Sharon Wilson, age 11, of Tacoma, Wash., for her question:

WHERE CAN YOU FIND A PACK RAT?

A pack rat looks very much like a house rat but it has softer fur and a hairy, instead of a naked, scaly tail. The pack rat also has cleaner habits. It can be found all across North and Central America. Some of the pack rats live on mountains and build their nests on rock ledges. Others live in deserts in clumps of cactus and scrubby growth. They make their nests of sticks.

A female pack rat will have one or two litters each season, with from three to six babies in each litter.

A pack rat will pick up and hide or carry home small articles that catch his fancy. Sometimes in his nest you'll find silverware, nails, brightly colored stones or buttons. This is why he received his name.

Sometimes the animal will drop and leave behind something it is carrying, in order to pack off a more attractive item. Because of this habit, he is sometimes called the trade rat.