194 FALCONS, HAWKS, EAGLES, ETC. 



o^. Back fuscous, fourth 'primary longest, outer tail-feathera half an 

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



333. Cooper's Hawk. 

 *. "Wing over 10-00. 

 Ji. Second primary longest, tail generally over 9'00. 

 i2, " Lower tail-coverts immaculate white." 353. White Gyrfaloon. 

 J». " Lower tail-ooverts always more or less marked with dusky." 

 354:. Gray Gyefalcok and Haces. 

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

 If. Tarsus shorter than middle toe without nail, upper parts hlackish. 



356. Duck Hawk. 

 «'. Tarsus longer than middle toe without nail, upper parts 



trownish 355. Prairie .FALOOif. 



<f>. Third or fourth primary longest. 



{p. Upper tail-ooverts white 331. Marsh Hawk. 



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

 JS. 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. Addhbon's Caeaoara. 



b. Tarsus entirely feathered . . 348. FEERnGiNous Eough-leq. 



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.). 



rfs. Wing over 12-00 342. Swainson's Hawk (Im.). 



«i. Four outer primaries emarginate or " notched." t 

 e\ 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. Eed-shouldered Hawk (Im.). 

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

 coverts not conspicuously margined with rufous. 



337. Eed-tailed Hawk and Races. 

 S. 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 Caeacaea. 



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



square. 

 M. Four or five outer primaries emarginate or " notched." f 

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



330. EvEEOiADE Kite. 



• See Fig. 70, t See Fig. 69. 



