The Secret Lives of Bats
These flying mammals are in decline, but Sacramento bat advocates want to reverse that. Their message: Bats help the ecology and economy, and they won’t hurt you.
Ordinarily, the second-graders who filled the classroom probably wouldn’t have sat so still in their little plastic chairs, but guest speaker Dharma Webber kept their rapt attention.
For her presentation, Webber brought three animals and used a video camera to project their images onto a television that, appropriately enough, hung from the ceiling. Her subject was bats.
But, instead of menacing animals showing off their fangs, these bats were so small, it was hard to see them. They sat inside a modified messenger bag with padding on one side and plastic mesh on the other. They occasionally interrupted Webber with their squeaky calls or crawled on their folded wings to rearrange themselves in the folds of fabric. Contrary to the mythic behavior ascribed to bats, these timid little fuzzballs didn’t seem so bloodthirsty. Johnny Carson would’ve been disappointed.
It was the week before Halloween, and Webber was visiting classes at Jackson Elementary School in El Dorado Hills. She debunked several bat myths as she went.
“Do you know that saying, ‘blind as a bat'? Well, it’s just not true,” Webber said. “They can see you in the day as well as I can see you, except they see in black and white.”
Webber runs Bat World Sierra, a rescue operation that cares for sick and injured bats, out of her home. She releases most of her bat patients but keeps some that couldn’t survive in the wild.
She began her slide show, running through decidedly non-sinister images of furry, flying creatures with strange faces. One slide showed a helpless-looking little bat with pointy ears and a tiny, pink nose. It looked something like a tiny possum with a pink pig snout.
“This is the mighty vampire bat,” Webber said. “No fangs here.”
“Ooohhh,” cooed a few students.
Although the bat’s bloodthirsty image, thanks mostly to Bram Stoker’s 1897 novel Dracula and decades of less-sophisticated Hollywood offerings, doesn’t quite mesh with reality, some bats really do drink blood. Three species of vampire bats, found only in Latin America, live on the blood of livestock and poultry by making tiny incisions with their teeth and lapping up two teaspoons or so of blood at a time.
Vampire bats are small and harmless, especially to humans, but they’ve done plenty to ruin the images of the more than 1,000 other species of bats in the world.
Another slide showed a California leaf-nosed bat, which lives in the deserts of Southern California, Arizona and Mexico. With its big ears; gray fur; upturned nose; and tiny, black eyes, the leaf-nose looks a bit like a rabbit. But its ears are highly evolved microphones that can hear dinner: a cricket’s footsteps or a caterpillar’s chewing.
The leaf-nosed bat, Webber told students, is declining in numbers because people in Mexico mistake it for a bloodsucker and burn the caves where it lives.
Countering bats’ bad rap is Webber’s mission with these presentations. With centuries of lousy bat PR to overcome, she has her work cut out for her.
Bats often are considered pests and disease carriers, and few people have noticed or cared throughout the years as increased human settlement and development have thinned bats’ numbers. Half of the 45 species found in the United States are threatened or are in decline, and six are endangered. Of California’s 24 species, 14 have declined to the point at which they are classified as “species of special concern.”
But most of what ordinary people know—or think they know—about bats isn’t true. Bats aren’t dangerous or mean. They mind their own business, and, by pollinating plants and eating bugs, they play an essential role in agriculture and natural ecosystems. One step toward reversing the decline is to change the bat’s lousy image, and a handful of biologists and bat fans around Sacramento have been working to do just that.
To do her part, Webber quit her job as an environmental planner for Sacramento County a few years ago to focus full-time on bat rescue and education. She keeps several bats in large cages in her Placerville home, and about 50 in an even larger cage outside. The cages, quiet all day, come alive with aerobatics at night.
The bat’s natural reticence is part of the reason that even scientists who have dedicated their lives to studying bats don’t know that much about them. Though researchers have made huge leaps in the last couple decades, thanks in part to high-tech tools, they still don’t know much about how bats migrate, socialize, mate or hunt.
In her presentation, Webber made sure to emphasize that no one should pick up a bat. They’re wild animals, she said, and a few have rabies, just like dogs, cats, skunks or raccoons. If a bat is on the ground, it is probably sick.
Near the end of class, Webber brought out the first bat. She held the tiny animal in her gloved hand and walked around so everyone could look closely. The bat, called a “big brown,” wasn’t much bigger than a strawberry. It stayed motionless in her hand, with its black wings tucked under its furry brown body. Under big, round ears, a pair of tiny, black eyes set deep in the face looked up at the kids. The children stared back, open-mouthed.
One mom sitting in on the class turned to the teacher: “Cute!” she whispered.
Next, Webber took out a Mexican free-tailed bat seized from a Davis woman who kept it as a pet. It was dark, almost black, with big ears protruding forward from its forehead.
“She’s the fastest bat in North America,” Webber said, gently stretching out one of the bat’s tiny 5-inch wings. “She can go 65 miles per hour and fly two miles high.”
The last bat, a “pallid,” was the biggest, at maybe 4 inches long. It had light yellow fur; a pink nose; and tiny, black eyes set deep under tall, paper-thin ears. “He can hear a cricket’s footstep 20 feet away,” Webber said.
This class, the last one of the day, had ended 10 minutes before, but the kids sat, spellbound, until the bats went back into their customized bag.
Before the children left, Webber made sure to reiterate what she had said earlier: “Bats are the most endangered land mammal in the world, and it’s because of fear.”
People like Webber are part of a small but growing network of bat lovers and researchers scattered around the country. It’s a definite subculture, one in which everyone knows everyone else by name. And one name everyone seems to know is Gregg Erickson, who has a kind of celebrity status as a conservationist. He also works for Caltrans.
As Caltrans’ senior wildlife biologist, Erickson is, in a way, the biggest bat landlord in California. About one-tenth of the department’s 12,000 bridges and overpasses are home to bats—17 of the state’s 23 bat species, to be exact. Erickson oversees more than 100 biologists charged with helping those bats and other animals coexist with highways.
Freeways may not sound like good habitats, but they’re great for bats, and they make great places for specialists to observe bats in the wild. Because bats have such an attraction to the agency’s many concrete structures, Caltrans works to protect the animals, even by designing bat-friendly features for new bridges.
As insect eaters, bats are critically important to the ecology and agriculture of the state, Erickson said, but it’s also in Caltrans’ best interest to make sure bats remain healthy. Habitat loss is one of the most important factors in the decline of bats in the Central Valley, so, if bats can find a home underneath highway bridges, that’s good for them and for Caltrans.
“We’ve realized,” he said, “that if we can prevent a species from becoming rare, that’s a lot cheaper than having to do extraordinary measures for endangered animals.”
Erickson showed off some of the tools he uses to monitor bats. He grabbed a small, black case and removed what looked like one half of a binocular. It was the newest kind of night-vision scope, which he can attach to a special video camera to record bats emerging in darkness. From another black case, Erickson took out a set of infrared floodlights. “They’ll light up a room like it’s daytime, but you can’t see it,” he said.
From a third black case, Erickson revealed one of the most important tools bat researchers have ever had: AnaBat.
It didn’t look like much: a laptop and a plastic, yellow box with a speaker and a few knobs. This contraption, called a bat detector, picks up the inaudible calls bats use to find bugs in the darkness and then remodulates the sound for humans. It also can display the sounds on the laptop’s screen. The display tells bat researchers how many bats are flying around and what kind they are. Most bats, including California’s, use sound to find bugs in the dark. These sounds, called echolocation, are high-frequency calls outside of the human hearing range, like a dog whistle. But they’re loud, sometimes more than 100 decibels, and bats hear the sound waves bounce off of insects.
Of all the bats under California’s state highways, the biggest colony is under the Yolo Causeway. During the summer months, when the local bat population peaks, Erickson said, 250,000 to 500,000 will live under that elevated stretch of I-80.
As their natural habitat vanishes, bats have no problem moving into manmade structures.
“All a bridge is to a bat is a limestone outcropping,” he said, “It’s a very good limestone outcropping with excellent thermal dynamics.” Concrete soaks up the daytime heat, which the bats need to stay warm, and retains it into the night.
On a bright, fall morning, Erickson parked his state car near the causeway; put on a hardhat and green, reflective vest; and grabbed a powerful, handheld spotlight. Under the freeway, he shined the light up into the inch-wide crack between two concrete girders. Small clusters of free-tailed bats hanging inside wiggled at the intrusion of light.
At another spot—Erickson didn’t want to say exactly where, out of concern that curious types or vandals could disturb the colony—were hundreds more. In this spot, below a freeway, were evenly spaced, black lines that looked like markers on a football field. The lines were guano, fallen from the parallel spaces above. There were thick drifts in some places, and the guano gave off a musty smell with a hint of ammonia. The stinky little droppings, however, can be a goldmine for bat watchers, who can tell how many bats live nearby and what kind they are even without seeing the bats. Caltrans, Erickson said, is starting to send the guano out for DNA analysis to pinpoint exactly what species has been leaving its calling card.
A few days later, the bats under the causeway woke at dusk, peeping out from within the concrete structure. As the steely, overcast sky grew dark on the flat horizon, the lights of downtown Sacramento flickered on. The swishing rhythm of passing cars, randomly broken by the whine and rumble of big rigs, made it hard to hear the bird-like calls, but the quiet screeching and clicking increased as more bats awoke.
As rush-hour traffic slapped at the expansion joints, the first fast-moving shadows swirled around the pillars. About a dozen bats, nearly impossible to see in the twilight, circled under the freeway and then swam up into the overcast sky. Many more emerged—dozens at a time—and wove as they rose silently, heading south. A half-hour later, the pace had slowed, but still more bats, silhouetted in the dull, orange glow of the clouds over the city, emerged and then vanished.
On a walnut farm just west of Woodland, Rachael Long peered up into a bat house mounted on the side of an old, wooden barn. The house, about 2 feet tall, was slightly narrower in width. It had a sloped roof on top but no floor. As they come home, Long said, bats swoop down and then shoot up into the bottom. At the last second, they flip their feet around and land upside-down. Leaving is easier: They drop and then fly. This bat house, about 4 inches deep, had internal dividers about an inch apart. Long said a typical bat house can hold 1,000 bats in the small compartments.
Though the bats were gone, she could tell what they’d been eating, by picking up a few little pellets of guano and rubbing them on the palm of her hand.
“See how it’s like coffee grounds?” Long said. “If you put it in the sun, it’ll also sparkle. It’s all insect parts. This looks like a lot of beetles.”
Long is a University of California entomologist who advises farmers through the UC Cooperative Extension office in Woodland. Though she’s an insect expert, she is also one of the country’s top experts on using bats for pest management. By giving homes to bats, Long said, farmers can cut pesticide use, which is a costly expense for farmers and which has environmental effects for the rest of the ecosystem.
Long spent eight years finding the best way to attract bats. They’re wild animals that can’t be herded, so it took a lot of trial-and-error work. Bats may or may not show up at a new house. And, if they do move in, it may take a year, two years or longer. Long said she has found that bats around here like it best about 15 feet above the ground, with morning sun and afternoon shade.
At another farm just off Highway 16, Long recently found that a house she put up four years ago is occupied. About 40 free-tails hung inside.
“Finally, I have bats,” she said. “I’ve been waiting so long.”
Now that she has the formula down, Long has put up more than 125 bat houses on farms around the region, and she’s been teaching farmers to appreciate the fuzzy little pest controllers.
Because of the fiscal and environmental benefits, more farmers are looking to bats for help controlling pests, especially the increasing number of organic farmers who avoid pesticides.
Without being asked, bats suck tons of insects out of the air every night and consume as much as their own body weights in a single night.
The tiny free-tails, one of California’s most common species, are about the size of a sparrow and weigh less than an ounce. They take off at dusk, drink on the wing by swooping low over ponds and rivers and then blast the darkness with echolocation calls. Also called Brazilian free-tails, these bats get their name because their tails hang down past the wing membrane that stretches between the legs.
They happen to love dining on the corn earworm, which lays its eggs in corn and is one of the top crop pests.
They work hard, too.
One bat researcher, zoology professor Gary McCracken at the University of Tennessee at Knoxville, used Doppler radar to watch free-tails chase swarms of moths up to 10,000 feet.
Fred March, who grows wheat, alfalfa and tomatoes in Yolo County, has two of Long’s bat houses on his farm.
He said it’s impossible to know exactly how many insects the bats eat, but he tries to spray as little as possible, so he welcomes the help.
He said he knows the bats are out there devouring bugs.
“In summer, we harvest the tomatoes at night, and we use the lights out there on the trailers,” he said. “They’ll come in around those lights because the light attracts a lot of insects. I see [the bats] around the lights. You’ll see as many as 20 or so, but who knows how many you’re not seeing?”
In typical bat fashion, they do something nice for farmers, but only at night, when nobody can see.
The very invisibility that aroused March’s curiosity about the bat is the root of the fear and contempt people traditionally feel for bats, no matter how many truckloads of bugs they eat.
It goes back centuries. The bat’s role in European and North American folklore is not an enviable one and often portends death. A bat living in or flying around inside a house, for example, can signify that a member of the family that lives there will die soon. Bats show up in mythology as symbols of vampires, evil spirits or the devil.
All of that may explain why bats found in a home are frequently sentenced to death by frying pan. Bat lovers say the animals—which, by the way, produce prodigious amounts of excrement—are wild and don’t belong in a house anyway. Bat lovers also preach that the humane way to get rid of bats is to let them out and keep them out.
Betsy Bolster, who coordinates bat management for the state Department of Fish and Game, said the best thing to do is an exclusion. The procedure involves putting up a net where bats come and go. Bats can crawl out through the net, but they can’t get back in by flying. If a bat flies into a house, she added, it’s best to open the doors and windows until it leaves.
There are as many different myths about bats as there are cultures, but not all the myths are bad. In traditional Chinese art, bats symbolize good luck.
However, in Latin America, where some bats do drink blood, bats are routinely exterminated.
Bat Conservation International, an Austin, Texas-based organization that supports conservation, education and research to save bats, has been working with the Mexican government to teach farmers that bats play a key role in agriculture and shouldn’t be exterminated. It’s an important mission for BCI because many bat species migrate between the United States and Mexico.
BCI, generally regarded as the top authority on bats, is led by Merlin Tuttle, who founded the organization 20 years ago and who generally is considered the patron saint of the bat-lover movement.
Mexico isn’t the only place where conservationists are needed. Large bat populations have been wiped out in California, too, often because of vandalism or human intrusion. Bolster, of Fish and Game, said there’s documentation of vandals who have scared bats, shot them, or sprayed them with hairspray and lighted them on fire.
As the department’s bat manager, Bolster fields questions from all kinds of people, from bat lover to bat hater. One caller hated bats so much that she wanted to know where she could move that didn’t have any bats. Bolster had bad news for her: “They’re pretty much everywhere.”
To make sure they stay that way, Bolster and other bat conservationists in the West are drafting a bat-conservation strategy.
Pat Brown, a University of California at Los Angeles researcher who lives in Bishop, is one of the top experts on bats in caves and mines. She has been studying bats since the 1960s and said two new threats are mine closures and increased interest in mine exploration by cavers.
If bats like overpasses, they love mines. Brown said she’s found bat use in 75 percent to 80 percent of the 7,000 mines she’s studied.
Because they can be a hazard, old mines in the Sierra Nevada that date from the gold- and silver-mining days are being sealed off. Brown often consults for agencies doing the work to make sure the closures don’t kill bats. The solution usually involves installing metal bars over the mine opening.
But even inadvertent contact with bats can endanger colonies. Bats that don’t fly south for the winter will find someplace in the Sierra Nevada or the coast range to hibernate for the winter instead. They survive for months by lowering their body temperature. But, if they’re awoken by cave or mine explorers, the bats can burn their fat storage and starve to death before spring arrives. And, in spring, after the pups are born, a disturbance can frighten away mothers, who leave their young to die. When this happens, it’s hard for bats to rebuild a population because, for the most part, they only have pups once a year.
The unknowable habits of bats, which move to different roosts at different times of the year, make it hard to say how much their numbers have declined.
Even bat researchers who want to find out must keep their distance to avoid hurting the animals they’re trying to learn about.
“We don’t know what we’ve lost,” Brown said.
BCI founder Tuttle probably has done as much to demystify the creatures as anyone has. Tuttle also is an unparalleled nature photographer who has shot tens of thousands of photos of bats throughout the years. In these photos, bats don’t bare their fangs like dangerous predators. Rather, Tuttle uses complex photo gear, including remote triggers, to photograph bats in ways they’ve never been seen before: from dramatic photos of a bat swooping down on a scorpion to close-up shots of their small, fuzzy heads. In September, the U.S. Postal Service released a series of bat stamps featuring four of Tuttle’s close-ups.
Still, though bat advocates can explain away the myths, a tiny percentage of bats really do carry rabies. And, though it rarely happens, they can infect humans. In March, a man in the Glenn County town of Willows died after contracting the disease from a bat. At the time, public-health officials said the 28-year-old may not have known he’d had contact with a bat.
According to Dr. Ben Sun, one of the top two experts on bats and rabies at the California Department of Health Services, 75 percent of Americans who die from rabies contracted the disease from a bat, as confirmed by postmortem genetic analysis of the strains. In California, he said, there have been eight confirmed rabies deaths since 1990, and five of those came from bats. Rabies is fatal if untreated before the onset of symptoms but is easy to survive if treated in time.
Though bats can transmit rabies, bat advocates criticize public-health officials for exaggerating the danger.
The danger associated with bats has been a source of conflict between BCI and public-health officials, including the Centers for Disease Control and Prevention, but the two organizations recently issued a pamphlet on bats and rabies that’s acceptable to both sides and that’s considered the definitive source for the public.
On Halloween day, Dharma Webber stayed home. The weeks leading up to the holiday are the busiest of the year for her, but she was taking the rest of the day off.
“I never do events on Halloween,” she announced.
Webber has two cages in a sunroom off the back of her house. The small one holds the bats she used in class as well as a few other small bats. They sleep all day in soft compartments that look like two potholders sewn together.
Next to the small cage was a larger one about 10 feet squared and almost as tall as the ceiling.
It looked empty.
Webber opened the door and slowly walked in, toward what looked like a bunch of plastic leaves that hung in the back corner.
Then, the bats flushed.
Instantly, several bats swirled around, whooshing in circles on skin wings. Somehow, they managed to avoid one another.
Thirteen were Jamaican fruit bats, all males that were the offspring of bats used in a DNA study and that were to be euthanized. These were medium-sized bats—dark, almost black in color. Their upturned noses made them look like tiny rhinoceroses.
The other five bats, Egyptian fruit bats, were illegal pets confiscated in Detroit.
Living in captivity, the fruit bats still need to eat two-and-a-half times their bodyweight each night, Webber said, and they love bananas and tomatoes. The smaller bats, like the free-tails, dine on live mealworms.
As the bats settled down, some hung from the wire-mesh ceiling. Webber gingerly grabbed an Egyptian in her gloved hand and brought it outside. Its face made it look like a squirrel, or maybe a fox (fruit bats, which can have wingspans of up to 6 feet, also are called flying foxes).
Webber slowly stretched out one of the bat’s wings, which was maybe a foot long.
Bat wings are actually hands, with a thin membrane stretching between four fine finger bones and all the way down to the legs. A tiny thumb protrudes from the front of the wing.
Even as she takes her bats on the road to show that they needn’t be feared, Webber said, she isn’t always welcomed. A few days ago, she said, a parent called the health department when she found out that Webber was bringing bats to her child’s school.
“It’s a huge witch hunt,” she said, somehow not sounding bitter. “I’ve had parents that wouldn’t let their children attend lectures, and some even say it’s because of religious beliefs—because they think [bats] are the spawn of the devil.” Some kids believe that a bat could turn them into a vampire.
Webber did get a chance to take her message—or her bats, anyway—to a wider audience two years ago. When an X-Files episode featured a storyline about a human bat that was killing people, the director wanted to use live bats in one scene. Webber got the call.
She brought the bats to Los Angeles on one condition: that they not be shown in some way that made them look big and threatening. The director agreed and also incorporated into the script a few things Webber taught him.
The shoot took four days for just 26 seconds of on-screen time. But Webber came home with a big paycheck, which she used to build a big flight cage for bats in her backyard. But Webber’s bats weren’t shown as scary monsters, and that counts as a victory for her.