BIRDS OF NEW YORK II 



each was protected as by an umbrella under the overhanging leaves near 

 the top of the twig selected for its perch. Everyone has noticed how rapidly 

 the birds disappear during a severe storm, each seeking its proper refuge 

 and almost without exception this refuge is some kind of vegetation. The 

 importance of a shelter from the heat of the sun is illustrated by the actions 

 of mother robins and other birds when the sun shines directly upon their 

 nesthngs. Then they stand on the edge of the nest and shade the birds 

 with their outstretched wings. In a similar way the older birds themselves 

 are affected by the extreme heat of midday. As everyone knows, the 

 time to go birding is in the morning or in the afternoon. During the 

 middle of the day the birds are quiet and a greater portion of them are 

 hidden away in the shadows of the trees and shrubs. During the hottest 

 days of midsummer one may often notice our common birds standing 

 with drooping wings and open mouths within the shade of the foliage 

 seeking to avoid the overheating due to the direct rays of the sun. 



Under biotic factors must also be classed the various animals which 

 affect the bird as a part of its environment, either food, allies or enemies. 

 As food it is evident that all carnivorous, piscivorous and insectivorous 

 species will necessarily be present or absent according as their favorite 

 food may be found. One may not seek for Belted kingfishers in the midst 

 of a plain, nor for insectivorous birds over the middle of the lake or sea. 

 During the winter of 1901 meadow mice were very abundant in the fields 

 of western New York, and the Rough-legged hawk, their principal enemy, 

 appeared in abundance. The withdrawing of water from the Erie canal 

 left large numbers of small fish stranded in the wide waters of eastern 

 Rochester, and immediately great numbers of Herring and Ring-billed 

 gulls appeared and remained there until the fish were devoured. During 

 the migration seasons of 191 1 and 1912 the author noticed an unusual 

 number of warblers of eleven species frequenting a group of beech trees 

 on a tree-covered campus in Geneva, and on investigation discovered 

 that this group of trees was infested with an innumerable swarm of plant 

 lice upon which the birds were feeding. Other groups of trees which 



