Lemming

Taxobox
name = Lemmings

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image_width = 205px
image_caption = "Lemmus lemmus"
regnum = Animalia
phylum = Chordata
classis = Mammalia
ordo = Rodentia
familia = Cricetidae
subfamilia = Arvicolinae
tribus = Lemmini*
subdivision_ranks = Genera
subdivision ="Dicrostonyx"
"Lemmus"
"Synaptomys"
"Myopus"
* Incomplete listing: see vole

Lemmings are small rodents, usually found in or near the Arctic, in tundra biomes. Together with the voles and muskrats, they make up the subfamily Arvicolinae (also known as Microtinae), which forms part of the largest mammal radiation by far, the superfamily Muroidea, which also includes the rats, mice, hamsters, and gerbils.

Description and habitat

Lemmings weigh from convert|30|to|112|g|abbr=on and are about convert|7|to|15|cm|abbr=on long. They generally have long, soft fur and very short tails. They are herbivorous, feeding mostly on leaves and shoots, grasses, and sedges in particular, but also on roots and bulbs. Like other rodents, their incisors grow continuously, allowing them to exist on much tougher forage than would otherwise be possible.

Lemmings do not hibernate through the harsh northern winter. They remain active, finding food by burrowing through the snow and utilising grasses clipped and stored in advance. They are solitary animals by nature, meeting only to mate and then going their separate ways, but like all rodents they have a high reproductive rate and can breed rapidly in good seasons.

There is little to distinguish a lemming from a vole. Most lemmings are members of the tribe Lemmini (one of the three tribes that make up the subfamily).

Behavior

The behaviour of lemmings is much the same as that of many other rodents which have periodic population booms and then disperse in all directions, seeking the food and shelter that their natural habitat cannot provide.Lemmings of northern Norway are one of the few vertebrates who reproduce so quickly that their population fluctuations are chaotic, [(Turchin & Ellner, 1997)] rather than following linear growth to a carrying capacity or regular oscillations. It is unknown why lemming populations fluctuate with such variance roughly every four years, before plummeting to near extinction. [ [http://www.hww.ca/hww2.asp?id=91 Hinterland Who's Who - Lemmings] ]

While for many years it was believed that the population of lemming predators changed with the population cycle, there is now some evidence to suggest that the predator's population may be more closely involved in changing the lemming population. [ [http://www.innovations-report.com/html/reports/environment_sciences/report-22885.html Predators drive the lemming cycle in Greenland] ]

Myths and misconceptions

Misconceptions about lemmings go back many centuries. In the 1530s, the geographer Zeigler of Strasbourg proposed the theory that the creatures fell out of the sky during stormy weather (also featured in the folklore of the Inupiat/Yupik at Norton Sound), and then died suddenly when the grass grew in spring. [ [http://www.abc.net.au/science/k2/moments/s1081903.htm ABC.net.au - Lemmings Suicide Myth] ] This was refuted by the natural historian Ole Worm, who first published dissections of a lemming, and showed that lemmings are anatomically similar to most other rodents.Fact|date=September 2008

While many people believe that lemmings commit mass suicide when they migrate, this is not the case. Driven by strong biological urges, they will migrate in large groups when population density becomes too great. Lemmings can and do swim and may choose to cross a body of water in search of a new habitat [ [http://www.wildlifenews.alaska.gov/index.cfm?adfg=wildlife_news.view_article&issue_id=6&articles_id=56 Lemming Suicide Myth Disney Film Faked Bogus Behavior] ] . On occasion, and particularly in the case of the Norway lemmings in Scandinavia, large migrating groups will reach a cliff overlooking the ocean. They will stop until the urge to press on causes them to jump off the cliff and start swimming, sometimes to exhaustion and death. Lemmings are also often pushed into the sea as more and more lemmings arrive at the shore. [ [http://www.britannica.com/eb/art-18465/Lemming-migration-along-the-Norwegian-coast?articleTypeId=1 Lemming video at Britannica Online] ]

The myth of lemming mass suicide is long-standing and has been popularized by a number of factors. In 1955, Carl Barks drew an Uncle Scrooge adventure comic with the title "The Lemming with the Locket". This comic, which was inspired by a 1954 National Geographic article, showed massive numbers of lemmings jumping over Norwegian cliffs. [Blum, Geoffrey. 1996. "One Billion of Something," in: "Uncle Scrooge Adventures by Carl Barks", #9] Even more influential was the 1958 Disney film "White Wilderness" in which footage was shown that seems to show the mass suicide of lemmings. The film won an Academy Award for Documentary Feature. [ [http://www.snopes.com/disney/films/lemmings.asp snopes.com: White Wilderness Lemmings Suicide ] ]

Due to their association with this odd behaviour, lemming suicide is a frequently-used metaphor in reference to people who go along unquestioningly with popular opinion, with potentially dangerous or fatal consequences. This is the theme of the video game "Lemmings", where the player attempts to save the mindlessly marching rodents from walking to their deaths.

Classification

* Order Rodentia
** Superfamily Muroidea
*** Family Cricetidae
**** Subfamily Arvicolinae
***** Tribe Lemmini
****** "Dicrostonyx"
******* St Lawrence Island Collared Lemming ("Dicrostonyx exsul")
******* Northern Collared Lemming ("Dicrostonyx groenlandicus")
******* Ungava Collared Lemming ("Dicrostonyx hudsonius")
******* Victoria Collared Lemming ("Dicrostonyx kilangmiutak")
******* Nelson's Collared Lemming ("Dicrostonyx nelsoni")
******* Ogilvie Mountain Collared Lemming ("Dicrostonyx nunatakensis")
******* Richardson's Collared Lemming ("Dicrostonyx richardsoni")
******* Bering Collared Lemming ("Dicrostonyx rubricatus")
******* Arctic Lemming ("Dicrostonyx torquatus")
******* Unalaska Collared Lemming ("Dicrostonyx unalascensis")
******* Wrangel Lemming ("Dicrostonyx vinogradovi")
****** "Lemmus"
******* Amur Lemming ("Lemmus amurensis")
******* Norway Lemming ("Lemmus lemmus")
******* Siberian Brown Lemming ("Lemmus sibiricus")
******* North American Brown Lemming ("Lemmus trimucronatus")
****** "Myopus"
******* Wood Lemming ("Myopus schisticolor")
****** "Synaptomys"
******* Northern Bog Lemming ("Synaptomys borealis")
******* Southern Bog Lemming ("Synaptomys cooperi")
***** Tribe Ellobiini: mole voles, 5 species
***** Tribe Microtini: voles, 121 species
****** "Eolagurus"
******* Yellow Steppe Lemming ("Eolagurus luteus")
******* Przewalski's Steppe Lemming ("Eolagurus przewalskii")
****** "Lagurus"
******* Steppe Lemming ("Lagurus lagurus")
****** 118 other species known as voles or muskrats

References

External links

* article by Nils Christian Stenseth on the population cycles of lemmings and other northern rodents.
** See also [http://64.233.161.104/search?q=cache:24ZpDO3p6_oJ:www.cas.uio.no/Publications/Jubilee/The_lemming_cycle.pdf The Lemming Cycle, in HTML format] .
* Article about Collared Lemming, see also the main page on [http://aknhp.uaa.alaska.edu/zoology/Zoology_ADFG_mammals.htm Alaskan mammals]
* Rebuttal of lemming suicide:
** [http://www.wildlifenews.alaska.gov/index.cfm?adfg=wildlife_news.view_article&articles_id=56&issue_id=6 Alaska Wildlife News] .
** [http://www.drbeetle.com/lemming.html Lemmings, dying on camera] .