150 I'lELD Museum of Natural History — Zoology, Vol. TX. 



Upper surface of tail, dark brown, barred with white (adult). 



Buteo lineatus. 

 Red-shouldered Hawk. 



See No. 159. 



Throat, white; breast, dull brown; thighs, barred rufous brown 

 and white; three outer primaries, emarginate, or notched (adult). 



Buteo swainsoni. 

 Swainson's Hawk. 

 See No. 160. 



Throat, buflf or buff white; breast, heavily marked with dark 

 brown; thighs, pale rufous or buff with or without bars; three outer 

 primaries, emarginate, or notched (immature). Buteo swainsoni. 



Swainson's Hawk. 



See No. 160. 



Throat and under parts finely barred with gray and dull white, 

 the feathers with dark shafts; thighs, barred and mottled with gray 

 and white; tail, g.50 or over; wing, over 11.50 (adult). 



Astur atricapillus , and races. 

 American Goshawk. 

 See Nos. 157, 157a. 



Throat and under parts and thighs, white, or tawny white, 

 streaked with dark brown; tail, strongly barred (immature). 



Astur atricapillus. 

 American Goshawk. 

 See No. 157. 



GROUP 5. Wing, 15 to 17 inches long. 



SECTION 1. Second primary, longest; only first primary, emarginate, 



or notched. 



Length, under 19; primaries, dark brown, banded on inner web 

 with pale rufous. Falco peregrinus anatum. 



Duck Hawk. 

 See No. 169. 



Length, over 1 9 ; under tail coverts, marked with dusky or spotted ; 

 general plumage, gray and white, with more or less black marking; 

 primaries, not dark brown. Falco rusticolus. 



Gray Gyrfalcon. 

 See No. 167. 



