JAN., 1909. BIRDS OF ILLINOIS AND WISCONSIN CORY. 153 



Thighs, tinged with deep rufous, with numerous bars. 



Archibuteo ferrugineus. 

 Ferruginous Rough-legged Hawk. 

 See No. 163. 



SECTION 7. Fourth-primary, longest; three outer primaries, 

 emarginate, or notched. 



Tarsus, partly feathered; throat, white (adult); throat, -tawny 

 or buff (immature). Buteo swainsoni. 



Swainson's Hawk. 

 See No. 160. 



GROUP 6. Wing, 17 to 21 inches long. 

 SECTION 1. Third primary, longest; tarsus, wholly feathered. 



Basal portion of inner web of primaries, largely white, without 

 bars; thighs, tawny or buff, more or less barred; tarsus, thickly 

 feathered. Archibuteo lagopus sancti-johannis. 



American Rough-legged Hawk. 

 See No. 164. 



Basal portion of inner web of primaries, largely white, without 

 bars ; thighs, tinged with deep rufous, heavily barred. 



Archibuteo ferrugineus. 

 Ferruginous Rough-legged Hawk. 



See. No. 163. 



General plumage, entirely sooty brown or black; primaries and 

 tail, with more or less white or gray. 



Archibuteo lagopus sancti-johannis. 

 American Rough-legged Hawk (black plumage). 



See No. 164. 



SECTION 2. Third primary, longest; tarsus, not wholly feathered. 



Wing, from 16.90 to 21; a part of inner web of outer primaries, 

 white, showing numerous imperfect bars; three outer primaries, 

 notched ; belly and thighs, pure white ; back, dark brown. 



Pandion haliaetus carolinensis. 

 American Osprey. Fish Hawk. 

 See No. 172. 



