Collar lemmings
| Collar lemmings | ||||||||||||
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Genuine collar lemming ( Dicrostonyx torquatus ) |
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| Scientific name | ||||||||||||
| Dicrostonyx | ||||||||||||
| Gloger , 1841 |
The collar lemmings ( Dicrostonyx ) are a genus of arctic voles that are distributed over Siberia , northern Canada and Alaska . Although they are very similar to the mountain lemming in many ways, they are no longer counted as part of the tribe Lemmini , as new research has given rise to the assumption that the Lemmini and the collar lemmings are of different origins and that the similarities are based on convergent evolution .
features
Collared lemmings have a head body length of 10 to 15 cm, plus a tail that is only one to two centimeters long. The fur is gray, beige or reddish brown in summer depending on the species. In winter it becomes pure white. Collared lemmings are the only rodents with a white winter coat , as is characteristic of other mammals ( arctic hare , ermine ).
Collared lemmings have a stocky build and a stubby tail in common with the Lemmini , as well as their arctic habitat. The seasonal growth of the third and fourth claws of the front legs is unique in them. These are normal in size in summer, but grow considerably in winter, becoming thicker and stronger. So they can dig even in frozen earth.
Collared lemmings use burrows in summer that they dig in the tundra soil. A tunnel up to six meters long leads to a nest chamber, which has a diameter of 15 cm and is padded with grass. In winter, most collar lemmings are content with tunnels in the snow. They are nourished by grasses, flowers and fruits in summer, bark, twigs and buds in winter.
The white winter fur of the collar lemmings is used by some Eskimos to make clothes, but has no national significance.
species
Jarrell and Fredga recognized the following three types in 1993:
- Real collar lemming or fork claw lemming, Dicrostonyx torquatus , Siberian tundra
- Northern Collared Lemming , Dicrostonyx groenlandicus , Greenland , Nunavut , Northwest Territories , Yukon , Alaska
- Ungava Collared Lemming , Dicrostonyx hudsonius , northern Quebec , mainland Newfoundland and Labrador
The number of species is controversial, however. Sometimes all Collared Lemmings were assigned to a single species; Wilson and Reeder, on the other hand, distinguish eleven species, in addition to the above-mentioned mainly endemics from Arctic islands. Other types:
- Nelson collar lemming ( Dicrostonyx nelsoni )
- Richardson's collar lemming ( Dicrostonyx richardsoni )
literature
- Don E. Wilson , DeeAnn M. Reeder (Eds.): Mammal Species of the World. A taxonomic and geographic Reference. 2 volumes. 3. Edition. Johns Hopkins University Press, Baltimore MD 2005, ISBN 0-8018-8221-4 .
- Ronald M. Nowak: Walker's Mammals of the World. 2 volumes. 6th edition. Johns Hopkins University Press, Baltimore MD et al. 1999, ISBN 0-8018-5789-9 .
- GH Jarrell, K. Fredga: How many kinds of lemmings? A taxonomic overview. In: Nils Christian Stenseth, Rolf Anker Ims: The biology of lemmings (= Linnean Society Symposium Series. No. 15). Academic Press for the Linnean Society of London, London et al. 1993, ISBN 0-12-666020-4 , pp. 45-57.
