Mammal Species of the World
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- Original description: Merriam, C.H., 1889. Description of a new spermophile from California, p. 317. Annals of the New York Academy of Sciences, 4:317-321.
endemic to a single nation
Regularity: Regularly occurring
Type of Residency: Year-round
Global Range: Western U.S.; eastern Oregon south through northeastern California, southwestern Idaho, north-central Nevada, and extreme southeastern Utah.
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)
Biogeographic Regions: nearctic (Native )
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.
Average basal metabolic rate: 0.796 W.
Length: 30 cm
Weight: 340 grams
Size in North America
Average: 300 mm males; 290 mm females
Range: 270-315 mm males; 265-295 mm females
Average: 360 g males; 300 g females
Range: 300-450 g males; 230-400 g females
Comments: Inhabits alpine and subalpine meadows, sagebrush flats, mixed brush and grass habitats, pastures and croplands. Usually found in fairly open habitat (Jenkins and Eshelman 1984). Young are born in underground burrows.
Habitat and Ecology
Young are born in underground burrows. Breeding occurs shortly after hibernation. Gestation lasts 23-28 days. Females are reported to produce one litter of 4-12 young, or an average of eight young per litter (Hall 1946). Sexually mature in two years. Lives in colonies. Predators include coyotes, badgers, and weasels.
Feeds primarily on grass, leaves of meadow plants, and seeds. Remains active for longer periods during the spring and summer than are other species of Spermophilus, which live in more arid habitats at lower elevations (Larrison and Johnson 1981). Usually hibernates from late September-May or June (Hall 1946).
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)
Terrestrial Biomes: mountains
Non-Migrant: Yes. At least some populations of this species do not make significant seasonal migrations. Juvenile dispersal is not considered a migration.
Locally Migrant: No. No populations of this species make local extended movements (generally less than 200 km) at particular times of the year (e.g., to breeding or wintering grounds, to hibernation sites).
Locally Migrant: No. No populations of this species make annual migrations of over 200 km.
Comments: Feeds primarily on grass, leaves of meadow plants, and seeds. Diet may be less varied than that of other ground squirrels (Sumner and Dixon 1953).
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)
Lives in colonies. In California, population density estimates range from 1.2/ha in an alpine meadow, to well over 100/ha in an alfalfa field (Jenkins and Eshelman 1984). Predators include coyotes, badgers, and weasels.
Life History and Behavior
Comments: Remains active for longer periods during the spring and summer than are other species of SPERMOPHILUS, which live in more arid habitats at lower elevations (Larrison and Johnson 1981). Usually hibernates from late September-May or June (Hall 1946).
Lifespan, longevity, and ageing
Breeding occurs shortly after hibernation. Gestation lasts 23-28 days. Females are reported to produce 1 litter of 4-12 young, or an average of 8 young/litter (Hall 1946). Sexually mature in 2 years.
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)
Average birth mass: 6.87 g.
Average gestation period: 26 days.
Average number of offspring: 5.7.
Average age at sexual or reproductive maturity (male)
Sex: male: 547 days.
Average age at sexual or reproductive maturity (female)
Sex: female: 365 days.
National NatureServe Conservation Status
Rounded National Status Rank: N5 - Secure
NatureServe Conservation Status
Rounded Global Status Rank: G5 - Secure
IUCN Red List Assessment
Red List Category
Red List Criteria
- 1996Lower Risk/least concern
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).
IUCN Red List of Threatened Species: least concern
Relevance to Humans and Ecosystems
Comments: Agricultural pest in some areas.
Belding's ground squirrel
Belding's ground squirrel (Urocitellus beldingi), also called pot gut, sage rat or picket-pin, is a squirrel that lives on mountains in the western United States. In California, it often is found at 6,500 to 11,800 feet (2,000–3,600 m) in meadows between Lake Tahoe and Kings Canyon. This species is not of conservation concern, and its range includes some protected areas.
Physical description[edit source | edit]
The Belding’s ground squirrel is medium sized with "a relatively short tail, short limbs, and small ears". It has a gray pelage become more cinnamon at the underside and reddish-brown on the back. Its body length is 230 to 300 millimetres (9.1–12 in). The tail is 44 to 76 millimetres (1.7–3.0 in) and is bushy but also flattened. The distal hairs of the tail have three color bands, one black, one white and one red. On average, the ground squirrel weighs 290 grams (0.64 lb). Its feet are covered in little to no hair. Compared to other ground squirrel species, its cheek pouch are moderate in size.
Ecology[edit source | edit]
Range and habitat[edit source | edit]
Being native to the northwestern United States, the Belding’s ground squirrel ranges covers northeastern Oregon and part of Washington, north California, southwestern Idaho, north and central Nevada and northwestern Utah. The ground squirrel prefers to live at higher altitudes, occurring in alpine and subalpine meadows. It is also found in sagebrush flats, brush/grass habitats and cultivated areas. The grounds squirrels are largely restricted open areas with enough fresh vegetation and water. They do not live in dense forests, tall grasses, rocky slopes or thick shrubbery as they can’t watch for predators. In addition they do not prefer grass that is too short as they can’t hide from predators.
Food and feeding[edit source | edit]
Belding’s ground squirrels have a largely herbivorous diet. However they will also eat insects, carrion, other vertebrates, and even other conspecifics. They mostly eat flowers and seeds. They also eat nuts, grains, roots, bulbs, mushrooms and green vegetation. Belding’s ground squirrels do not keep food in caches. Instead they store fat reserves. As such, the ground squirrels may eat a great amount of food before hibernation. They most spend as much of 40% of the summer eating. When eating, the ground squirrel feeds itself with its front paws while stand on its back paws.
Hibernation[edit source | edit]
Belding’s ground squirrels hibernate at different times, depending on the sex and age of the individual and the altitude of their environment. Adult males go into hibernation between late July and early September when at higher altitudes. Females may follow them in late September, depending on the elevation. Juveniles follow their parent into hibernation with juvenile females first going when they are 13 weeks old and males when they are 10 weeks old. They enter when the grass begins to dry and turn brown. This way they can avoid the hot, dry end of the summer.
The ground squirrels hibernate in burrow chambers called hibernacula. Males tend to hibernate alone while females tend to hibernate together. The time in which ground squirrel emerge from their hibernation also depends on different factors. At lower elevations, males emerge in February while at higher elevations, they emerge at the end of April. Female emergence is spread over several weeks.
Activities[edit source | edit]
Belding’s ground squirrels leave their burrows at sunrise. The first squirrel to enter the surface will stay at the burrow entrance until there are enough following squirrels above ground to watch for predators. The squirrels then move farther from the burrows. Most activity occurs in the morning with digging and feeding. Squirrel activity tends to decrease when the temperature increases. Much of the day is spend stretched out on rocks or on the ground getting warmth from the sun. They will also maintain burrows and groom each other. When the young are above ground they will engage in play. The ground squirrels will go back into their burrows in the afternoon. Juveniles enter later than adults.
Behavior[edit source | edit]
Family relations[edit source | edit]
Belding’s ground squirrels live in a nepotistic society where most interactions occur between females and their offspring and kin. It seems that cooperation between individuals correlates with their degree of relatedness. Ground squirrels recognize their kin by comparing their phenotypes with these of squirrels they encounter. These phenotypes come in the form of scent though dorsal and anal glands that leave a "pungent" odor in the dust bathing areas. Each squirrel has its own repertoire of scents that others can use to recognize it. If an individual’s phenotype matches, it may be a relative. A female may also use her sister’s phenotype as a basis for determining the relatedness of unfamiliar females. Recognizing their relatives is important for female Belding’s ground squirrels. This allows them to know who to act nepotistic towards when defending nests or territories or when making alarm calls. Related females will also, at times, share food and shelter. Adult males do not display nepotistic behavior and are nomadic between seasons. Although many ground squirrels live in colonies, there is little social interaction between them and it is mostly agonistic.
Alarm calls[edit source | edit]
Belding’s ground squirrels are prey for various predators such as coyotes, bobcats, weasels, eagles and badgers. Ground squirrels will also perceive humans, livestock and cars as threats. Ground squirrels have two specific alarm calls used to warn others of predators. One call, known as the churr call or the trill, is made of a series of more than five notes given rapidly. These calls are given for predators that pose less immediate threats, usually terrestrial predators. Individuals that are close to the alarm caller will respond by standing on their back legs (posting), running on a rock to get a better view of the predator or by returning to their core area.
Another alarm call is known as the whistle, which is a single high-pitched note. This call is made in response to immediate threats, usually aerial ones. All individuals in hearing range will exhibit evasive behavior such as crouching or fleeing into the nearest shelter. When running from aerial predators, squirrels call while escaping. By contrast, when running from terrestrial predators, escaping squirrels don’t call until they make it to safety. In addition, with aerial predators, all squirrels will call while with terrestrial predators, only females with kin will call. The squirrel that first sounds the alarm posts while calling, looking at the predator and will not try to hide.
Reproduction and parenting[edit source | edit]
For Belding’s ground squirrels mating occurs after hibernation, usually in late May to early June. The ground squirrels mate promiscuously, as both males and females mate with multiple partners. Females are sexually receptive for less than five hours each year. Thus when a female is receptive, the males immediately gather around her. They will fight viciously to gain access, grappling, kicking, scratching, and biting each other. Larger, older, and stronger males are more likely to mate. A single female can mate with as many as five males during her estrous; this increases the chance of pregnancy, and also increases genetic diversity.
Females give birth to one litter a year. Pregnant females will dig nesting burrows and gather grass and grass roots to make nests. Nesting-only territories are established around these burrows. Females protect the burrows against intruding unrelated conspecifics by attacking and chasing them. Defense of the territories lasts until the young are weaned. The gestation period of the ground squirrel lasts 23–31 days and young are born late June to early July in higher elevation regions, while in lower areas such as Central Oregon young are born in March and emerge from their dens en-mass about mid-April when the first warm days of spring begin. Litter sizes range from 3-8 young. Females do all the parenting for the young as males disperse directly after mating. In their first few weeks of life, the pups are raised underground in the nesting burrow. They first emerge from the burrows in July and early August, at least in higher elevations, and are weaned at 27 days old. At first, the young stay near the entrance to the burrow but start to explore on their third day. Males disperse from their natal burrow after they are weaned and continue to disperse after they breed successfully. The male that mates the most moves farther away from the colony he mated in. Females rarely disperse from their natal burrows. Infanticide is known to occur in Belding’s ground squirrels. An intruding squirrel will drag a squealing, squirming juvenile out of the nest burrow, and promptly kill it by biting its head. The killer will also sometimes eat the carcass. Adult females and yearling males are more often the killers. The perpetrators of infanticide do not reside in the same area as the victim. Females never kill their relatives and they will help their kin in protecting their young from infanticide.
Taxonomy[edit source | edit]
- U. b. beldingi (Merriam, 1888)
- U. b. creber Hall, 1940
- U. b. oregonus (Merriam, 1898)
References[edit source | edit]
- Linzey, A. V. & NatureServe (Hammerson, G.) (2008). Spermophilus beldingi. In: IUCN 2008. IUCN Red List of Threatened Species. Retrieved 8 January 2009.
- "Animal Life in the Yosemite (Mammals)". National Park Service. Retrieved 2009-09-03.
- Stephen H Jerkins, Bruce Eshelman. 1984. Spermophilus beldingi. Mammalian Species. 221:1-8
- Sherman, P. W. a. M. L. M. (1979). "Four Months of The Ground Squirrel." Natural History 88: 50-57.
- Holekamp, K. E. (1986). "Proximal Causes of Natal Dispersal in Belding's Ground Squirrels." Ecological Monographs 56(4): 365-391.
- Turner, L. W. (1972). Autecology of the Belding ground squirrel in Oregon. Department of Biological Sciences. Tuscan, University of Arizona
- Loehr, K. A. a. A. C. R. J. (1977). "Daily and Seasonal Activity Patterns of the Belding Ground Squirrel in the Sierra Nevada." Journal of Mammology 58(3): 445-448.
- Morton, M. L. a. J. S. G. (1975). "Reproductive Cycle of the Belding Ground Squirrel (Spermophilus beldingi): Seasonal and Age Differences." Great Basin Naturalist 35(4): 427-433.
- Sherman, P. W. (1981). "Kinship, Demography, and Belding's Ground Squirrel Nepotism." Behavioral Ecology and Sociobiology 8: 251-259.
- Turner, L. W. (1973). "Vocal and Escape Response of Spermophilus beldingi to Predators." Journal of Mammology 54(4): 990-993.
- Robinson, S. R. (1980). "Anti-predator Behavior and Predator Recognition in Belding's Ground Squirrels." Animal Behavior 28: 840-852.
- Mateo, J. M. (1996). "The development of alarm-call response behavior in free-living juvenile Belding's ground squirrels." Animal Behavior 52: 489-505.
- Sherman, P. W. a. M. L. M. (1984). "Demography of Belding's ground squirrels." Ecology 65(5): 1617-1628.
- Hanken, J. a. P. S. (1981). "Multiple Paternity in Belding's Ground Squirrel Litters." Science 212: 351-353.
- Sherman, P. W. (1981). Reproductive Competition and Infanticide in Belding's Ground Squirrels and Other Animals. Natural Selection and Social Behavior. R. D. A. a. D. W. Tinkle. New York and Concord, Chiron Press: 311-331.
- Wilson, D. E.; Reeder, D. M., eds. (2005). Mammal Species of the World (3rd ed.). Johns Hopkins University Press. ISBN 978-0-8018-8221-0. OCLC 62265494.
- A Natural History of California, Allan A. Schoenherr, 1992, University of California Press.
Names and Taxonomy
Comments: Recent molecular phylogenetic studies suggest that the traditionally recognized genera Marmota (marmots), Cynomys (prairie dogs), and Ammospermophilus (antelope ground squirrels) render Spermophilus paraphyletic, potentially suggesting that multiple generic-level lineages should be credited within Spermophilus (Helgen et al. 2009). As a result, ground squirrels formerly allocated to the genus Spermophilus (sensu Thorington and Hoffman, in Wilson and Reeder 2005) are now classified in 8 genera (Notocitellus, Otospermophilus, Callospermophilus, Ictidomys, Poliocitellus, Xerospermophilus, and Urocitellus). Spermophilus sensu stricto is restricted to Eurasia.