410 GENERAL ZOOLOGY 



during their period of infancy and feeds them on milk, 

 which is secreted by the mammary glands on her ventral 



surface. 



Relation to Environment. When the young have been 

 reared, the winter nest in a hollow tree is usually deserted 

 for a structure of leaves and twigs built high among the 

 branches of a tree. This outside nest is occupied (at least in 

 the colder regions) throughout the summer. 



The food of the squirrel in the spring consists largely of 

 buds, especially of the maple and elm. In the summer, fungi 

 and berries are added to the bill of fare, and in the fall nuts 

 form a large part of the diet. The gray squirrel has been 

 accused of varying its vegetable diet with such animal food 

 as the young and the eggs of song birds, but it is probably 

 not as frequent an offender as the red squirrel, whose bad 

 habits in this respect are well known. The nuts of autumn 

 are gathered and stored in secret places beneath stumps and 

 in hollow trees, and many are separately buried in the 

 ground. Some observers are inclined to think that their 

 sense of smell guides them to the buried food, though it is 

 doubtful if these individual hoards are always located again. 



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, how- 

 ever, 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. 

 Pennsylvania was overrun with squirrels in 1749, and a 

 bounty of threepence a head was offered for their destruc- 

 tion. It is estimated that about six hundred and forty 



