232 NORTH AMERICAN BIRDS. 



men 1.00-1.15, tarsus 3.15-3.40, middle toe 

 1.60-1.70, weight 3-4 pounds. Nest usually 

 in tall trees. Eggs 2-4, 2.30, or more, X 1-80, 

 or more, dull white or bluish white, usually 

 more or less spotted or blotched with brown. 

 i l . Tail of adult always (?) with a subterminal 

 black bar, or else prevailing color of plu- 

 mage white. 

 /. Plumage never chiefly blackish. 



k l . Deeper colored, with dusky and 

 grayish brown prevailing on 

 upper parts, the lower parts 

 more or less buffy, especially 

 posteriorly ; adult with tail deep 

 rusty rufous. Eggs 2.38 X 1-81. 

 Sab. Eastern North America, 

 west to border of Great Plains ; 

 occasional in eastern Mexico ; 

 Panama (casual ?). 



337. B. borealis (Gmel.). 

 Red-tailed Hawk. 

 #". Lighter colored, with much white 

 on upper parts, tail pale rufous 

 (usually without the dusky sub- 

 terminal bar), the lower parts 

 entirely pure white, or pale 

 bufly only on thighs, etc.,' with 

 little if any spotting across belly. 

 Eggs 2.31 X 1-80. Sab. Great 

 Plains, from Minnesota to Texas ; 

 east, irregularly or casually, to 

 Iowa and northern Illinois. 



337a. B. borealis kriderii 

 Hoopes. Krider's Hawk. 

 f. Plumage often chiefly blackish, some- 

 times entirely sooty, except tail and 

 its upper coverts. 



Adult : Varying, individually, from 

 a light extreme which is scarcely 

 distinguishable from true B. bo- 

 realis to a uniform dark sooty 

 brown, through every conceiva- 

 ble intermediate plumage ; some 

 melanistic specimens have the 

 whole chest and breast rusty 



