Squirrels of the World

Tamias senex 337

quarters, well-defi ned eye stripes, postauricular patches,
and the distinctively shaped baculum. Coastal populations
have a dark olive dorsum and a grayish pink venter, whereas
inland populations are light olive with a pale gray wash on
the dorsum and creamy white underparts. The pale gray
wash is most apparent on the head, the hips, and the tail.
Two white to buff lines on the side of the face are off set by
ochraceous to red orange brown. It has white to buff eye
rings, and white to cream postauricular patches. There is a
dark cinnamon to sepia to black longitudinal stripe with
two faint additional stripes on each side; white to grayish
white stripes off set the dark stripes. The stripes generally
fade before reaching the rump. The thin tail is grizzled gray
suff used with reddish orange, with an ochraceous under-
side; the tail is often frosted with buff.

size: Female—HB 147.5 mm; T 107.3 mm; Mass 94.0 g.
Male—HB 146.3 mm; T 103.7 mm; Mass 86.0 g.
Sex not stated—HB 142.6 mm; T 102.9 mm; Mass 89.7 g.

distribution: The range of T. senex extends from central
Oregon southward through the Sierra Nevada in California
and the northwestern tip of Nevada to the southern termi-
nus of its range in California’s Yosemite National Forest, as
well as across northern California from the coast to the
northern Nevada border.

geographic variation: This species was previously con-
sidered to be monotypic, but inland populations of T. senex,

like those of T. siskiyou, are smaller and paler than those on

the Pacifi c coast, and the interspecifi c convergence of these

characters is so signifi cant that the two species are nearly

indistinguishable farther inland. Genital characters, how-

ever, indicate that the two are separate species, thus sup-

porting the designation of one new subspecies for each of

the two species.

T. s. senex—found inland in the Sierra Nevada, Cascade, and

other ranges east of coastal redwood (Sequoia sempervirens)

forests (USA). This subspecies is generally ochraceous

tinged with pale gray, and it is slightly larger than T. s.

pacifi ca. While similar in size and color to T. quadrimacula-

tus, T. s. senex is grayer, with less white behind the ears.

T. s. pacifi ca—narrow belt of coastal redwood forests on the

northwestern California coast, inland to 32 km (USA).

The new subspecies is similar in coloration (dark olive)

and size to T. ochrogenys.

conservation: IUCN status—least concern. Population

trend—stable.

habitat: The shadow chipmunk is found in the Canadian

and upper transition life zones, preferring dense brushy un-

derstory in closed canopy primary forests that are generally

free of disturbances such as logging. T. senex is ecologically

isolated from congeneric species (T. alpinus, T. amoenus, T.

Tamias senex. Photo courtesy Chris Wemmer.