22 U. S. P. E. R. EXP. AND SUEVEYS ZOOLOGY — GENEEAL EEPOET. 
List of specimens. 
Measurements. 
Locality. 
When collected. 
Whence obtained. 
Collected by — 
end 
'S to 
O hn 
rpal 
alogue numl 
c and age. 
ginal numbe 
int of bill to 
of tail. 
tween tips of 
tretched winj 
ng from ca 
joint. 
O 
sq 
O 
o 
Pi 
3 M 
6152 
9 
Little Missouri river.. 
Sept. 12, 1856 
Lieut. Warren 
Dr. Hayden 
22. 00 
52. 00 
16. 50 
5151 
9 
do 
20. 50 
46.00 
15. 75 
Loup Fork, of Platte.. 
San Luis valley, Upper 
Rio Grande 
1857 
8542. 
Lieut. Beckwith 
8 
Mr. Kreutzfeldt 
BUTEO CALURUS, Cassin. 
Red-tailed Black Hawk. 
Buteo calurus, Cassin, Proc. Acad. Philada. VII, p. 281, (1855.) 
Similar in general form to Buteo vulgaris and Buteo augur. Bill rather strong ; edges of the upper mandible with distinct 
rounded lobes ; wings long, fourth and fifth quills longest ; tail moderate, or rather short ; tarsi feathered in front for nearly 
half their length ; naked behind, naked portion in front having about ten transverse scales ; claws large, strong, fully curved. 
Tail bright rufous above, white at base, with about eight to ten irregular and imperfect narrow bands and one wide sub- 
terminal band of brownish black, and narrowly tipped with reddish white ; beneath silky reddish white. 
Entire plumage above and below brownish black, deeper and clearer on the back and abdomen, and paler on the throat and 
breast. Plumage of the upper parts with concealed transverse bands of white at the base of the feathers, and of the under parts 
with circular spots and transverse bands of the same also at the base of the feathers ; quills brownish black, with a large portion 
of their inner webs white, banded and mottled with pale ashy brown ; under tail coverts transversely barred with brownish 
black and pale rufous. 
Total length, female, about 21 inches ; wing 164 , tail 9 inches. Male rather smaller. 
This remarkable buzzard bears a greater resemblance to Buteo augur, Riippell, an African 
species, than to any other with which we are acquainted. It resembles no other American 
species except Buteo insignatus, Cassin, but is much larger, and presents other strong points of 
difference. To a casual observer this bird would present somewhat the appearance of the black 
hawk of the United States, Arcliibuteo sanctijohannis, with the tail attached of the common 
red-tailed buzzard, Buteo borealis, a combination hitherto quite unknown in the American 
falconida3, but which does exist in the African Buteo augur. 
This species was described by us, as above, from a single specimen in the collection brought 
by the party in charge of Captain John Pope, United States army, which was obtained by T. 
Charlton Henry, M. D., United States army, in the vicinity of Fort Webster, New Mexico. 
This able and zealous naturalist is the discover of this curious species, and has added a large 
amount of information to the knowledge of the ornithology of western North America. To the 
collections of this gentleman we shall have frequent occasions to allude. 
One other specimen is in the present collection, and was obtained by Mr. E. Samuels at Peta- 
luma, Sonora county, California, who found it breeding, and had the good fortune to obtain the 
eggs. These have recently been described by Dr. Thomas M. Brewer, in his very valuable work 
on North American Oology, now in the course of publication by the Smithsonian Institution. 
