The Richardson's collared lemming (''Dicrostonyx richardsoni'') is a small

North America North America is a continent in the Northern Hemisphere and almost entirely within the Western Hemisphere. It is bordered to the north by the Arctic Ocean, to the east by the Atlantic Ocean, to the southeast by South America and the Car ...

n lemming. At one time, they were considered to be a subspecies of the

Arctic lemming The Arctic lemming (''Dicrostonyx torquatus'') is a species of rodent in the family Cricetidae. Although generally classified as a "least concern" species, the Novaya Zemlya subspecies ''(Dicrostonyx torquatus ungulatus)'' is considered a vulner ...

, ''Dicrostonyx torquatus''. Some sources believe they are a subspecies of the

northern collared lemming The northern collared lemming or Nearctic collared lemming (''Dicrostonyx groenlandicus''), sometimes called the Peary Land collared lemming in Canada, is a small lemming found in Arctic North America and Wrangel Island. At one time, it was consi ...

, ''Dicrostonyx groenlandicus''. This species has a short, chunky body covered with grizzled brown fur, which varies from red-brown to grey-brown, with a thin dark stripe along its back and a reddish-grey belly. It has small ears, short legs and a very short tail, and a reddish collar across its chest. In winter, it is covered with white fur, and develops enlarged digging claws on its front feet. It is about 13 cm long with a 1 cm tail, and weighs about 60 g. These animals are found in the

tundra In physical geography, tundra () is a type of biome where tree growth is hindered by frigid temperatures and short growing seasons. The term ''tundra'' comes through Russian (') from the Kildin Sámi word (') meaning "uplands", "treeless moun ...

west of

Hudson Bay Hudson Bay ( crj, text=ᐐᓂᐯᒄ, translit=Wînipekw; crl, text=ᐐᓂᐹᒄ, translit=Wînipâkw; iu, text=ᑲᖏᖅᓱᐊᓗᒃ ᐃᓗᐊ, translit=Kangiqsualuk ilua or iu, text=ᑕᓯᐅᔭᕐᔪᐊᖅ, translit=Tasiujarjuaq; french: b ...

in north-central

Canada Canada is a country in North America. Its ten provinces and three territories extend from the Atlantic Ocean to the Pacific Ocean and northward into the Arctic Ocean, covering over , making it the world's second-largest country by tot ...

. They feed on grasses, sedges and other green vegetation in summer and twigs of

willow Willows, also called sallows and osiers, from the genus ''Salix'', comprise around 400 speciesMabberley, D.J. 1997. The Plant Book, Cambridge University Press #2: Cambridge. of typically deciduous trees and shrubs, found primarily on moist s ...

aspen Aspen is a common name for certain tree species; some, but not all, are classified by botanists in the section ''Populus'', of the ''Populus'' genus. Species These species are called aspens: *'' Populus adenopoda'' – Chinese aspen (China ...

and

birch A birch is a thin-leaved deciduous hardwood tree of the genus ''Betula'' (), in the family Betulaceae, which also includes alders, hazels, and hornbeams. It is closely related to the beech-oak family Fagaceae. The genus ''Betula'' contains 30 ...

es in winter. Predators include snowy owls,

mustelid The Mustelidae (; from Latin ''mustela'', weasel) are a family of carnivorous mammals, including weasels, badgers, otters, ferrets, martens, minks and wolverines, among others. Mustelids () are a diverse group and form the largest family in ...

s, and Arctic foxes. Females have two or three litters of four to eight young in a year. The young are born in a nest in a burrow or concealed in vegetation. They are active year-round, day and night. They make runways through the surface vegetation and also dig burrows above the

permafrost Permafrost is ground that continuously remains below 0 °C (32 °F) for two or more years, located on land or under the ocean. Most common in the Northern Hemisphere, around 15% of the Northern Hemisphere or 11% of the global surface ...

. They burrow under the snow in winter. Lemming populations go through a three- or four-year cycle of boom and bust. When their population peaks, lemmings disperse from overcrowded areas. This animal was named after Sir John Richardson, a

Scottish Scottish usually refers to something of, from, or related to Scotland, including: *Scottish Gaelic, a Celtic Goidelic language of the Indo-European language family native to Scotland *Scottish English *Scottish national identity, the Scottish ide ...

naturalist who explored the Canadian Arctic.

References

{{Taxonbar, from=Q1770407 Dicrostonyx Mammals described in 1900 Taxa named by Clinton Hart Merriam Mammals of Canada