]^o. 2. 

 REPORT ON BIRDS COLLECTED ON THE SURVEY. 



BY S. F. BAIKD. 



BUTEO SWAINSONI, Bonaparte, (p. 19.)'— Swainson's Buzzard. 



Plates XII and XIII. 



Buteo swainsoni, Bonap. Comp. List, p. 3, (1838.) 



Buteo vulgaris, Kioh. & Sw. Faun. Bor. Am. Birds, p. 47. 



There are few results of any of the expeditions more interesting than the discovery hy Captain 

 Beckwith's party that this hawk was abundant in the Eocky mountains. The species first 

 figured and described by Eichardson and Swainson as the common buzzard of Europe had been 

 variously identified by American authors, but most agreed in supposing it to be the young bird 

 of the western red-tailed hawk, now known as Buteo montanus. That such is not the fact, 

 however, is clearly shown by Captain Beckwith's collection, in which are three good specimens, 

 all difiering from each other, and one of them exactly in the plumage figured in the Fauna 

 Boreali- Americana, as quoted above. 



8540. Cochetope Pass. Iris grayish brown (24.) — 8539 do. same locality. Iris whitish 

 25. — 8541. San Luis valley, 13. Iris whitish. 



BUTEO CALUEU8, Cassin, (p. 22.)— Eed-tailed Black Hawk. 



Plate XIV. 



Buteo caiurus, Cassin, Proo. Acad. Philad. VII, 1855, 281. 



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 curyed. 



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 31 inches ; wing 16 J, tail 9 inches. Male rather smaller. 



Not rare in the Eocky mountains. 



BUTEO OXTPTEEUS, Cassin, (p. 30.) 

 Plate XV. 



This species is about the size oi Buteo pennsylvanicus, but the wings and legs are much longer. 

 The inner webs of the quills are dark cinereous, their inferior surfaces of a bronzed or silky 



1 The number in parentheses after the scientific name refers to the page of the General Report on Birds, Pacific Railroad 

 Survey, vol. ix, where the species is described in detail. 



