Lemming

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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

Lemmings are small rodents, usually found in or near the Arctic, in tundra biomes. They are subniveal animals and 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.

[edit] Description and habitat

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.

[edit] 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,^[1] 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.^[2]

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.^[3]

[edit] 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.^[4] This myth was refuted by the natural historian Ole Worm, who accepted that the lemmings could fall out of the sky but that they had been brought over by the wind rather than created by spontaneous generation. It was Worm who first published dissections of a lemming, which showed that they are anatomically similar to most other rodents, and the work of Carl Linnaeus proved that the animals had a natural origin.^[5][6]

When large numbers of lemmings get on the move, some of them will inevitably drown while crossing rivers and lakes, like this one in Norway.

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 groupings 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.^[7] 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.^[8]

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 Society article, showed massive numbers of lemmings jumping over Norwegian cliffs.^[9] Even more influential was the 1958 Disney film White Wilderness, which won an Academy Award for Documentary Feature, in which footage was shown that seems to show the mass suicide of lemmings.^[10] A Canadian Broadcasting Corporation documentary, Cruel Camera, found that the lemmings used for White Wilderness were flown from Hudson Bay to Calgary, Alberta, Canada, where they did not jump off the cliff, but in fact were launched off the cliff using a turntable.^[11]

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 mindlessly marching creatures (with little physical resemblance to real-life lemmings) from walking to their deaths.

[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) or
            • Ungava Collared Lemming (Dicrostonyx hudsonius)
            • Victoria Collared Lemming (Dicrostonyx kilangmiutak)
            • Nelson's Collared Lemming (Dicrostonyx nelsoni)
            • Ogilvie Mountains 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)
            • Wrangel Island Lemming (Lemmus portenkoi)
          • Myopus
            • Wood Lemming (Myopus schisticolor)
          • Synaptomys
            • Northern Bog Lemming (Synaptomys borealis)
            • Southern Bog Lemming (Synaptomys cooperi)
        • Tribe: Ellobiusini
          • Ellobius
            • Alai Mole Vole (Ellobius alaicus)
            • Southern Mole Vole (Ellobius fuscocapillus)
            • Transcaucasian Mole Vole (Ellobius lutescens)
            • Northern Mole Vole (Ellobius talpinus)
            • Zaisan Mole Vole (Ellobius tancrei)
        • 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

[edit] External links

Look up lemming in Wiktionary, the free dictionary.

• 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.
• Collared LemmingPDF (177 KiB) Article about Collared Lemming, see also the main page on Alaskan mammals
• Rebuttal of lemming suicide:
  • Alaska Wildlife News.
  • Lemmings, dying on camera.