National Museum, 27; Philadelphia Academy, 2; Boston Society, 1; Museum,
Cambridge, 1; Cab. G. N. Lawrence, 2; W. Brewster, 1; R. Ridgway, 5.
Total, 39.
_Measurements._
+----+-----------+-----------+---------+---------+-----------+----------+
|Sex.| Wing. | Tail. | Culmen. | Tarsus. |Middle Toe.|Specimens.|
+----+-----------+-----------+---------+---------+-----------+----------+
| ♂ |14.40–15.25| 8.25–9.00| .80–.90|2.30–2.65| 1.50–1.60| 11 |
+----+-----------+-----------+---------+---------+-----------+----------+
| ♀ |14.75–16.50| 9.00–0.00| .80–.95|2.50–2.70| 1.55–1.65| 11 |
+----+-----------+-----------+---------+---------+-----------+----------+
HAB. Western regions of North America, east to the Mississippi Valley,
north to the Arctic regions; Wisconsin; Arkansas; Canada; Massachusetts.
Localities: S. Texas (DRESSER, Ibis, 1865, 324); Arizona (COUES?);
Guatemala (SCL. Ibis, I, 216, “_insignatus_”).
The young plumage described above is the _Buteo bairdi_, Hoy, of
authors. The melanistic plumage is _B. insignatus_, Cassin.
The young birds of this species are as variable as the adults; thus,
No. 53,210, ♂, has the fine ochraceous of the lower parts entirely free
from spots, except across the breast; on the upper parts the ochraceous
spotting is so extended as to almost prevail, while another, from the
same nest, has the black beneath exceeding the ochraceous, the tibiæ
being thickly spotted, and the lower tail-coverts barred. Both these
specimens belong to a brood of four, which were hardly able to fly, and
were shot, with their parents, the male of which is the one described,
while the female (No. 53,206) is a very dark example of _insignatus_,
Cassin.
The type of _bairdi_, and another Wisconsin specimen, are in the
collection of the Philadelphia Academy. In plumage, they are unlike
any others I have seen, though there is as little resemblance between
these two as between any I have compared. Dr. Hoy’s type (Racine,
Wisc., January, 1854) differs from others, in exceedingly pale colors;
the cream-color beneath is scarcely spotted, there being only a few
triangular spots and shaft-lines of black on the sides; the lining
of the wing is entirely immaculate. Above, the black is unusually
continuous; the under surface of the primaries is unusually white. Wing,
15.00; tail, 8.00.
The other specimen (Menonomee Marsh, Milwaukee, Wisc., spring of 1851)
is just the opposite extreme in plumage, being unusually dark, for a
young bird. Beneath, the black spots are so large as to nearly cover
the whole surface, while the continuity of the black of the upper part
is almost unbroken. The head above, and nape, and broad “mustache”
stripe from angle of mouth down to the jugulum, with nearly the whole
pectoral area, unbroken black, leaving the gular region and side of the
head pale, but thickly streaked. Wing, 15.00; tail, 8.80; tarsus, 2.35;
middle toe, 1.50. These specimens may be said to form about the extremes
of the young plumage. An Iowa skin (No. 59,052; Ricksecker) is like the
average of far-western examples.
The melanistic condition bears to the normal plumage of _swainsoni_
precisely the same relation that the black _calurus_, Cassin, does to
the usual style of the western variety of _borealis_ (_borealis_ var.
_calurus_ = _montanus_, Cassin); the variable series, connecting these
two extremes, and designated by the name _borealis_ var. _calurus_,
which covers the whole, finds an exact parallel in the present species.
A specimen from the Platte (5,576, ♂, August; W. S. Wood) is entirely
dark rufous-brown beneath (excepting the lower tail-coverts), with the
shafts of the feathers black.
This species is entirely distinct specifically from the _B. vulgaris_
of Europe. The latter has four, instead of only three, outer primaries
deeply emarginated, and is very dissimilar in every stage of plumage.
Var. oxypterus, CASSIN.