Arctic Ground Squirrel

Arctic Ground Squirrel, Spermophilus parryii

The Arctic ground squirrel is adapted to live in the extreme cold of arctic environments, but its burrowing nature restricts it to areas where permafrost occurs more than a meter below the surface. Currently, this animal is found in Alaska, northern British Columbia, and the Yukon and Northwest Territories, where it is known alternatively as a gopher or sik-sik. Its recovery from late Pleistocene sites in the central U.S. indicates that this region experienced much cooler temperatures during that time period. 

Arctic Ground Squirrel

Arctic Ground Squirrel in the Yukon Territory, Canada. By Alan Vernon [CC-BY-2.0 (www.creativecommons.org/licenses/by/2.0)], via Wikimedia Commons.

Order: 
Rodentia (Rodents)
Family: 
Sciuridae (Squirrels)
Statistics: 

Length: 33.2-49.5 cm (13.1-19.5 in)

Weight: 530-816 g (1.2-1.8 lb)

Status: 
Migrated
Physical Description: 

The arctic ground squirrel is the largest ground squirrel in the western hemisphere. It has a short, stocky body, stubby limbs, strong claws, and a short bushy tail. It has reddish brown to beige fur on its face, belly, and legs, and mottled gray, white and brown fur on its back. 

Habitat: 

Arctic ground squirrels live in alpine and arctic tundra and brushy meadows, moraines, lake shores, riverbanks, and sandbanks. They prefer areas with sandy or gravelly soil, which is easy to dig and has good drainage during spring thaws and heavy rains. They also prefer to establish burrows on sites with good visibility, which affords better predator detection. 

Diet: 

These animals are primarily, although not exclusively, herbivorous and eat a variety of grasses, stems, roots, leaves, berries, seeds and mushrooms . They will also occasionally eat insects, small vertebrates (e.g., baby mice) and fresh carrion. Arctic ground squirrels begin storing food materials, such as willow leaves, grass seeds and berries, in their burrows during the summer months for use in the spring when they wake from hibernation. 

Behavior: 

Arctic ground squirrels are social, burrowing animals. They live in colonies of hundreds of squirrels within a system of underground burrows and tunnels, although each individual burrow is occupied by only a single adult or a mother with nursing young. These animals are extremely vocal, particularly in response to perceived threats, and will use different warning calls to indicate whether a predator is approaching from the ground or the air.  They also issue different warning calls depending on the type of approaching predator. In order to survive the harsh conditions of their chosen habitat, these animals hibernate for 7-8 months a year, with brief arousals every 10-21 days during this period. These animals have a unique and fairly extreme hibernation physiology that allows them to survive soil temperatures as low as -15°C while maintaining a constant body temperature of -2.0°C. At lower soil temperatures, body temperatures may drop as low as 2.9°C; they resist freezing and tissue damage at these extreme temperatures by supercooling (Boyer and Barnes 1999). During hibernation, females lose roughly 33% of their stored body mass. Males presumably lose a similar proportion of body mass; however, they also store seeds in their burrow for consumption prior to spring emergence, and therefore are only 3% lighter when they leave their burrows after hibernation (Yensen and Sherman 2003).

North American Ice Age Distribution: 

Although the current range of this animal is restricted to Alaska and northwestern Canada, it has been recovered from late Pleistocene sites in the midwestern U.S., including sites in eastern Iowa. 

Status at the end of the Pleistocene: 

As with other mammals that survived the end of the Pleistocene, arctic ground squirrels followed their preferred habitat north to their current range in the arctic. 

Midwestern Paleontological Finds: 

Arctic ground squirrel remains have been recovered from several Midwestern late Pleistocene sites, including the Elkader and Prairieburg sites in eastern Iowa. 

Fun Facts: 
  • The arctic ground squirrel is the only known mammal that allows its body temperature to drop below freezing. This supercooling is part of the hibernation strategy that allows the animal to survive harsh arctic winters. 
  • The Eskimo name for this animal, "Sik sik", derives from it's "sik-sik-sik" warning call
Web Resources: 

https://www.mnh.si.edu/mna/image_info.cfm?species_id=347

https://www.nps.gov/dena/naturescience/arcticgroundsquirrel.htm

https://www.env.gov.yk.ca/wildlifebiodiversity/mammals/agsquirrel.php

References: 

Foley, R. L., & Raue, L. E. (1987). Lemmus sibiricus from the Late Quaternary of the midwestern United States. Current research in the Pleistocene, 4, 105-107.
Fulton, T. L., Norris, R. W., Graham, R. W., Semken, H. A., & Shapiro, B. (2013). Ancient DNA supports southern survival of Richardson's collared lemming (Dicrostonyx richardsoni) during the last glacial maximum. Molecular ecology, 22(9), 2540-2548.
Semken Jr, H. A., Graham, R. W., & Stafford Jr, T. W. (2010). AMS 14C analysis of Late Pleistocene non-analog faunal components from 21 cave deposits in southeastern North America. Quaternary International,217(1), 240-255.
Woodman, N., Schwert, D. P., Frest, T. J., & Ashworth, A. C. (1996).Paleoecology of subarctic faunal assemblages from the Woodfordian age (Pleistocene: Wisconsinan) Elkader site, northeastern Iowa. Natural History Museum, the University of Kansas.
Yensen, Eric and Paul W. Sherman. 2003. Ground Squirrels, in Wild Mammals of North America, edited by Feldhamer, G. A., and B. C. Thompson, pp. 211-231 . The Johns Hopkins University Press, Baltimore, MD.