Christine Didas, age 11, of Someville, Massachusetts, for her question:
Why do lemmings jump into the water?
No sensible person takes a flying plunge into a deep pool unless he or she has first learned how to swim. Lemmings, of course, are animals. Their actions are governed by the strict voice of nature. And nature wipes out animals that tend to take foolish chances, especially when they carelessly risk their lives.
Lemmings jump into the water because they are expert swimmers. They are born with a built in know how for coping with streams and rivers. When the grass looks greener on the other side of a creek, into the water they plunge and boldly strike out for the opposite shore. Lemmings are voles, first cousins of the dainty meadow mice. All these small, furry members of the big rodent clan are vegetarians. Their diets include grasses and mosses and other low growing greenery within their reach.
The adult lemming is a sprightly bundle of fur about six inches long. As a rule, his coat is buff or golden brown. One type wears a darker stripe down his back. The Scandanavian lemming has a glossy black head and shoulders. The lemming is a native northerner of the wintry polar region. His paws are padded with fur to protect his tiny toes from ice and snow. He has no outer ears to get frost bitten and his smooth round face has the rather bewildered expression of a puzzled kitten.
The lemming's character is very, very sociable. He shares his life with a large community of friends and relatives. In winter, the tribe lives under the protective blanket of snow. They dig themselves a network of tunnels at ground level where mosses and other small plants also thrive under the snowy blanket. In summer they scuttle around for greenery and often swim gushing streams of melting snow to find it.. Out in the open, many of them are caught and devoured by foxes and weasels, owls and other birds of prey.
All would be well if the female lemmings had fewer babies. But oh, how they multiply. The breeding season lasts through the long months of the northern summer. And every 18 days, each mother in the community produces a litter of about five new babies. The youngsters grow up fast. These extra mouths need extra food. The local plants cannot grow fast enough to meet their needs. Soon the hungry lemming must forage far from home, walking long distances over the tundra land and swimming across the many streams in their path.
But the multiplication continues to increase the lemming population and things get worse. After three to five years, something drastic must be done. So most of the adults leave the community to find a new home far away in an unpopulated area. Thousands of them start forth on a long trek, crossing streams and dining on the greenery along the way. The furry travelers are joined by swarming companions from other over populated lemming communities. Finally they reach what seems to be a big lake or an extra wide river. It is the sea. The bold little travelers plunge forward into billowy waves and the immense, unswimmable ocean swallows them up.
People who observed these disasters assumed that from time to time the lemmings commit mass suicide. But this notion was hard to explain. After all, nature has strict rules against self destruction and deliberate suicide is unknown in the animal kingdom. Nevertheless, thousands of lemmings do plunge into the sea. However, it seems likely that the splendid little swimmers simply mistake the immense ocean for just another stream or lake to be crossed on their way to a greener landscape.