Bats | Research & Encyclopedia Articles

Bats, the only mammals that fly, are among nature's least understood and unfairly maligned creatures. They are extremely valuable animals, responsible for consuming huge numbers of insects and pollinating and dispersing the seeds of fruit-bearing plants and trees, especially in the tropics. Yet, superstitions about and fear of these nocturnal creatures have led to their persecution and elimination from many areas, and several species of bats are now threatened with extinction.

There are over 900 species of bats, representing almost a quarter of all mammal species, and they are found on every continent except Antarctica. Most types of bats live in the tropics, and some 40 species are found in the United States and Canada. The largest bats, flying foxes, found on Pacific islands, have wingspreads of five feet (1.5 m). The smallest bats, bamboo bats, are the size of the end of a person's thumb.

Bats commonly feed on mosquitoes and other night-flying insects, especially over ponds and other bodies of water. Some bats consume half of their weight in insects a night, eating up to 5,000 gnat-sized mosquitoes an hour, thus helping to keep insect population under control. Some bats hunt ground-dwelling species, such as spiders, scorpions, large insects, and beetles, and others prey on frogs, lizards, small birds, rodents, fish, and even other bats. The infamous vampire bat of Central and South America does actually feed on blood, daily consuming about a tablespoon from cattle and other animals, but it does not generally bother humans.

Bats that live in tropical areas, such as fruit bats (also called flying foxes), often feed on and pollinate plants. Bats are thus extremely important in helping flowers and fruit-bearing plants to reproduce. In tropical rain forests, for example, bats are responsible for pollinating most of the fruit trees and plants.

Bats are usually social animals. Some colonies consist of millions of bats and use the same roost for centuries. Bat manure (guano) is often collected from caves and used as fertilizer. Most bats come out only at night and spend their days in dark roosts, hanging upside down, sleeping, nursing and tending their young, or grooming their wings and fur. Bats become active an hour or so before dark, and at dusk they leave their roosting areas and fly out to feed, returning home before dawn. Many bats flying at night navigate and locate food, such as flying insects, by echolocation, emitting continuous high frequency sounds that echo or bounce off of nearby objects. Such sounds cannot be heard by humans. Most bats have just one or two young a year, though some have up to four offspring at a time. The newborn must hold onto its mother, sometimes for several weeks, and be nursed for six to eight weeks. Some species of bats live up to 25 years. Most bats in North America migrate or hibernate in caves during the winter, when food is scarce and temperatures reach freezing point. Superstitions about and prejudice against bats have existed for hundreds of years, but most such tales are untrue. Bats do not carry bedbugs or become entangled in women's hair; they are not blind and indeed do not even have poor vision. In fact, except for the occasional rabid bat, these creatures are not dangerous to humans and are quite timid and will try to escape if confronted. In recent years, public education programs and conservationists, such as Dr. Merlin Tuttle, head of Bat Conservation International in Austin, Texas, have helped correct these misconceptions about bats and have increased appreciation for the valuable role these creatures play in destroying pests and pollinating crops. Bracken Cave, located between San Antonio and Austin, is owned by Bat Conservation International and with some 20 million Mexican freetailed bats residing there in the spring and summer, the cave is said to shelter the world's largest bat colony and the largest collection of mammals anywhere on the planet. The pregnant females migrate there in early March from central Mexico to nurse and raise their young, and the colony can consume 250 tons of insects a night.

According to Dr. Tuttle, a colony of just 150 big brown bats can eat almost 40,000 cucumber beetles in a summer, which "means that they've protected local farmers from 18 million root worms, which cost American farmers $1 billion a year," including crop damage and pesticide costs. Dr. Tuttle and his organization suggest that people attract the creatures and help provide habitat for them by constructing or buying bathouses, which his groups sell. Nevertheless, bats continue to be feared and exterminated throughout the world. Major threats to the survival of bats include intentional killing, loss of habitat (such as old trees, caves, and mines), eviction from barns, attics, and house eaves, pesticide poisoning, and vandalism and disturbance of caves where they roost. According to Dr. Tuttle, "Bats are among the most endangered animals in America. Nearly 40 percent of America's 43 species are either endangered or candidates for the list."

Over a dozen species of bats worldwide are listed by the U.S. Department of the Interior as endangered species, including the gray bat (Myotis grisescens)of central and southeastern United States; the Hawaiian hoary bat (Lasiurus cinereus semotus); the Indiana bat (Myotis sodalis) of the eastern and mid-western United States; the Ozark big-eared bat (Plecotus townsendii ingens) found in Missouri, Oklahoma, and Arkansas; the Mexican long-nosed bat (Leptonycteris nivalis) of New Mexico, Texas, Mexico, and Central America; Sanborn's long-nosed bat (Leptonycteris sanborni) of Arizona, New Mexico, Mexico, and Central America; and the Virginia big-eared bat (Plecotus townsendii virginianus) found in Kentucky, North Carolina, West Virginia, and Virginia.

Neuweiler, Gerhard. The Biology of Bats. Translated by Ellen Covey. New York: Oxford University Press, 2000.

Tuttle, Merlin D. America's Neighborhood Bats. Austin: University of Texas Press, 1988.

Raver, Anne. "Batman Returns (The Real One)." The New York Times (May 23, 1993): 18.

U.S. Fish & Wildlife Service. December 2001 [cited May 2002]. <http://ecos.fws.gov/webpage� 03E;.

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