74 



NORTH AMERICAN FAUNA 66 



greatest length of skull 62.6, 62.4, 62.8 ; zygomatic breadth 33.4, 33.4, 

 33.6; least interorbital breadth 16.9, 19.2, 18.2; length of maxillary 

 toothrow 10.9, 11.6, 11.2. 



Habitat and habits. — ^This is a squirrel of the hardwood and mixed 

 coniferous-hardwood forests, particularly those with nut-bearing trees 

 and bushy undergrowth. It is quite common in the parks of Washing- 

 ton, D.C., particularly Eock Creek Park. Most of these are descended 

 from introduced stock. Bailey (1923, p. 108) says: 



The late Dr. William L. Ralph purchased many gray squirrels and liberated 

 them in the Smithsonian grounds, where up to the time of his death in 1907 he 

 fed and cared for them . , . They soon became common in the Mall . . . and 

 spread to the White House grounds, LaFayette Square, and other city parks. 



Melanistics squirrels were introduced and liberated into the Na- 

 tional Zoological Park and are still frequently seen there. Of these, 

 Bailey (1923, p. 109) says: 



The first shipment of 10 (black squirrels) was from Rondeau Provincial Park, 

 Morpeth, Ontario, 18 May 1906 ; and these squirrels were immediately liberated 

 in the northwestern part of the zoo where they were very much at home. They 

 have since been constanly in the park, especially from the vicinity of the great 

 flight cage to the Klingle Valley and they have spread northward to Cleveland 

 Park and nearly to Chevy Chase. 



Five of the 31 skins of gray squirrels in the National Museum collec- 

 tions from the District of Columbia show melanistic tendencies. 



Tlie gray squirrel is common throughout Maryland. Hampe (1939, 

 p. 6) says that it is the most common squirrel in the Patapsco State 

 Park and has been observed in the Park every month of the year; 

 young squirrels are numerous there after the first of July. Bures 

 (1948, p. 67) says the gray squirrel is quite common in the Bare Hills- 

 Lake Roland area. I found them numerous on the Delmarva Penin- 

 sula ; in southern Maryland ; in the Piedmont region, particularly in 

 the vicinity of Sugar Loaf Mountain; and in the mountains of the 

 western part of the State. Gray squirrels do not occur on Assateague 

 Island, but I have seen them in the thickets back of the dunes several 

 miles north of Ocean City. 



The gray squirrel is most at home in trees and descends to the ground 

 only when necessary to obtain food and bury nuts. It does not hiber- 

 nate, even in the coldest northern portions of its range. This squirrel 

 is diurnal and is most active in the early morning and late afternoon. 



Its bulky nest is generally constructed in an enlarged natural cavity 

 of an old oak tree, but sometimes an outdoor nest of firmly woven 

 leaves is constructed among the branches or in the crotch of a tree. 



Squirrels mate during midwinter, and the gestation period is about 

 40 days. A second mating usually occurs sometime in May or June. 

 The young are two to five (generally four) in number. When 2 months 



