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Arctic ground squirrel

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Arctic ground squirrel
Scientific classification Edit this classification
Domain: Eukaryota
Kingdom: Animalia
Phylum: Chordata
Class: Mammalia
Order: Rodentia
Family: Sciuridae
Genus: Urocitellus
Species:
U. parryii
Binomial name
Urocitellus parryii
Subspecies

10 ssp., see text

Synonyms

Spermophilus parryii

The Arctic ground squirrel (Urocitellus parryii) (Inuktitut: ᓯᒃᓯᒃ, siksik)[2] is a species of ground squirrel in the squirrel family Sciuridae that is native to the Arctic and Subarctic regions of the Northern Hemisphere, mainly in North America and Asia. For some people in Alaska, particularly around the Aleutian Islands, the rodents are known as "parka" squirrels, likely due to their pelts being used for the ruff on parkas and other cold-weather clothing.[3]

Taxonomy

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Subspecies listed alphabetically.[4]

Description

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The Arctic ground squirrel typically has a beige-tan pelage with a lightly-spotted backside. Similar to the related prairie dog, it has a shorter face than the typical arboreal squirrels–due to its lifestyle of burrowing–as well as smaller ears, with a dark tail and white markings around the eyes.

During the brief boreal summer, Arctic ground squirrels undergo an annual molting (coat shedding/re-growth) cycle in preparation for the onset of colder weather; this is seen in other Arctic species, as well, such as the white winter coat of the Arctic fox, Arctic and snowshoe hares, ermine (stoat), and even some birds, such as the rock ptarmigan. Summer coats include reddish and yellow colorations along the cheeks and sides of the body; in the fall, these red patches are shed and replaced by a more silvery color. The lighter coloration in winter helps the ground squirrels to camouflage against the often snow-white ground and better evade predators, such as snowy owls or foxes. The average length of an Arctic ground squirrel is approximately 39 cm (15 in). Since Arctic ground squirrels undergo drastic seasonal changes in body mass, it is difficult to give an average mass;[7] adult females are close to 750 g (26 oz), while males may weigh nearly 100 g (3.5 oz) heavier.[8]

Distribution and habitat

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The Arctic ground squirrel can be found in parts of western Northern Canada, from the Arctic Circle to the Yukon, northern British Columbia and the Northwest Territories; west into Alaska, the Aleutian Islands archipelago, and across to the Russian Far East (Siberia), including the Kamchatka Peninsula.[1] The St. Lawrence Island subspecies (U. p. lyratus) of Arctic ground squirrel is found on its namesake island in the Bering Sea; the Kodiak Island subspecies (U. p. kodiacensis) is found on the Alaska Peninsula, namely Kodiak.

The Arctic ground squirrel has evolved with and is found on the North American Arctic tundra; depending on the subspecies, its preferred habitats are typically hillside or mountain slopes, riparian areas (such as river flats, banks or lake shores) or tundra ridges. Arctic ground squirrels prefer to live in sandy soil due to its ease of manipulation for burrowing, and its superior drainage as opposed to richer soils.[9] Arctic ground squirrels make shallow tunnels and burrows in locations where the permafrost will not prevent them from digging.[10] The more southerly subspecies typically inhabit open meadows and open tundra habitats.[8]

Fossil record

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The Arctic ground squirrel has an extensive fossil record from the Pleistocene. During the Last Glacial Maximum, it was abundant in areas such as the Klondike region where it is currently rare or absent.[11] Fossilised Arctic ground squirrel nests and caches have also been used for palaeoenvironmental reconstruction; Calamagrostis canadensis, Carex albonigra, and Koeleria sp. are common in caches from Late Pleistocene Alaska, indicating the presence of an aerially extensive mammoth steppe ecosystem in the region at this time.[12]

On tundra, Kugluktuk, Nunavut

Behaviour

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20,000-year-old Arctic ground squirrel mummy

The diurnal Arctic ground squirrel lives on the tundra, where it may fall prey to the Arctic and the red fox, wolverine, Canada and Eurasian lynx, brown bear, snowy owls and eagles. It is one of the few Arctic mammal species which hibernates in the winter, similarly to the little brown bat and the closely-related marmot.[13] In the summer, it forages for tundra plants, seeds, and fruit to increase body fat for its winter hibernation. By late summer, the male Arctic ground squirrel begins to store food in its cache so that, come springtime,[14] it will have a food source until the any new vegetation has grown. Their burrows are lined with lichens, leaves, grasses, and muskox hair, amongst other animal fibers they may find.

Communication between squirrels is done through both vocal and physical means. When they meet, nose to nose contact is made or other body parts are pressed together. The "tsik-tsik" calls are made in response to threats and vary as between different predators. Deep guttural sounds are used to indicate land-based predators while short "band whistle" chatter indicates danger from the air.[8]

Hibernation

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The Arctic ground squirrel hibernates over winter from early August to late April in adult females and from late September to early April for adult males,[15] at which time it can reduce its body temperatures from 37 °C (99 °F) to as little as −3 °C (27 °F).[16] During hibernation, its core body temperature reaches temperatures down to −2.9 °C (26.8 °F)[17] and its heart rate drops to about one beat per minute. Peripheral, colonic, and blood temperatures become subzero. The best theory as to why the squirrel's blood doesn't freeze is that the animal is able to cleanse their bodies of ice nucleators which are necessary for the development of ice crystals. In the absence of ice nucleators, body fluids can remain liquid while in supercooled state. This process is being studied with the hope that mechanism present in arctic ground squirrels may provide a path for better preservation of human organs for transplant.[18] The connections between brain cells also wither away in this state. The damage should have resulted in death, but research on related species show that these connections regrow after waking up. In the warmer months, the squirrel is active during the day.

Diet

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This squirrel feeds on grasses, sedges, mushrooms, bog rushes, bilberries, willows, roots, stalks, leaves, leaf buds, flowers, catkins, and seeds. They will also eat insects and, occasionally, even supplement their diet with carrion (such as mice, snowshoe hares and caribou)[19] as well as juvenile Arctic ground squirrels.[20] Sometimes these squirrels carry food back to their den in their cheeks.[8]

Reproduction

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During the mating season, males engage in male-male aggressive encounters for mating rights.[21]

Arctic ground squirrels live individually in burrow systems. Mating occurs between mid-April and mid-May (depending on latitude) after winter hibernation. Mating includes male-male competition for access to females, and litters are typically sired by multiple males. Gestation is approximately 25 days, and results in a litter of 5 to 10, 10 g (0.35 oz) hairless pups. After six weeks, the pups are weaned and this is followed by rapid growth to prepare for the upcoming winter.[8]

Conservation

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Arctic ground squirrel in Alaska Maritime National Wildlife Refuge

Although Environment Yukon has not estimated their population size, their conservation status is currently said to be "secure" (Environment Yukon 2013).[14] The Arctic ground squirrel is classified as least concern (LC) on the IUCN Red List (Arkive 2013).[22]

References

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  1. ^ a b Cassola, F. (2016). "Urocitellus parryii". IUCN Red List of Threatened Species. 2016: e.T20488A22262403. doi:10.2305/IUCN.UK.2016-3.RLTS.T20488A22262403.en. Retrieved 12 November 2021.
  2. ^ "Welcome to Tusaalanga | Inuktut Tusaalanga". tusaalanga.ca. Retrieved 2019-02-22.
  3. ^ Antarctica and the Arctic Circle: A Geographic Encyclopedia of the Earth's Polar Regions
  4. ^ Urocitellus parryii, MSW3
  5. ^ "Urocitellus parryii nebulicola | NatureServe Explorer".{{cite web}}: CS1 maint: url-status (link)
  6. ^ "Urocitellus parryii osgoodi | NatureServe Explorer".{{cite web}}: CS1 maint: url-status (link)
  7. ^ Buck, C.L.; Barnes, B.M. (1999). "Annual cycle of body composition and hibernation in free-living arctic ground squirrels". Journal of Mammalogy. 80 (2): 430–442. doi:10.2307/1383291. JSTOR 1383291.
  8. ^ a b c d e Animal Diversity Web
  9. ^ Nadler C, Hopkins RS (1976). Patterns of evolution and migration in the arctic ground squirrel, Spermophilus parryii (Richardson). [Internet]. Chicago (ZL) U.S.A.: Department of Medicine, Northwestern University Medical School, and the University of Kansas, Lawrence (KS) U.S.A.: Museum of Natural History and Department of Systematics and Ecology; [updated 1976 Oct 20; cited 2013 Nov 10]. Available from: http://www.nrcresearchpress.com/doi/pdf/10.1139/z77-097.
  10. ^ "BBC Nature - Arctic ground squirrel videos, news and facts". BBC Earth. Retrieved 6 November 2013.
  11. ^ Zazula, Grant D.; Froese, Duane G.; Elias, Scott A.; Kuzmina, Svetlana; Mathewes, Rolf W. (April 2007). "Arctic ground squirrels of the mammoth-steppe: paleoecology of Late Pleistocene middens (∼24000–29450 14C yr BP), Yukon Territory, Canada". Quaternary Science Reviews. 26 (7–8): 979–1003. doi:10.1016/j.quascirev.2006.12.006. Retrieved 12 August 2024 – via Elsevier Science Direct.
  12. ^ Gaglioti, Benjamin V.; Barnes, Brian M.; Zazula, Grant D.; Beaudoin, Alwynne B.; Wooller, Matthew J. (November 2011). "Late Pleistocene paleoecology of arctic ground squirrel ( Urocitellus parryii ) caches and nests from Interior Alaska's mammoth steppe ecosystem, USA". Quaternary Research. 76 (3): 373–382. Bibcode:2011QuRes..76..373G. doi:10.1016/j.yqres.2011.08.004. ISSN 0033-5894. Retrieved 27 August 2024 – via Cambridge Core.
  13. ^ The Long Sleep: Which Animals Hibernate?
  14. ^ a b "Arctic Ground Squirrel". Environment Yukon. 3 March 2015. Archived from the original on 29 December 2010. Retrieved 17 May 2015.
  15. ^ Buck, C.L.; Breton, A.; Kohl, F.; Toien, O.; Barnes, B.M. (2008). "Overwinter body temperature patterns in free-living Arctic Ground Squirrels (Spermophilus parryii)". Hypometabolism in Animals: Hibernation, Torpor and Cryobiology: 317–326.
  16. ^ Barnes, Brian M. (1989-06-30). "Freeze Avoidance in a Mammal: Body Temperatures Below 0°C in an Arctic Hibernator" (PDF). Science. 244 (4912). American Association for the Advancement of Science: 1593–1595. doi:10.1126/science.2740905. PMID 2740905. Archived from the original (PDF) on 2008-12-16. Retrieved 2009-08-12.
  17. ^ Liu Y, Hu W, Wang H, Lu M, Shao C, Menzel C, Yan Z, Ying L, Zhao S, Khaitovich P, Liu M, Chen W, Barnes BM, and Yan J: Genomic analysis of miRNAs in an extreme mammalian hibernator, the Arctic Ground Squirrel. Physiological Genomics Archived April 2, 2015, at the Wayback Machine 42A:39-51. (2010)
  18. ^ Asher, Claire. "When your veins fill with ice". www.bbc.com. Retrieved 2019-05-02.
  19. ^ Torsten Bernhardt. "Canadian Biodiversity: Species: Mammals: Arctic Ground Squirrel". Canadian Biodiversity. Redpath Museum; McGill University. Archived from the original on 14 June 2013. Retrieved 6 November 2013.
  20. ^ McLean, Ian G (1983). "Paternal behaviour and killing of young in Arctic ground squirrels". Animal Behaviour. 31 (1): 32–44. doi:10.1016/S0003-3472(83)80171-7. S2CID 53147479.
  21. ^ Buck, C.L.; Barnes, B.M. (2003). "Androgen in free-living arctic ground squirrels: seasonal changes and influence of staged male-male aggressive encounters". Hormones and Behavior. 43 (2): 318–326. doi:10.1016/s0018-506x(02)00050-8. PMID 12694642. S2CID 37114468.
  22. ^ Arkive, 2013. Arctic Ground Squirrel. [Internet]. [Cited November 7th 2013]. Available from: http://www.arkive.org/arctic-ground-squirrel/spermophilus-parryii/image-G78548.html Archived 2013-11-12 at the Wayback Machine

Further reading

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  • Hall, E. Raymond (1981). The Mammals of North America. 2 volumes. Ronald Press.
  • Helgen, K. M.; Cole, F. R.; Helgen, L. E.; Wilson, D. E. (2009). "Generic revision in the Holarctic ground squirrel genus Spermophilus". Journal of Mammalogy. 90 (2): 270–305. doi:10.1644/07-mamm-a-309.1.
  • Thorington, R. W. Jr. and R. S. Hoffman (2005). Family Sciuridae. pp. 754–818 in Mammal Species of the World a Taxonomic and Geographic Reference. D.E. Wilson and D.M. Reeder eds. Johns Hopkins University Press, Baltimore.
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