September 26, 2009

Lemming

The life and mythology of a northern rodent

The Dominion - http://www.dominionpaper.ca

Lemmings are small, hardy rodents who live in the tundra of northern Canada, Greenland, Europe and Asia. Rather than hibernating through the winter, lemmings eat stored grass clippings, and forage beneath the snow for roots and bulbs. The lemming's long, soft fur keeps it warm in harsh weather, and its extremely short tail cuts down on heat loss.

Though they are close relatives of hamsters, gerbils and mice, lemmings have long been distinguished by their place in pseudo-scientific folklore. A 16^th century geographer from Strasbourg, France, posited that lemmings fell from the sky during stormy weather. A century later, this theory was refuted by a Danish scholar, who concluded that lemmings could be carried by the wind, but were not generated by clouds.

More recently, lemmings have come to be known as creatures that spontaneously commit group suicide, gripped by a sort of herd mentality. The myth largely dates to a 1958 Disney documentary, White Wilderness. The film's producers had difficulty finding migrating lemmings in northern Alberta, where the creatures are not native. Disappointed but not discouraged, a photographer paid Inuit children from Manitoba to catch dozens of lemmings. The furry rodents were placed on a turntable covered in snow and made to run, simulating migration. Later, the hapless creatures were herded off a cliff, with cameras recording the apparent suicide from a low angle.

The myth of lemming suicide has its roots, however, in what appears to be adaptive migratory behaviour on the part of these industrious furballs. In times of abundant food, lemmings can reproduce rapidly. From birth, the creatures can reach sexual maturity within a month, and produce litters of around 10 baby lemmings. When the lemming population in an area outstrips the food supply, the small herbivores disperse in all directions in search of shoots, grass and roots. In their migratory fervour, lemmings will sometimes overestimate their capacities, and die while swimming across a particularly swift river or large body of water.

In addition to limited food supply, lemmings must also contend with predators that depend on the long-toothed rodents for much-needed sustenance in a sparse landscape, including the snowy owl, the arctic fox and the long-tailed skua.

While lemmings' periodic population booms and busts have led to some misunderstanding, the behaviour may be a potent strategy for the species' continued existence. In a land where food is quite scarce, these population explosions and migrations keep the lemming population vital over a vast, inhospitable, globe-circling expanse. Some observers have noted that in areas with much less variable conditions such as rainforests, lemming-like population growth is far less likely to occur.

Beyond its own survival, the lemming is a major source of food for other northern animals such as ermines and gyrfalcons, whose populations in many cases rise and fall with that of the lemmings. —DOJ

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