NORTHERN GRAY SQUIRREL 23 



and chest; hairs of tail yellowdsh at base followed by blackish and 

 tipped with white. Winter: Above silvery gray, the bases of the 

 brown hairs on the head entirely or almost concealed. 



Measurements. — Total length, 19.75 inches; tail vertebrae, 9.00 

 inches ; hind foot, 2.70 inches. 



This is another form which varies markedly in color from en- 

 tirely black to gray with many intergradations ; sometimes also 

 albino specimens are found. In the Museum of the State Univer- 

 sity of Iowa is a mounted specimen with the under parts and sides 

 of the head entirely black. This squirrel may be separated from 

 its closest ally in our fauna by the fact that it usually possesses five 

 teeth of the molar series on either side of the upper jaw; two of 

 these teeth are premolars and three are molars; in addition, the 

 hairs of the tail are tipped with white. 



Habits, Distribution, Etc.— The northern gray squirrel seems to 

 prefer the more heavily wooded regions of the state, and towards 

 the extreme east and northeast is reported as more common than 

 the fox squirrel. In these regions densely timbered areas are not 

 uncom.mon, while farther west many of the extensive timbered 

 sections have been destroyed and along with them the gray squir- 

 rels. At Ottumwa and Albia this species was formerly rather 

 abundant, but the numbers have been much lessened of late, as the 

 miners have killed a great many for food. 



It is seldom that in restricted localities the gray squirrel and 

 the fox squirrel are found in equal numbers, the advantage in this 

 respect being usually wdth the former. The gray squirrels are 

 the more pugnacious of the twO' and will not tolerate the presence 

 of the fox squirrels, making life so miserable for them that they 

 soon abandon the locality. 



This is one of the more gregarious species of our arboreal squir- 

 rels and considerable numbers of them in some instances occupy a 

 limited area. In early days the species was more or less migra- 

 tory; but while it may at the present time migrate somewhat, the 

 numbers have been so greatly reduced that attention is not directed 

 to the phenomenon. These migrations occurred at irregular inter- 

 vals and were probably undertaken for the purpose of securing 

 a more adequate food supply. 



The northern gray squirrel nests in hollow trees and in ha])ita- 

 tions constructed of leaves, twigs, and bark which are placed 

 among the branches. These exterior nests have a roof and an en- 



