There are over 900 species of bats worldwide. They are mammals, accounting for about one fifth of the mammals species population. They are the slowest reproducing mammal for their size. Most species only give birth to one pup per year, but some species do give birth to three to four. Females give birth to live young and they are fed on milk produced by the mammary glands. Some species of bats live up to 30 years.
Bats range in size from .07 ounces to three pounds. The smallest species of bat is the Bumblebee bat. This tiny bat weighs less than a penny. The largest species of bat is the flying fox.
Bats typically live in caves. They will also sometimes live in abandoned buildings or barns. They are nocturnal. They sleep hanging from their feet during the day and fly at night. Bats are extremely clean animals that groom themselves daily.
Bats are the only true flying mammal. Most bats have reasonably good eyesight, but they depend mainly on echolocation for navigation. They emit a very high frequency sound, too high for the human ear to detect. They use this to locate objects in their path and also to locate food. Their abilities are so precise that they can avoid an obstacle no wider than a piece of thread.
Most United States species of bats feed on insects. They capture insects either in their mouths or by scooping them into their tail or wing membrane. Bats are the only major predators of night flying insects. A single bat can eat as many as 1,000 mosquitoes in one hour.
Some species of bats outside the US feed on other things. Some feed on fruit and others feed on nectar and pollen. Many of these bats are an important part of pollination. Some species of plants depend on them entirely for pollination.
One of the most well known species of bats is the vampire bat. They are found in Mexico, central and South America. They feed on the blood of warm blooded animals, such as birds and cattle. They do not suck the blood as some believe. Instead, they use their teeth to make an incision in the skin and they drink the blood as it flows out. Their saliva contains an anticoagulant that helps prevent clotting. The amount of blood consumed is usually very small and normally causes little or no harm to the animal. This species of bat is also unique in that it will adopt orphaned pups. They will also risk their own lives to provide food for other bats.
Bats are not usually aggressive towards humans unless they are frightened. There is a common misconception that bats carry rabies. Less than half of 1% of bats actually carry rabies. Less than 40 people in the US have contracted rabies from bats in the last 40 years. Of course, you should use the same caution with bats as you should with any wild animal and avoid any physical contact. Any warm blooded animal is capable of contracting rabies.
Many species of bats are declining. There are six species of bats in the United States listed as endangered. There are three others outside the Continental US that are also endangered. 20 other species may be listed on the threatened or endangered list in the near future.
Disturbance of hibernating bats is a significant threat. Because many bats feed on insects, they hibernate during the winter to conserve fat and energy. When they are disturbed by humans entering their caves, they use up some of the stored fat needed to get through the winter. A single disturbance can use up enough fat to sustain a bat for two to three weeks. If disturbed too often, the bats will starve to death before spring.
Disturbance of maternal colonies is also a problem. Mother bats that are panicked will often drop their babies. The babies, too young to fly, fall to their deaths. They may also abandon the babies when frightened by intruders.
Other threats to the bat include pesticides and other chemicals, loss and destruction of habitat, and killing.
Division of Endangered Species, Bats
Organization for Bat Conservation