BIRDS — BUTEONINAE BUTEO MONTANUS. 
27 
In this plumage, which is evidently that of the young bird, the dark spots of the under parts are usually much larger and 
more numerous than in the young of Buteo borealis, in which we have never seen the tibiae and under tail coverts so strongly 
barred as in the present bird. 
Dimensions.— Adult female, total length 23 to 25 inches, wing 16| to 17, tail 9 to 10 inches. Male, total length 19 to 22 
inches, wing 15 to 16, tail 8% to 9 inches. 
This is a species much resembling and nearly related to the red-tailed buzzard {Buteo borealis) 
of the States on the Atlantic, and in the examination of collections like the present made during 
journeys across the continent, it is not without difficulty that a distinct range of locality can be 
assigned to the two species. The most strongly characterized specimens of the bird now before 
us are from the countries west of the Rocky mountains, but it is evident from specimens in this 
collection that this species is not restricted to those regions. It not only inhabits the moun- 
tains, but e extends into the countries at their eastern base. 
Of this rather difficult and obscure species, we have in the present collection no less than 
thirty specimens, which, with several others from the collection of the Philadelphia Academy, 
make a series probably representing all the stages of plumage dependent on age, sex, or season. 
This series admits of division into the three stages above described. 
Our comparisons are made with a series of twenty-eight specimens of Buteo borealis from 
various parts of the United States east of the Rocky mountains ; generally, however, from the 
vicinity of Philadelphia. The present species appears to be the larger, averaging in total length 
about 24 inches in adult females, which, so far as can be determined from prepared specimens, 
is nearly two inches greater than the average of the same sex of Buteo borealis. The wing is 
about 1^ inches longer. There are in the entire series of both species now before us not more 
than three specimens that we have any difficulty in assigning to one species or the other, 
though specimens of both constantly occur which cannot be recognized without difficulty, unless 
series are at hand for comparison. 
List of specimens. 
Catalogue number. 
Sex and age. 
Locality. 
When collected. 
Whence and how ob- 
tained. 
Original number. 
Collected by- 
Measurements. 
Point of bill to end 
of tail. 
Between tips of out- 
stretched wings. 
Wing from carpal 
joint. 
5836 
5834 
4581 
8531 
8538 
4372 
8535 
8534 
4416 
4521 
4611 
8536 
8533 
8549 
6957 
6956 
4986 
4985 
8532 
9 
Aug. 8, 1856 
Sept. — , 1856 
527 
23.50 
24.50 
53.00 
51.00 
16.75 
9 
do 
536 
Dr. Suckley 
23.00 
24.00 
22.00 
49.00 
54.00 
48.00 
9 
s 
Oct. — , 1854 
March 21, 1854 
Aug. 4, 1853 
8 
Dec. — , 1854 
Nov. 23, 1854 
March 16, 1854 
Feb. 6, 1854 
14 
185 
71 
371 
369 
Camp 149, N. SI 
s 
9 
North Platte 
Aug. 1, 1857 
22.50 
25.00 
54.50 
53.00 
18.00 
17.50 
Nov. —,1855 
