Moreover a mother bat is just as devoted to her babies as any other mammal. She takes entire charge of them, with never any help from the father bat. Young bats are blind at birth, but their eyes open on the fifth day, and on the thirteenth day the baby bat no longer clings to its mother, but roosts beside her. The bat has from two to four young, depending on the species. Most young bats can fly and forage for themselves when they are about three months old, although the silvery bat begins to fly when it is three weeks old. No bat makes a nest. Titian Peale, of Philadelphia, in an early natural history, tells a story of a boy who, in 1823, caught a young red bat and took it home. Three hours later, in the evening, he started to take it to the museum, carrying it in his hand. As he passed near the place where it was caught, the mother bat appeared and followed the boy for two squares, flying around him and finally lighting on his breast, until the boy allowed her to take charge of her little one. The bat has but few enemies. They are occasionally caught by owls, probably taken unawares or when hanging in some dark tree. In fact, virtually the only enemies a bat has are fur-lice, which breed upon them in enormous quantities. It is this misfortune, and the fact that a bat has a strong rank smell like that of a skunk, which keep it from being popular as a pet. A friend of mine once, however, kept a little brown bat, which had been drowned out from a tree by a thunder-storm, for a long time under a sieve as a pet. The bat became tame and would accept food, and it was most interesting to see the deft, speedy way in which he husked millers and other minute insects, rejecting their wings, skinning their bodies, and devouring the flesh only after it had been prepared entirely to its liking. He would wash himself with his tongue and his paw, like a cat, using the little thumb-nail at the bend of his wing, and stretching the rubbery membrane into all kinds of shapes, until it seemed as if he would tear it in his zeal for cleanliness. A bat always alights first by catching the little hooks on its wings. As soon as it has a firm grip with these, it at once turns over, head downward, and hangs by the long, recurved nails of the hind feet, and in this position sleeps through the daylight. It sleeps through the winter in the top of some warm steeple or, far more often than we suspect, in dark corners of our houses, and sometimes in hollow trees and deserted buildings and caves. Only when caught by the cold does the bat hibernate. Often it migrates like the birds.