Squirrels of the World

Pteromys volans 129

conservation: IUCN status—least concern. Population
trend—no information.

habitat: This species typically occupies montane conifer-
ous forests, just below tree line.

natural history: P. momonga i s om n ivorou s; it e at s se e d s,
nuts, and fruits, but also leaves, buds, and bark. This species
often occupies nest cavities and will inhabit artifi cial nest
boxes readily. Tree bark is used for nest construction. The
Japanese fl ying squirrel is locally common and generally
widespread within its range. Although its range is limited, it
is found in several protected areas and is not considered
threatened by human activity. Its range overlaps less than
expected by chance with its sister species, P. volans, al-
though the latter is similar in its ecological tolerances and
body size. Molecular analyses (based on the sequence of the
mitochondrial cytochrome b gene) of several genera of fl y-
ing squirrels suggest that the genus Pteromys is most closely
related to Petaurista.

general references: Andō 2005; Ishii and Kaneko 2008b;
Lee and Liao 1998; Letcher et al. 1994; Millien-Parra and
Jaeger 1999; Oshida, Hiraga, et al. 2000; Oshida and Yoshida
1999.

Pteromys volans (Linnaeus, 1758)

Siberian Flying Squirrel

description: The Siberian fl ying squirrel is somewhat
smaller (10%–20%) than its sister species, P. momonga. The

dorsal pelage is gray or dark gray, and the ventral pelage is

white to yellowish white. The tail is edged with dark-tipped

hairs, and the feet are pale below and dark above. Based on

sequences of the mitochondrial cytochrome b gene, the ge-

nus appears to be most closely related to Petaurista.

size: Female—HB 160.8 mm; T 111.7 mm.

Male—HB 157.1 mm; T 112.9 mm; Mass 137.5 g.

Sex not stated—HB 168.7 mm; T 113.9 mm; Mass 131.3 g.

distribution: The Siberian fl ying squirrel is found in the

boreal forests of the Palearctic region, from northern Fin-

land south to the eastern shore of the Baltic Sea and east-

ward to Chukotka (Russia). It occurs in the southern Ural

and Altai mountains of Russia; the Sakhalin Islands (Rus-

sia); Mongolia; northwestern, northeastern, and central

China; the Korean Peninsula, and the island of Hokkaido

(Japan).

geographic variation: Four subspecies are recognized.

P. v. volans—the type locality is Russia; this subspecies

ranges from Finland to Chukotka, and into Mongolia.

The upperparts are a uniform pale silvery gray. There is

a narrow black eye ring, and the underparts are dull

buff y white.

P. v. athene—Japan. The upperparts are drab gray. The un-

derparts are dull whitish. The sides are washed with red-

dish brown.

P. v. buechneri—China and the Korean Peninsula. The overall

Pteromys momonga. Photo courtesy Yusuke Iwasaki.