AQVILA. 241 



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

 normal i)lumago by a series of specimens possessing, in every pos- 

 sible degree, intermediate characters.) Nest variously situated. 

 E'jgs 2-3, 2.22 X 1-77, white, butty white, or pale butty, usually 

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

 Ilab. Whole of North America, breeding chiefly north of United 



States 347i/. A. lagopus sancti-johannis (Gmel.). 



American Eough-legged Hawk, 

 o'. 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. Youny : 

 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, usuallj- with several, more or less distinct, darker 

 narrow bands. Melanistic phase (cidult) : Genei'al 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. JS'est 

 usually in trees. Eggs 2-3, 2.50 X 1-93, white, or buff'y white, usually 

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

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

 (occasional!}' to Illinois), north to the Saskatchewan, south into ^Mexico. 

 348. A. ferrugineus (Light.). Ferruginous Eough-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, cuhnen 1.50-1.C2, tarsus 3.65-3.80, middle toe 2.40-2.80. Female: 

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

 culmen 1.68-1.85, tarsus 4.15-1.25. middle toe 2.55-2.80. Nest usually on clifl"s, but 

 Bometimea on trees. .£^7175 2-3, 2.95 X 2.28, oval or rounded-ovate, whitish, usually 



81 



