Bill Cann, age 13, of Arlington Heights, Ill., for his question:

HOW MANY ENDANGERED SPECIES ARE THERE?

A number of wild animals and plants have become extinct since 1600 in North America including the Carolina parakeet, the passenger pigeon, the California grizzly bear, the Florida black wolf, a birch from Virginia and the Franklinia tree in Georgia. But efforts continue and we are winning some of the battles. Now classified as saved were the once endangered American bison and the California big tree.

Now endangered is the California condor, a bird that is down in numbers to about 50. Threatened is the gray wolf and on the rare list is Southern California's Torrey pine tree.

Still facing danger is the blue whale, the Asiatic lion, the Bengal tiger, the whooping crane, the orangutan, the ivory billed woodpecker and the Asian rhinoceros.