176 



MAMMALS OF AMERICA 



EASTERN FLYING SQUIRREL 



Sciuropterus volans (Linnaeus) 



General Description. — A small, soft-haired arboreal 

 Squirrel. Head blunt and rounded; ears low and 

 broad ; hair on ears very short : body small : tail about 

 as long as head and body, broad and flat ; an extension 

 of skin from the sides of the body reaching from wrist 

 to ankle forming when the legs are spread, a flat plane ; 

 legs of moderate length ; hair very soft and of moderate 

 length; eyes large and soft; general color above gray- 

 ish-brown, below white ; hairs on tail very soft, and 

 while tail is broad it is not bushy. Nocturnal in habit. 



Dental Formula. — Incisors, '~' ; Canines, ^^ '> 

 Premolars, ~ ; Molars, |~ = 22. 



Pelage. — Adults: Sexes identical. Summer. Upper 

 parts grayish-brown washed with rusty-brown, becom- 

 ing deeper on upper surface of tail; upper portion of 

 lateral membrane dark drab brown ; below white, the 

 hairs entirely white to the bases; under surface of tail 

 tawny to tawny-white. IVintcr. Similar to summer, but 

 upper parts tinged with grayish-brown. Young: 

 Mouse-gray above. 



Measurements. — Total length. 9.3 inches ; tail verte- 

 brae, 4 inches; hind foot, 1.22 inches. 



Range. — Northern New York and southern New 

 Hampshire south to Florida, west to the Plains. 



Food. — Omnivorous to a considerable extent ; nuts, 

 seeds, insects, birds' eggs and occasionally young birds. 



Related Species 



Eastern Flying Squirrel. — Sciuroplcrus volans 

 7'olans (Linnaeus). Typical animal as described above. 

 Northern New York, southern New Hampshire to 

 Florida, west to tlie Plains. 



Florida Flying Squirrel. — Sciuroftcrus volans 

 qucrccti Bangs. Underparts washed with rusty. 

 Florida to southern Georgia, west to Louisiana. 



Northern Flying Squirrel. — Sciuropterus sabrinus 

 sahrinus (Shaw). Decidedly larger than Eastern Fly- 

 ing Squirrel ; fur of underparts gray at base instead 

 of all white. Boreal North America south to northern 

 New York and southern New Hampshire. 



Alpine Flying Squirrel. — Sciuropterus alpinus 

 atpinus (Richardson). Larger than Northern Flying 

 Squirrel with longer tail ; above yellowish-brow'n. From 

 MacKenzie River along east side of Rocky Mountains 

 to northern border of the United States. 



Cascade Flying Squirrel. — Sciuropterus alpinus 

 fuliginosus Rhoads. Similar to Alpine Flying Squirrel 

 in size, but color darker. Cascade coast and Sierra 

 Nevad:i Mountains at high elevations. 



Olympic Flying Squirrel. — Sciuropterus alpinus 

 olyiiipicus Elliot. Largest of the Flying Squirrels. 

 Color dark. Total length 13.5 inches. Northwestern 

 Washington in Olympic Mountains. 



The Flying Squirrel is a very specialized 

 animal and stands in a .group well differentiated 

 from the other North American Squirrels. Its 

 so-called flying membrane at once marks it out 

 from the other Squirrels, and in addition the 

 texture of the pelage is very much softer, the 

 individual hairs being rather long, very lax and 

 exceedingly soft to the touch. The lateral mem- 

 brane is supported mainly by the limbs, but in 

 addition a cartilaginous spur or slender rod 

 runs backward for a short distance from the 

 wrist, and serves to stiffen the forward edge of 

 this gliding plane. A number of Flying Squir- 

 rels have been described, some eighteen species 

 and sub-species in all, and while the differences 

 between many of these varieties appear slight, 

 there are several well-marked groups best singled 

 out on the basis of size difference. 



The Flying Squirrel is a specialized member 

 of his family, possessing a pectdiar, hair-covered 

 membrane of skin on each side of the body, 

 between the fore and hind legs, and attached to 

 both as far as the wrist and the ankle. When 

 the Squirrel is about to " fly " it spreads its 

 " wings," and from the summit of a tree springs 

 into the air and then glides swiftly on an in- 



clined air-plane, always in a slightly descending 

 direction, until a movement, probably of both 

 bodv and tail, inclines it upward, and it alights 

 gently upon the object for which it set out. The 

 tail, being thin and flat, with closely set silken 

 hairs, probably serves a double purpose on these 

 short " flights " — that of rudder and parachute. 

 I do not mean by this that the tail can in any 

 way turn the animal from a straight line, except 

 that probably by bending it downward, and at 

 the same time elevating the head, it brings the 

 body in a convenient position for alighting upon 

 an upright object. The distance that the Squirrel 

 can " fly " depends entirely upon the elevation 

 from which it starts. The angle of descent is 

 ordinarily from twenty to thirty degrees, 

 although the desire of the animal and the direc- 

 tion and force of the wind probably command 

 an extreme range of from forty or fifty degrees 

 to a nearly perpendicular drop. The powerful 

 hind legs of the Flying Squirrel are important 

 factors at the beginning of the " flight." for by 

 means of these it is projected into the air with 

 considerable force. The usual mode of travel 

 from place to place, if trees are convenient, is 

 sailing from the top of one to the base of 



