Squirrels of the World

Tamias umbrinus 347

mys sabrinus and Tamia s c iur u s, are part of an important sciurid
community whose members collectively serve as important
indicators of overall forest health. These species are most
abundant in mature or primary forests where seed produc-
tion is high, or in secondary forests managed by the variable-
density thinning technique, coupled with the retention of old
live, dead, and fallen trees, which together imitate the com-
plexity of older forests. However, although some studies have
reported higher densities in later-stage forests, at least one
noted that only the chipmunk’s mass increases, whereas den-
sity, sex ratios, and the distance moved do not diff er, possibly
owing to the mild climates and high primary productivity
in Pacifi c coastal forests (e.g., the Oregon Coast Range). On
southern Vancouver Island, T. t. townsendii often consumes
or hoards conifer seeds (lodgepole pine [Pinus contorta] and

white spruce [Picea glauca]) infected with the fungus Caloscy-

pha fulgens, which appears to arrest seed germination and

rotting and may, in turn, facilitate long-term storage of these

seeds in larder-hoards. T. t. townsendii may also disperse this

fungus, which is common in the conifer litter; however, the

full extent of their relationship is not known and deserves

further attention. Population densities average about 2.6

animals/ha in one study and, in another, 0.6 -1.1 animals/ha

in primary stands. Home range sizes average 0.8 ha. This

species may be trap prone; hence estimates based on live-

trapping methods should be evaluated with caution. T. town-

sendii is often sympatric with T. amoenus. Both are often ag-

gressive, but T. townsendii appears to negatively infl uence

both the habitat use and reproduction of T. amoenus. The

only parasites reported from T. townsendii are three species

of Eimeria and the botfl y (Cuterebra).

general references: Carey 2001; Carey, Colgan, et al.

2002; Carey and Wilson 2001; E. C. Cole et al. 1998; Colgan

and Claridge 2002; Hammond and Anthony 2006; Hayes et

al. 1995; Lidicker 1999; A. W. Linzey and Hammerson 2008q;

North et al. 1997; Sutton 1993; Waldien et al. 2006.

Tamias umbrinus (J. A. Allen, 1890)

Uinta Chipmunk

description: Uinta chipmunks have a generally brownish

dorsum with white longitudinal stripes. This species has

Tamias townsendii. Photo courtesy A. Coke Smith, http://www.coke
smithphototravel.com.