FIELDIANA • ZOOLOGY

Published by
CHICAGO NATURAL HISTORY MUSEUM

Volume 31 August 30, 1946 No. 6

NOTES ON SOME NEOTROPICAL HAWKS

BOARDMAN CONOVE»
Research Associatb, Division op Birds

Recently it became necessary to list the specimens of American
Falconiformes in the Wheeler Collection of Chicago Natural History
Museum. During his lifetime Mr. Leslie Wheeler built up a very
fine collection of hawks, especially from the Neotropics, and this
collection, which he gave to the Museum, has been increased since
his death by generous gifts from his widow. In checking over these
specimens a number of rare forms were found, and at least one ques-
tion of taxonomic interest came to light. It is thought that several
of these findings should be written up at greater length than will
be feasible in the footnotes of the Catalogue of Birds of the Americas,
Part I, No. 2, which is in press.

I am indebted to the following institutions for the loan of mate-
rial: The American Museum of Natural History, the Museum of
Comparative Zoology, the Museum of Zoology, University of Michi-
gan, and the Academy of Natural Sciences of Philadelphia.

Accipiter bicolor pileatus Temminck

Falco pileatus Temminck, PI. Col., livr. 35, pi. 205, 1823— Brazil =Ilha Cachoei-
rinha, Rio Belmonte, Bahia, fide Hellmayr, Field Mus. Nat. Hist., Zool.
Ser., 12, p. 458, 1929.

Range. — Tableland of southern Brazil from Maranhao and
Piauhy south in the west to central Matto Grosso and in the east to
Rio Grande do Sul, and eastern Paraguay (?).

Accipiter bicolor guttifer Hellmayr

Accipiter bicolor guttifer Hellmayr, Verhandl. Om. Ges. Bayem, 13, p. 200,
1917 — Bolivia (new name for Sparvius guttatus auct. not Sparviu^ guttattis
Vieillot= Acczpiter pileatus Temminck).

Range. — Tropical Bolivia (from Santa Cruz to Tarija), western
Matto Grosso (Urucum near Corumba), Paraguayan Chaco, and
northern Argentina from Jujuy south to Tucuman and east to
Formosa and the Chaco Austral.

No. 579 39

40 FIELDIANA: ZOOLOGY, VOLUME 31

In the manuscript of Part I of the Birds of the Americas Dr.
Hellmayr has treated the above forms as specifically distinct, placing
pileatus as a race of A. bicolor Vieillot and guttifer as a race of A.
chilensis Philippi and Landbeck. In studying the specimens in
Chicago Natural History Museum grave doubts were raised as to
the specific distinctness of the two. Therefore specimens were bor-
rowed that had been collected in the area where these forms were
supposed to overlap or meet, that is, southeastern Bolivia, south-
western Brazil, Paraguay, and northern Argentina.

Discussion. — Guttifer differs from pileatus by the tawny rufous
coloration of the breast and abdomen, which are generally spotted or
barred with white and sometimes partially barred with dusky gray.
In pileatus these parts are uniform light gray. To give an idea of
the individual variation found in adults from southern Matto Grosso,
Bolivia, the Paraguayan Chaco, and northern Argentina a brief
description of the specimens examined is given below.

Matto Grosso: A male from Chapada has light gray under
parts as in pileatus but at the base of some of the breast feathers
there are hidden blotches of light rufous. A second male from
Urucum, near Corumba, is typical of guttifer, the under parts from
the chest down being rufous with scattered white spots except for
the vent and under-tail coverts, which are white with rufous blotches.

Bolivia: A female from San Lorenzo, Tarija, is typical of gutti-
fer, with reddish breast and abdomen indistinctly barred with white
and dusky gray.

Paraguayan Chaco: Five females, from 195 to 265 km. west of
Puerto Casado, are rufous below as in the Bolivian female mentioned
above, but one has very little barring, while the others are well
marked with white and dusky. One male from the same region is
also typical of the Bolivian form. In a second male, however, the
entire under parts are gray, with the breast and the abdomen crossed
by indistinct light rufous and white bars which are more pronounced
on the abdomen; in other words an individual variant of guttifer
which is almost typical of pileatus.

Argentina: From Rio de Oro, Chaco Austral, there is a female
with reddish breast and abdomen but with a number of dusky gray-
ish and white bars on the under parts. Another of the same sex
from Jujuy is typical of guttifer while a male from the same province
has gray under parts heavily washed (not barred) with rufous
and indistinctly spotted with white. The only specimen from Salta,
a male, has the light gray breast of typical pileatus, but it is spotted

CONOVER: NEOTROPICAL HAWKS 41

here and there with dabs of light rufous that become thicker toward
the vent until it and the under-tail coverts are almost solid rufous.
FVom Tucuman four females have been examined, none of which
are typical of either form. Two, from Concepcion and Cumbre de
Raco, have gray under parts rather heavily washed with rufous,
especially about the abdomen, and they also show some white
spotting. The other two, both from Concepcion, have very dark
gray under parts. On one this plumage is practically immaculate
except for a suggestion of reddish wash about the vent. The other has
small, more or less hidden white spots about the lower breast and
abdomen with an indistinct rufous wash on the latter and white
under-tail coverts broadly barred with dark gray and rufous. A
male from Taficillo is pure pileatus in coloration except for a sug-
gestion of rufous here and there on the under parts.

Thus, nineteen adult specimens of guttifer and pileatus have been
examined from the above localities. Many more are needed before
the ranges of the two forms can be defined. From the examples
studied, however, there can be little doubt that the so-called speci-
mens of pileatus recorded as occurring in the same territory as gutti-
fer are merely individual variants of the latter wholly or partially
lacking its reddish under parts.

Twenty immature specimens were also examined from the same
regions. Birds from Bolivia and the Paraguayan Chaco average
more rusty ochraceous on the under parts. In two out of three from
Bolivia and six out of nine from the Paraguayan Chaco the ground
color of the ventral surface is rusty ochraceous while in the others it
is much whiter. There are no other differences.

The ranges of the two forms appear to be approximately as
given above (p. 39).

•
Accipiter gundlachi Lawrence

Accipiter Gundlachi Lawrence, Ann. Lye. Nat. Hist. N. Y., 7, p. 262, 1860
— Hanabana, Cuba.

Discussion. — The status of this rare hawk has been in doubt but
so far as coloration is concerned it most closely resembles Accipiter
hicolor guttifer but is larger (wing of male 245 and of female 298 mm.)
and has a much heavier foot and tarsus. A female examined has
less reddish under parts than typical specimens of guttifer from
Bolivia and the Paraguayan Chaco, but is very much like the two
females from Concepcion and Cumbre de Raco, Tucuman, described
under the preceding species. It differs from them, however, for

42 FIELDIANA: ZOOLOGY, VOLUME 31

the thighs, the under-wing coverts, and the axillaries are spotted
with white instead of being immaculate rufous, and the indistinct
white spotting and barring on the breast are more numerous and
extensive, while the chest is lighter gray. On the dorsal surface it is
grayer and the light bars on the tail are wider.

In an adult male the white spotting of the under parts is rather
indistinct and is confined to the crissum, while the thighs are pure
rufous, except that each feather is tipped by a very narrow, almost
obsolete line of white. The foreneck, chest, upper breast, and flanks
are grayish ash indistinctly tinged with dull rufescent along the
shafts of the feathers.

An immature male resembles immatures of guttifer but the throat
is finely streaked with dusky and the brown shaft lines to the feathers
of the under parts are lighter and narrower. The specimen is in
transition plumage as the thighs are reddish barred with white as
are some of the flank feathers.

This hawk does not appear to be extinct, since one of the examples
examined was taken in 1935.

Accipiter collaris Sclater

Accipiter collaris Sclater, Ibis, 1860, p. 148, pi. 6 — "Interior of New Grenada"
=BoKOt4, Colombia.

Swann (1925, p. 250) states that at that time this rare hawk was
known from only five specimens. These were an adult (Bogota)
skin in the British Museum and another in the Philadelphia
Academy of Sciences, an immature (Bogota) skin in the Norwich
Museum, and two immatures from Merida, Venezuela (Swann,
1921, p. 357), one in the British Museum and one in the Museum of
Comparative Zoology.

Discussion. — The two American specimens have been examined.
The immature from Venezuela in the Museum of Comparative
Zoology proves to be an example of Accipiter superciliosus Linnaeus,
not Accipiter collaris Sclater, a fact known to Dr. Stresemann, as Mr.
James L. Peters informs me. It is in the tawny phase of plumage
common to both hawks, but lacks on the hind neck the light rufous
collar that is the distinguishing character of collaris. However,
Mr. J. D. Macdonald of the British Museum informs me that their
immature from Merida has a distinct light collar on the hind neck
and a wing of 173 mm. The ranjge of Accipiter collaris, therefore,
does extend into Venezuela.

CONOVER: NEOTROPICAL HAWKS 4S

Since 1938 Chicago Museum has received through the Wheeler
Collection of birds of prey six examples of this hawk from the Cauca
Valley of Colombia and from western Ecuador. There are two adults
and four immatures. A study of these specimens and a comparison
of them with a series of eleven Accipiter superciliosus has brought to
light some facts that seem worth recording.

As pointed out by Gurney (1875, p. 471) Accipiter collaris and
Accipiter tinus (= superciliosus Linnaeus) are very similar in color-
ation and pattern of plumage in both adult and immature stages.
However, the specimens in this Museum show that collaris can
always be identified by the light collar on the hind neck and by its
larger size.

In the adult dress collaris when compared to superciliosus is
darker, more brownish, less grayish above and has an ill-defined,
half hidden collar on the hind neck; below, the dark barring is much
broader and darker. Three females have wings from 171 to 174 and
tails from 118 to 121 mm., as against a measurement in one adult
female of superciliosus of wing 158 and tail 103 mm. I have seen no
adult male of the larger species, but six of the smaller hawk have
wings from 135 to 146 and tails from 91 to 99 mm.

In the immature stage this species has two types of plumage,
as does superciliosus. Three of the four immatures are in what can
be called the tawny phase, which would appear to be the commonest
in both species. In this plumage the only constant distinguishing
character of collaris is the light rufous nuchal collar that separates
the dark brown crown from the more rufous brown of the mantle.
However, four examples of superciliosus in the same phase do show
a tendency to have darker rufous cheeks and three have more closely
barred under parts. Specimens in transitional plumage of both
species show that the succeeding stage is that of the adult.

The fourth young example of collaris is in what can be termed
the brown-backed phase. Unfortunately, I have no specimen of
superciliosus in this dress with which to compare it. However, it
would appear to resemble very closely the plumage described by
Sharpe (1874, p. 139) as the immature of A. tinus. The upper
parts are brown, slightly lighter than the color of the adults, and the
wing coverts, scapulars, and feathers of the back and rump are indis-
tinctly edged with rufous. The head is slightly darker than the rest
of the upper parts and is separated from them by an indistinct white
nuchal collar that becomes light buff on the sides of the neck.
Underneath, the rufous barring is lighter, more buffy and narrower.

44 FIELDIANA: ZOOLOGY, VOLUME 31

It is probable that this is a color phase rather than a younger stage
of plumage than the tawny one, because in the latter case it should
be the more common. Instead it appears to be the rarer.

The four immature specimens of collaris are all sexed as males,
but it is plain from their measurements that three must be females
(wings 170, 171, and 175 mm.; tails 124 mm.). The fourth specimen
has a wing of 148 and a tail of 109 mm. Four young examples of
superciliosus have wings of 151, 153, 161, and 164, with tails mea-
suring 104, 106, 112, and 116 mm. respectively. Although three are
sexed as males, comparing these measurements with those of the
adults given previously I judge them all to be females.

Range. — From the Merida region of Venezuela through Colom-
bia, west of the eastern Andes to western Ecuador (Nanegal and
Gualea, Pichincha).

Spizaetus devillei Dubois

Spizaetus devillei Dubois, Bull. Acad. Roy. Belgique, (2), 38, p. 129, pis. 1, 2,
1874 — Baeza, Ecuador.

Discussion. — The Wheeler Collection possesses a specimen of
this rare hawk, hitherto known only from the two original examples
described by Dubois. It is in the white-breasted plumage which
Dubois considered to be that of the adult. The bird agrees very
well in coloration with both the plate (pi. 1) and the description
except that the top of the head and the back of the neck are much
whiter than they are shown in the figure. In its dimensions it also
agrees with those given by Dubois, being a male with a wing of 470,
tail of 320, and tarsus of 116 mm. While in this plumage devillei
superficially resembles the juvenile stage of S. ornatus it can be
separated at a glance by its much larger size, by the lack of black
barrings on the flanks and thighs, by the three instead of five black
tail bands, and by the white-edged upper wing coverts and tertials.

Hellmayr (Part I, No. 2, Catalogue of Birds of the Americas, in
press) has suggested that this white-breasted plumage is that of the
juvenile not the adult. This is borne out by the example in Chicago
Museum. In it some of the old worn white-edged feathers of the
back have been replaced by new unworn ones that are dark brown
(almost black) without any white edges. These feathers agree in
color with the plate (pi. 2) and description of the supposed young
example in the Brussels Museum.

The specimen was collected in 1939 at Saloya (altitude 1,100
meters) on the Saloya River, on the southwest slope of the Pichincha

CONOVER: NEOTROPICAL HAWKS 45

volcano. The species therefore would seem to be found in both
eastern and western Ecuador.

Below is given a rough translation of the original description of
both juvenile and adult:

Juvenile (adult of Dubois). — Head, neck and under parts white;
feathers of the crown of the head, the nape, the flanks, and the
thighs marked with a longitudinal streak of brown; feathers of the
crest white at the base, brown at the tips, but all with a little white
tip; back and greater wing coverts ashy; all the feathers more or less
edged with white; lesser wing coverts brown, edged with white; pri-
maries ashy, brown at their tips but ended with a little white tip
and crossed by five or six black bands and bordered with white
at their inner edge for three-fourths of their length from the base;
fifth primary the longest, secondaries brown, tipped with white,
banded more or less distinctly with black, and marbled on their
inner edge with white; under wing coverts white, striated or blotched
with brown; tail ashy gray, blotched with brown, tipped with white
and crossed by three black bands. Bill and claws black; cere and
feet probably yellow.

Adult (young of Dubois). — Head and neck tawny, spotted with
brown; throat white, with some black feathers under the bill and
surrounded with a half collar equally black; back black, wings an
irregular mixture of black and brown feathers, the rear ones often
bordered with white; primaries as in the juvenile; under parts red-
dish brown, mixed with white, but all the feathers with a deep brown
center and generally edged with white; feathers of the thighs and
under tail coverts pale tawny; tail as in the juvenile, but tipped with
tawny, the black tip of the middle tail feather extending as far as
the second band.

Measurements. — Length of wing 47 cm., tail 32, tarsus 32,
middle toe 6 (without claw).

REFERENCES

GURbfEY, J. H.

1875. Notes on a "Catalogue of the Accipitres in the British Museum," by R.
Bowdler Sharpe (1874). Ibis, (3), 5, pp. 468-484.

Sharpe, R. B.

1874. Catalogue of the birds in the British Museum. 1, xiii + 479 pp., 14 pis.

SWANN, H. K.

1921. Notes on a collection of Accipitres from the Merida district, W. Venezuela.

Auk, 38, pp. 357-364.
1925. Monograph of the birds of prey. 1, 267 pp., 13 pis.