ALABAMA A&M AND AUBURN UNIVERSITIES

ALABAMA

Bats & Bat Houses SYSTEM

CIRCULAR ANR-757

Bats are among the most misunderstood animals in Alabama. Because they are secretive and active only at night, bats are often feared and needlessly killed. Contrary to common myths, bats are neither blind nor dirty. They do not get caught in people's hair or infest homes with bedbugs.

Like other mammals, a few (less than 0.5 percent) contract rabies. But even rabid bats rarely become ag­gressive or transmit the disease to other animals. When people are harmed by bats, it is usually because they have foolishly picked up a sick bat that bites in self-defense. Records show that pet dogs are far more dangerous.

Bats Are Valuable One bat may eat 3,000 or more insects, including

many mosquitoes, in a single night. Large bat colo­nies can consume billions. The Blowing Wind Cave colony of gray bats in northern Alabama, numbering roughly 300,000 individuals, eats up to a billion in­sects nightly!

Fruit-eating bats are nature's most important seed­dispersing mammals. And nectar-eating bats, along with some fruit bats that visit flowers, pollinate thou­sands of tropical and subtropical trees and shrubs. The extensive list of valuable fruits, nuts, and spices produced by bat-dependent plants includes peaches, bananas, mangoes, guavas, avocados, dates, figs, cashews, carob, and cloves.

Bats use highly sophisticated sonar for navigation, and they are exceptionally long-lived and disease resis­tant. Consequently, they are becoming increasingly

important for research. In the southwestern United States, 100,000 tons of bat guano (bat droppings) was mined from a single cave. Guano continues to be a major source of fertilizer in developing countries, where it is used to fertilize ,a number of crops.

Bat Biology Bats, like human beings, are mammals. They have

hair and give birth to young that feed on milk produced by the mother bats. Forty species of bats occur in the United States, and sixteen of those oc­cur in Alabama.

Bats are the only mammals that truly fly, and they make their living by capturing insects. Most of their feeding is done at night althqugh they may fly in the early evening and during daylight hours on warm winter days.

Although they have good eyesight, they use echolo­cation (sonar) to navigate and capture insects. Bats emit high-frequency sound pulses (human beings can­not hear them) at a rate of 3 to 500 per second. By listening to the echoes, they can "see with their ears:'

Most birds that catch insects "on the wing" use their mouths or beaks. Bats usually capture insects by scooping them into their tail or wing membranes. They then reach down and take the insects into their mouths. This feeding behavior results in the erratic flight pattern you see when watching a bat feed at dusk. Bats drink by skimming close to the surface of a water source and gulping occasional mouthfuls.

Most female bats produce one offspring per year. Alabama bats breed in autumn, and the female stores the sperm until spring, when fertilization takes place. Gestation is short, lasting only a few weeks, and baby bats are born in May or June. The young can fly 2 to 5 weeks after birth. Bats are long-lived for their small size: they can live 30 years or longer.

Few insects are available during the winter, so bats must migrate to warmer areas where there are more insects. Bats that do not migrate must hibernate to survive. Hibernation is a state of inactivity during

which the normal body functions are greatly reduced. For example, a bat's temperature drops from the nor­mall000F to between 40° and 60°F during hiberna­tion. The heart rate slows from 1,000 beats per minute to 12 to 15 per minute. During hibernation, bats live off of stored fat reserves.

Many bats in Alabama hibernate in caves during the winter and move to buildings or trees in the sum­mer. Tree bats roost in trees in summer and move into hollow trees or caves in the winter.

When Bats Meet People Human Habitat. Occasionally a bat may wander

into human living quarters. Th prevent this occurrence, cover chimneys and vents with hardware cloth screens, install draft guards beneath appropriate doors, and seal other access holes, especially around win­dows and plumbing.

Large colonies of bats in attics or walls can become a nuisance and might require eviction. In these in­stances, observe the bats carefully at dusk to find their entry-holes. Plug these holes while the bats are out feeding or during their winter absence. Poisons used against "house bats" are costly and ineffective, and they often create problems far worse than those they are supposed to solve.

Bat Habitat. Millions of bats have been killed by people who explore caves. Although some people in­tentionally kill bats, many others are unaware of the damage they do. Each human entry into a winter hibernating cave causes bats to arouse and waste 10 to 30 days of stored fat reserve. Hibernating bats must conserve their limited fat supplies until spring or face starvation. In the summer, flightless young may be dropped or abandoned when human beings disturb nursery roosts.

The relatively few caves that shelter bats are sel­dom used year-round. Warm summer nursery caves should not be explored from April through Septem­ber. Colder hibernation caves should be avoided from late August through mid-May. Many important caves have signs explaining when they can be visited without harm to the bats.

Alabama's Endangered Bats Two bats that occur in Alabama are classified as

endangered species. They are the gray bat and the In­diana bat. The Endangered Species Protection Act mandates stiff fines and possible imprisonment for those who kill or disturb endangered bats or harm their habitat.

What Can You Do To Help Bats? Never shoot, poison, or otherwise harm bats.

Bats are extremely beneficial insect-eaters. Nuisance bats can be encouraged to move elsewhere without killing them.

Avoid maternity colonies and hibernating bats. Disturbances, no matter how slight, can be harmful.

Do not disturb bat habitats. Cave habitats are fragile and easy to disturb. If you enter caves, do so only as an observer. Leave everything as you found it. Remember, disturbing endangered bats is a fed­eral offense and carries serious penalties.

Put up a bat house. They are easy to build and can attract bats to help control insects around your home and garden.

Construction And Placement Of Bat Houses

Bat houses, like those shown in Figures 1 and 2, have been used successfully for a variety of bat spe­cies. Regardless of the kind of house you build, the inner surfaces must be rough enough for the bats to climb. Do not paint your bat house: paint or varnish may be a repellent to bats. Rough-sawn cedar or cypress is best to use because no painting is needed.

Bat houses should be fastened to a tree trunk or the side of a building about 12 to 15 feet above the ground. The best place is where they will get morn­ing sun but will be shaded in the afternoon.

Sometimes bats move into a bat house within a few weeks. However, bats may require a year or two to find a new bat house. Chances of early occupancy can be increased by hanging your houses before April. Houses are usually occupied more quickly if bats are already present in nearby barns or attics.

References Information in this publication was adapted from: Arkansas Bats: A Valuable Resource, by Michael J.

Harvey, Arkansas Game and Fish. Suggestions for Building Bat Houses and Attracting

Bats, by Bat Conservation International, Milwaukee, Wisconsin.

About Thur Bat House, by Bat Conservation Inter­national, Austin, Texas.

Bats and Their Conservation, U.S. Fish and Wild­life Service, Washington, DC.

H. Lee Stribling, Extension Wildlife Scientist, Associate Professor, Zoology and Wildlife Science, Auburn University

For more information, call your county Extension oftice. Look in your telephone directo· ry under your county's name to find the number.

Issued in furtherance of Cooperative Extension work in agriculture and home economics, Acts of May 8 and June 30, 1914, and other related acts, in cooperation with the U.S. Department of Agriculture. The Alabama Cooperative Extension System (Alabama A&M University and Aubum University) offers educational programs, materials, and equal opportunity employment to all people without regard to race, color, national origin, religion, sex, age, veteran status, or disability. UPS, 10M06, Rep. 10:96, ANR-757

Materials: one 12-foot piece of 1" x 8" (actual measurements will be slightly smaller) untreated, rough-sided cedar one 11-inch piece of 1" x 10" untreated, rough-sided ce­dar (This will be the top.) about 20 six-penny galvanized nails Tools: skil saw with crosscut blade hammer ruler tape measure pencil

Dimensions: Back Sides Front Partition, 2 Partition, 1 Roof

1 X 22" X 7 14" 2 X 22" X 714" 1 X 1714'' X 714" 2 X 12" X 714" 1 X 11" X 714" 1 x 11" x 914" wide

Spacing Between Partitions: Front to back %", %", %", 11/z"

9"

22"

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Materials: one 10-foot piece of 1" x 10" (actual measurements will be slightly smaller) untreated, rough-sided lumber one 6-foot piece of 1" x 12" untreated, rough sided lum­ber (This will be the roof and sides.)

1-- 9%''~1 about 30 six-penny galvanized nails 1-i Tools: skil saw with crosscut blade jigsaw hammer ruler tape measure pencil

Dimensions: Roof Front Back Ceiling Partitions, 3 Partitions, 2 Sides

16 Vz x llW' 18% X 91/4" 27 X 91/4" 9% X 9%" 9 W' wide x 8" high 9 W' wide x 14" high 11 W' wide x 27" at back & 18 %" at front

Spacing Between Partitions: Front to back%",%" , %", 1", 11/z", 1%"

11;4"

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