Bat Not Forgotten

Virginia’s little brown bats fight for survival.

Illustration by Robert Meganck

When it came to endowing Myotis lucifugus with a common name, creativity seems to have been running in short supply. In a world that has offered us the hellbender salamander, the prothonotary warbler and the cloudless sulfur butterfly, what M. lucifugus got landed with was the prosaically literal “little brown bat.” 

On the other hand—points for accuracy. This is a bat that is indeed brown, and undeniably little, tipping the scales, at full adult size, at around 7 to 8 grams, or about the weight of 2 teaspoons of sugar. That weight wouldn’t be for lack of appetite, however. Little brown bats, like most bats you will find in the Eastern U.S., are insectivores. And, according to Dr. Karen Powers, a professor of biology at Radford University, one single LBB can consume up to its own body weight—or about 3,000 insects—in a single night. “These bats are nature’s pesticides,” she says. “Estimates from a 2011 study suggest that the bats of North America provide a service equivalent to $3.7 billion a year.”

Bats are the only true flying mammal, and the night-hunting LBBs dodge and wheel though the evening air on wings made of “a flexible epidermal tissue” that is like a thick, leathery balloon says Powers, noting that these wings also have impressive healing ability. “The wings can get holes from thorns, fights and more, and can heal most small ones in a matter of weeks,” she says.

The bats feed in flight, and while LBBs do in fact have perfectly good eyesight, they hunt their prey through echolocation, emitting a high-frequency call (outside the range of human hearing). “The calls they emit bounce off objectsand return to the bat, whose ears act like little satellite dishes,” explains Powers. “This givesthe bats a sense of relative size and distance of the object. It essentially tells them what mightbe edible and what should be avoided.”

As the bat zeroes in on an insect, the call gets faster: This is called a “feeding buzz,” says Powers, and if you visually graph the sounds you can see how the pulses get closer together. If you could slow down the calls to a rate that humans could hear, they sound like a series of clicks. But as the bats get closer to their prey, “the clicks increase to the point where you cannot distinguish a single click,” she says. “It sounds like a zipper to our ears.” 

Interestingly, different bats emit calls at different frequencies, with smaller, fast-moving bats like the LBB emitting at the higher end. “The high-frequency calls ‘rebound’ faster and allow for more quick moments and adjustments in flight,” says Powers, although the bats can alter the frequency of calls depending on how “cluttered” the environment is.

Nevertheless, the misapprehension that bats will get tangled in your hair seems to have remarkably global reach; an article in Bat Conservation International’s BATS magazine offered variations on this bit of folkloric fright-mongering, from France to Canada and Ireland to the U.S. If you’ve ever heard that warning, Powers can reassure you: “Their ability to echolocate would prevent that.” 

Sadly, however, that’s not the only reason you’re not likely to have a close encounter with an LBB. Once they were the most common species of bat in the Eastern U.S., says Powers. But then in 2009, a fungal infection called White Nose Syndrome (WNS), first documented a few years earlier in New York state, was found in several Virginia bats. LBBs are a bat species that spend winters in hibernating colonies; in Virginia, these are often found in caves and mines, where the damp environment and close proximity of the colonies’ bats allow the fungus to spread via spores. 

There is no effective large-scale treatment either. As a result, in less than a decade, WNS has virtually wiped out Virginia’s little brown bat population. “We’re looking at a decline of 99 percent,” says Powers. 

And because LBBs reproduce slowly, giving birth only to a single pup each year, even if the small number of bats that have survived manage to pass to their offspring some form of resistance to WNS, “It’ll likely be hundreds of years before they can make a comeback,” says Powers.

So, in the unlikely event that an LBB, or any bat, should find its way into your home and you discover it swooping about your bedroom, as sometimes happens on summer evenings, forget the fishing nets and tennis rackets—avoiding contact is safer both for you and the bat. Plus, notes Powers, bats are a protected group in Virginia and shouldn’t be harmed. Instead, opt for an easier (and gentler) way to shoo them out. Simply open the windows (including screens, of course), turn out the lights, shut the door, and the bat will let itself out.  

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