Urocitellus parryu

199.

Arctic Ground Squirrel

Urocitellus parryu

French: Spermophile arctique / German: Arktis-Ziesel / Spanish: Ardilla terrestre del Artico

Taxonomy. Arctomys parryii Richardson, 1825,

no type locality given. Restricted by

E. A. Preble in 1902 to “

Five Hawser Bay,

Lyon Inlet, Melville Peninsula, [Hudson Bay, Keewatin District, Northwest Territories,| Canada.”

Ten subspecies are recognized.

Subspecies and Distribution.

U.p.parryiRichardson,1825—extremeNEAlaska(USA)andNcoastofYukonandtheNorthwestTerritories(Canada).

U.p.ablususOsgood,1903—W&SWcoastofAlaska(USA).

U.p.kennicottiiRoss,1861—NWcoastofAlaska(USA).

U.p.kodiacensisJ.A.Allen,1874—KodiakIinSWAlaska(USA).

U.p.leucostictusBrandt,1844—NESiberia(Russia).

U.p.lyratusHall&Gilmore,1932—St.LawrenceI,Alaska(USA).

U.p.nebulicolaOsgood,1903—ShumaginIsofSWAlaska(USA).

U.p.osgoodiMerriam,1900—SoftheBrooksRangeinCAlaska(USA).

U.p.plesiusOsgood,1900—SEAlaska(USA),Yukon,NorthwestTerritories,Nunavut,andNBritishColumbia(Canada).

U. p. stejnegeriJ. A. Allen, 1903 — Kamchatka Peninsula (Russia).

Descriptive notes. Head-body mean 257-1 mm (males) and 266-1 mm (females), tail mean 87-7 mm (males) and 109-8 mm (females); weight mean 673 g (males) and 524-3 g (females). The Arctic Ground Squirrel has a reddish brown to cinnamon to fuscous dorsal pelage, with white to buff spots. Head is tawnier with a white to cream ring around eyelids. Sides, feet, and legs are buff to tawny to cinnamon, becoming gray in winter. Ventral pelage is white to straw yellow to cinnamon buff. Tail is ocherous tawny, cinnamon, or cinnamon buff, grizzled with black in upper side, and tawny to russet ventrally. Dorsum of nominate parryii is yellowish brown and dusky, with gray spots. Top of head and sides of neck are a rich reddish brown to yellowish brown. Terminal part oftail is black. Subspecies ablusus has a brown and weakly spotted dorsum. Subspecies kennicottii is a pale form. Subspecies kodiacensis is heavily spotted with smallish flecks that are sometimes faint. Subspecies leucostictus has yellowish brown dorsum, heavily spotted with white and top of head is a deep rufous. Subspecies lyratus is pale and grayish brown. Subspecies nebulicola is a diminutive, brown, and weakly spotted form. Subspecies osgoodi is the largest subspecies, with a very red venter. Subspecies plesius is small and pale gray. Subspecies stejnegeri has a dorsum that lacks fulvous suffusion, and the tail is more extensively black.

Habitat. Open arctic tundra, forest meadows, and meadow-steppe habitats, particular ly meadows with talus in alpine and subalpine zones in mountains. The Arctic Ground Squirrel can be found near human settlements. Populations of some islands in the Kodiak archipelago and vicinity are relatively recent introductions (c.100 years).

Food and Feeding. Primarily herbivorous, feeding on leaves, shoots, flowers, seeds, and the berries of more than 40 species of tundra grasses, sedges, and forbs. Fungi, mosses, lichens, insects, and small vertebrates are also consumed. Males, in particular, collect seeds in their cheek pouches late in the active season to build substantial underground caches that will provide a food source to last until the following spring.

Breeding. Mating occurs during a two-week period soon after females emerge from hibernation, involving all individuals that are more than one-year-old; more than 75% of females produce a litter each year. Although females mate with 1-4 males, the first male sires the offspring in more than 90% of cases; and the resident territorial male is most often first male to mate. After a gestation of 25 days,a litter of 6-8 (maximum of 14) young is born within burrow. Juveniles emerge after c.6 weeks, typically in late June or early July, and weaning occurs at c.8 weeks of age. Infanticide is reported in this species.

Activity patterns. The Arctic Ground Squirrel is diurnal. It hibernates for up to seven months in burrows. Adult females enter hibernation in September, followed by males a few weeks later in October. Juveniles emerge by the end of October.

Movements, Home range and Social organization. In March or April, males emerge from hibernation to establish large territories; females emerge 2-3 weeks later and establish their home ranges within a male’s territory. A male defends access to several females within his territory. Colonies are composed of a complex system of burrows, which tend to be shallow (less than 1 m deep) and with several entrances and nest chambers, except the short and shallow escape burrows, which are very simple. The Arctic Ground Squirrel has distinct alarm vocalizations for terrestrial predators (a “cheek-chick” call) and for aerial predators (a shrill whistle). Annual survival rates

for adults and juvenile females are 25-40%, with most deaths occurring during winter. Average home range was estimated at 1-5-3-5 ha in Atqasuk, Alaska.

Status and Conservation. Classified as Least Concern on The IUCN Red List. The Arctic Ground Squirrel is considered scarce in British Columbia; is vulnerable in Manitoba, Canada. Some subspecies are restricted to Alaskan islands and are likewise of conservation concern. Its overall current population trend is unknown. The Arctic Ground Squirrel is hunted primarily for its pelt, but also for meat, and it can be a nuisance around human structures. Grazing pressure from increasing livestock populations and drought are degrading habitat for the Arctic Ground Squirrel.

Bibliography. Batzli & Sobaski (1980), Boonstra et al. (2001), Cook et al. (2010), Eddingsaas et al. (2004), Gillis, Hik et al. (2005), Gillis, Morrison et al. (2005), Hayssen (2008a), Karels et al. (2000), Lacey & Wieczorek (2001), McLean (1982), Preble (1902), Thorington et al. (2012).