lemming

[lem-ing]

lemming, name for several species of mouselike rodents related to the voles. All live in arctic or northern regions, inhabiting tundra or open meadows. They frequently nest in underground burrows, particularly in winter, although they do not hibernate. They feed on grasses, mosses, and roots, and probably on insects. All are about 5 in. (13 cm) long, with stout bodies, thick fluffy fur, small ears, very short tails, and long claws. The brown to black Norway lemming, Lemmus lemmus, of Scandinavia, is the best known, because of its spectacular periodic swarming. Two or three times per decade, this species undergoes a population explosion of such proportions that the lemmings set out in all directions in search of food. They cross bodies of water by swimming and occasionally some reach and enter the ocean, where they drown. This behavior has given rise to folklore about lemmings committing mass suicide, but the population crashes mainly because lemming predators increase in number in response. Other species of the genus Lemmus are found in the northern portions of Eurasia and North America and sometimes exhibit similar swarmings. The snow, or collard, lemmings, Dicrostonyx, found in the arctic regions of Asia and North America, are pure white in winter and brown, gray, or reddish in summer; this color change is unique among rodents. They are also distinguished by the growth in winter of an extremely long two-pronged claw on the third and fourth finger of each forefoot; these claws may function in shoveling snow. Bog lemmings, members of the genus Synaptus, are found in marshy places in North America as far south as the N United States. The wood lemming, Myopus schisticolor, is found in N Eurasia. The steppe lemmings, members of the genus Lagarus, of S Russia and Mongolia, are properly classified as voles; the North American species of this genus, Lagarus curtatus, is found in the W United States and is known as the sagebrush vole. Lemmings are classified in the phylum Chordata, subphylum Vertebrata, class Mammalia, order Rodentia, family Cricetidae. See mouse.

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lemming

Any of several species of small rodents belonging to the family Cricetidae and found primarily in northern temperate and polar regions of North America and Eurasia. Lemmings have short legs, small ears, and long, soft fur. They are 4–7 in. (10–18 cm) long, including the stumpy tail, and are grayish or reddish brown above, paler below. They feed on roots, shoots, and grasses and live in burrows or rock crevices. They are noted for regular population fluctuations, and for their periodic migrations in spring and fall. Those of the Norway lemming (Lemmus lemmus) are the most dramatic, because many of the migrants drown in the sea. However, lemmings are hesitant to enter water and, contrary to legend, do not plunge into the sea in a deliberate death march.

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Encyclopedia Britannica, 2008. Encyclopedia Britannica Online.

Lemming

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 and are about 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, 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.

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.

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.