191 FALCONS, 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. 

 b. Wing over 10-00. 



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



b^. "Lower tail-coverts immaculate white." 353. White GYRFALCOTf. 

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



354. Gray Gyrfalcon and Kaces. 

 c*. Second primary longest, tail under 9-00. 

 c2. 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^. Third or fourth primary longest. 



d^. Upper tail-coverts white 331. Marsh Hawk. 



d^. Upper tail-coverts brownish . . . 334. Am. Goshawk (Im.). 

 £. 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 .... 848. Ferruginous Kough-leo. 



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



364. Am. Osprey. 



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



square. 

 d^. 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.). 



el. Four outer primaries emarginate or " notched." f 



e^. Upper tail-coverts pure white 331. Marsh Hawk. 



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

 wing-coverts conspicuously margined with rufous. 



339. Eed-shouldered Hawk (Im.). 

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

 coverts not conspicuously margined with rufous. 



337. Ked-tailed Hawk and Eaces. 

 2. Feathers of under parts -vrith 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. 



^. Scales on front of the tarsus sharply defined, transverse, more or less 



square. 

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

 «!. Tail white at the base and tipped with whitish. 



330. Everglade Kite. 



* See Fig. 70. t See Fig. C9. 



