Arctic Lemming
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The Arctic lemming (''Dicrostonyx torquatus'') is a species of
rodent Rodents (from Latin , 'to gnaw') are mammals of the Order (biology), order Rodentia ( ), which are characterized by a single pair of continuously growing incisors in each of the upper and Mandible, lower jaws. About 40% of all mammal specie ...
in the family
Cricetidae The Cricetidae are a family of rodents in the large and complex superfamily Muroidea. It includes true hamsters, voles, lemmings, muskrats, and New World rats and mice. At over 870 species, it is either the largest or second-largest family ...
. Although generally classified as a "least concern" species, the Novaya Zemlya subspecies ''(Dicrostonyx torquatus ungulatus)'' is considered a
vulnerable species A vulnerable species is a species which has been Conservation status, categorized by the International Union for Conservation of Nature as being threatened species, threatened with extinction unless the circumstances that are threatened species, ...
under Russian nature conservation legislation (included in Red Book of Russian Federation since 1998).


Biology

It is found only in the
Arctic The Arctic (; . ) is the polar regions of Earth, polar region of Earth that surrounds the North Pole, lying within the Arctic Circle. The Arctic region, from the IERS Reference Meridian travelling east, consists of parts of northern Norway ( ...
biome A biome () is a distinct geographical region with specific climate, vegetation, and animal life. It consists of a biological community that has formed in response to its physical environment and regional climate. In 1935, Tansley added the ...
s in the
Russian Federation Russia, or the Russian Federation, is a country spanning Eastern Europe and North Asia. It is the list of countries and dependencies by area, largest country in the world, and extends across Time in Russia, eleven time zones, sharing Borders ...
, and it is the most common mammal on Severnaya Zemlya. Specimens were once found in England, but they are now extirpated. For the most part, lemmings of the genus ''Lemmus'' can coexist with those of genus ''Dicrostonyx''. Arctic lemmings migrate when population density becomes too great, and they resort to swimming in search of a new habitat. The disappearance of lemmings and the lemming cycles in the Arctic have shown that they are the causes of fluctuations in local breeding among geese and waders. Recovery of lemmings after years of low density is associated with a period of successful breeding and maintenance of their young in the snow. The diet of the Arctic lemming has been studied, and it has been found to consist of 86% dicotyledons, 14% monocotyledons, and less than 1% mosses. The diet of a family of lemmings consists mostly of Saliceae, although
Poaceae Poaceae ( ), also called Gramineae ( ), is a large and nearly ubiquitous family of monocotyledonous flowering plants commonly known as grasses. It includes the cereal grasses, bamboos, the grasses of natural grassland and species cultivate ...
are also in their diet. They are a well studied example of a cyclic predator−prey relationship. Terns in the Arctic target lemmings that move in groups; after attacks, lemmings seek shelter in holes or elsewhere out of the terns' territory to avoid additional attacks.


Environment

During the winter, Arctic lemmings make nests in order to help maintain thermoregulation, maintaining their young, and aids in their survival against predators. One of their predators is the Arctic Fox and they would find that it difficult to hunt lemmings because they would burrow themselves deep within the snow. The fox would then have to dig through the snow in order to reach them. When snow is scarce and there isn't much for the lemmings to make a nest or burrow in, there are periodic disappearances of lemmings because of hunting by other predators and their inability to protect themselves.


References


External links

* {{Taxonbar, from=Q305615 Dicrostonyx Mammals of the Arctic Mammals of Russia Endemic fauna of Russia Arctic land animals Mammals described in 1778 Taxonomy articles created by Polbot