Spermophilus armatus
Uinta ground squirrel

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)

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)

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)

Spermophilus armatus are borrowers. In the winter these squirrels hibernate, and in the summer they aestivate (that is become dormant for the summer). Adults begin aestivation in July whereas juveniles do not go into aestivation until later. By September the Uinta ground squirrels can no longer be seen above ground. From aestivation they go directly into the long period of hibernation, where they will remain until March or April. This means that individuals only remain active above ground about three to three and a half months out of the year.

Population density is high for ground squirrels, around 23-28 individuals per square hectare. S. armatus live in matrilineal colonies. Males disperse as juveniles to other colonies. Individuals are territorial though home ranges do overlap. Females especially become territorial and aggressive during pregnancy. Males are quite aggressive during the breeding season. Aggression is indicated by fights and warning "chirps." "Chirps" are also used as mating calls and as warnings to the colony of avian predators.

(Whitaker 1996, Nowak 1999, Balph 1984)

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)

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)

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