The Canadian lemming or Nearctic brown lemming (''Lemmus trimucronatus'') 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 ...

lemming A lemming is a small rodent, usually found in or near the Arctic in tundra biomes. Lemmings form the subfamily Arvicolinae (also known as Microtinae) together with voles and muskrats, which form part of the superfamily Muroidea, which also include ...

Taxonomy

The taxonomy of the Canadian lemming is tangled with the Siberian brown lemming and the

Beringian lemming The Beringian lemming or Beringian brown lemming (''Lemmus nigripes'') is a species of lemming found in Russia and North America. Taxonomy It was formerly considered conspecific with the Canadian lemming (''L. trimucronatus'') with both spec ...

. The Canadian lemming was formerly thought to be a subspecies of the Siberian brown lemming ( ''Lemmus sibiricus''), but those were split into two distinct species. They were still considered the same species as the Beringian lemming ( ''Lemmus nigripes''); the combined species was named the North American brown lemming with the scientific name ''L. trimucronatus'', and was thought to range from eastern

Siberia Siberia ( ; rus, Сибирь, r=Sibir', p=sʲɪˈbʲirʲ, a=Ru-Сибирь.ogg) is an extensive geographical region, constituting all of North Asia, from the Ural Mountains in the west to the Pacific Ocean in the east. It has been a part of ...

to North America. Recent phylogenetic studies showed them to also be distinct species, although

sister group In phylogenetics, a sister group or sister taxon, also called an adelphotaxon, comprises the closest relative(s) of another given unit in an evolutionary tree. Definition The expression is most easily illustrated by a cladogram: Taxon A and t ...

s to one another.

Physical characteristics

Lemmings are a brown in colour, with an reddish-brown back and rump, while the head and shoulders are grey. In the winter, the coat becomes longer and greyer. The female averages 12.5 cm (5.7 in) in length and weighs 58 g (2.4 oz), while the male averages 13 cm (5.9 in) and weighs 68 g (2.7 oz). Like other lemmings, it has small ears, short legs and a very short tail. The feet, both the soles and toes, are covered with bristles and are adapted for burrowing.

Habitat

The lemming is 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 ...

areas of northern

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 ...

(

Nunavut Nunavut ( , ; iu, ᓄᓇᕗᑦ , ; ) is the largest and northernmost Provinces and territories of Canada#Territories, territory of Canada. It was separated officially from the Northwest Territories on April 1, 1999, via the ''Nunavut Act'' ...

Northwest Territories The Northwest Territories (abbreviated ''NT'' or ''NWT''; french: Territoires du Nord-Ouest, formerly ''North-Western Territory'' and ''North-West Territories'' and namely shortened as ''Northwest Territory'') is a federal territory of Canada. ...

Yukon Yukon (; ; formerly called Yukon Territory and also referred to as the Yukon) is the smallest and westernmost of Canada's three territories. It also is the second-least populated province or territory in Canada, with a population of 43,964 as ...

), and southern

Alaska Alaska ( ; russian: Аляска, Alyaska; ale, Alax̂sxax̂; ; ems, Alas'kaaq; Yup'ik: ''Alaskaq''; tli, Anáaski) is a state located in the Western United States on the northwest extremity of North America. A semi-exclave of the U.S., ...

south of the

Alaska Range The Alaska Range is a relatively narrow, 600-mile-long (950 km) mountain range in the southcentral region of the U.S. state of Alaska, from Lake Clark at its southwest endSources differ as to the exact delineation of the Alaska Range. ThBoar ...

. It is also found on the west coast of

British Columbia British Columbia (commonly abbreviated as BC) is the westernmost province of Canada, situated between the Pacific Ocean and the Rocky Mountains. It has a diverse geography, with rugged landscapes that include rocky coastlines, sandy beaches, ...

almost as far south as

Vancouver Island Vancouver Island is an island in the northeastern Pacific Ocean and part of the Canadian Provinces and territories of Canada, province of British Columbia. The island is in length, in width at its widest point, and in total area, while are o ...

. Although this species was formerly thought to exist in eastern Siberia and most of Alaska, that species has now been found to be '' L. nigripes''. They feed mainly on grass shoots and will also eat tundra grass,

sedge The Cyperaceae are a family of graminoid (grass-like), monocotyledonous flowering plants known as sedges. The family is large, with some 5,500 known species described in about 90 genera, the largest being the "true sedges" genus ''Carex'' wit ...

moss Mosses are small, non-vascular flowerless plants in the taxonomic division Bryophyta (, ) '' sensu stricto''. Bryophyta (''sensu lato'', Schimp. 1879) may also refer to the parent group bryophytes, which comprise liverworts, mosses, and hor ...

, bark,

berries A berry is a small, pulpy, and often edible fruit. Typically, berries are juicy, rounded, brightly colored, sweet, sour or tart, and do not have a stone or pit, although many pips or seeds may be present. Common examples are strawberries, raspb ...

lichen A lichen ( , ) is a composite organism that arises from algae or cyanobacteria living among filaments of multiple fungi species in a mutualistic relationship.root In vascular plants, the roots are the organs of a plant that are modified to provide anchorage for the plant and take in water and nutrients into the plant body, which allows plants to grow taller and faster. They are most often below the sur ...

s. Predators include most

carnivore A carnivore , or meat-eater (Latin, ''caro'', genitive ''carnis'', meaning meat or "flesh" and ''vorare'' meaning "to devour"), is an animal or plant whose food and energy requirements derive from animal tissues (mainly muscle, fat and other sof ...

s and certain

bird Birds are a group of warm-blooded vertebrates constituting the class Aves (), characterised by feathers, toothless beaked jaws, the laying of hard-shelled eggs, a high metabolic rate, a four-chambered heart, and a strong yet lightweigh ...

s, and some evidence suggests

caribou Reindeer (in North American English, known as caribou if wild and ''reindeer'' if domesticated) are deer in the genus ''Rangifer''. For the last few decades, reindeer were assigned to one species, ''Rangifer tarandus'', with about 10 subspe ...

may sometimes eat them. In years when the brown lemming is scarce, some predators, such as the

Arctic fox The Arctic fox (''Vulpes lagopus''), also known as the white fox, polar fox, or snow fox, is a small fox native to the Arctic regions of the Northern Hemisphere and common throughout the Arctic tundra biome. It is well adapted to living in co ...

, may be unable to reproduce.

Colonies

They live underground, in colonies, and may produce up to three

litters Litter consists of waste products that have been discarded incorrectly, without consent, at an unsuitable location. Litter can also be used as a verb; to litter means to drop and leave objects, often man-made, such as aluminum cans, paper cups ...

each year, including under the snow in winter. With a

gestation period In mammals, pregnancy is the period of reproduction during which a female carries one or more live offspring from implantation in the uterus through gestation. It begins when a fertilized zygote implants in the female's uterus, and ends once it ...

of 23 days, the female will give birth from four to nine young. The brown lemming is not migratory and when overpopulated (and during mating season), they will fight amongst themselves. Bylot Island has several wetlands with shallow polygons and many types of mosses, grasses and sedges, which suits the North American brown lemming very well for several reasons (Rochefort et al. 1996). On Bylot Island they prefer to live in the South plain of the island and mostly live in the polygon fen, also known as wetlands, which mostly supports the graminoids that they rely on for food (Bety et al. 2002). During winter brown lemmings live in insulated burrows in the ground made out of sedges and grasses (Reid et al. 2011). They make their nests in these confined burrows underground because it increases insulation and allows them to reproduce during winter (Duchesne et al. 2011). Studies on Bylot Island have shown that brown lemmings prefer to burrow under increasing snow depth rather than more dense. They believe that brown lemmings do this because the more snow depth the better energy is trapped and the number of nests increased. Deeper snow cover also protected lemmings and their nests from avian predators; mammalian predators can still forage for them but since their nests are so deep it decreases the ability of some predators to see, therefore, they are very well protected from predators (Duchesne et al. 2011; Reid et al. 2012). During summer, brown lemmings do not have the cover of snow and their territories become a lot more widespread across Bylot Island (Reid et al. 2012).

References

External links