BIRDS OF NEW YORK 89 



rare in the eastern and southern highland regions, but common, some 

 winters, in the larger river valleys, the Lake Ontario lowlands, and the 

 central lake region, and sometimes on eastern Long Island. At intervals 

 of a few years there appear large flights of these hawks in western New 

 York, especially in the Genesee valley and the extensive farm lands which 

 lie south of Lake Ontario. This was the case in the winter of 1905-6, 

 when Roughlegs were fairly abundant about Canandaigua, Geneseo, Cayuga, 

 and many other localities. The birds begin to arrive from the north late 

 in October, or some years not till the middle, of November, and depart 

 for their breeding grounds between March 25 and April 12, except for 

 disabled or delayed stragglers which have been seen as late as May 30. 

 This species prefers an open country of wide marshes, river bottoms, 

 or rolling plains, with scattered trees from which to watch for its humble 

 prey. When trees are too few it is often seen coursing back and forth 

 over the fields somewhat after the manner of the Marsh hawk, but with 

 heavier flight and, whenever he discovers a luckless mouse, pounces silently 

 upon it. Its flight seems low and labored, even when compared to the 

 Red-tail, although its wings are longer and more pointed. Its habit of 

 hunting largely in the twilight is correlated with its choice of diet, which 

 consists almost exclusively of meadow mice. I have frequently found the 

 remains of 7 to 9 mice in the stomach of one Rough-legged hawk, and 

 never found a beneficial animal on its bill of fare. It therefore must be 

 regarded as the most beneficial of all our Raptores, and the farmer should 

 distinguish it carefully from such injurious species as the Goshawk, and 

 protect it as one of his most valued allies. As recently as twenty years 

 after the publication of Fisher's " Hawks and Owls," one of the most 

 intelligent and extensive landholders in New York State was paying a 

 hunter to rid his fields of dozens of this valuable mouser under the mis- 

 apprehension that it was destroying his game birds. Thus there is need 

 of spreading further the knowledge of our birds. 



