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 

 yellowish-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. 



A species 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 

 (Thome apiid 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 



