Squirrels of the World

316 Tamias alpinus

in June, while their habitat is still covered in snow. This al-
lows time for territorial establishment and subsequent for-
aging during the limited growing season. Alpine chipmunks
produce young in early summer; nestlings are active by late
July–early August, and young-of-the-year are reported to
reach adult size by October. Litter size is between four and
fi ve young. The distribution of T. alpinus at lower elevations
is limited by territorial exclusion by its larger congener, T.
speciosus, which is reported to be more aggressive, more suc-
cessful in territorial disputes in the wild, and more effi cient
at foraging in the dense vegetation where the two species
are sympatric. In captivity, however, T. alpinus appears more
aggressive and dominant over T. speciosus, which suggests
that the outcome of aggressive encounters in the wild are in
part infl uenced by habitat structure.

general references: Clawson et al. 1994a; R. M. Davis
et al. 2008; Hayssen 2008a, 2008b, 2008c; A. W. Linzey and
Hammerson 2008e; Piaggio and Spicer 2000.

Tamias amo enus J. A. Allen, 1890

Yellow-Pine Chipmunk

description: T. amoenus is a small member of the genus.
The dorsal surface is reddish brown and dark in appearance.

The fi ve dark stripes are usually black. The lateral dark

stripes are each bordered by a white stripe. The more me-

dian light stripes are grayish. Females are larger than males,

and T. amoenus in general is smaller in body mass than T.

speciosus. It is suggested that genital bones may be necessary

to distinguish T. amoenus from several other species.

size: Female—HB 123.2 mm; T 90.3 mm; Mass 50.6 g.

Male—HB 119.3 mm; T 86.5 mm; Mass 58.3 g.

Sex not stated—HB 119.3 mm; T 95.5 mm; Mass 43.0 g.

distribution: The yellow-pine chipmunk ranges from

central British Columbia and the southwestern edge of Al-

berta (Canada) south to central California and east to central

Montana and northwestern Wyoming (USA). It also occurs

in a limited number of locations in western and northern

Nevada.

geographic variation: Fourteen subspecies are recog-

nized. The subspecies exhibit subtle diff erences in color-

ation. Genetic studies reveal considerable variation within

this species and show that two subspecies (T. a. canicaudus

and T. a. cratericus) are not grouped with the 12 other clades,

some of which are not consistent with current subspecifi c

designations.

T. a. amoenus—USA, in the “transition and boreal zones

from northwestern California north through central

and eastern Oregon and Washington” (Anthony). The

fi ve dark lines on the back are black, well defi ned, and

Tamias alpinus. Photo courtesy Oleksandr Holovachov.

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