_Buteo cooperi_, CASS. P. A. N. S. Philad. VIII, 1856, 253.—IB. Birds
N. Am. 1858, 31, pl. xvi.—COOP. & SUCK. P. R. R. Rept. XII, ii,
1860, 148.—GRAY, Hand List, I, 8.—RIDGWAY, P. A. N. S. Dec. 1870,
142.—COUES, Key, 1872, 43.
[Illustration: =8525.= ½
_Buteo cooperi._]
SP. CHAR. _Adult_ (8,525, Santa Clara, California, Oct. 1856; Dr. J. G.
Cooper). Head, neck, and whole lower parts white; feathers of the head
and neck with medial longitudinal streaks of black, the white prevailing
on the occiput and superciliary region,—the black predominating over
the cheeks, forming a “mustache”; throat with fine lanceolate blackish
streaks; sides of the breast with broader, more cuneate markings of the
same; flanks with narrow, lanceolate stripes, these extending sparsely
across the abdomen; tibiæ, and lower tail-coverts immaculate, the
inner face of the former, however, with faint specks. Upper plumage in
general dark plumbeous-brown, inclining to black on the back; plumbeous
clearest on primaries, which are uniformly of this color, the inner
ones inclining to fine cinereous. Scapulars and wing-coverts spattered
with white beneath the surface. Rump black; upper tail-coverts white
tinged with rufous, and with irregular, distant transverse bars of
blackish. Tail with light rufous prevailing, but this broken up by
longitudinal daubs and washes of cinereous, and darker mottlings running
longitudinally on both webs; basally, the ground-color approaches white;
tips white, and a distinct, but very irregular, subterminal band of
black, into which the longitudinal mottlings melt; outer webs of lateral
feathers entirely cinereous, and without the black band. Under side of
the wing white, with a large black space on the lining near the edge;
under surface of primaries white anterior to their emargination, finely
mottled with ashy, and with indistinct transverse bands terminally.
Fourth quill longest; third shorter than fifth; second equal to sixth;
first equal to tenth. Wing, 15.75; tail, 9.10; tarsus, 3.25; middle toe,
1.70.
[Illustration: _Buteo cooperi_ (adult).]
This remarkable Hawk is certainly not to be referred to the _B.
borealis_, as has been suggested, the proportions of the two being quite
different, while there is no similarity of plumage. In plumage, _Buteo
cooperi_ very closely resembles the adult of _Archibuteo ferrugineus_,
and the suggestion has been made that it is a hybrid between this and
the Red-tail. The markings of the head, and the general tint of the
upper parts, are almost precisely as in the former bird, while the
tail is exactly similar in character of markings, the only difference
being the more reddish tinge and black subterminal band, which are, in
fact, the only characters approximating it to the _Buteo borealis_. The
feet are, however, very much stronger than in the _A. ferrugineus_,
while the tarsus is very much longer than in _borealis_, scarcely more
so, however, than in the former. The black patch on the lining of the
wing, however, is a feature shared by neither of these birds, being
one entirely peculiar to the _Buteo cooperi_. But one specimen—the one
described above—is known to have been obtained. Mr. J. A. Allen, in
his “Notes on some of the Rarer Birds of Massachusetts” (see “American
Naturalist,” Vol. III, p. 518, and a separate paper, p. 14), mentions
the capture of this species near Cambridge, Mass., but probably did not
actually see it. The specimen in question being in the possession of
Mr. C. J. Maynard, he kindly sent it to the Smithsonian Institution. On
examination, it proved to be a young _Buteo lineatus_, differing from
the average in somewhat lighter colors.
HAB. Santa Clara County, California.
The nearest ally of this species is the _B. ferox_, of the Palæarctic
Realm (Northern Asia and Africa and portions of Europe), which has
exactly the size and proportions of the present bird, and in certain
stages a very similar plumage. I have not seen an unquestionable
adult of _B. ferox_, but specimens almost adult, in the collection of
the Boston Society of Natural History, from the Himalaya Mountains,
come remarkably close to _B. cooperi_ in plumage, having like it a
black spot on the under side of the wing, but apparently on the under
primary-coverts, instead of on the lining, near the edge; the tail
is also very similarly colored. Upon the whole, I consider the _B.
cooperi_ to be a good species, with _B. ferox_, Gmelin, of Asia, etc.,
as its nearest relative, unless it proves to be a hybrid between _Buteo
borealis_ and _Archibuteo ferrugineus_, which I think is less likely to
be the case.
HABITS. A single individual of this bird was shot by Dr. Cooper near
Mountain View in Santa Clara Valley, California, in November, 1855.
It still remains unique in collections, and during his more recent
explorations Dr. Cooper has not been able to obtain any additional
specimens or see any like it. Those he mistook for this bird and to
which he refers in his report on the birds of Washington Territory, he
is satisfied were only the _Archibuteo ferrugineus_. The suggestion
of Sclater, that the bird is not distinct from _Buteo erythronotus_,
is negatived, according to Mr. Ridgway, by the fact of their actually
belonging to different sections of the genus.