AqUILA. 241 



condition affects both old and young, and is connected with the 

 normal plumage by a series of specimens possessing, in every pos- 

 sible degree, intermediate characters.) Nest variously situated. 

 Eggs 2-3, 2.31 X 1-74, white, buffy white, or pale buffy, usually 

 more or less marked (sprinkled, spotted, or blotched) with brown. 

 Hab. "Whole of North America, breeding chiefly north of United 



States 347<z. A. lagopus sancti-johannis (GMEL.). 



American Bough-legged Hawk. 



a 2 . Bill much larger and stronger, and broader at base, the width of gape (measured 

 from corner to corner of mouth) 1.70-1.90. 



Adult, normal phase : Upper parts generally and thighs ferruginous, the 

 former streaked, the latter barred, with dusky ; secondaries and quills 

 plumbeous, the latter with a hoary cast ; tail white, washed with pale 

 ash-gray, more or less stained, usually longitudinally, chiefly along edges 

 of feathers, with light rusty, and sometimes crossed near tip by an in- 

 distinct subterminal bar or narrow band of dusky ; lower parts (except 

 thighs) pure white, sometimes slightly streaked with dusky. Young : 

 Above grayish brown, the feathers edged with rusty or ochraceous; 

 thighs white, more or less spotted with dark brownish or dusky; tail 

 with basal third (approximately) white (inner webs wholly white), the 

 rest brownish gray, usually with several, more or less distinct, darker 

 narrow bands. Melanistic phase (adulf) : General color deep chocolate- 

 brown, more or less varied above by rusty spotting and edgings ; lower 

 parts mixed rusty and chocolate, either tint prevailing ; tail as in nor- 

 mal phase. Male : Length about 22.50, wing 15.90-17.00, tail 9.50-10.50. 

 Female: Length about 24.00, wing 17.00-18.80, tail 10.50-11.00. Nest 

 usually in trees. Eggs 2-3, 2.42 X 1-88, white, or buffy white, usually 

 more or less spotted, blotched, or clouded with brown or grayish purple 

 (or both). Hab. Western United States, east to across Great Plains 

 (occasionally to Illinois), north to the Saskatchewan, south into Mexico. 

 348. A. ferrugineus (LIGHT.). Ferruginous Rough-leg. 



GENUS AQUILA BRISSON. (Page 223, pi. LXIX., fig. 2.) 



Species. 



Adult: Nearly uniform dark brown, the lanceolate feathers of hind-neck and 

 feathers of tarsus of a paler or more tawny hue ; quills black ; tail blackish, more 

 or less clouded, or very irregularly banded, with grayish. Young : Similar to 

 adult, but basal half to two-thirds of the tail plain white, the feathers of breast, 

 etc., white beneath surface, and feathers of tarsi paler (sometimes nearly white). 

 Male: Length about 30.00-35.00, extent about 6J-7 feet; wing 23.00-24.70, tail 

 14.00-15.00, culmen 1.50-1.62, tarsus 3.65-3.80, middle toe 2.40-2.80. Female: 

 Length about 35.00-40.00, extent about 7-7 feet, wing 25.00-27.00, tail 15.00-16.00, 

 culmen 1.68-1.85, tarsus 4.15-4.25, middle toe 2.55-2.80. Nest usually on cliffs, but 

 sometimes on trees. Eggs 2-3, 2.93 X 2.34, oval or rounded-ovate, whitish, usually 



31 



