THE GRAY SQUIRREL 411 



thousand squirrels were killed at that time. In their migra- 

 tions bodies of water were crossed by swimming, though 

 ordinarily squirrels are not lovers of water. The cause of 

 the migrations is probably to be looked for in scarcity of 

 food supply. 



The general color of the gray squirrel's fur is protective, 

 and the animal has the habit of flattening itself on the upper 

 side of a horizontal branch, so that it is invisible from below. 

 Of their enemies, the hawks probably give them most 

 trouble. It is said that the red-tailed hawks hunt them in 

 pairs, thus making futile their habit of dodging to the far 

 side of a branch. 



Spread over a large area from Maine to Minnesota and 

 south as far as Florida, it is to be expected that the different 

 individuals will vary considerably. In general, it is found 

 that the colors increase in intensity southward and in 

 regions of copious rainfall, while the legs, tail, and ears show 

 a tendency to increase in length. In all parts of their range 

 individuals are sometimes born in which the normal 

 coloring matter of the hairs is replaced by black pigment, 

 and others in which the pigment is lacking, leaving the fur 

 white. The black individuals are examples of melanism; 

 the white, of albinism. Both conditions are quite common 

 among squirrels. 



The calls of the gray squirrels to each other may often be 

 heard in the woods, especially in the fall. The "barking," as 

 it is termed, consists of a series of notes ending in a longer 

 snarl. It expresses anger, alarm, or warning. Gray squirrels 

 have sometimes been encouraged to make their homes in 

 city parks, where they soon learn to accept and finally to be 

 largely dependent on contributions of food from human 

 visitors. 



