NORTH AMERICAN BIRDS. 
more, dull white or bluish white, usually more or 
less spotted or blotched with brown. 
Wi. Tail of adult always (?) with a subterminal 
black bar, or else prevailing color of plumage 
white. 
@, Plumage never chiefly blackish. 
j. Deeper colored, with dusky and grayish 
brown prevailing on upper parts, the 
lower parts more or less buffy, espe- 
cially posteriorly; adult with tail 
deep rusty rufous. Eggs 2.38 X 1.81. 
Hab. Eastern North America, west 
to border of Great Plains; occa- 
sional in eastern Mexico; Panama 
(casual?). 337. B. borealis (GmEz.). 
Red-tailed Hawk. 
j. Lighter colored, with much white on 
upper parts, tail pale rufous (usually 
without the dusky subterminal bar), 
the lower parts entirely pure white, 
or pale buffy only on thighs, etc., 
with little if any spotting across 
belly. Hggs 2.31 x 1.80. Hab. Great 
Plains, from Minnesota to Texas; 
east, irregularly or casually, to Iowa 
and northern Illinois. 
337a. B. borealis kriderii Hoorzs. 
Krider’s Hawk. 
?, Plumage often chiefly blackish, sometimes 
entirely sooty, except tail and its upper 
coverts. 
Adult: Varying, individually, from a 
light extreme which is scarcely dis- 
tinguishable from true B. borealis to 
a uniform dark sooty brown, through 
every conceivable intermediate plu- 
mage; some melanistic specimens 
have the whole chest and breast 
rusty or rufous (corresponding to the 
white area of very light-colored 
birds), but this is wholly obliterated 
in the complete melanism. Young: 
Darker throughout and more heavily 
spotted beneath than in true B. 
