Friday, November 21, 2008

Lemmings under threat

You know lemmings. The small furry rodents that supposedly arrive in plague proportions and then suicide en masse as the food runs out. Incidentally, does anyone else remember the game “Lemmings”, which was released in the 1990s? The obsession of a generation of kids, you can play it here if you are in the market for some time wasting or nostalgia… But I digress! Some new research has revealed that global warming is threatening the lemmings in a most peculiar way. No, these little critters haven’t been driven to suicide by frustration about the lack of human action to prevent climate change…

In fact, the idea that lemmings commit suicide is a myth. What really happens is that in some years they become superabundant (because more young than usual survive- female lemmings can have up to three litters of 12 young per year!), which means that food becomes scarce. During these times they can become so hungry that they disperse in large numbers and to find food. Occasionally, large groups will leap into the sea (sometimes from a cliff!) and swim off to find food, which led to the myth that they commit suicide.

But where does climate change fit in? The new research, published in Nature this month, has shown that lemming numbers are declining because the ‘wrong’ type of snow has been falling in Norway. During winter, lemmings live in the subnivean space that forms between the top layer of snow and the ground. Here, they can remain protected from predators and insulated from cold weather, feeding on the exposed herbage, until the end of winter. Recently, though, this type of snow has not been forming, and worse still, freeze-thaw cycles have meant that a layer of impenetrable ice has been forming over the moss. This has led to a decline in lemming numbers, which will of course have knock-on effects up the food chain on populations of predators such as Arctic foxes and snowy owls. This is just another example amongst many showing that we humans must change our ways if we are going to ensure the survival of the planet.

A lemming- the real kind!

1 comment:

  1. The wrong sort of snow also stops trains in the UK.
    Oh, and leaves on the tracks.

    Always thought this odd as in Australia we have camels on the track and they don't appear to stop the Ghan, but in the UK the snow and leaves do. Also would have thought they would anticipate this, it being the UK, with deciduous trees and snow and all.