406 GENERAL ZOOLOGY 



When winter comes on, gray squirrels are likely to be 

 later in rising in the morning, preferring to come out in the 

 warmest part of the day, and on some inclement days they 

 may not venture forth at all. There is no evidence, however, 

 that they truly hibernate. 



Gray squirrels have been known to travel in bands from 

 place to place. Of late years, either on account of their 

 much diminished numbers or because of change in the food- 

 supply, we see little of the great migrations which formerly 

 occurred. Many such visitations have been recorded. Penn- 

 sylvania was overrun with squirrels in 1749, and a bounty of 

 threepence a head was offered for their destruction. It is 

 estimated that about six hundred and forty thousand squirrels 

 were killed at that time. In their migrations 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 connection with the scarcity of the 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 tend- 

 ency to increase in length. In all parts of their range indi- 

 viduals 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. 



