Lemming

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Lemmings
A lemming
Scientific classification
Kingdom: Animalia Phylum: Chordata Class: Mammalia Order: Rodentia Family: Cricetidae Subfamily: Arvicolinae Tribe: Lemmini*
Genera
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.

Lemmings mostly weigh 30 to 112 grams (1–4 oz) and are about 7 to 15 centimetres (2.75 – 6 in) long. They usually have long, soft fur and very short tails. They are herbivorous, feeding mostly on leaves and shoots, grasses, and sedges in particular, but also roots and bulbs in some cases. Like many rodents' teeth, 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).

Contents 1 Population fluctuations 1.1 Suicide myth 2 Classification 3 References 4 External links

[edit] Population fluctuations

The behavior 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.

Misconceptions about lemmings go back many centuries. In the 16th and 17th centuries, there was much speculation in learned circles that lemmings were in fact spontaneously generated by conditions of the air. This was argued against, successfully, by the natural historian Ole Worm, who provided one of the first published dissections of a lemming. In his investigation, Worm showed that a lemming contained anatomy similar to most other rodents.

Lemmings of northern Norway are one of the few vertebrates who reproduce so quickly that their population fluctuations are chaotic^[1], rather than following linear growth to a carrying capacity or regular oscillations. Chaos in population fluctuations only occurs (in theory) when each adult female is able to produce 2.7 or more living daughters per year.

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.^[2]

[edit] Suicide myth

While many people believe that lemmings commit mass suicide when they migrate, this is not actually the case. Lemmings will often migrate in large groups and as a result some lemmings will occasionally be pushed off cliffs or drowned in bodies of water simply by the press of their compatriots. The myth of lemming mass suicide is long-standing and has been popularized by a number of factors. It is usually stated that the main source of the belief in the suicide myth was propagated by The Walt Disney Company documentary White Wilderness which includes footage of lemmings running head-long over a ledge. However, subsequent research has shown that the filmmakers contrived this scene.^[3]

Due to their association with this odd behavior, lemmings are a frequently-used metaphor in reference to people who go along unquestioningly with popular opinion, with potentially dangerous/fatal consequences.

[edit] 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

[edit] References

1. ^ (Turchin & Ellner, 1997)
2. ^ Predators drive the lemming cycle in Greenland
3. ^ http://www.snopes.com/disney/films/lemmings.htm

[edit] External links

• The Lemming CyclePDF (92.6 KiB) article by Nils Christian Stenseth on the population cycles of lemmings and other northern rodents.
  • See also The Lemming Cycle, in HTML format.

• Rebuttal of lemming suicide:
  • Alaska Wildlife News.
  • Snopes (Urban Legends Reference Pages) entry on Disney's White Wilderness.
  • Lemmings, dying on camera.