Charles Drake, age 10, of Old Bridge, New Jersey, for his question.
Why do lemmings try to cross the sea?
People used to say that droves of lemmings jump into the sea to commit suicide. Now we know that nature's animals are brave enough to go on living as long as possible. So we must look for another reason to explain why droves of lemmings plunge into the sea.
The famous lemming lives high on the slopes of Norway, Sweden, Finland and north¬western Russia. The pretty creature looks like a large fat mouse. He is four or five inches long, plus a short one inch tail. His furry coat may be brown or marigold yellow, with a black shoulder shawl and a few black smudges on his mousy face.
In summer, he scuttles over the ground, dining on lichens and mosses and low¬ growing grasses. In winter, he lives in tunnels under the snow and keeps on munching the lost growing plants. He shares his life with numerous relatives. And their story is a sad tale of what happens when a crowded population multiplies beyond control.
The little lemmings stay busy summer and winter and the females bear several litters during the year. The three to nine babes are born in a ball shaped nest made of mosses and lichens and shredded stems. Many of those born during the summer are captured by weasels and stoats, by buzzards and owls and other hungry animals. But in winter, when the tribes of lemmings live in safe burrows below the snow, more of them survive. The population multiplies, multiples and multiplies.
After a few years, this population explosion becomes too crowded for comfort. There may not be enough food for everybody. There is no peaceful privacy and the stress becomes unbearable.
But more broods keep arriving and the crowded conditions get worse. From time to time, groups of older lemmings leave the neighborhood in search of food. Usually they migrate to lemming free valleys across the mountains. But sometimes a serious popula¬tion explosion sends swarms of lemmings out searching for new homes.
This does not happen very often, but when it does, many lemmings wander down, down the mountain slopes. Lemmings are fine swimmers with waterproof coats. So when they come to a lake or river they do not hesitate to jump in and swim to the other side.
On their way down the slopes, the lemmings may cross several lakes and rivers successfully. But at last they come to the shores of the sea. As far as they know, it is quite safe to swim across to the other side. But the choppy waves are too much for them and countless lemmings perish.
No, the little lemmings do not plan to commit mass suicide. Far from it. They are searching for new homes where they can continue to feed and multiply. They mistake the wave tossed sea for a crossable stream and this mistake proves fatal.