The only mammal that flies is the bat. Because of this trait, bats are often mistaken for birds. Bat wings differ from bird wings, however, in that they are covered with skin, not feathers.

Where bats live

About 900 kinds of bats are known, more than any other kind of mammal except rodents. They are found worldwide but are particularly abundant in the tropics. The United States is known to have 40 species of bats. In North America the little brown bat is the most common type.

Bats generally prefer dark places such as caves, hollow trees, or attics. Some bats, however, rest outdoors on trees or rocks. Usually bats are found in groups, or colonies, ranging from a few dozen to hundreds of thousands of individuals.

Physical characteristics

Bats vary greatly in size. The largest of the bats known as flying foxes has a wingspread as wide as 5 feet (1.5 meters). The wingspread of the tiny Kitti's hognose bat, however, is only about 6 inches (15 centimeters).

Bats also display variety in color, fur texture, and facial appearance. The muzzle often resembles that of a rodent or fox. The ears point forward and are usually very large. Bats have fur in shades of gray, tan, brown, or black on the back and in lighter shades on the sides.

Bats have long arms and hands, with especially long fingers. The fingers are joined by a thin membrane that extends from the arms to the tiny legs. This membrane serves as the bat's wings.

Feeding habits

Nearly all bats rest during the day and search for food at night. Most bats eat insects. A brown bat may eat half its weight in insects in one night. In some parts of the southern United States, huge roosts, or shelters, have been erected for bats because the bats are so useful in controlling the insect population.

Some bats have specialized diets. Several species are carnivorous, or meat eating. They feed on a variety of prey, including birds, smaller bats, rodents, and fish. Other bats feed on fruit, pollen, and nectar. The famous vampire bats of South and Central America feed on the blood of mammals and large birds. These bats sometimes serve as carriers of rabies.

Life cycle

Female bats usually bear one young at a time. The pregnancy can last from six or seven weeks to five or six months, depending on the species. Infants are born nude or with light fur. They nurse for five or six weeks or for as long as five months.

Bats have a long life span for animals of their size. Some bats are known to have lived more than 20 years.

Flight and navigation

Bats are well adapted for flying. Most bats cannot walk or run. A bat's legs and feet are only strong enough to hold on when it hangs upside down from a perch, which is how bats rest or sleep. To start flying, a bat drops from its perch. If it is on the ground it usually crawls to some height, using its wing hooks and weak legs, until it can drop into the air. It can, however, take off from a position on the ground if necessary.

Bats can chase insects through thick forests on the darkest night without striking a branch or twig. While flying, most bats send out a continuous cry, so high-pitched that people cannot hear it. These sounds are reflected by obstacles in the bat's path and echo back to the bat's sensitive ears. The animal instantly responds to the signals and avoids the obstacles.