Baron Poulin, age 9 1/2, of San Diego, California, for his question:

Why does a beaver build a dam?

The fat, furry beaver is a gentle character and not very fast on his feet. Foxes and coyotes, mountain lions and other hungry hunters would like to eat him. He cannot outrun these enemies or hope to hide in the bushes. But he can outsmart them    because they are poor swimmers and some of there hate to get net. The beaver happens to be more at home in the water than he is on land.

He is a champion swimmer. When a hungry foe approaches, he dives in without a ripple and disappears under water. He builds a home on a small private island. But if the streams and ponds dry up, the beaver and his family are left high and dry with no protection from their hungry enemies. So, before this happens, he builds dams across his streams. They are bar¬riers that slow down the flowing water and make iv back up into storage pools. The beaver builds his dams to keep plenty of water nearby at all times.