Perception Channels: tactile ; chemical
US Federal List: no special status
CITES: no special status
IUCN Red List of Threatened Species: least concern
Like other ground squirrels, Spermophilus armatus are destructive to crops, eating vegetables and harvesting seeds. Their winter stores of food consist almost entirely of seeds, including a significant amount dug up from farmers' plantings.
(Nowak et al. 1987)
Spermophilus armatus eat seeds, green vegetation, invertebrates and some vertebrates. They are often found near water, as they prefer succulent plants. They are strong swimmers and swim to retrieve species of aquatic plants. Uinta ground squirrels collect food for their periods of hibernation, during which they rely mostly on seeds stockpiled in their burrows.
(Whitaker 1996, Nowak et al. 1987)
Spermophilus armatus are found only in a small area of the United States. Their range includes southwestern Montana, western Wyoming, southeastern Idaho and northern central Utah.
(Whitaker 1996)
Biogeographic Regions: nearctic (Native )
Spermophilus armatus are found in the sagegrass mountain meadows of the western United States. Here they burrow in the soft soils. They can be found near timberline, in valley pastures, cultivated fields or along irrigation ditches. They are also sometimes found in lawns. They prefer moist habitats with lush vegetation and/or aquatic plants.
(Whitaker 1996, MacClintock 1970)
Terrestrial Biomes: savanna or grassland
Spermophilus armatus are fairly large ground squirrels with a body length of 280-303 mm and tail length 63 to 81 mm. Skull length is 46 to 48 mm. The Uinta ground squirrels, as they are commonly named, have mixed, brown-buff colored coats. Their sides are slightly paler and their underbellies are pale buff to white. Their tails are black mixed with buff on top and bottom, with paler buff colored edges. The noses, ears and faces are more cinnamon colored. The ears are small and rounded with short fur.
(Whitaker 1996, Hall 1981)
Range mass: 284 to 425 g.
Other Physical Features: endothermic ; bilateral symmetry
The breeding season begins immediately after the end of hibernation in March or April. During this season males attract females with calls and scent markings. Scents are laid down by wiping their faces, which have aprocrine scent glands, against the ground. Breeding is also in part dependent on the social rank of individuals within the colony.
Females give birth to one litter per year usually sometime in May. Gestation length is 28 days. Young first emerge from burrow, 24 days after birth. After this female parental investment is minimal. First-year females bear, on average, 4 to 5 yong per litter, whereas older mothers bear 7 to 8 on average.
(Whitaker 1996, Balph 1984)
Key Reproductive Features: gonochoric/gonochoristic/dioecious (sexes separate); sexual
The Uinta ground squirrel (Urocitellus armatus), commonly called a "chisler"[2][3] and Potgut in northern Utah,[4] is a species of rodent native to the western United States.
The Uinta ground squirrel is a moderately sized ground squirrel, measuring 28 to 30 cm (11 to 12 in) in total length. They weigh about 210 g (7.4 oz) when they emerge from hibernation, a figure that steadily increases until they are ready to hibernate again in the fall. Their fur is brown to cinnamon in color, being paler on the underside and grey on the sides of the head and neck. The 6 to 8 cm (2.4 to 3.1 in) tail is buff with a grey underside, as distinct from the ochraceous or reddish color found in closely related species such as Belding's or Wyoming ground squirrels. Females have ten teats.[5]
First described from the Uinta Mountains, the squirrels are found in Wyoming west of the Green River, in southwestern Montana, eastern Idaho, and northern and central Utah.[1] They inhabit open areas, such as meadows, pasture, and shrub-steppe habitats, at elevations between 1,220 and 2,440 m (4,000 and 8,010 ft). There are no recognised subspecies.[5]
Uinta ground squirrels are primarily herbivorous, and mostly eat grass, seeds, and the leaves of forbs, along with a small amount of earthworms and discarded human food. The exact composition of the diet changes throughout the year. Their most common predators are coyotes, badgers, weasels, and raptors.[6][7]
Although they often live in colonies, adults react aggressively towards one another outside of the breeding season, with females being more intolerant than males. Males mark their territories with scent glands in their cheeks, which they rub on the ground, but do not mark the entrances to their burrows. The squirrels greet one another by sniffing, escalating to threat postures and bristling the hair on their tails, and eventually to wrestling, boxing, and chasing if the intruder does not retreat.[5]
The squirrels make six distinct vocalisations: chirps, squeals, squawks, trills, growls, and teeth clattering. These are used primarily as a means of gaining attention, and all are used in aggressive interactions between individuals. However, chirps are also used to warn of aerial predators, and trills to warn of predators on the ground, with squirrels hearing them either adopting an alert posture or running for their burrows.[8]
Uinta ground squirrels are only active for a few months each year. Adult males wake from hibernation around mid March, but may wait a few weeks before emerging, depending upon the weather.[9] Females emerge slightly later, followed by female and then male yearlings. Adults return to their burrows to hibernate between late July and mid August, with juveniles following about two weeks later.[5]
During their active periods the squirrels are diurnal.
Females enter estrus for a single afternoon each year, about two to four days after emerging from hibernation. They mate underground, and each male may mate with several females. Gestation lasts 23 to 26 days, and results in an average litter of five young, which are born in early May. Yearling females typically have less opportunity to mate, because they emerge from their burrows later, and give birth to smaller litters than older females when they do mate.[5]
The young are weaned at about 22 days of age, and emerge from the burrow at around the same time. Although they are still small, weighing only around 60 g (2.1 oz), the mother almost completely abandons them after weaning, and they disperse to establish their own territories over the next two to three weeks.[5] They can live for up to seven years in the wild.[6]
The Uinta ground squirrel (Urocitellus armatus), commonly called a "chisler" and Potgut in northern Utah, is a species of rodent native to the western United States.
