BATS' NEW IMAGE

By Anastasia Toufexis

If ever a creature seemed conjured by the forces of darkness, it is the bat. With webbed wings and feral face, the furry little beast appears to be the offspring of some monstrous union of bird and rodent. Over the years, legend has had it that bats are filthy and nasty (they feed on human blood) and that they possess spooky supernatural powers (they shift shape from bat to man). No wonder they have been a motif of countless horror tales and films.

This image, however, is the product of imaginative folklore, stubborn myth and terrible p.r. The bat, say scientists, is actually one of nature's most dazzling and precious creations. Today researchers are striving to correct common misapprehensions about them--and racing to save them from extinction. Last week in Boston, the largest ever convocation of bat experts met to trade new findings from the weird and wonderful world of bats. Among recent discoveries:

While most species of bats live in vast colonies in caves or trees, some nest in spider webs; others fashion "tents" out of leaves. In southern India, for example, the male short-nosed fruit bat spends as long as two months painstakingly chewing the veins of leaves and palm fronds until they collapse into a shelter that will house him and a harem of as many as 20 females.

Bat pups can weigh as much as a quarter of their mother's heft--the equivalent of a 100-lb. woman giving birth to a 25-lb. baby.

Most mammals wean their young when they reach 40% of adult size, but bats continue nursing their offspring until they are almost fully grown. The reason: pups need the extra time to attain the large wingspan and wing surface required to fly.

Bats' built-in echolocation system is so finely tuned that it can detect insects' footsteps, changes in air currents caused by vibrating insect wings, even the ripple in a pond as a minnow's fin breaks the surface.

According to the fossil record, bats were soaring in the sky at least 55 million years ago. These ancient flyers, says evolutionary biologist Nancy Simmons of New York City's American Museum of Natural History, were "virtually indistinguishable from today's echolocating bats." Though laymen think they most resemble rodents, bats' closest cousins are primates. Modern bats are amazingly diverse; about 1,000 species account for nearly a fourth of all mammal species. The only known group of flying mammals, they range in size from Thailand's tiny bumblebee bat, weighing less than a penny, to Indonesia's giant flying fox, with wingspans of nearly 6 ft. Many bats feed on insects, while others prefer fruit, nectar or pollen. A few feast on fish, frogs, rodents and, yes, blood. Contrary to legend, however, vampire bats, which dwell in Latin America, suck the blood of grazing cattle and horses, not sleeping humans.

Essentially docile, bats play a vital role in maintaining ecological balance. For one thing, they protect crops from marauding insects. The 20 million Mexican free-tailed bats that roost in Bracken Cave near San Antonio, Texas, from spring to fall consume 250 tons of insects every night as they swarm to altitudes of 10,000 ft. Farmers are not the only ones who benefit. A single little brown bat can speedily clear a suburban backyard of pesky mosquitoes, lapping up 600 bugs an hour.

Flower-browsing bats are prodigious pollinators and spreaders of seeds. When bats were kept away from an area in Curacao, researchers found that one type of cactus produced 90% less fruit and another produced no fruit at all. "The whole island fauna--birds and animals--relies on the cactus fruit to get through the dry season," observes zoologist Merlin Tuttle, founder of Bat Conservation International, based in Austin, Texas. In North America, long-nosed bats pollinate more than 60 species of agave, including those used by Mexico's tequila industry.

While folklore has enshrined the notion that bats are blind, all of them can see, and some species, such as Asia's fruit bats, boast extraordinary night vision, which they use to find food. But most bats rely on echolocation, emitting pulses of ultrahigh-frequency sound some 10 times a second, then decoding the sound waves that bounce back from objects. "The time delay and the angle together give the bat the position of the target," explains neurobiologist Uli Schnitzler of the University of Tubingen in Germany. The scans are so discriminating that "bats can discern the scales on a moth or the difference between a rock and a beetle," notes Boston University biologist Thomas Kunz. And so fast--the brain analyzes the data in microseconds--that a bat can snatch two insects within a single second.

Despite such stunning skills, bats are struggling for survival. Pollution and human encroachment are destroying their habitats. New Mexico's Carlsbad Caverns, once home to 8.7 million bats, now harbor fewer than a million. More than 40% of the U.S.'s 44 species are threatened or endangered. Fear has also taken a heavy toll. In Latin America, people routinely dynamite and burn caves and roosts. "They think every bat is a vampire bat, and they kill all they can find," laments Kunz.

Scientists are lobbying hard to save the bat. Captive-breeding programs have been established in the Philippines as well as on several islands in the Indian Ocean. In India, legislation is being pushed to remove bats from the vermin category. The Convention on International Trade in Endangered Species (cites) bans traffic in fruit bats in the Pacific, where some people eat them.

In the U.S., Bat Conservation International has spearheaded education efforts, offering workshops for government officials and distributing books and videos to the public. In the past five years, more than 100 iron gates have been installed at cave mouths and over mine shafts to let bats in while keeping vandals and spelunkers out. On a smaller scale, Americans are busily erecting bat houses in their backyards along with the birdhouses.

Nowhere has the change of heart been more visible than in Austin. In 1980, when repairs under the Congress Avenue bridge inadvertently created attractive roosts for more than a million Mexican free-tailed bats, frightened citizens demanded their ouster. Familiarity, however, bred content. The bridge has now become a tourist attraction, and others like it are being built. And the city's new minor-league baseball team may wind up being called--what else? --the Bats.

--Reported by Sam Allis/Boston and S.C. Gwynne/Bracken Cave

With reporting by SAM ALLIS/BOSTON AND S.C. GWYNNE/BRACKEN CAVE