FERRUGINOUS ROUGHLEG 289 



to become more extensively white, nearly immaculate in the oldest 

 birdSj except for the brown tibiae and barred flanks; the tail be- 

 comes progressively whiter and finally pure white, except for faint 

 gray or tawny clouding on the outer webs; and the upper parts 

 become paler, with more white in very old birds. 



The above descriptions apply to birds in the light phase. Dark- 

 phase birds are not especially rare and are often found mated with 

 light phase birds. Nearly half of the birds we saw in Saskatchewan 

 were in melanistic plumage. Two young birds were taken from a 

 nest and reared in captivity, one of which developed into a mela- 

 nistic bird and one into the light phase. A brood of four young, 

 taken from a nest in North Dakota in 1902 by Dr. Louis B. Bishop, 

 developed into four dark juvenals. 



In the extreme melanistic phase the entire plumage, except the 

 tail, varies from "bister" to "bone brown", with faint "tawny" spots 

 scattered over the belly, flanks, and upper and under tail coverts; 

 the tail is mainly "neutral gray", mottled with white on the inner 

 webs. A modification of this, which might be called an erythristic 

 phase, is similar, except that the under parts are largely "hazel" or 

 "burnt sienna", with more or less restricted dark centers on the 

 feathers ; the wing coverts and feathers of the upper back are edged 

 with the same colors; and the upper tail coverts are mainly reddish 

 brown. 



Adults apparently have a complete annual molt from August to 

 November. 



Food. — The ferruginous roughleg is a highly beneficial hawk and 

 should be encouraged as a great destroyer of injurious rodents. Mr. 

 Cameron (1914) says that in eastern Montana this hawk "feeds 

 chiefly upon prairie dogs and meadow mice." It eats snakes, but 

 he thinks it never takes frogs. He has seen these hawks hunting 

 in pairs and attacking jack rabbits; one which they killed, but could 

 not carry away, weighed about 8 pounds. He writes : 



On May 28, 1893, my wife and I witnessed the capture of a prairie dog by 

 two of tliese liawks, and one of tlieni was proceeding to devour it as we rode up. 

 Tlie methods of the crafty coyote and the Ferruginous Rough-leg are identical 

 in "dog-towns." Both wait patiently, the hawk also on the ground, for a prairie 

 dog to amble afield from its burrow, and thereupon make a dasli, the first ter- 

 restrial, the latter aerial, to intercept it. A prairie dog always endeavors to 

 gain its own burrow when danger threatens, and is marvellously quick to reach 

 it, but if cut off from home, the beast becomes so bewildered that it neglects 

 the nearer intermediate holes. When two coyotes, or two hawks hunt together, 

 the fate of the intended victim is sealed, but with one assailant only, it has 

 an even chance. 



His opinion that this hawk never attacks poultry is confirmed by 

 W. P. Sullivan, who for 16 years has protected several pairs that 

 breed on his ranch ; "they are constantly flying around the buildings. 



