The

genus Genus ( plural genera ) is a taxonomic rank used in the biological classification of living and fossil organisms as well as viruses. In the hierarchy of biological classification, genus comes above species and below family. In binomial nomencla ...

''Lemmus'' contains several species of

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 includ ...

sometimes referred to as the true lemmings. They are distributed throughout the

Holarctic The Holarctic realm is a biogeographic realm that comprises the majority of habitats found throughout the continents in the Northern Hemisphere. It corresponds to the floristic Boreal Kingdom. It includes both the Nearctic zoogeographical regio ...

, particularly in the

Palearctic The Palearctic or Palaearctic is the largest of the eight biogeographic realms of the Earth. It stretches across all of Eurasia north of the foothills of the Himalayas, and North Africa. The realm consists of several bioregions: the Euro-Si ...

Description

Head and body is 10-13.5 cm, and tail length is 18–26 mm. Weight ranges from 40-112 g. They are grey or brown. Unlike the

collared lemming ''Dicrostonyx'' is a genus of rodent in the family Cricetidae. It contains the collared lemmings. They are the only North American rodents that turn completely white in winter. It contains the following species: * Northern collared lemming The ...

s, their coats do not change color in winter. They stay brown and grey.

Natural history

These lemmings are found predominantly in

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 ...

or high elevations. Populations can fluctuate widely and mass migrations do take place. This mass migration is probably the source of the myth that lemmings commit

mass suicide Mass suicide is a form of suicide, occurring when a group of people simultaneously kill themselves. Overview Mass suicide sometimes occurs in religious settings. In war, defeated groups may resort to mass suicide rather than being captured. Su ...

. These intense population booms appear to be most common in the northern part of its range (such as Lapland). Gestation is 16–23 days. Litters are 1-13 (7 average). Young are sexually mature after 14 days. When conditions are favorable, these

demographic Demography () is the statistical study of populations, especially human beings. Demographic analysis examines and measures the dimensions and dynamics of populations; it can cover whole societies or groups defined by criteria such as ed ...

parameters allow for a veritable explosion in population size.

Species

* Amur lemming - ''(Lemmus amurensis)'' *

Norway lemming The Norway lemming, also known as the Norwegian lemming (''Lemmus lemmus'') is a common species of lemming found in northern Fennoscandia, where it is the only vertebrate species endemic to the region. The Norway lemming dwells in tundra and fell ...

- ''(Lemmus lemmus)'' * Beringian lemming - (''Lemmus nigripes'') * East Siberian lemming - (''Lemmus paulus'') * West Siberian lemming - ''(Lemmus sibiricus)'' * Canadian lemming - ''(Lemmus trimucronatus)''

References

*Duff, A. and A. Lawson. 2004. Mammals of the World A Checklist. New Haven, Yale University Press. *Musser, G. G. and M. D. Carleton. 2005. Superfamily Muroidea. pp. 894–1531 ''in'' Mammal Species of the World a Taxonomic and Geographic Reference. D. E. Wilson and D. M. Reeder eds. Johns Hopkins University Press, Baltimore. *Nowak, R. M. 1999. Walker's Mammals of the World, Vol. 2. Johns Hopkins University Press, London. {{DEFAULTSORT:True lemming *