Spermophilus beldingiBelding's ground squirrel

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Geographic Range

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 (Nowak 1991). (Jenkins and Eshelman 1984)

Habitat

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. (Jenkins and Eshelman 1984, Nowak 1991)

Physical Description

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. (Jenkins and Eshelman 1984, Macdonald 1985, Nowak 1991)

  • Average mass
    290 g
    10.22 oz
    AnAge
  • Average basal metabolic rate
    0.796 W
    AnAge

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. (Jenkins and Eshelman 1984, Macdonald 1985)

  • Key Reproductive Features
  • gonochoric/gonochoristic/dioecious (sexes separate)
  • sexual
  • Average number of offspring
    5.7
    AnAge
  • Average gestation period
    26 days
    AnAge
  • Average age at sexual or reproductive maturity (female)
    Sex: female
    365 days
    AnAge
  • Average age at sexual or reproductive maturity (male)
    Sex: male
    547 days
    AnAge

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. (Jenkins and Eshelman 1984, Macdonald 1985)

Communication and Perception

Food Habits

Spermophilus beldingi is primarily herbivorous but also eats insects, small invertebrates, birds' eggs, and some carrion. Its primary food sources are seeds, flowerheads, nuts, grains, roots, bulbs, mushrooms, and green vegetation. Seeds are the appropriately preferred food of Spermophilus (which means "seed loving") beldingi (Macdonald 1985). (Jenkins and Eshelman 1984, Nowak 1991)

Economic Importance for Humans: Negative

Spermophilus beldingi can be an agricultural nuisance, feeding on crops and other vegetation. (Jenkins and Eshelman 1984)

Conservation Status

Spermophilus beldingi is not endangered but is in fact the focus of many population control measures. In many areas, poisonous baits are used in order to keep population numbers of S. beldingi down. Some natural predators of S. beldingi are coyotes, badgers, long-tailed weasels, raptors and snakes (Jenkins and Eshelman 1984).

Other Comments

A lot of research has been done regarding S. beldingi, much of which focuses on the nepotistic and altruistic behavior involved in relation to predation. Emitting a warning call is altruistic because it puts the individual in danger in order to protect others. However, it has been observed that these warning calls are usually nepotistic, involving closely related individuals. Most squirrels do not give a warning cry for unrelated or distantly related individuals. It has also been found that S. beldingi has different calls for different situations. Calls are multiple-note trills when warning of terrestrial predators and single-note chirps when aerial predators are near. Males may even call after copulation, possibly to advertise their dominant status. (Leger et al 1984, Robinson 1984, Sherman 1981)

Contributors

Lindsay DuVall (author), University of Michigan-Ann Arbor.

Glossary

Nearctic

living in the Nearctic biogeographic province, the northern part of the New World. This includes Greenland, the Canadian Arctic islands, and all of the North American as far south as the highlands of central Mexico.

World Map

bilateral symmetry

having body symmetry such that the animal can be divided in one plane into two mirror-image halves. Animals with bilateral symmetry have dorsal and ventral sides, as well as anterior and posterior ends. Synapomorphy of the Bilateria.

chemical

uses smells or other chemicals to communicate

endothermic

animals that use metabolically generated heat to regulate body temperature independently of ambient temperature. Endothermy is a synapomorphy of the Mammalia, although it may have arisen in a (now extinct) synapsid ancestor; the fossil record does not distinguish these possibilities. Convergent in birds.

motile

having the capacity to move from one place to another.

mountains

This terrestrial biome includes summits of high mountains, either without vegetation or covered by low, tundra-like vegetation.

native range

the area in which the animal is naturally found, the region in which it is endemic.

sexual

reproduction that includes combining the genetic contribution of two individuals, a male and a female

tactile

uses touch to communicate

References

Jenkins, S.H. and Eshelman, B.D. 1984. Spermophilus Beldingi. Mammalian Species. The American Society of Mammolgists. No. 221. pgs. 1-8.

Leger et al. 1984. Ground Squirrel Vocalizations. Animal Behaviour. Bailliere Tindall, London. Vol 32(3,4). pgs 761-763.

Macdonald, Dr. D. 1985. Encyclopedia of Mammals. Facts on File, New York. pgs. 624-625.

Nowak, R.M. 1991. Walker's Mammals of the World. Johns Hopkin's University Press, Baltimore. Vol 1. pgs. 570-573.

Robinson, S. 1980. Antipredator Behaviour and Predator Recognition. Animal Behaviour. Bailliere Tindall, London. Vol 28(3). pgs. 840-852.

Sherman, P.W. 1981. Kinship, Demography, and Belding's Ground Squirrel Nepotism. Behavioral Ecology and Sociobiology. Springer International. Vol 8. pgs. 251-259.