I04 



MEMOIRS OF THE NUTTALL ORNITHOLOGICAL CLUB 



All phases of plumage are described in my notes of the Ipswich birds. A 

 light phase is nearly white below with a black liar across the upper belly, and a 

 black square patch in the middle of the white of the lower surface of the wing 

 near the wrist joint. The tips of the primaries are dark. I have also noted indi- 

 viduals that lacked the black bar on the upper belly. In the light phase the upper 

 brownish surface is relieved by the strikingly white rump or base of the tail. In 

 one the tail was white above to within a short distance of the tip so as to give the 

 effect of a white tail with a black terminal band. In the dark phase the bird is as 

 black as a Crow both above and below and lacks any sign of white rump patch. 

 Intermediates occur, dark brown in color, with or without an obscure white rump. 



My notes describe a dark bird seen several times at Ipswich during the spring 

 of 1905. In the winter and spring of 1908-09, four birds were seen; one in the 

 dark, two in the light phase, and one was intermediate. In 1912, a bird in the 

 light phase was seen. In the winter of 1913-14, two birds were at Ipswich, one 

 dark, the other light. In the winter of 1916-17, a bird in the light phase was 

 seen several times. In the fall of 1918, a bird in intermediate plumage, and in the 

 spring of 1919, two in light plumage were seen. I have other records but they 

 lack the descriptions of plumage. 



Perched, the Rough-legged Hawk sits very erect. One bird that I watched 

 seemed to have a special liking for windmills. On one occasion he visited and 

 perched on three in succession. 



The flight of the Rough-legged Hawk is graceful and indicative of skill and 

 power. In soaring, the wings and tail are spread to their full extent; the first 

 half-dozen primaries are spread out separately like fingers and curve upward at 

 their tips. On motionless wings, if the wind be favorable, this bird may often be 

 seen soaring high up over the land. In April and May, I have several times seen 

 two of them, probably a pair, rising up higher and higher as they circled, and, 

 arrived at a considerable elevation, striking out in flight for the northeast. 



When soaring they may be seen looking down, and I have several times seen 

 them partially close their wings, lower their long feathered tarsi and drop like a 

 plummet. On one occasion the bird secured a large mouse with which it flew 

 to the marsh and perched on an ice cake. On another occasion a fine Rough-leg 

 pounced successfully on a cotton-tail rabbit and bore it off. 



In searching the ground for game of this sort they often fly slowly, alternately 

 flapping and sailing, from fifty to a hundred yards up in the air. Occasionally 

 they hang over one place by hovering, and often drop their legs preparatory to 

 pouncing on the prey and draw them up behind when they change their minds. 

 If the wind be favorable, they hang suspended in the air as motionless as a kite. 

 The wind needed for this is an up-current over the brow of a steep hill or cliff. 



