The mating season is normally in March. Along about June the young are born, with this species only one to a female, although in some species a litter of four is born.
The single baby will weigh a fourth as much as its mother. Upon birth it clings to its mother's body night and day until it is strong enough to fly by itself, remaining tight even while the mother flies into the night in search of food.
© BY ROBERT NYMEYER
The habits of bats vary in respect to their living quarters. When insects are abundant, the size of the bat population increases, having been estimated at times to be as high as 7 million in the Carlsbad Caverns alone. As the supply of insects decreases, so does the number of bats. Where they go, and whether or not the same specific bats return in times of insect plenty is not definitely known.
One of the first surveys of the bats in the Caverns discovered that the number seems to grow in the fall, indicating that the cave was used primarily as a home principally for hibernation during the winter.
More recent observations indicate that, at the present time at least, the bats winter somewhere else and live in the cave only during the summer months, going elsewhere to spend the winter. Recently several thousand bats were banded by naturalists and of those which have been returned, one came from Jalisco, Mexico, some 800 miles south of the Caverns.
If both observations were correct, and it may be assumed that they were, for both were made by naturalists, then the habits of the bats do change, but what prompts these changes is still a matter of speculation.
Other matters of speculation are just how the bat flies so accurately in the dark, darting swiftly past innumerable objects yet never hitting one of them. Scientists call this phenomenon "echolocation," a sort of sonar principle by which the little mammals let out a high frequency squeak and judge the distance of objects by the time required for the echo to bounce back to their sensitive ears.
Another mystery is how they find their way unerringly back to the cave, in the early morning as well as after a sojourn to some other area of the world, and how they know when the supply of food has increased to the point that it is sufficient for them to return.