THE SECRET LIFE OF BATS
At times they have been considered to be demons that are in league with witches and the Devil. In some parts of the world bats are hunted down and exterminated even today. Many people are afraid of them—in part because of their reputation for spreading disease. But in recent years scientists have been discovering more and more about their positive qualities: Bats are a lot more beneficial than they are given credit for—indeed, like their namesake Batman, some of them even rise to the rank of superheroes.
As the last rays of sunlight illuminate the majestic sandstone formations throughout Brazil’s Catimbau National Park, the treetops have already been shrouded in the darkness of night. “They’re coming.” You can hear the word being passed on from house to house. The area’s inhabitants gather up their belongings and seek safety in their homes. The creatures they are fleeing from approach soundlessly to human ears, calling out to one another at frequencies above the range of our hearing. Deprived of their usual fare, they are on the hunt for human blood. Unlike the other two known species of vampire bat, Diphylla ecaudata had not been known to take any interest in human victims until fairly recently. The hairy-legged vampire bats were believed to feed exclusively on wild and domestic birds. However in 2017 examination of fecal samples from a colony residing in a cave in Catimbau National Park found traces of blood from other animals: humans. In earlier experiments this bat species refused to eat goat or pig blood, sometimes choosing to starve instead. So what triggered the drastic dietary change? Deforestation has been threatening the bird populations in the forests around the national park, and the bats probably turned to human blood out of desperation. “They are adapting to their environment and exploiting new resources,” says Enrico Bernard, who heads a team of researchers from the Federal University of Pernambuco in
Recife. And the fare swap could have some very unpleasant consequences: “Past research has revealed that the species carries the hantavirus,” says University of Georgia ecologist Daniel Becker. But that’s not the only deadly disease that can be transmitted by bats. In addition to the rabies virus, bats have also been known to harbor Bartonella, a genus of bacteria that can cause potentially life-threatening endocarditis. Nevertheless, scientists caution that the reputation of bats is much worse than they deserve…
VILLAINS OR HEROES?
Bats have had a bad rap in Western culture that dates as far back as the sixth century BC. In one of Aesop’s Fables, a bat borrows money it can’t repay so it hides during the day from its creditors. In the fable of the battle between the birds and the beasts, the bat is portrayed as duplicitous, unable to decide which side to take. But Native American cultures have a different and far more positive view. In Navajo folklore the bat is identified with one of their foremost deities. A myth of the Pomo Indians of California describes a bat swallowing a hunk of obsidian and then spitting out large numbers of finished arrowheads. The dark legend of vampires in Western culture appears to have originated in the Balkans in Eastern Europe, where it circulated widely in the 18th century. There are no vampire bats in Europe, but bats—as they are flying nocturnal animals—have long been associated with the supernatural. A contributing factor to this misconception is the fact that for a long time the nocturnal animals were studied much less than their diurnal counterparts and were therefore poorly understood. That is being rectified by researchers across the globe who are broadening our knowledge of the scientific study of bats, chiropterology. The unanimous
conclusion: Bats play a significantly beneficial role in environments all over the world.
In tropical and subtropical regions, nectar-eating bats are very important pollinators for more than 500 plant species, including those that produce many tropical fruits such as mangos, bananas, and guavas. The plants they pollinate often have pale nocturnal flowers rather than bright blossoms that are open during the day. However bats’ greatest benefit to humankind is their diet of insects. In fact, at least 40 species of bats in America eat nothing else, making them the most important predator of night-flying insects. While we are sleeping bats are out and about, decimating the numbers of flies, mosquitoes, moths, beetles, and many other bug species. By decreasing the amount of insects, bats save billions of dollars that U.S. agriculture would otherwise have to spend on pest control, with estimated savings as high as $53 billion annually.
A MODEL SUPERHERO
The reason bats are such fabulous insect hunters comes down to their active flying ability. They are the only mammals that possess this ability, and they are truly acrobats of the air among the flying animals. The fairly rigid wings of birds and insects move in only a few directions. A bat’s wing, however, is similar to a human’s arm and hand, with more than two dozen joints covered by a thin membrane. This structure allows them to stretch their wings in many different ways to catch the air, giving them superb flight control. “Bats are basically operating with the same skeleton that we have,” explains Sharon Swartz, a professor of biology and engineering at Brown University. “Insect wings only move at what for insects is a shoulder, and a bird’s wing can’t compare with that of a bat in complexity. Bats can make fine adjustments in the shape of their wings during flight.” And they can do it all in complete darkness. Bats see quite well with their eyes, but when it gets really dark they’ll use their ears to navigate by echolocation. So if you were really “as blind as a bat,” you’d actually be able to “see” better than almost anyone else. Echolocation in
“Bats are brilliant. They are among the most sophisticated, incredible animals on the planet.”
MERLIN TUTTLE, FOUNDER OF BAT CONSERVATION INTERNATIONAL
bats involves short bursts of sound at frequencies between 30,000 and 120,000 Hz—pitches inaudible to humans. The rate may reach several hundred bursts a second in a bat that is nearing its target. Bats will also use bursts of sound to communicate with one another. Given such superhuman abilities, it should be no wonder that the bat was chosen as the model for one of our best-known superheroes:
Batman. But while the protector of Gotham has to compensate for his human limitations with high-tech equipment, bats already have tech built in to their bodies. In the Batman sequel The Dark Knight, Lt. James Gordon says: “He’s the hero Gotham deserves, but not the one it needs right now.” In contrast to the Batman of the movie, bats are the heroes we need all the time.