BIRDS OF NEW YORK 7 



genial to them, and because of the humidity, the rate of evaporation from 

 their bodies is proportionately reduced. In the hard wood tract described 

 on page 27, it was noticeable that as the lower thickets disappeared 

 by growth of the taller poles, the amount of humidity within ten feet of 

 the ground was perceptibly lower, so that it undoubtedly was not only 

 the lack of favorable nesting sites, but the slight change in htunidity 

 acting with it, which caused the Hooded warbler and the Wood thrush 

 to disappear. Conversely, on many bushy hillsides, if the atmosphere is 

 comparatively dry, the Field sparrows, chewinks and thrashers will be in 

 evidence. In damper thickets yellowthroats and Yellow-billed cuckoos 

 will appear, undoubtedly attracted not primarily by the edaphic condition 

 but by the humidity of the bush stratum which lies just above the ground. 



Another climatic factor of great import is rainfall, which affects the 

 forest growth ; but apart from its influence upon vegetation and thus upon 

 bird life, it is also a direct factor when flooding marshes and destroying 

 the nests with eggs and young, or when beating down nests directly from 

 their support, and sometimes even destroying the full-grown birds them- 

 selves,^ and by the destruction of migrating birds, often observed, while 

 crossing the sea or large lakes. When the rain is dense enough birds 

 frequently lose their bearing and fly headlong into the water without 

 realizing the direction they are taking. 



Ice and snow are also factors worthy of consideration as they frequently 

 cover the food of many species during the winter season. In this way 

 Quail are frequently winterkilled, and in the early spring meadowlarks 

 and Savannah sparrows in western New York may often be observed in 

 severe straits during the days of late March and early April. Many species 

 during an extensive ice storm or snow storm are in danger of starvation. 

 In the winter of 1895, as elsewhere noted, the Bluebird was nearly 

 exterminated by continued ice storms in its winter home and its numbers 

 were again decimated by the severe winter of 1911-12. During a severe 



1 Great numbers of sparrows killed in Providence by cold rain and sleet (Bumpus, Wood's Hole 

 Biological Lectures 1898, p. 24). 



