Bat Houses Educate an Entire Community

SIX YEARS AGO, Amanda Lollar found an injured Mexican freetailed bat (Tadarida brasiliensis) lying on the sidewalk in Mineral Wells, Texas, and the experience changed her life. She nursed it back to health, wrote a book about the experience, joined Bat Conservation International, and began enthusiastically educating people about bats.

In the spring of 1993, she began her most successful educational effort yet when she convinced leading businesses in town to put up bat houses. As word of her work with bats spread in the small town, business owners began to turn to her to solve their problems with free-tailed bats in their buildings. They complained that the bats' odors and unexpected appearances were hard on business. The owner of the funeral home was especially distressed; bats flying around coffins did not create a very comforting atmosphere for visitors, he explained.

They struck a deal: she would help if each business agreed to provide an alternate roost for the evicted bats in the form of a bat house hung close to where bats entered their buildings. No one wanted to be first, but as soon as several of the more prominent businesses erected their bat houses, others followed.

Amanda's father, who had agreed to build the houses, was soon overwhelmed with requests, so they enlisted the Mineral Wells High School woodworking class to help. The students were enthusiastic about the project and between them turned out 21 houses. The houses are now prominently displayed on businesses throughout town, many of which are on buildings that never had a bat problem. Some of them blend into the building's architecture and color and are hardly noticeable, while others incorporate bits of artwork to the bat houses along with the name of the business and company logo emblazoned across the front. People who were once upset that bats were living in their buildings now boast about how large their colonies are, and tourists wander around town in the evenings watching for bats to emerge from the bat houses.

In addition to educating a town, Amanda has contributed greatly to knowledge of bat preferences in hot southern climates. Fifteen (71%) of her first 21 bat houses were occupied last summer by colonies ranging in size from 5 to 250 bats each, averaging about 80. She suspects that numbers are substantially higher this spring; most of the houses will hold up to 500 bats, a few over a thousand. She began erecting them, one by one, in February. Most were put up during the spring, and several more were installed from August to as late as November. The first four houses were put up adjacent to where colonies were excluded in the spring of 1993 and were occupied by the next morning. Ten of her occupied houses were chosen without exclusion.

Amanda's bat houses are similar to BCI designs, though she has included sloping bottoms that allow droppings to fall out through an inch-wide entry along the back. Each includes a single partition and two one-and-a-half-inch-wide roosting chambers covered with fiberglass screening. Her exterior dimensions vary, but are most often about 10 inches tall by four inches wide and 30 inches long. Backboards extend two inches above and five inches below the house to facilitate mounting. In addition, the bottom extension is horizontally grooved for the bats to land on before entering the house. Several inches above both sides of the main entrance at the bottom, there are also side slots with one-inch-wide "landing platforms." These three-quarter-inch high by three-inch-wide slots were intended as additional entry points, but since most bats enter and exit through the bottom, the slots simply serve as vents similar to those BCI now recommends.

All houses were sealed with two to three coats of outdoor house paint, mostly either white or brick red (to match the building) and average 4.8 hours of daily sun.* Some receive as little as two hours or as much as 10. Of houses attached to brick buildings, nine that are brick red and receive two to seven hours of daily sun are all occupied. Two tan houses receiving 4.5 and 10 hours of sun are both used, as are three cream-colored houses that receive 4-4.5 hours. Four white houses exposed to one to five hours are not occupied, though two that receive six and eight hours are. Brickred houses contained, on average, three times more bats than cream or white houses. All occupied houses are attached to stone or brick buildings, 25 to 60 feet above ground. Height is a known advantage, and stone surfaces act as heat sinks, lowering bat house temperatures by day and warming by night. In this case, house color appears not to be as great a factor as sun exposure and mounting substrate.

This summer, Amanda will test her design, as well as BCI's newest nursery designs, mounted in east-west facing pairs, 15 to 20 feet high on poles, to determine the extent to which local bat needs can be met without houses being mounted high on buildings.

Important clues to Mexican free-tailed bat needs can be gained from close examination of Amanda's five bat houses that failed to attract occupants. Three are painted white and face north. Current data indicate that even southern bats like four to six hours of daily sun on their houses, probably explaining failure. The only house mounted on a tin-sided building failed, perhaps either because it lacked the heat-sink effect of stone or because bats had difficulty landing. The fifth unoccupied house is located within a few feet of a bright and noisy street light. However, about 40 feet away from the light, on the same side of the same building, another identical and similarly mounted house is successful.

With so many newfound bat enthusiasts to help, Amanda intends to expand her bat house project. Additionally, she has founded the nonprofit Beneficial Animal Teaching Society and has a goal of building a local bat education center. Her presentations, using BCI audiovisual programs and other materials, are popular throughout her community of 14,000 people. Now she will focus primarily on local schools, also involving students in her bat house research. Clearly, a community where bats outnumber people has a good reason to learn about bats!

(Amanda Lollar's book, The Bat in My Pocket, is available from BCI's catalogue.)

*Sun-exposure times were taken in mid April.