Swainson’s Hawk 177 
The female is larger—wing 16, and has the pectoral-patch dark sooty- 
brown instead of rufous-brown. In the complete dark or melanistic 
phase the under-parts are dusky brown throughout with the under 
tail-coverts spotted or barred with rufous and white; between this 
and the normal phase every gradation exists, 
Young birds are dark, almost black above, varied with tawny or 
yollowish-white edgings to the feathers, especially on the head ; below 
pale tawny, spotted with dusky to a varying extent, sometimes only a 
few spots on the breast, sometimes almost completely covered with 
spots. 
Aspecies with very puzzling changes of plumage, but easily recognized 
in any stage by the cutting out of the three outer primaries only. 
Distribution.—Western North America from Alaska and Manitoba 
south to Arkansas, and west to the Pacific; further south through 
central and South America as far as the Argentine; north of about 
40° a summer migrant, south of 40° a resident. 
In Colorado, Swainson’s Hawk is an abundant resident, perhaps more 
abundant in summer than in winter, and more frequently met with on 
the eastern plains than in the mountains, though it is reported to breed 
up to 10,000 feet in the Wet Mountains by Lowe, at Breckenridge 
(Carter) and at Crested Butte (Warren). 
Other localities are: Weld co., breeding (Dille) ; near. Limon, breed- 
ing (Aiken); El Paso co., March, June (Aiken coll.); Fort Lyon 
(Thorne apud Fisher) ; Mesa co., common in summer, resident, but not 
known in winter (Rockwell); La Plata co., breeding (Morrison). 
Habits—Swainson’s Hawk is chiefly a bird of the 
open prairie or sage-brush country, and is seldom found 
in heavy timber or in the mountains strictly speaking. 
It is reputed to be a gentle and unsuspicious bird, and 
most inoffensive for a Hawk, frequently sharing a nesting- 
tree with a King-Bird or Oriole. Its food consists almost 
entirely of small rodents, mice and gophers, while in the 
autumn it preys largely on grasshoppers and_ locusts, 
hopping after them across the fields in a rather ludicrous 
manner. It is occasionally found in large flocks. Aiken 
saw about a dozen birds, March 11th, 1901, in a tree 
in one of the chief streets of Colorado Springs. Those 
he secured were all in the melanistic phase, and he was 
told that there was a large flock of at least five hundred 
in the Fountain Valley, just below the town. A similar 
N 
