154 PROCEEDINGS OF UNITED STATES NATIONAL MUSEUM. 



143. Circus hudsonius, (Linn.) 



Probably the most common species of Hawk during the winter 

 months, arriving in September and leaving in April. A large propor- 

 tion are in immature plumage. — (Dresser, Ibis, 1865, 328. — C. cyaneiis 

 hudsonius, Sennett, B. Eio Grande, 40.) 



144. Nisus fuscus, (Gmel.) 



Found sparingly in winter. — {Accipiter /., Dresser, Ibis, 1865, 324.) 



145. Nisus cooperi, (Bon.) 



Like the last. — {Accipiter c. Dresser, Ibis, 1865, 323. — Sennett, B. 

 Rio Grande, 42.) 



146. Antenor unicinctuB rar. harrlsi, (Aud.) 



Resident and quite abundant. In its habits, this bird resembles the 

 Caracara Eagle, but is not so active. The nests are hardly distinguish- 

 able in situation or construction, and the two eggs are also deposited 

 at an interval of three or four days. Six eggs average 2.08 by 1.62; 

 they are dull bluish or yellowish-white, faintly stained with yellowish- 

 brown. — {Craxirex unicinctus, Dresser, Ibis, 1865, 329.— Buteo unicinc- 

 tus harrisi, Sennett, B. Rio Grande, 42.) 



147. Buteo pennsylvanicus, (Wils.) 



Uncommon winter visitor. — (Dresser, Ibis, 1865, 325. — Sennett, B. 

 Rio Grande, 43.) 



148. Buteo swainsoni, Bon. 



Occurs sparingly in winter. — (Dresser, Ibis, 1865, 324.) 



149. Buteo borealis, (Gmel.) 



A pair seen January 10, 1877, near Fort Brown, seemed to approach 

 var. Icrideri in the extent and purity of white beneath, although the 

 subterminal baud of black on the tail was very distinct. The birds 

 sailed several times quite near me, and I had a very good view of 

 them.— (Dresser, Ibis, 1865, 324.) 



150. Buteo harlani, And. 



Early in November, 1876, 1 observed a single specimen of this species 

 sailing in easy circles at no great distance from the ground ; but, not 

 having my gun, I was unable to secure it. — (Dresser, Ibis, 1865, 324.) 



151. Buteo albicaudatus. — The White-tailed Buzzard. 



Aquila coUblanca, Azara, Apuuo. 1, 1803, 69. 



Buteo albicaudatus, Vieiix.,Nouv. Diet. IV, 1816, 477 (ex Azara, /. c.).— Strickl., 

 Oru. Syn. 1, 1855, 35.— Salvin, P. Z. S. 1H70, 215 (Veragua). 



Tachytriorchis albicaudatus, Sharpe, Cat. Ace. Brit. Mus. I, 1874, 162. 



Craxirex albicaudatus, Ridgw., Pr. Ac. Nat. Sci. Phila. 1875, 92. 



Buteo {Craxirex) albicaudatus, Ridgw., t. c. 98 (monographic). 

 Spizaetus leucurus, Vieill., Noiiv. Diet. XXXII, 1819,59. 



Buteo leucurus, Lafi;., Rev. Zool. 1849, 100. 



