472 FIELD MUSEUM OF NATURAL HISTORY ZOOLOGY, VOL. IX. 



the basal portion of inner webs white; upper portion of tail, whitish, 

 lower portion, dark, with whitish bars; under parts, white or buff, 

 more or less streaked and spotted; belly, heavily marked with black- 

 ish and buff, forming an irregular dark band; thighs, tawny or 

 brownish buff, more or less barred with black, but not ferruginous or 

 deep rufous brown, as in A. ferrugineus. 



Immature: Resembles the normal adult, but the terminal portion 

 of tail not barred; the under parts more heavily marked and the 

 blackish band on the belly broader and more perfect. 



Dark phase, adult and immature: General plumage, blackish, or 

 dark brown, with the exception of forehead and inner webs of anterior 

 portion of primaries; primaries and tail, with pale bars. 



Various intermediate plumages, too varied to be described, occur 

 between the light and dark forms. 



Adult male: Length, about 20; wing, 16 to 18; tail, 9 to 10.75. 



Adult female: Length, about 22.50; wing, 16.25 to 18.25; tail, 

 9.25 to ii. 



The American Rough-legged Hawk is not uncommon in Illinois 

 in spring and fall during the migrations, and a few remain during the 

 winter. Although the majority go farther north it has been known 

 to breed in Wisconsin. 



Kumlien and Hollister (Birds of Wisconsin, 1903, p. 64) state: 

 "In May, 1872, a pair of these hawks was found nesting in the 

 eastern part of Dane County, by L. Kumlien. The nest was placed 

 in a low burr oak, about eight feet from the ground, and contained 

 three eggs well incubated." 



Genus AQUILA Brisson. 

 165. Aquila chrysaetos (LINN.). 

 GOLDEN EAGLE. 



Distr.: North America and part of Mexico (also parts of Europe, 

 Asia, and Africa) ; breeding nearly throughout its range, usually in the 

 mountainous parts of unsettled localities. 



Adult: Tarsus, entirely feathered; general plumage, dark brown, 

 lighter brown on the wing and tail coverts ; feathers on back of head 

 and nape, golden brown; primaries, dark brown; tail feathers, dark 

 brown, more or less variegated with lighter brown and grayish at the 

 bases. 



Immature: Similar to the adult, but somewhat darker and the 

 basal two thirds or less, of the tail feathers, white; feathers of the tarsi, 

 pale brown or whitish. 



