194 FALCOXS, HAWKS, EAGLES, ETC. 



a. Back fuscous, fourth "primary longest, outer tail-feathers half an 

 inch or more shorter than the middle ones; wing over 9-00. 



333. COOPER'S HAWK. 

 6. Wing over 10-00. 



b l . Second primary longest, tail generally over 9-00. 

 tf. " Lower tail-coverts immaculate white." 353. WHITE GYRFALCON. 

 b*. " Lower tail-coverts always more or less marked with dusky.'' 



354. GRAY GYRFALCON and Races. 

 e l . Second primary longest, tail under 9'00. 



c*. Tarsus shorter than middle toe without nail, upper parts blackish. 



356. DUCK HAWK. 

 c*. Tarsus longer than middle toe without nail, upper parts 



brownish 355. PRAIRIE FALCON. 



d 1 . Third or fourth primary longest. 



d*. Upper tail-coverts white 331. MARSH HAWK. 



d*. Upper tail-coverts brownish . . .334. AM. GOSHAWK (1m.). 

 . Outer primary generally one color, base sometimes whitish or with 

 a few imperfect bars. 



a. Tarsus entirely bare, scales on its front large, rounded. 



362. AUDUBON'S CARACARA. 



b. Tarsus entirely feathered .... 348. FERRUGINOUS ROUGH-LEG. 

 e. Tarsus partly feathered, scales on its front small, rounded. 



364. AM. OSPKEY. 

 d. Tarsus partly feathered, scales on its front transverse, more or less 



square. 



d 1 . Three outer primaries emarginate or " notched." * 

 d*. Wing under 12-00 .... 343. BROAD-WINGED HAWK (Im.). 



d*. Wing over 12-00 342. SWAINSON'S HAWK (Im.). 



'. Four outer primaries emargiuate or " notched." t 



*. Upper tail-coverts pure white 331. MARSH HAWK. 



*. Upper tail-coverts not pure white; wing under 13-50; lesser 

 wing-coverts conspicuously margined with rufous. 



339. RED-SHOULDERED HAWK (Im.). 



.e*. Upper tail-coverts not pure white ; wing over 13-50 ; lesser wing- 

 coverts not conspicuously margined with rufous. 



337. RED-TAILED HAWK AND RACES. 

 2. Feathers of under parts with more or less numerous 



cross-bars. 

 A. Scales on front of the tarsus numerous, rounded. 



a. Wing under 15-00 356; DUCK HAWK. 



b. Wing over 15-00 362. AUDUBON'S CARACARA. 



S. Scales on front of the tarsus sharply denned, transverse, more or less 



square. 



a. Four or five outer primaries emarginate or " notched." t 

 a 1 . Tail white at the base and tipped with whitish. 



830. EVERGLADE KITE. 



* See Fig. 70. t See Y\g. 89. 



