Squirrels of the World

Marmota sibirica 287

conservation: IUCN status—least concern. Population
trend—declining.

habitat: M. olympus inhabits open grass, sedge, and forb
subalpine and alpine meadows and talus slopes near and
above timberline; most of its habitat is within the borders of
Olympic National Park (USA).

natural history: This species is diurnal. It hibernates
in burrows in communal social groups for seven to eight
months, emerging in late spring. Polygynous colonial groups
are the rule, commonly consisting of a single dominant adult
male; fewer than three adult females; and numerous 1–year-
olds, 2–year-olds, and young-of-the-year. Olympic marmots
are among the most social of squirrels. Colonial territories
typically average 5.4 (2–8.7) ha. Subordinate males can live
on the periphery of colonies, but typically they are not part
of the social group unless the dominant male dies. Burrows
are numerous within colonies and are employed for mater-
nal nests, sleeping dens, and escape. Larger burrows are
most often used for sleeping, and they usually have small
mounds of soil and rocks at their entrance from frequent
excavations. Sleeping chambers are often lined with dry
plant material. M. olympus forages on the ground in mead-
ows, eating sedges, herbs, and grasses; it will excavate the
roots of some forbs. Olympic marmots may remove up to 30
percent of the biomass; however, this grazing promotes a
high level of plant diversity. The bark and cambium of coni-
fers are sometimes gnawed. This species will occasionally
eat animal material; cannibalism has been observed. Dry

grasses may be collected underground for either food or

bedding. Under the best conditions, females typically repro-

duce in alternating years. Litter size is about four, and the

young remain in their natal area until at least their third

year, when dispersal occurs. About 53 percent of the young-

of-the-year and 85 percent of the yearlings survive, with

no diff erence between the sexes. Mortality occurs mostly

during the winter, especially in years with little insulating

snowpack. Their major predators are raptors, as well as

larger mustelids, canids, and felids. Scent-marking on rocks

and plants, using their oral and cheek glands, is common.

Four distinct alarm calls are produced in response to poten-

tial threats; and a number of whistles, tooth chatters, growls,

“yips,” and “chucks” are used in a variety of contexts. Due

to this species’ localized distribution, high-elevation habi-

tat, and protected status, M. olympus is not harvested for

food, pelts, or sport. Olympic marmots are not considered

to be pests.

general references: Barash 1973, 1989; Blumstein et al.

2001; Edelman 2003; Griffi n et al. 2009.

Marmota sibirica (Radde, 1862)

Tarbagan Marmot

description: Tarbagan marmots are often a light grizzled

buff on the dorsum but vary in color, with some very pale

Marmota olympus. Photo courtesy Duke Coonrad, http://www.flickr
.com/photos/skagitman/.