Lemming

Lemmings
Lemmus lemmus
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

Lemming is the common name for various, small, furry rodents within the subfamily Arvicolinae (syn. Microtinae) of the Muridae family (sometimes Cricetidae), characterized by a small compact body with short legs and short tails. Arvicolinae, which sometimes is raised to family status as Arvicolidae, also includes rodents commonly known as voles and the muskrat. Lemmings have a widespread distribution across northern North America, Europe, and Asia and usually found in or near the Arctic, in tundra biomes.

The true lemmings comprise genus Lemmus, but among other genera including lemmings are Dicrostonyx (collared lemmings), Synaptomys (bog lemmings), and Myopus (M. schisticolor, wood lemming), all in tribe Lemmini, with the steppe lemmings of genera Lagurus and Eulagurus in tribe Microtini.

Overview and description

Lemmings,voles, and the muskrat (Ondatra zibethicus) comprise the subfamily Avicolinae of the family Muridae of the order Rodentia. Muridae is a huge family that has over 1,300 species, while about 143 species are placed in the 26 genera of the subfamily Arvicolinae,the third largest subfamily of Muridae (Jordan 2004). Arvicolinae is also known by its junior synonym (Microtinae). The Muridae family, however, has long been undergoing considerable revision. Arvicolinae sometimes is raised to the level of family as Arvicolidae, and for some time the voles and lemmings were placed in the Cricetidae family with the closely related hamsters (Jordan 2004).

The lemmings generally are seen as being in the tribe Lemmini, with the four genera of Lemmus, Dicrostonyx, Synaptomys, and Myopus. However, the term lemming is a common name, not a taxonomic designation, and some members in tribe Microtini also are known as lemmings, notably members of the genera Lagurus and Eulagurus, whose members are known as steppe lemmings.

In general, lemmings are similar to the voles but tend to have, in most species, more thickset, robust bodies and shorter tails. Both voles and lemmings tend to be small (20-75 grams or 0.7-2.6 ounces) stocky animals with short legs and tails and compact bodies. Member of the genus Lemmus, the true lemmings, have a fur that is highly patterned with gray, white, brown, and buff colors. Members of the genus Dicrostomyx, the collared lemmings, tend to be pure white in winter and develop in winter an enlarged third and fourth claw on the forefeet, a feature unique among rodents (Jordan 2004).

Lemmings weigh from 30 to 112 g (1.1 to 4.0 oz) and are about 7 to 15 cm (2.8 to 5.9 in) 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 utilizing 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 when food is plentiful.

Behavior

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. Lemmings of northern Norway are one of the few vertebrates who reproduce so quickly that their population fluctuations are chaotic, 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.

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.

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. 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.^{[citation needed]}

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. 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.

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. 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.. A CBC Documentary, "Cruel Camera", found that the lemmings used for White Wilderness were flown from Hudson's Bay to Calgary, Alberta, Canada, where they did not jump off the cliff, but in fact were launched off the cliff using a turn table.

Due to their association with this odd behavior, 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

ISBN links support NWE through referral fees

• Jordan, M. J. R. 2004. Rats, mice, and relatives I: Voles and lemmings (Arvicolinae). Pages 225-238 in B. Grzimek et al. Grzimek's Animal Life Encyclopedia. Detroit, MI: Thomson/Gale. ISBN 0787657921.

External links

• PDF article by Nils Christian Stenseth on the population cycles of lemmings and other northern rodents.
  • See also The Lemming Cycle, in HTML format.
• PDF Article about Collared Lemming, see also the main page on Alaskan mammals
• Rebuttal of lemming suicide:
  • Alaska Wildlife News.
  • Lemmings, dying on camera.

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