148 Field Museum of Natural History — Zoology, Vol. IX. 



Upper tail coverts, white; tarsus, over 2.25; wing, over 12 inches 

 long ; third and fourth primary, nearly the same length ; a common 

 species in Illinois. Circus hudsonius. 



Marsh Hawk. 

 See No. 154. 



Fourth outer primary, not decidedly notched; no white on upper 

 surface of outer webs of primaries; under surface of primaries, not 

 strongly barred with dark brown and white ; tail, less than 9.50; upper 

 tail coverts, not white. ' Buteo platypterus. 



Broad-winged Hawk. 

 See No. 161. 



Fourth outer primary, decidedly notched; under surface of outer 

 primaries, not heavily barred with dark brown and white; tail, 9.50, 

 or over; wing, over 11.50. Astur atricapillus, and races. 



American Goshawk. 



See Nos. 157, isya. 



Fourth outer primary, decidedly notched; under surface of outer 

 primaries, not heavily barred with dark brown and white; tail, less 

 than 9.50 ; upper surface of tail, with distinct white bars. 



Buteo lineatus. 

 Red-shouldered Hawk. 

 See No. 159. 



Under surface of primaries, heavily barred with dark brown and 

 white; wing, under 11.50. Accipiter cooperii. 



Cooper's Hawk. 

 See No. 156. 



GROUP 4. Wing, 13 to 15 inches long. 



SECTION 1. Second primary, longest; first and second primaries, 

 emarginate, or notched. 



Length, always under 19; primaries, hoary gray, without bands; 

 breast and belly, white ; a patch of black on the shoulder. 



Elanus leucurus. 

 White-tailed Kite. 



See No. 152. 



