156 FALCONS, HAWKS, EAGLES, ETC. 
1.08. Female: length 23-25, wing 15.25-17.75, tail 9.50-10.50, bill 1.00- 
1.15. 
Distribution. — Eastern North America, west to the Black Hills and 
Colorado, and south to northeastern Mexico. Breeds nearly throughout 
its range. 
Nest. — Usually in tall trees. Eggs: 2 to 4, white or bluish white, 
more or less spotted or blotched with brown. 
Food. — Mainly mice, ground squirrels, and other injurious mammals. 
The eastern red-tail goes as far west as Colorado. 
337a. B. b. kriderii Hoopes. Krider Hawk. 
Adults. — Under parts entirely white or pale huffy; upper parts brown, 
largely marked with white ; tail pale rufous, usually without subterminal 
band. Young: similar, but tail tipped with white and with about ten 
dark brown bands, feathers more or less tinged with reddish brown and 
with inner webs largely white between bands. Size of B. borealis. 
Distribution. — Great Plains, from Minnesota to Texas, and from Wyo¬ 
ming east casually to Illinois. 
Nest and eggs similar to those of the red-tail. 
337b. B. b. calurus (Cass.). Western Red-tail. 
Adults. — Varying greatly in plumage — Light extreme : under parts 
white or buffy, with broad reddish brown streakings on throat, belly, and 
sides; tail bright reddish brown , with one or more subterminal blackish 
bars; rest of upper parts dark brown, more or less marked with yellowish 
brown and whitish. Dark extreme: uniform dark sooty brown except for 
rufous tail. Intermediates : reddish brown underneath, and with more or less 
reddish brown wash on upper parts. There are also all grades of plumage 
in this form between the light and dark extremes. Young: tail grayish 
brown varying to dull yellowish brown, crossed by 9 to 10 blackish bands; 
rest of plumage dark brown heavily spotted beneath, sometimes wholly 
dusky. Male : length 19.00-22.50, extent of wings 49-53, wing 13.50-16.50, 
tail 8.50-10.00, bill .95-1.08. Female: length 23-25, extent 54.00-57.50, 
wing 15.25-17.75, tail 9.50-10.50, bill 1.00-1.15. 
Distribution. — Western North America, from the Mississippi valley, 
casually east to Illinois, west to the Pacific, and south to Guatemala. 
Nest. — Sometimes used a number of years, made of sticks and lined 
with roots or inner bark, placed usually 30 to 50 feet from the ground, 
generally in deciduous trees, but also in evergreens and giant cactus, and 
occasionally on cliffs. Eggs: usually 2 or 3, creamy white or bluish 
white, unspotted or irregularly blotched with yellowish and reddish brown. 
Food. — Rabbits, ground squirrels, chipmunks, mice, snakes, lizards, 
frogs, grasshoppers, and other insects. 
“The western red-tail, though nowhere very abundant, is pretty 
generally distributed over western North America at large, and is, 
next to Swainson’s hawk, the commonest of the larger raptores found 
in these regions. ... It is fond of the tall timber bordering the banks 
of streams, and is as often found far in the mountain passes and 
deep canyons as in the more open country in the foothills and the 
adjacent plains, but seems to shun the dense and extensive forests, 
and is rarely seen except on the borders of these. In some of the 
