Creatures Of The Night Help Guage Timber Practices

In a three-year study begun recently at Mississippi State, bats--the only mammals that fly--are helping university researchers gauge the environmental health of a commercially managed forest. Led by vertebrae ecologist Francisco J. Vilella, the effort is being funded by the Weyerhaeuser Corp.

Vilella, an assistant leader of the Mississippi Cooperative Fish and Wildlife Research Unit in the Forest and Wildlife Research Center, said bats are a major component of forest ecosystems and will provide one measure of how timber operations affect biodiversity.

As a leading international forest products company, Weyerhaeuser holds distinctions, among other things, as the world's largest owner of merchantable softwood timber and the world's largest producer of softwood and hardwood timber.

"A commercial forest, unlike an undisturbed native forest, is made up of trees that are usually of the same age and type," Vilella explained. "Focusing on an intensively managed pine forest in Mississippi, we are looking at the roost site selection, habitat use and movement of red bats in particular."

Vilella said bats, like birds, "are a good indicator of environmental health" because they feed on insects and are highly susceptible to environmental influences.

Evaluating the effects of timber management practices on bats can help commercial companies make decisions about when and how to harvest trees while simultaneously protecting animal habitats, Vilella said.

While they migrate during winter to Central America, the Caribbean and Mexico, red bats spend their summer months in Mississippi and other Southeastern states. Females of the species also spend the summer--a primary timber-harvesting season--giving birth to their young.

To gather his airborne assistants, Vilella and graduate student Leslie D. Welch of Jakin, Ga., string nets around the sides of bridges and over streams, both primary areas in a bat's flight pattern. When safely in hand, the animals are gently fitted with tiny radio transmitters that are secured with surgical cement. After a couple of weeks, the radios fall off.

"It's a challenge to work with the radios because they are really small and their range is short," Vilella said. Further defining both "challenge" and "short," he explained that bat flight patterns must be monitored no farther than a quarter of a mile from where the animals go about their nightly routines.

Based on early results of what he readily admits is a most-unusual study, Vilella said the initial data shows adult female red bats with young to have an average home range of 138 acres, while the home ranges of breeding females may be as large as 264 acres. For adult males, the home ranges are larger, averaging 363 acres but extending to as much as 553 acres, he said.