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Belding's Ground Squirrel
Spermophilus beldingi is found in the mountainous regions of the
western United States. Its range extends from eastern Oregon to
southeastern Idaho, northeastern California, northern Nevada, and
northwestern Utah.
Spermophilus beldingi is a meadow-dweller. It is found in alpine and
subalpine meadows and pastures. The habitats of S. beldingi seem to
be limited to open areas as opposed to forests or rocky slopes.
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Belding's Ground Squirrel
Spermophilus beldingi is a relatively small ground squirrel with a
head to tail length of 230-300mm. Its tail is 44-76mm long and is
bushy yet flattened, with reddish coloring on the ventral side. The
pelage of the rest of the body is gray with touches of cinnamon on
the undersides, and reddish-brown on the back. The tail may also
contain red, black and white bands of colors on the distal hairs.
Spermophilus beldingi has short limbs and small ears. The skull of
S. beldingi has a short rostrum and convex dorsal profile. Auditory
bullae are small and postorbital processes are conspicuous. The
dental formula is 1/1, 0/0, 2/1, 3/3=22. Molars are hypsodont and
there is a continuous metaloph on the fourth premolar.
Reproduction
Spermophilus beldingi reaches sexual maturity at approximately 2
years. Mating occurs shortly after emergence from hibernation in May
or June. Females are usually receptive to mating for only one day,
and on that day may mate with numerous (between 3 and 5) different
males. Some males may however, never mate. Mating occurs above
ground but females create "nests" in their burrows for their litter.
Gestation lasts approximately 23-28 days. Females have only 1 litter
per year, and most litters are multiply sired. Litter sizes range
from 1-11 but typically average around 5. Females usually have 5
pairs of teats and lactation lasts 26-31 days. Young are born at
5.4-8 g and are very altricial. Juveniles spend about 25-28 days
below ground before emerging. Females of S. beldingi are the sole
caregivers, with fathers spending no time helping to care for the
young. Oftentimes the males never see the young because they are
hibernating before the young emerge from their burrows.
Behavior
Spermophilus beldingi is diurnal, spending its nights in burrows and
its days foraging for food. Burrows can be of 2 types: short with
one entrance, or more complex with multiple entrances. Spermophilus
beldingi hibernates in these burrows for 7-8 months. Hibernation is
a very dangerous time for S. beldingi with 2/3 of young and 1/3 of
adults not making it through the winter. Those that do survive
emerge from their burrows to copulate. Much of the rest of the
summer is spent gathering food and watching for predators.
Spermophilus beldingi shows forms of nepotism and altruism when it
comes to warning others of predators. When warning of predators, S.
beldingi emits loud cries. There is a frequent infanticide in S.
beldingi populations. Unattended litters may be killed by males,
which appear to do so out of hunger. Females may also kill young. If
a female's litter is killed by predators, she may migrate to another
population. In order to obtain an area to live in, she will kill the
litter of a resident female and take over. Females are usually
sedentary, however, with males migrating to other populations.
Food Habits
Spermophilus beldingi is primarily herbivorous but also eats
insects, small invertebrates, birds' eggs, and some carrion. Its
primary food sources are seeds, flower heads, nuts, grains, roots,
bulbs, mushrooms, and green vegetation. Seeds are the appropriately
preferred food of Spermophilus.
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