49 



6. Tail deeply forked; above glossy bluish black, the head, rump, 



and under parts white Swallow-tailed Kite. 



6. Tail but slightly if at all forked ' (7) 



7. Wing 7 or more times as long as tarsus ; bill with no sharp teeth or notches ; 



nostrils elongated and without inner bony tubercle (8) 



7. Wing 7 times as long as the tarsus; bill with a sharp notch and tooth back 



of tip; nostril circular and with an inner bony tubercle (9) 



7. Wing 6 or less times as long as tarsus (10) 



8. Tail white without bars and square tipped. White-tailed Kite. 



8. Slaty blue above, gray below; tail black, unbarred 



Mississippi Kite. 



9. Tarsus hardly at all feathered above ; sides of head black. . . Duck Hawk. 



9. Tarsus feathered less than half way down in front Prairie Falcon. 



9. Tarsus feathered over half way down in front and on sides 



Gray Gyrfalcon. 



10. Upper tail-coverts white; tail gray (male), ferruginous (female); 



barred with blackish Marsh Hawk. 



10. With neither the general plumage black nor the upper tail-coverts 



white (11) 



11. Nostril circular and with a conspicuous central bony tubercle; upper 



mandible with a strong tooth and notch back of hooked tip (12) 



11. Nostril oval and the upper mandible without more than one lobe or 



tooth, and that weak (16) 



12. Wing 11 to. 17 inches long; only one primary notched on inner 



web. Duck Hawk, Prairie Falcon, Gray Gyrfalcon. 



12. Wing 5 to 9J inches long; two primaries notched (13) 



13. Back bluish slate-color, ot blackish and without bright rufous (14) 



13. Back or belly with more or less of bright brownish red (15) 



14. Above slaty blue; middle tail feather with not more than four 



black bands Pigeon Hawk. 



14. Similar to preceding, but paler; middle tail feather crossed by 



six light bars, counting the terminal one Richardson Merlin. 



15. Tail with one black bar; male spotted below; whole back barred; 



female tail with numerous black bars ; below streaked . Sparrow Hawk. 



15. Similar to preceding, but slightly larger and appreciably paler, black 



bars and streaks narrower Desert Sparrow Hawk. 



16. Tail about J as long as wing (17) 



16. Tail not over § as long as. wing (19) 



17. Wing under 9 inches long; the tail square Sharp-shinned Hawk. 



17. Wing 9 to 11 inches long; the tail rounded Cooper Hawk. 



17. Wing 11 J to 14^ inches long (18) 



18. Above bluish slate-color, crown darker, a whitish line over eye 

 .to the nape; below finelymarked with gray and white. . . . 



American Goshawk. 



18. Above dark plumbeous, markings on lower parts heavier and 



darker Western Goshawk. 



19. Outer web of primaries with white buffy or reddish spots; four outer 



