R. a., and N. Tinbergen
1958 The comparative study of species-specific behavior. In Behavior and Evolu-
tion (A. Roe and G. G. Simpson, ed.), Yale Ihiiv. Press, New Haven :251-268.
Leiikman, I). S.
1961 Gonadal hormones and parental behavior in infrahuman vertebrates. In
Sex and Internal Secretion; Vol. II (W. C. Young, ed.), Williams and
Wilkins Co., Baltimore: 1268 1382.
Leiihman, I). S., P. N. Brody, and R. P. Wortis
1961 The presence of the mate and of nesting material as stimuli for the develop-
ment of incubation behavior and for gonadotropin secretion in the Ring Dove
{ Streptopelia risoria) . Endocrinology, 68:507-516.
Lr, .1. C. R.
1964 Statistical Inference: Vol. I. Edwards Bros., Ann Arbor, Michigan.
Matthews, L.
1939 Visual stimulation and ovulation in pigeons. Proc. Royal Soc., 126B :557-560.
PoLIKARPOVA, E.
1940 Influence of external factors upon the development of the sexual gland of
the sparrow. C. R. Acad. Sci. U.R.S.S., 26:91-95.
Shoemaker, H. H.
1939 Effect of testosterone propionate on behavior of the female canary. Proc.
Soc. Exp. Biol. N.Y., 41:299-302.
Tinbergen, N.
1964 The evolution of signaling devices. In Social Behavior and Organization
Among Vertebrates (W. Etkin, ed.), Univ. Chicago Press, Chicago :206-230.
VAN Tienhoven, a., H. C. Thomas, and L. J. Dreesen
1956 The effect of sulfamethazine feeding on the thyroids, combs, and testes of
single combed white leghorn cockerels. Poultry Sci., 35:179-191.
Warren, R. P., and R. A. Hinde
1961 Does the male stimulate oestrogen secretion in female canaries? Science,
133:1354-1355.
DEPARTMENT OF ZOOLOGY AND ENTOMOLOGY, THE OHIO STATE UNIVERSITY,
COLUMBUS, OHIO, 30 JUNE 1966.
AN IMPROVED CAGE DESIGN FOR EXPERIMENTATION
WITH PASSERIEORM BIRDS
Elden W. Martin
ONE of the essential laboratory items needed for experimental studies of
the bioenergetics of birds in captivity is a properly designed cage.
Cages used at the University of Illinois were first constructed entirely of
hardware cloth ( Kendeigh, 1949 ) , but many improvements were made in
later years. In the author’s nutritional studies with the Tree Sparrow {Spizella
arborea) , begun in 1962, several new modifications were incorporated in
the cages in the interest of decreasing food loss, lessening the chance for
birds to escape, and increasing the efficiency of separation of feed from
accumulated feces. Since there are frequent inquiries concerning these cages,
it seemed desirable to publish a set of directions for their construction.
DETAILS OF CONSTRUCTION AND DISCUSSION
The cage proper measures 31 X 16 X 31 cm, and is built with galvanized
sheet-metal walls which extend above the level of the perch (Fig. 1). The
upper two inches of the walls and the top of the cage are of one-half inch
mesh welded hardware cloth which permits adequate light entry and air
circulation. The vertically sliding door reduces chances of escape whenever
the birds are handled. The cage, as illustrated, is equipped for recording of
bird activity. The switch assembly ( S in Fig. 1) on top of the cage, similar
to that used on the older-type cages, consists of an adjustable spring-assisted
microswitch that supports a hooked center rod to which the perch and move-
able cage bottom are attached. The switch closes whenever the bird jumps
onto or off of the perch or cage bottom. The moveable cage bottom is
suspended approximately one inch above the excrement-pan floor.
The cage is easily modified to a non-activity type. For that purpose, a
one-inch mesh screen bottom (less center rod) is supported by four one-
eighth inch bolts arranged two on a side about one inch above the floor
pan. A centrally positioned one-half inch wooden dowel perch, with ends
tooled to fit one-quarter inch holes in the cage sides replaces the rod perch.
A handle formed from number nine galvanized wire and attached to the top
of the cage aids in the cleaning operations. The simple conversion feature
of this type of cage reduces the number of cages necessary for the conduct
of studies alternately considering or ignoring activity. Detailed construction
plans for the cage and its attachments are shown in Figure 2. The floor pan
I Fig. 1 ) consists of a simple one-half inch deep pan with rolled edges except
at the open end which extends about two inches in front of the cage to collect
any accidentally spilled feed.
335
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VUE WILSON BULLKTIN
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Fig. 1. A: Cut-away view from the riglit side of experimental eage showing relative
positions of feeder (F) and water eup (W), and pereh-liottom unit hooked to aetivity
switch assembly (S). B: ('mneral view of eage as placed on the excrement jian,
showing feeder attachment and vertically sliding door.
The placement of the food source outside the cage prevents, to a large
extent, scattering of feed inside the cage. The birds quickly learn to reach
through the one-inch diameter hole to feed, being encouraged to do so by
purposeful displacement of some feed through the hole onto the cage floor
when they are first introduced. Part (Fig. 2 and Fig. lA), in addition
to forming the front of the feeder, includes an apron portion which serves
j)artially to separate the feeding area and storage area, thus preventing gross
scattering of feed. This also serves to encourage the birds to eat most of the
feed in the feeding area before fresh unpicked feed falls from the storage area.
When food is offered in the form of finely ground mash, it is advisable to
release any compressed mash by passing a spatula or similar tool down
through the storage area at least once a day so that the feeding area constantly
contains food. The portion of the food hopper immediately outside the feeder
hole is covered by a fitted lucite strip so that the feeding area is well lighted.
In actual use, the cage is usually cleaned at three-day intervals. After
cleaning, a labeled, pre-weighed sheet of aluminum foil (both Reynolds Wrap
and Kaiser Foil in 12-inch widths have been used at one time or another)
is placed under the cage proper so that the floor pan is lined. At the end of
the three-day interval, the accumulated excreta is separated from any feed
CAGE DESIGN
337
Fig. 2. Scale drawing of composite parts of experimental cage. W — Back side of
cage with watering hole over which waterer (Wt>) fastens on clips D. Points e and f
are soldered points of attachment for perch (P). W;i is cage side of waterer. F — Front
side of cage with feeding hole and door opening. Feeder (Fid has a top front (F;d
which attaches at common letter points (a to a, 1) to h, etc.) and a bottom front (F4)
which provides extensions (c and d) to hold feeder to the cage hy hooking on clips 1).
Sliding door (C) runs in cdiannels formed hy bending strip E double. A & B — identical
side pieces for cage. Wire Top — piece cut from V2 inch mesh hardware cloth; to he
soldered to main c-age frame formed hy soldering W, F, A, and B. Dotted lines represent
break-points for 90-degree bends except for piece E which reipures a bend of about 170
degrees.
338
THE WILSON BULLETIN
Soptcmlier 1967
Vol. 79, No. 3
(finely ground I which may have been spilled, with the aid of a draftsman’s
brush and a one-sixteenth inch wire screen sieve. The excreta is gathered
into the bottom foil, which is then folded loosely (to j^revent loss) and oven-
dried.
Other investigators that have used the cage have not employed the foil
liner, simply allowing excreta to accumulate on the bottom pan. However,
the use of foil eliminates the necessity of scraping, and thus fragmenting the
excrement. When foil is used, granules of feed readily tap free from the
polished surface at the time of cage-cleaning whereas scraping from the
excrement pan requires drying of spilled (and uneaten) feed and excrement
together, followed by screening and mechanical agitation to dislodge food
particles. The latter process would seem to encourage further fragmentation
of the excrement with a resultant loss of part of the excrement quantity
through the sieve. Where metabolism or bioenergetics studies are in pro-
gress, this loss of raw material may result in underestimation of excrement
quantity produced, and overestimation of feed not eaten.
SUMMARY
Several new ideas were incorporated in the design of an experimental cage for
passeriform birds. Detailed construction plans are included and some of the design
features are discussed. Suggestions for routine application procedures of the cage
are offered including the use of aluminum foil as a disposable medium to aid in
(juantitative excrement collection and handling.
ACKNOWLEDGMENTS
I wish to thank August Kosowski for his timely design suggestions and for his skill
and care employed in the actual construction of the cages. 1 am indebted to Dr. S.
Charles Kendeigh for his encouragement in this endeavor and for his criticism of the
manuscript. The project was supported in part by National Science Foundation grants
awarded to Dr. Kendeigh. The paper was based on part of a doctoral thesis in the
Department of Zoology, University of Illinois, Urhana, Illinois.
LITERATURE CITED
Kendeigh, S. Charles
1949 Effect of temperature and season on energy resources of the English Sparrow.
Auk, 66:113-127.
DEPARTMENT OF BIOLOGY, BOWLING GREEN STATE UNIVERSITY, BOWLING GREEN,
OHIO, 43402, 25 January 1966.
GENERAL NOTES
Flightless Green-winged Teal in southeast Missouri. — On 25 September 1963, four
adult female Green-winged Teal i Anas carolinensis) were caught in a night drive-
trapping operation on the Duck Creek Wildlife Management Area near Puxico, in
southeast Missouri. All had recently molted their wing feathers and were flightless.
New flight feathers were at various stages of development: in three birds the longest
primaries (the ninth primary in each case) were 70-75 mm long; in one bird the longest
primary was 48 mm long. The flight feathers all had soft, blood-filled shafts. In con-
trast, the full-grown ninth primary is about 120 mm long in adult females, and feather
shafts are hard and translucent. This information is reported here because there appear
to he no previous observations of flightless Green-winged Teal in Missouri or in other
areas so far south of the breeding grounds. No further drive-trapping has been done
at Duck Creek so it is not known if such molting occurs regularly here. — John P. Rogers,
University of Missouri, Gaylord Memorial Laboratory, Puxico, Missouri, 2 August 1966.
Disgorging of food by Wood Ducks. — Malone (1966. Wilson Bull., 78:227-228)
reported regurgitation of Chara by Mallards (Anas platyrhynchos) about 45 minutes
after ingestion. The Chara was disgorged in loosely compacted balls, each ball being
about one inch in diameter. Malone postulated that disgorging resulted from overeating.
No comparison was made of the moisture content of the food when eaten and when
disgorged. It is the purpose of this note to report somewhat similar behavior by the
Wood Duck (Aixsponsa).
In Ohio during 1955-57, I trapped and banded some 600 Wood Ducks. Traps were
placed at the water’s edge, with the corn on dry soil at the rear of the traps and the
funnel entrance of the traps in shallow water. The birds could thus drink water as they
fed on the dry corn. An al)undance of corn was kept in the traps, and Wood Ducks
regularly entered the traps and ate to the limit of their capacities. Crops and gullets
were often crammed so full they literally could not hold another kernel. Feeding was
completed in a few minutes.
These corn-filled ducks were sometimes kept overnight in burlap bags before work
with them could be completed, and corn was often found loose in the bags. In one
bag holding 12 ducks, 264 kernels were found, for an average of 22 kernels per bird.
The corn was necessarily disgorged by the ducks. Even after such a night in confine-
ment, the ducks often had well-filled crops and gullets. The corn presumably did not
move through the alimentary tracts sufficiently rapidly to keep pace with the increase
in volume resulting from imbibition.
In the morning, a total of 190 kernels of corn was removed from the digestive tract
of one of these corn-filled ducks, 136 kernels coming from the crop and gullet. In a
supplementary test, 158 (136 plus 22) kernels of corn were soaked in water overnight;
the increase in volume was such that 46 kernels were displaced. With 22 kernels
disgorged per bird and tbe crops and gullets being al)out ecjually well-filled in the
morning as the preceding evening, approximately 24 kernels moved from the crop
farther into tbe digestive tracts.
This ability to disgorge food in excess of capacity may operate to avert rupture of tbe
crop wall. If tbe crop is filled to capacity, increase in volume of crop contents i)resumably
would be hazardous to the crop wall.
Malone ( oj). cit.) commented on tbe possibility of regurgitation of food by ducks
o{)crating in the diss<‘mination of j)lant pro{)agules. In this case with the Wood Ducks,
:v,v)
340
TWK WILSON BULLETIN
S(*pt<‘ml)er 1967
Vol. 79, No. .1
tlu* (lisgorfiino; of food can he .seen as an effective means for transporting vialile
propaguh's from the birds’ feeding places to their roosting places.
Tlu* observations reported in this note wert* made when I was a Research Fellow
of the Ohio (iooiieralive Wildlife Kes<*arch Unit. — Paul A. Stkwaht, Entomology Research
Dirision, Agrirnltural Research Service, USDA, Oxford, North Carolina, 13 July 1966.
|{ul‘f-hreastetl Sandpiper in northwestern Ohio. — On 11 .June 1%6 I was partici-
pating in a state-wid(* breeding bird census. I, accompanied by five of my students, ran
a 25-mile transect stopping to make a 3-minute observation every half mile. Approximately
half of my transect was in Hardin County and the remainder in Wyandot County.
At 10:00 AM we were standing outside the car beside a plowed field on Wyandot County
Road 294, five miles west of Harpster, Ohio. While I was listening for bird songs from
a nearby woodlot my attention was drawn to a sandpiper moving among the clods in the
adjacent field. It was a Ruff-hreasted Sandpiper iTryngites suhruficoHis) . Within a
few minutes we located six other individuals. They were exceedingly tame and fed over
the plowed field independently. On several occasions they approached within 30 feet
and we observed them for 20 minutes. At the end of that time the birds got up as one
and flew off to the east. The only previous spring record of this species in Ohio is
given as 6 May 1923 hy Borror (1950. Ohio Jour. Sci., 50:1-32). Although the spring
record of the Buff-hreasted Sandpiper in Ohio is unusual, the date is not. Oring ( 1%6.
Wi/.son Bull., 78:173) had this species in Oklahoma on 3 .June. — Richard S. Phillips,
834 Liberty Street, Findlay, Ohio, 23 July 1966.
Egg teeth and hatching methods of the Long-hilled Curlew. — Recent discussions
on egg teeth (Wetherhee, 1959. Bird-Banding, 30:119-121; Clark, 1961. Wilson Bull.,
73:268-278; Parkes and Clark, 1964. Wilson Bull., 76:147-154) stress the paucity of
information on Scolopacidae, so some recent observations on three hand-reared Long-
hilled Curlews iNumenius americanus) seem pertinent. The set of four eggs was
obtained from a nest west of Brigham City, Box Elder Co., Utah on 24 May 1966. Upon
pipping, all four chicks had cream colored egg teeth on both upper and lower hills.
The upper tooth was a raised projection 1 mm from the distal tip of the culmen. The
lower tooth, on the distal tip of the lower mandible, was smaller, rounded, and barely
raised from the surface of the hill. Both teeth were ephemeral and deciduous. In each
of the three birds that survived, the lower mandibular teeth were lost on the first day
after hatching, and the upper tooth persisted until the second day. The same situation
has been described for the American Woodcock (I^hilohela minor) hy Wetherhee and
Bartlett (1962. Auk, 79:117), and for the Willet i Catoptrophorus semipalmatus) hy
Tomkins (1965. Wilson Bull., 77:151-167). Conflicting data have been reported for
other members of the genus Numenius. Willink (cited in Clark, op. cit. ) found only a
lower egg tooth in Numenius sp. ; while Parkes and Clark (op. cit.) found only an
upper hill tooth in N. tahitiensis.
Observations on the hatching method of N. americanus showed that the pip hole
was started approximately one third the distance from the large end of the egg. It
was progressively enlarged until a circle about 1.5 cm in diameter was formed. The
chick then pushed out the large end and emerged hy splitting the remaining shell into
three approximately triangular pieces. This method is similar to that utilized hy the
September l‘)67
Vol. 79, No. 3
GENERAL NOTES
341
Willet (Tomkins, op. cit.) but different from that of the woodcock (Wetherbee and
Bartlett, op. cit.) .
I wish to thank K. L. Shirley for cooperation in gathering data and Dr. K. L. Dixon
for criticisms of this note. This study was supported by an NDEA Predoctoral Fellow-
ship.— Dennis M. Forsythe, Department of Zoology, Utah State University, Logan,
Utah, 18 July 1966.
Foreign Eggs in Nests of California Gulls. — During a study on the interactions
between California (Larus californicus) and Ring-billed gulls (Larus delawarensis) at
Miquelon Lake, located at 53°15'N and 112°55'W in Alberta, in 1964 and 1965, three
coot, two grebe and two Lesser Scaup (Aythya af finis) eggs were found intact in
California Gull nests and were being incubated. Neither coots nor grebes nested on the
island or had been seen visiting gull nests. It appears, therefore, that they were ingested
whole by the gulls and regurgitated in the nest. On several occasions grebe and duck
eggs were observed which were pecked open just outside and over the nest rims. As a
rule, when the gulls bring whole eggs back from different localities and regurgitate
them outside the nest, they are pecked open and devoured. However, when the eggs are
regurgitated within the nest, the drive to incubate these eggs may be stronger than the
urge to eat them.
Twomey (1948. Condor, 50:97-100) observed California Gulls bringing other birds’
eggs to their nests in Idaho. Sometimes they were carried in the bill, but more often
they were swallowed and regurgitated at the nest. The eggs brought were those of
Cinnamon Teal (Anas cyanoptera) , Ring-necked Pheasant ( Phasianus colchicus) ,
American Coot (Fulica americana) , Black-necked Stilt i Himantopus mexicanus) , and
Eared Grebe (Podiceps caspicus) . Sugden (1947. Condor, 49:93-96) found Ring-necked
Pheasant, Shoveler (Spatula clypeata) and Cinnamon Teal eggs in the California Gull
nests in Utah. These data all confirm the suggestion that California gulls swallow eggs
whole and regurgitate them later in the nest. — Kees Vermeer, 10177-104 Street, Edmonton,
Alberta, 2 August 1966.
Bonaparte’s Gull feeding on walnut meat. — The food of Bonaparte’s Gulls (Larus
Philadelphia) wintering along the seacoast usually consists of live marine life, mostly
taken from the surface of the water (Bent, 1921. U.S. Natl. Mus., Bull., 113:178).
During many years of observation of gull concentrations in New Jersey, I have never
seen a Bonaparte’s Gull at garbage dumps, pig farms, or the other scavenging areas
where the larger gulls congregate. Therefore, I was surprised to find the crop of a
Bonaparte’s Gull crammed full of walnut meat. This food was also in the gizzard,
whereas no other food was present. The walnut meat was in the form which is commonly
used by housewives.
The bird, a female in immature plumage, was collected on 22 April 1963 at South
Amboy, Monmouth County, New Jersey from a flock of about 200 Bonaparte’s Gulls.
This species is common at this time of year at this location. Large numbers are often
noted feeding in the tidal rifts in Raritan Bay.
I have no idea where this individual could have obtained its unusual meal. The
specimen is no. 210605 in the University of Michigan Museum of Zoology. — Robert (7
Froiiling, Howell, Michigan, 6 April 1966.
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Predation by the Chuek-v^ill’s-widow upon migrating warblers. — That the Chuck-
will’s widow { Caprimiilgus carolinensis) captures birds was known to Audubon <1859.
Birds of America, 1:154) who suggested that the species might he “carnivorous.” Suh-
secpient reports of bird-capture liave shown Ids supposition to he, to an extent, valid
(see e.g.. Bent, 1940. U.S. Natl. Mas. Bull. 176:506.) and have, as Terres 11956. Auk,
73:290) expressed it, indicated that the Chuck-will’s-widow may he “a seasonal if not
regular eater of small Iiirds.” Additional evidence of the seasonal aspect of its predatory
habits is herewith presented.
A Chuck-will's-widow, found dead during the morning of 18 October 1961 in Miami
.Shores, Dade County, Florida, was brought to Mrs. Arthur Gasche of that municipality
who presented the specimen to me. Wedged tightly into the throat of the caprimulgid,
its head well down into the esophagus, was a male Yellowthroat ^Geothlypis trichas) .
Death of both birds would seem to have been by suffocation. During preparation of the
two as study skins for the University of Miami Research Collections (UMRC), further
pertinent information was obtained.
The \ ellowthroat, weighing 12.9 grams, contained much suhdermal fat. In its stomach
were small insects. The Chuck-will’s-widow, a female, weighed — apart from the fellow-
throat — 121.4 grams. It likewise contained considerable fat. In the stomach of the
Chuck-will’s-widow was a nearly intact male Cape Warbler i Dendroica striata). Only
the warbler’s skull, from which the feathers and skin loosened when the bird was re-
moved from the stomach, gave evidence that digestion of it had begun. Remains of this
warbler weighed approximately 8.0 grams. (The combined weights of the two warblers,
incidentally, are equal to about 17 per cent of the weight of the Chuck-will’s-widow minus
its warbler content.) In addition, there were in the stomach two large glassy-winged
locusts iStenacris vitreipennis) , these showing but little evidence of digestion.
In mid-October, migration down the Florida peninsula is at a peak. That the Chuck-
will’s-widow and the Yellowthroat were migrating seems probable from their considerable
content of fat. The Cape May Warbler is present in Florida only as a migrant. It
seems logical to assume that, under ordinary circumstances, only during the seasons of
migration would small birds such as warblers he available to nocturnal predators seeking
flying prey. Here then, within the range of the Chuck-will’s-widow, is one more hazard
which small night-migrants face. In this instance, however, circumstances allow a
certain degree of speculation as to the time of capture of the warblers. Judging from
the condition of the three birds, it seems unlikely that they were captured before dusk
on 17 October or, for that matter, early that night. Considering the stage of digestion
of the insects in the stomach of the Yellowthroat and of that of the diurnal locusts in the
stomach of the Chuck-will’s-widow, it seems far more likely that these insects were taken
in daylight on 18 October. Thayer (1899. Auk, 16:273-276) presented a fascinating
account of Chuck-will’s-widows capturing migrating warblers over the open ocean during
daylight. Similarly, this Chuck-will’s-widow at Miami .Shores may be suspected of
gathering its warblers at dawn or during early morning hours, both prey and predator,
possibly, being engaged in building up or replenishing fat reserves prior to migration
beyond the shores of Florida.
The fact that the Chuck-will’s-widow can capture small birds in daylight requires
emphasis, for as Thayer’s (op. cit.) observations showed, this migrant stands in the
unique position of being able to feed while enroute over the ocean, a potential which
exclusively terrestrial birds quite generally lack. — Oscar T. Owhe, Department of Biology,
University of Miami, Coral Gables, Florida 25 August 1966.
Septemlier 1907
Vol. 79, No. 3
GENERAL NOTES
343
Josselyn Van Tyne’s Common Nighthawk nesting return. — Among the notes and
files turned over to me for “Fundamentals of Ornithology,” I found three paragraphs
of a first draft of a paper which Josselyn Van Tyne obviously intended to finish as a
general note on the return of a Common Nighthawk (Chordeiles minor) to its breeding
ground. Van Tyne had prepared some bibliography cards on the subject through 1952.
The three paragraphs are hand-written on the hack of a page of Conservation News,
dated 15 May 1955, so we can only assume that this is the approximate time that he
jotted down his first ideas. It is almost certain that he did no further work on the
project because, despite his remarkable command of current world literature on birds,
he did not include a reference to Dexter’s second paper on Common Nighthawk returns
( 1956. Bird-Banding, 27 :9-16) .
Why Van Tyne did not complete the short note is purely conjectural at this time. He
spent the period of 10 to 26 June 1955, in field studies: 12-13 and 24-26 June in his
Kirtland’s Warbler study area in Crawford County, and the intervening period in Michi-
gan’s Upper Peninsula with Dr. L. H. Walkinshaw and Dr. and Mrs. W. Powell Cottrille.
He was also devoting a considerable amount of time to the AOU Check-List during this
general period.
Van Tyne’s hand-written notes read as follows:
“While studying Kirtland’s Warblers with us in June, 1942, ten miles southeast of
Mio, Oscoda County, Michigan, Frances Hamerstrom found a Nighthawk nest with 2
eggs in a little open area on a hillside among the jack pines that sheltered the Kirtland’s
Warblers.
“On 20 June 1942, 1 set a carefully concealed bow-net at the nest and caught and
banded the incubating female (No. 41-222357).
“We studied the same area in 1943 but found no Nighthawk nest. However, on 24
June 1944, I found a nest in a similar habitat 450 feet south of the 1942 nest. Capturing
the female with a bow-net, 1 found that 1 again had No. 41-222357.”
The area “ten miles southeast of Mio, Oscoda County” was in Section 19, T25N, R4E.
Parks (1946. Bird-Banding, 17:168) reported on a Common Nighthawk which returned
to lay its eggs on the roof of the same high school in two successive years, in Hartford,
Connecticut, and Dexter (1952. Bird-Banding, 23:109-114; 1956. Bird-Banding, 27:9-16)
told of the return of a banded bird to the roofs of several buildings of Kent State
University in Ohio. Van Tyne, however, appears to have been the first person to make
observations on a banded Common Nighthawk returning to the same general nesting
area on the ground, the original primitive nesting site for this species. It may he re-
called that Van Tyne also was the first ornithologist to show by banding that passerine
birds return to the same wintering ground in the tropics (1932. Bird-Banding, 3:110). —
Andrew J. Berger, Department of Zoology, University of Hawaii, Honolulu, Hawaii,
14 July 1966.
Retarded or arrested cranial development in Myiornis ecaudatus. — A pair of
Short-tailed Pigmy-tyrants, i Myiornis ecaudatus) were obtained, 19 August 1966, from
rain forest, near Los Guaraunos, Estado Sucre, Venezuela. They were feeding two
nestlings that were nearly ready to leave the nest.
While preparing the specimens, we observed that both had partially pneumatized or
incompletely ossified skulls. The frontals and parietals were almost ('ompletely un-
pneumatized (single-layered), thin, transparent and flexible structures. Only the
anterior parts of the frontals and posterior parts of the parietals were pneumatized
TIIK W1I.S()^ BULLETIN
S(‘|ilcml)cr 1967
\ ol. 79, No. ;5
< (louhlf-laycred ) . In jiasscrincs, this condition is usually found only in tlie sexually
immature birds wliereas, actually hrcedinjr adults have a comjiletely pneumatized skull.
Ihis condition of un{)n('umatized skull has been report«“d in individuals of several
jiasseriiK' species whicli were sexually mature or actually rejiroducing. Notewortliy are
tlu‘ followiiifi;: Luxia curvirostra (McCabe and .McCabe, 1933, (Condor, 35:136 147);
Qiielea quelea (Disney and Marshall, 1956. Proc. Zoo/. Soc. London, 127:379-387);
Lepidoco/apfes /achrymi^er, Eu.scarthmorni.s f'ronadensi.s, Eloenia ol)Scura, Mionecles
striaticoHis, Myadestes nd/oides, Mo/othrus Itonoriensis, Tanagra xanlhoga.ster (MilU'r,
1963. Univ. (ddifornia l*idd. Zoo/., 66:1-78), Syna//axi.s a//)e.scen.s ( Miller, 1955. Ada XI
(,ongr. Intern. Ornith. Base/, p. 495-503). Crant (1966. Arner. Mid/and Nat., 75:142-149)
also observed the same {ibenomenon in Myiopagis viridicata and gave a good review
of tlie genera and families in which retarded or arrested skull ossification has been
reported.
According to Dwight (1900. Ann. Netv Yor/c Acad. Sc/., 13:73 360) and Nero (1951.
W i/son Bu//., 63:84 88), the skulls of passerine species appear to pneumatize completely
at about eight months of age. On the other hand. Miller (1963. op. cit.), indicated that
in some of the tody-flycatchers there are single-layered regions in the skull that may
prove to he permanent. Concerning the genus Mionectes, Miller (1963) said, “the
skull either is slow in attaining adult double-layered condition throughout or never
attains this state in some individuals." He also reported (Miller, 1946. Bird-Banding,
27:33-35) that complete pneumatization (doubling) may never he complete in some non-
oscine families such as the Furnariidae. Since Ylyiornis ecaudatus is not biologically
well known, we can not specify whether or not the incomplete pneumatization is the
result of an arrested or a retarded process. Neither can we say that this phenomenon is
of usual occurrence in this species. It also seems possible that individuals of this species
are sexually mature or actually reproducing while still being very young as indicated
by the presence of unpneumatized skulls.
We thank Mr. .lames Dale Smith for helping in the preparation of the manuscript,
and the Shell Foundation of Venezuela who provided a vehicle for field work. This
study is a byproduct of ecological research while the senior author was a Ph.D. student
of the Department of Zoology of the University of Montreal. Financial support was given
by the University of Oriente in Venezuela anti the National Research Council of
Canada. — Raymond McNeil and Aida Mahtinp:z, Departamento de Bio/ogia, Universidad
de Oriente, Cumana, Sucre, V enezue/a, {Present Address iMcNeii), Department of
Zoo/ogy, University of Montreal, Montrea/, Canada.) P2 Septenii)er 1966.
The gaping response of nestling Bank Swallows. — Because of the hole-nesting
habit of Bank Swallow^s i Riparia riparia) the liehavior of the young on the nest is
difficult to observe. Beyer (1938. If i/son Bu//., 50:122-137) observed Bank Swallows on
their nest by digging an observation hole behind their burrow. He reported that the
parents gave a high pitched call when entering the nest. If this did not release gaping,
the adults would nudge the young. In the summer of 1964 I undertook to study the
gaping response of young Bank Swallows from an observation hole similar to that
described by Beyer (op. cit.).
On 7 .luly 1964 near the W. K. Kellogg Biological Station of Michigan State University,
Barry County, Michigan, I found a large Bank Swallow colony and began construction
of an observation hole. The nest contained three young estimated from Beyer's fledging
dates to he eight days old. Before completion of the hole I observed that the young birds
gaped vigorously and gave begging calls when I darkened the nest chamber by placing
Soiiteniher l'K)7
Vol. 7'), Nu. 3
GENERAL NOTES
345
my hand over the burrow entrance, as they did when I Ijrightened the nest chamber with
a flashlight.
The young birds were 10 days old when I was first able to observe them inside the
nest. The young gaped when the adults entered the burrow, even if the adults did not
walk hack to the nest chamber. Although I could hear the begging calls of the young,
in none of the observation periods did I hear the adults give any call upon entering
the nest. The nestlings lifted up their heads when a shadow from another bird passed
across the burrow entrance, but they did not gape. The next day I noted the same
behavior.
On the 12th day of the birds’ life it was cloudy and rainy all day. The young were
fed at intervals of 15 to 30 minutes. Perhaps due to the infrequent feeding, the young
gaped at shadows that passed over the burrow; and once when I shined a flashlight
through the glass plate between my observation hole and the nest chamber, they all
turned and gaped widely toward it.
In all previous observations the nestlings did not move off the nest; on the 13th,
14th, and 15th days, however, two of the nestlings were continually off the nest and
about one-third of the way down the burrow. A third nestling remained on the nest.
On the 16th and 17th days all three young were fed at the entrance of the burrow.
They gaped whenever another bird hovered about them. On the 18th day the nestlings
had fledged, and for the next three days I found them on the nest only at night.
Nestling Bank Swallows apparently do not gape in response to a call from the parents,
hut rather either to a change in lighting or to the approach of another swallow. — George
W. Fulk, Department of Zoology, Michigan State University, East Lansing, Michigan,
{Present address: Department of Zoology, University of Rhode Island, Kingston, Rhode
Island ) .
Seasonal variation in bill length of House Sparrows. — In the course of an investi-
gation of geographic variation of House Sparrows (Passer domesticus) , data were ob-
tained which further demonstrate seasonal variation in bill length of this species. Speci-
mens were collected at Kit Carson, Cheyenne Co., Colorado, in mid-October, 1964, and
in late August, 1965. Measurements of the bill were taken from the anterior margin
of the nostril to the tip of the mandible, and were recorded to the nearest 0.1 mm. Only
adult birds (as determined by cranial ossification) were used in the present study so
as to ensure that the samples are comparable. Statistical treatment was by analysis of
variance (Steel & Torrie, 1960. “Principles and Procedures of Statistics.” McGraw-Hill,
New York) .
A statistically significant variation in hill length among groups was indicated ( see
Table 1). However, no portion of this variation could be attributed either to differences
between sexes (P>0.10) or to an interaction component (P>0.10). All of the
variation in bill length could be assigned to effects of season of capture (0.025 >P>
0.010), birds obtained in August having longer hills than birds captured in October.
The results are in essential agreement with reports by Clancey (1948. Brit. Birds, 41:
115-116) and Davis (1954. Condor, 56:142 149) which indicate that hills of House
Sparrows are longer in summer than in autumn and winter. Presumably this variation
has as its basis seasonal changes in food habits of sparrows (Davis, op. cit.; Sclander
and .Johnston, 1967, Condor, 69:217-258) ; wear to the hill is thought to l)c greater during
late autumn and winter when the primary foods are seeds than it is in summer when a
substantial part of the diet is soft-hodied insects.
MG
TIIK WII.SON BULLETIN
September 1967
Vol. 79, No. 3
J^AliLE 1
Bill Llngiii ok Hou.sk Sparrows
(mkan plus standard krror)
Sex
Aufiust
Octolter
Female
9.42 ±0.122
9.27 ± 0.100
(6)*
(12)
Male
9.44 ± 0.053
9.04 ± 0.104
(7)
(9)
* Sample size.
Furthermore, ul)sence of differences in l)ill length tliat are related to sex supports
earlier contentions that North American House Sparrows have not undergone evolutionary
change effecting a partitioning of the food niche (Packard, 1967. Syst. Zool., 16:73-89;
Selander and Johnston, op. cit. ) . Presumahly, failure of House Sparrows to experience
evolutionary change of this sort is related to their exploitation of an abundant and
diverse food source, thereby obviating specialization of hill structure for restricted food
sources (Selander, 1966, Condor, 68:113-151). — Gary C. Packard, Department of
Zoology and Entomology, Clemson University, Clemson, S.C., 9 September 1966.
lliiusiial activities of a House Sparrow and a Blue Jay at a Tufted Titmouse
nest. — A Tufted Titmouse (Pams hicolor) pair nested in a Bluebird iSialia sialis) nest
box in my yard at Pennington, N.J. On the morning of 4 July 1965 the titmouse young
were fed by a female House Sparrow (Passer domesticus) on three occasions within a
40-minute period. She was also making frequent feeding flights to her nestlings in a
bird house 17 ft. away. The titmouse pair protested noisily by scolding and diving and
once successfully drove her away.
The following morning (5 July) as I watched closely to see if the sparrow would
return, a Blue Jay (Cyanocitta cristata) flew to the titmouse nest box just as an adult
titmouse left, perched on the lower rim of the nest hole, pushed its head and neck
well into the nest box and pecked eight times at the nest contents. Then it perched a
few moments on an adjacent branch, 10 inches away, before returning to peer in the
nest box and poke at the nestlings. Once again it perched on the branch, returned,
and poked into the nest box. The jay did not taken anything from the nest. Although
the titmouse pair protested noisily by scolding and diving at the jay as it perched on and
near the nest box, they did not deter the jay. The entire incident took nine minutes.
Twenty-nine minutes later a jay (same?) flew to the nest box, thrust its head and
neck into the box as before, poking three times at the contents before leaving slowly
up through the nest tree, branch by branch.
The design of the box was such that it was 8V2 inches deep in front hut only 8 inches
at the hack with the almost-square interior 5 inches wide. The nest rim was approxi-
mately 3)4 inches below the box entrance hole and it seems possible that the jay could
have reached the nestlings.
There were ample auditory and visual cues to the nest’s location for a potential
predator. The titmouse nestlings were very noisy when fed by the adults and at times
the nestlings continued calling after the feedings. Moreover, the adults generally flew
directly to the nest box hole with food.
Sei)teml)cr 1967
Vol. 79, No. 3
GENERAL NOTES
347
The four titmouse nestlings fledged on 5 July. I was unable to determine if the
nestlings were injured by the jay’s thrusts. Inspeetion of the nest and box disclosed
no signs of blood. — Kenneth W. Pkescott, New Jersey State Museum, Trenton, New
Jersey, 24 May 1966.
Exltralimital breeding of Painted Buntings in Florida. — On 8 July, 1966, two
singing male Painted Buntings ( Passerina ciris) were found on the northeastern out-
skirts of Apalachicola, Franklin County, Florida. The buntings were adjacent to the
Apalachicola River, about one-half mile from the Gulf coast, in an open growth of
willow {Salix sp.), chinaberry {Melia azedarach) , and wax-myrtle iMyrica cerijera),
with a thick understory, predominately of blackberry (Rubus sp.) and sesbania [Sesbania
sp.). On a second trip to the area on 29 July, 1966, two males were again singing, and
a third male, also in song, was located nearby in similar habitat. Breeding was
suspected when two juveniles were located near the third male. They were actively fed by
a dull, female-like hunting, showing faint reddish on its underparts.
This small colony at Apalachicola is located near the center of a hiatus in the Painted
Bunting’s breeding range; a 400 mile break between southern Alabama (Mobile County:
Imhof, 1962. “Alabama Birds”) and coastal portions of eastern Georgia and northeastern
Florida (Burleigh, 1958. “Georgia Birds”; Sprunt, 1954. “Florida Bird Life”). The
absence of breeding buntings in Florida portions of this hiatus has been corroborated
at Pensacola by Weston (1965. A Survey of the Birdlife of Northwestern Florida, Bull.
Tall Timbers Research Station, No. 5. Tallahassee.), and throughout the interior and
Gulf coastal regions of North Florida by H. AI. Stevenson and his workers during recent
state-wide field investigations of breeding birds. No Painted Buntings were found at
Apalachicola during previous summers (Stevenson, personal communication), however,
two summer records near Tallahassee, in 1962 and 1966 (Robertson, 1962. Audubon Field
Notes, 16:47; Stevenson, 1966. Audubon Field Notes, 20:564), of single, singing males, are
the first known summer occurrences for that area, and suggest that the appearance of
the Painted Buntings at Apalachicola may he part of a trend towards occupation of the
hiatus.
The factors which brought about this wide gap in breeding range are not understood.
Suitable breeding habitat appears to exist throughout the range-gap, and migrant
Painted Buntings are regularly found in small numbers along the northeast Gulf coast
in spring, adjacent to the unoccupied area. The presence of these migrant huntings
along the coast may he due to displacement of trans-gulf migrants by weather associated
with northwesterly cold fronts crossing the Gulf of Mexico. The possibility that such
displacement resulted in the establishment of the colony in Franklin County, Florida,
seems good. Several cold fronts did cross the Gulf during April and May, 1966, resulting
in eastward displacement of trans-gulf and western migrants ( Cunningham, 1966.
Audubon Field Notes, 20:497). An area-wide field count on 22 April, 1966, in Phanklin
and adjacent Wakulla Counties, produced 13 Painted Buntings, second highest numl)er in
the history of spring counts in these counties, and huntings at Alligator Point, Franklin
County, on 7 May, and at Pensacola on 11 May, were the latest or e(jualed previous
late spring records for those two areas respectively ( Cunningham, ( loc. cit.); Imhof,
1966. Audubon Field Notes, 20:518). — John C. Ogden and Frank L. (hi \pman. Depart-
ment of Biological Science, Florida State University, Tallahassee, Florida, I September
1966.
MH
TiiK WILSON hulu:tin
Sf'|)tpml)pr 1967
\ <.l. 79, No. :i
(rolcifilich accept young after long and short incubation. — In the summer of
1%5, in Toledo, Oliio an experiment was carried out in which ejigs of the American Gold-
fineh iSpinus Iri.sti.s) from clutelies just laid were exchanged for eggs that were in
advane(‘d incubation.
On 31 .July I exelianged eggs between nests of 11 day incubation and those where the
fifth egg had just been laid. The eggs that had been laid for only the short time were
taken by a predator on the following day. The other female Goldfinch continued to
ineuhat(; for an additional 12 days until tlu; entire clutch had hatched. .She had been
incubating for a total of 23 days. 1 was not able to examine this nest until 10 days later.
At that time the nest looked “used” hut since there was no defecated material on the
nest it would ap{>ear that the young had not been in the nest for long.
On 5 August, I exchanged eggs that were in day four of incubation with a clutch that
had two eggs pi{)ed. The eggs hatched in both nests and the young were all fledged.
The one female had incubated for about five days and the other had incubated for 19
days.
The mean incubation period for this species has been reported as about 11-12 days,
(Walkinshaw, 1938. Jack-Pine Warbler, 16:3-11 and 14-15). ITom the preceding
experiments it is obvious that at least in some instances, the female will accept young
after one-half the length of or twice the length of the mean incubation time. — L.AHtn'
C. Holcomb, Department of Biology, (Creighton University, Omaha, Nebraska, 11 July
1966.
New status for the Rufous-crowned Sparrow in Utah. — The first record of the
Rufous-crowned Sparrow ( Aimophila ruficeps) for Utah (Wauer, 1965. Condor, 67:447)
was based on a specimen taken at Oak Greek Canyon, Zion National Park, Washington
County, Utah, 5 November 1963. The writer reported the species as wintering in Zion
I’ark. He concluded that, “early fall records, in August, in Zion Park indicate a fall
wandering tendency for the species, hut the presence of Rufous-crowned .Sparrows
throughout the winter months appears to suggest a northerly movement in fall and, per-
haps, a return to southerly breeding grounds in spring.”
However, an immature Rufous-crowned .Sparrow (deposited at Museum of Vertebrate
Zoology, University of Utah), taken by the author at Oak Creek Canyon, Zion National
I’ark on 10 August 1965, suggested that the species may he more than a wintering resident
there. It, like a specimen collected on 5 November 1963, was of the race scottii,
according to Lester L. .Short. The possibility was suggested that the species resides
permanently in the vicinity, nesting on the upper slopes of the canyons and moving
into the lower canyons after nesting and to winter. In Arizona, the species is a spring to
late summer nester; its period of breeding closely tied with summer rainy season.
Brandt (1951. “Arizona and Its Bird Life” p. 702) reports a completed nest as early
as 24 May, nests as late as 15 August, and that the height of the season for fresh eggs is
during the latter half of June. Assuming that the species did reside within the Zion Canyon
area, the author searched appropriate habits during May and June, 1966; on 29 June
on the west slope of .Steven’s Wash, Parunuweap Canyon of Zion National Park, a lone
singing adult was found. 1 watched it for several minutes through 9X binoculars. It
moved to several perches within an approximate 100 foot circle singing all the while.
Suddenly a second Rufous-crowned .Sparrow, its hill full of grass, flew^ to a perch about
two feet from the singing bird. Both remained there for five to ten seconds before they
departed, flying up the slope and around a number of large rocks out of sight. I was
unable to locate them again.
Septt>inl)er 1067
Vol. 70, No. 3
GENERAL NOTES
349
Although I was not able to return to the scene before being transferred from Zion
Park, this observation of one singing adult and another carrying nesting material offer
good evidence of nesting. The habitat, too, is typical of Rufous-crowned Sparrow nesting
grounds. The elevation is about 4,200 feet. Huge sandstone boulders dominate the seven
degree slope where Pinus monophyl/a, Jiiniperus osteosperma, and Qiiercus garnbellii
are common. The heavy patches of grasses that occurred there were under study as a
choice “relict grassland” by LaMar Mason and James Carley of the Soil Conservation
Service. Mason’s identifications of the major grasses on the site include needle-and-
thread (Stipa comata) as the dominant grass, while Indian rice grass (Oryzopsis
hymenoides) , black grama iBouteloua eriopeda), and mutton grass i Poa fendleri) were
abundant.
A portion of the above data was obtained during field research supported by National
Science Foundation Grant No. GB-4035. — Roland H. Wauer, Big Bend National Park,
Texas, 12 September 1966.
ANNOUNCEMENT
The XV International Ornithological Congress
The International Ornithological Committee decided, at the close of the XIV Interna-
tional Congress, that the next Congress would he held in the Netherlands in 1970 and
appointed Professor N. Tinbergen as President. The Netherlands members of the
International Ornithological Committee elected Professor K. H. Voous as Secretary-
General and formed a Netherlands Executive Congress Committee.
The International Committee accepted the Dutch proposal that the date of the
Congress would fall within the first week of September, as it was feared that appropri-
ate accommodation would not be obtainable earlier in the summer months. No major
ornithological excursions will he organized, but in the middle of the congress week a
variety of one-day excursions will he held. After full consideration the Netherlands
Executive Congress Committee decided that the XV International Congress would he
held at ’s-Gravenhage (The Hague), with the provisional date: 30 August-5 Septem-
ber 1970.
Applications for membership in the Congress will be accepted until 4 months before
the opening date of the Congress, viz. till 1 May 1970. Applications for presenting
papers and for arranging “Specialists Meetings” should reach the Secretary-General not
late than 1 April 1969.
Further information regarding the Congress can be obtained from The Secretary-
General, XV International Congress, c/o Burgemeester de Monchyplein 14, The Hague,
Netherlands.
THE PKESJDENT’S PAGE
The I’roceedinjis of our excellent 1%7 meeting, lield during 15-18 June at the
(irawford House, New Hampshire, app(“ar elsewhere in this issue, as recorded hy
Pershing H. Hofslund, who has completed his fifth and final year as the dedicated
Secretary of this Society, As I exj)ress to him the grateful appreciation of all of us for
the fine work which he has done, I would welcome, with similar gratitude, his successor,
Jeff Swinehroad, who was elected Secretary at the June meeting.
This specific example of one good man taking over from another illustrates a general
point which one of our esteemed l^ast Presidents, Maurice Brooks, has made. Writing
to me, shortly after the meeting. Dr. Brooks commented: “The setting was great, the
crowd excellent, and the spirit encouraging as always.” He then said: “I never cease
to marvel at the viability of this organization; year after year it comes up with devoted
people who get the jobs done.”
The continuing devotion of Past Presidents, as exemplified hy Maurice Brooks, is a
large part of the viability of the Wilson Society. This continuity of devotion also can
he seen in the fact that the symposium on nocturnal migration and orientation, which
was an outstanding feature of the papers sessions at the meeting, was proposed hy a
Past President, Sewall Pettingill, and was organized and chaired hy one of our Vice
Presidents, William Gunn. Two Past Presidents, moreover, participated in the Saturday
evening program, after the Annual Dinner: Dr. Pettingill as Toastmaster, and Dr.
George Sutton as the speaker of the evening.
Next year’s meeting, to he held at Southern Illinois University, Carhondale, Illinois,
2-5 May, 1968, will provide still another example of a Past President’s contribution to
the viability of the Wilson Society. Roger Peterson will he the Chairman of a sym-
{)osium on the preparation of state and regional bird hooks. In writing to say how
pleasant the 1967 meeting was. Dr. Peterson said that he will enjoy planning and
chairing the 1968 Symposium. The latter will he concerned with a subject of timely
relevance. No one who is interested in North American birds can afford to miss it. But
the point is that, busy man though he is. Past President Peterson is sufficiently devoted
to the Wilson Society to take the time to organize this important symposium for next
May’s meeting.
Aaron M. Bagg
( As we go to i)iess, we learn that an unexpected commitment will make it impossible
for Dr. Peterson to attend the Carhondale meeting, hut we expect to continue with
the symposium which he had planned. — Ed.)
CORRECTION
The following correction should he made in the article, “A new subspecies of the
Boat-tailed Crackle from Mexico,” Wilson Bull., 78:129 131 (1966). In Table 1 the
weight data for females of the subspecies prosopidicola should read: (6) 117-137.6
(125.2)
350
ORNITHOLOGICAL NEWS
FROM THE AOU
At its annual meeting in Toronto, Ontario on 21 August 1966 the AOU elected the
following officers:
Harold F. Mayfield, President L. Richard Mewaldt, Secretary
John W. Aldrich, First Vice-President Burt L. Monroe, Sr., Treasurer
Eugene Eisenmann, Second Vice-President Oliver L. Austin, Jr., Editor
The Brewster Medal was awarded to W. E. Clyde Todd for his hook, “Birds of the
Labrador Peninsula.” Mr. Todd, the senior member of the AOU, is the first person
to win the Brewster Medal for the second time.
The Smithsonian Institution and the United States Department of the Interior have
designated part of their page allotment under the National Science Eoundation transla-
tion program for the six volumes of Dement’ev and Gladkov: “The Birds of the Soviet
Union.” The series is being translated in Jerusalem by the Israel Program for Scientific
Translations which holds the copyright. Drs. A. Birron and Z. S. Cole are the translators
and Dr. Cole is editor. Volume 1 has already appeared and is available for $3.00, paper-
bound, from the U.S. Department of Commerce, Clearing House for Federal Scientific
and Technical Information, Springfield, Virginia 22151. The translation for Volume 4
has been completed and page proof has been read. It should appear in late 1967,
barring unforeseen problems in the Middle East. Unfortunately, Dr. Cole died this year
and translation has been interrupted. Before he died, however. Volume 6 was almost
completed, volumes 2 and 3 were each about one third translated l)ut Volume 5 was
not yet started. The schedule for issuing the remaining four volumes will Ije announced
after a new translator and editor have been found.
Royal Terns from coastal Virginia have recently been color banded as part of a
study by P. A. and F. G. Buckley on variation in chick color. A total of ten different
colors have been used (including light blue, purple and dark blue); three at a time
plus one Fish and Wildlife band, have been placed on each bird, in unique combina-
tions. Anyone observing such a banded bird is asked to send a postcard to Dr. Buckley,
Department of Biology, Old Dominion College, Norfolk, Virginia 23508, with the
following information on it: date, location, and observer’s name, plus the hand colors
and their positions (upper/lower, right or left leg). Assistance in this project will be
greatly appreciated.
Joanna Burger and Richard Brownstein of Buffalo, New York, are working on the
distril)ution and migratory behavior of the Bonaparte’s Gull. The gulls are dyed a
bright color and banded. The color used denotes the date of the marking session. All
birds are color marked in Buffalo. If you see any unusually colored Bonaparte’s Gull,
please send the following information to Joanna Burger, Department of Biology, State
University College, 1300 Elmwood Avenue, Buffalo, New York 14222: Date, Location,
Color, Number of marked individuals, and the Number of unmarked Bonaparte’s Gulls
with the color marked gulls. Any other data from personal records on the distribution
and movement of these gulls would also he appreciated.
351
ORNITHOLOGICAL LITERATURE
'I'liK Him)S OK ( j>i,oK‘\i)o. 'I'wo volunu's. By Alfred \I. Bailey and Rol)ert J. Niedrach.
Denver Museum of Natural History, 1965: 9 x 12% in., vol. 1, xxii + 454 pp., vol.
2, X -|- 455 pp., 124 col. pis., over 400 hi. and wli. photos, hack endpaper map in each
volume. .Set of two volumes, .$85.00.
News that another “state list'’ is about to appear always i)rovokes certain expectations.
It will he a monumental piece of hook-makinji, sumi)tuous, an armload, and too hi