148 BULLETIN 1G7, UNITED STATES NATIONAL MUSEUM 



I have seen only one there in all my experience. In the inter- 

 vening territory, where the prevailing forest growth is white pine, 

 both species occur, but only in widely separated localities. In this 

 latter region, during recent years, persecution under the bounty sys- 

 tem has nearly exterminated all hawks. Meantime redtails began 

 to invade the hardwood region in western Bristol County, supplant- 

 ing the redshoulders in some of their long-established haunts. In 

 1929, 1930, and 1931, red-tailed hawks moved into three different 

 tracts of hardwood timber that had been occupied by red-shouldered 

 hawks for upward of 40 years, driving out the former tenants and 

 in two cases appropriating their old nests. The larger and stronger 

 bird seems to be the dominating species. 



William Brewster (1925) noted the reverse of this replacement, 

 for he writes: "That the Ked-shouldered Haw^k should have re- 

 mained almost unknown in the Umbagog Region until after the 

 Red-tailed Hawk had practically ceased to reappear, and that not 

 long thereafter it should have apparently established itself as a 

 summer resident in at least two localities, are matters of considerable 

 interest, in view of the fact that throughout much, if not most, of 

 Massachusetts there has been essentially similar and contemporaneous 

 replacement of the greater by the lesser bird." 



Spring. — Throughout the northernmost part of its range the red- 

 tailed hawk is mainly migratory, a large majority of the birds win- 

 tering somewhat farther south. But a few individuals remain dur- 

 ing winter, especially during mild seasons, not far from the northern 

 limits of their summer range. I have seen them in Massachusetts 

 during every winter month. Those that remain during winter or 

 those that return early in the season begin their nest building late 

 in February or early in March ; I have seen a wholly new nest half 

 completed and decorated with green pine twigs and down as early as 

 February 18, over a month before the eggs are laid. 



Gourtshi'p. — I believe that this and other large hawks remain 

 mated for life, but, if one of the pair is killed, the survivor soon 

 secures a new mate. The birds are apparently in pairs when they 

 arrive on their breeding grounds, but they indulge in nuptial demon- 

 strations more or less all through the nesting season. I have seen a 

 pair of these hawks, in May when there were young in the nest, in- 

 dulging in their joint flight maneuvers high above the woods where 

 the nest was located; they soared in great circles, crossing and re- 

 crossing each other's paths, sometimes almost touching, and mount- 

 ing higher and higher until almost out of sight ; finally one partially 

 closed its wings and made a thrilling dive from a dizzy height, 

 checking its speed just before it reached the woods. E. L. Sumner, 

 Jr., refers in his notes to such a flight: "About ten times, while 



