URI Prof. Peter August in front of one the barns on the Alton Jones campus that is the home to about 100 brown bats.

The Providence Journal / Kris Craig

WEST GREENWICH — It’s dusk at the University of Rhode Island’s Alton Jones campus and a group of middle school campers sits in a half-circle in front of the barn’s closed doors. Suddenly, a dark figure smaller than a child’s fist slips from a crack above the door, swoops low and careens into the woods.

Seconds later, another bat drops from the barn and disappears into the forest. Like miniature fighter pilots, they dive low and then break sharply right or left.

“We have to be real quiet,” Peter August tells the campers. “Don’t freak out. They’re not going to land on you.”

The children are rapt. Other than the occasional oohh and aahh, they barely make a sound.

August, a professor of natural resources at URI, is passionate in his defense of the mouse-size creatures with the outsize ears. First, he wants to dispel several popular misconceptions about these much-maligned mammals:

•Bats are blind. Wrong.

•Bats frequently carry rabies. Actually, only about 1 in 1,000 do.

•Bats will fly into your hair. Not true. Their echo-locator — a built-in sonar system — is incredible. A bat seemingly swooping down on a person’s head is probably chasing insects that are lured by the carbon dioxide emitted in the person’s breath. (The average adult bat eats 600 to 1,000 bugs a night.)

August, a bearded man with twinkling eyes, came by his fondness for bats by accident. In 1974, while studying rodents in Venezuela for his doctorate, he put out a net one day and trapped two dozen bats in 20 minutes. By the time he returned to the United States, he was hooked. As a grad student, August spent weeks hanging out in a bat cave in central Massachusetts, observing the social life of bats.

The most common bat species in Rhode Island, where there are seven kinds, are the little brown bat and the big brown bat. Bats mate in the fall, a no-nonsense affair that has none of the fancy courtship of butterflies and birds. The female stores the male sperm all winter — an unusual ability — and when she wakes up in the spring, she ovulates. By May, the female is pregnant with a single pup.

Bats deal with the cold weather in two ways: either they migrate to a warmer climate or they hibernate. The little brown bat hibernates, seeking shelter in caves in Vermont or western Massachusetts.

In the springtime, the females arrive in Rhode Island, where they hole up in maternity colonies, girls-only enclaves where they give birth and nurture their young. The males, meanwhile, live a solitary life in the forest, flying around and eating insects.

Bats like a home that is warm and cozy — the narrow spaces beneath the eaves of a house or the rafters of a barn. Every spring, the females roost in the cracks and crevices of an old barn on the Alton Jones campus, 2,300 acres of woodlands and fields, one of the largest stretches of open space between Boston and Washington, D.C.

How the bats migrate every spring from a cave elsewhere in New England to a barn in Rhode Island is one of the natural world’s many mysteries, August said. Somehow, the bats know how to find their way home.

When the babies are born, their weight is proportionate to a 40-pound human. Like humans, they are breast-fed. At night, the babies are left hanging in the safety of the barn while their mothers hunt for bugs.

“Female bats wean their young early and then eat like crazy,” August said. “That’s their best chance for survival.”

For baby bats, the odds of surviving the first winter are slim: 90 percent don’t make it, but the ones that do can live as long as three decades.

“The moral of this story,” August said, “is that bats have this incredibly complicated lifestyle that can last 30 years.”

In August, the babies are strong enough to start flying. This is the time of year when the paths of humans and bats are most likely to converge because juvenile bats are still learning the ropes. They get lost. They get tired. They get confused. And sometimes, they wind up scaring the pants off some unsuspecting home owner.

No one knows how many bats spend summers in Rhode Island, but there are many. They prefer rural areas, where there are plenty of old barns and plenty of fresh water.

If a bat is trapped inside your house, it wants to get out. Give it a way to do so by opening a window or a door, August said. If it won’t leave, call the local animal-control officer. If a bat is found in the same room with a sleeping baby, contact the state Department of Health because there are reports of bats biting babies, August said.

“Never touch a bat,” August cautioned. “A healthy bat won’t let you get anywhere near it.”

Back at Alton Jones, August opens the sliding door to the whitewashed barn. The bats are hidden in the dark, tucked away in the eves or in the cracks in the siding. But their traces are everywhere, from the pellet-like bat droppings on the floor, to the white stains of urine on the walls. The barn smells faintly of ammonia.

August shines his flashlight at a narrow ledge and a couple of tiny dark ears, no larger than a finger nail, pop out. Then another pair appears, and you can hear a slight rustling noise. Still, it’s hard to believe that 100 female bats are nesting in this barn, along with the swallows.

Everyone knows that bats eat mosquitoes. But only the true fan understands what a valuable role bats play in the environment. In tropical climates, bats are critical pollinators. Bananas, mangos, balsa wood, figs, peppers, hemp — none of these things would exist, August said, without bats.

Bats are so helpful to humans, yet many humans care nothing about their fate, August said. In Africa, people hunt giant bats, called flying foxes, for food. In some countries, including the United States, people unwittingly destroy bat habitats by cutting down forests and spraying potent insecticides on crops and lawns.

As the bats slip outside the barn in larger numbers, August turns on a special device that magnifies the high-pitched squeaking that bats make to navigate and track down insects. It makes a popping sound, like radio static.

“Can you hear them echo-locate?” August asked. “Listen. Hear the chi-chi-chi sound?”

Bats, he said, send out an acoustic pulse, like sonar, to navigate. If the sound bounces back right away, they know they’re close to something. If it takes a long time for their echo to return, the object is far away.

A bat’s echo-location system is so finely tuned that it can detect a beetle sitting on a tree at night.

“For me,” August said, “that’s truly incredible.”

lborg@projo.com