Gary Billmeyer, Age 13, Of Des Moines, Ia., for his question:

What is a jerboa?

The timid house mouse scuttles along close to the ground and scurries from one hiding place to the next. But he has hundreds of mousy cousins and not all of them scurry on four feet. Some of them stand up on their back legs and cover the ground with giant leaps. Some of these mousy leapers are the jumping jerboas.

The jerboa is in too much of a hurry to scuttle along like his mousy cousins. He is built somewhat like a miniature kangaroo with a long tail and a pair of extra long, strong hind legs. His tail is tipped with a tuft of hair, and his mousy head is  adorned with a pair of enormous ears. He has the large, bright eyes of an animal who needs to see his way around in the dark, and his round face is set off with a moustache of stiff whiskers.

We never see the true jerboa, because he is a native of the old world. He ranges over the deserts and warm fields of Africa, Asia and Eastern Europe, and he is rarely seen even in his native Chile. The little jumper is a night prowler. He spends the day dozing in his burrow, and after dark he is too small and quiet to be noticed.

He shares his underground tunnels with a colony of friends and relatives. After sunset, he ccmes forth and starts his activities by doing his sitting up exercises. He rolls joyfully around in the sand, stretches his long back legs one at a time and uses the hands on his tiny arms to clean and carefully comb his fur.

Then he stands up on his hind legs to look around. His mousy body may be two to eight inches long, plus a much longer tail. The jerboa may stroll along on his back feet or proceed with small hops in search of food. He dines standing up, using his tiny hands to stuff the food into his mouth.

When startled, or in a hurry, the jerboa covers the distance with giant kangaroo leaps. It is claimed that a large jerboa of Africa cat leap along at 40 miles an hour. His smaller cousins can hop along in two  to six foot leaps with no trouble at all.

There are other mousy mammals that follow the example of the jumping jerboas. But the true jerboas have special features which place them in a family of their own. Their family name is dipodidae  the two footed ones.

Australia has a variety of jumping rodents, and you might think that they had taken lessons frcm the great kangaroo himself. We even have jumping rodents in north America. Our jumping meadow mouse weighs less than an ounce., but the tiny fellow can travel in 12 foot hops. Another jumping mouse of the woodlands ranges all the way from the frozen north to California. But none of the leapers were true jerboas.