40.

Unalaska Collared Lemming

Dicrostonyx unalascensis

French: Lemming des Aléoutiennes / German: Unalaska-Halsbandlemming / Spanish: Lemming de collar de Unalaska

Other common names: Umnak Island Collared Lemming

Taxonomy. Dicrostonyx unalascensis Merriam, 1900, “Unalaska, Alaska,” USA.

Dicrostonyx unalascensis is considered a subspecies of D. groenlandicus by some authorities, but karyology and breeding studies have led to recognition of D. unalascensis as a distinct species by others. Additional systematic work is needed to fully understand species limits within the D. groenlandicus complex. Monotypic.

Distribution. Unalaska I in Aleutian Is of Alaska.

Descriptive notes. No specific measurements are available. The Unalaska Collared Lemming is larger and paler than other species of Dicrostonyx and is not seasonally dimorphic. In winter, it does not turn white or develop digging claws. Few specimens of Unalaska Collared Lemmings are known (two were collected in 1931 and two in 1964), but several skulls have been salvaged from owl pellets from the island.

Habitat. Sandy or rocky beach soils. The Unalaska Collared Lemming uses burrowsit digs to rest and escape predation.

Food and Feeding. The Unalaska Collared Lemming likely feeds on plant leaves, flowers, buds, and roots.

Breeding. Unalaska Collared Lemmings might breed year-round. Gestation likely averages 20-21 days, with litters of 1-8 young.

Activity patterns. Unalaska Collared Lemmings probably actively feed day or night and throughout the year.

Movements, Home range and Social organization. No information.

Status and Conservation. Classified as Data Deficient on The IUCN Red List. Because the Unalaska Collared Lemming is found on a single island, it could be considered as Endangered, but additional information on population status and threats is needed to determine if it is declining. Impacts of exotic rodent introductions such as the Brown Rat ( Rattus norvegicus), the House Mouse ( Mus musculus), and the Arctic Ground Squirrel ( Urocitellus parryi) are unknown. Furthermore, taxonomic status of many collared lemmings needs to be reviewed.

Bibliography. Bradley, Ammerman et al. (2014), Cook et al. (2010), Engstrom et al. (1993), Gilmore (1933), Linzey & NatureServe (Garibaldi & Hammerson) (2008), MacDonald & Cook (2009), Musser & Carleton (2005), Peterson (1967), Rausch (1977), Rausch & Rausch (1972), Stenseth & Ims (1993), Wilson & Ruff (1999).