Bats are mammals and warm blooded, just like us. They have fur, give birth to live young who feed on their mother's milk, see quite well, and are generally shy and gentle. There are close to 1000 different kinds of bats - about 20 percent of all the mammal species in the world. Bats are the only true flying mammals in the world. They range in size of a bumblebee which lives in Thailand and weighs less than a penny, to flying foxes in Asia with nearly six-foot wingspans and weighs around two pounds. Bats can be found throughout the world except for certain oceanic islands, the Arctic and Antarctic.

Bats are mammals belonging to the order Chiroptera, a name of Greek origin meaning "hand-wing," which accurately describes the animal's most unusual anatomical feature. Their wings are modified arms and hands with extremely long fingers. Stretching between these fingers on their arms, and also their hind legs and tail, are two very thin, tough, almost transparent layers of skin. The color of their fur can be gray, brown, black, white, reddish, yellow or brightly colored patterns. Bats are extremely clean animals. They groom themselves daily with their tongues, similar to cats.

There are two categories of bats: megabats and microbats. The larger, or megabats, generally have big eyes and small ears, and fox-like faces. About 150 species of bats feed on fruit, nectar, or pollen. They live in the tropics and usually do not hibernate. Microbats composes the rest of the bat families, some 17 in all. These families are further classified into about 900 species. They are smaller, are insect eaters and rely more on their ears than their eyes to find food. Some bats can eat as many as 600 mosquitoes per hour. Many of them must hibernate in the winter when insects are not available.

Bats are nocturnal, which means that they are mostly active at night and sleep during the day. They sleep upside down by hanging onto the tops of caves, trees, or buildings with toe claws. During the night bats search for food, using echolocation to find it. They send out hundreds of high-pitched sounds per second. By reading the echoes that return to them from nearby objects they can "see" what is around them.

Many species of bats live in huge colonies of thousands or even millions of bats, while others are solitary. In cold climates, as winter approaches, bats must either migrate to warmer areas or hibernate. Migrating bats may travel only a short distance or hundreds of miles. They can fly as fast as 60 miles per hour. Those bats that hibernate enter a state of dormancy; their body temperature drops, their breathing slows to once or twice a minute, and their heart rate drops from 200 to 20 beats per minute. In this state they are very vulnerable to being disturbed and could die.

Bats can live to relatively old age if they can survive the first few weeks. Mortality is high among young bats because some fall from the roof of their shelter and are unable to climb back up. Otherwise they could reach the age of about 20 and in one documented case of a brown bat, to 30. Certainly they attain a longer life span than other mammals of similar size such as rodents that live for only one to two years.