HAWKS 217 



§. Nostril small, circular and with a prominent central bony 

 tubercle; scales on front of tarsus numerous and rounded. 

 Duck Hawk. 

 §§. Nostril not rounded and without central bony tubercle ; scales 

 on front of tarsus transverse and squarish or no scales. 

 ?. Tarsus wholly feathered. American Rough-legged Hawk. 

 ??. Tarsus not entirely feathered. 



a*. Front of tarsus smooth or scales more or less obsolete. 

 b'. Wing under 8.80 ; tail feathers equal or nearly so. Sharp- 

 shinned Hawk, 

 b*. Wing over 8.80 ; outer tail feathers half an inch shorter 

 than inner ones or upper tail coverts white, 

 c'. Upper tail coverts not white ; outer tail feathers half 



an inch shorter than inner ones. Cooper's Hawk, 

 c*. Upper tail coverts white. Marsh Hawk, 

 a'. Front of tarsus with sharply defined, more or less square 

 transverse scales. 

 b'. Three outer primaries notched, 

 c'. Tail barred with many narrow blackish bars. Swain- 

 son's Hawk, 

 c*. Tail with only two or three broad whitish bars. Broad- 

 winged Hawk, 

 b". More than three of the outer primaries notched. 



c'. Tail reddish or rufous, occasionally with a black band 



Red-tailed Hawk 

 c*. Tail not reddish or rufous, 

 d'. Tail dark or black with several grayish or whitish 



cross bars. Red-shouldered Hawk, 

 d^ Tail gray with several blackish bands. American 

 Goshawk. 

 2. Breast or other under parts not barred. 



§. Under parts not streaked ; tarsus entirely feathered, American 

 Rough-legged Hawk. 

 §§. Under parts streaked or spotted. 



?. Outer primary not barred or rarely with a few imperfect bars 

 at its base only, 

 a*. Scales on front of tarsus numerous, small, rounded. Amer- 

 ican Osprey. 

 a*. Scales on front of tarsus more or less squared and trans- 

 verse, 

 b'. Only three outer primaries notched, 

 c'. Wing under 13.00. Broad-winged Hawk. (Immature). 

 c*. Wing over 13.00. Swainson's Hawk. (Immature). 

 b*. More than the three outer primaries (usually four) 

 notched. 



