Deaths of millions of bats in U.S., Canada have ecological, economic impacts

I do not like bats. Once, as a college student living in a third-floor apartment with no air-conditioning, a bat landed on me during a hot summer night. I fled my room, shrieking. Even today, on summer nights at my rural home, when bats fly low over my deck, I instinctively duck.

Bats have a bad rep. Think bat and you likely think bat with rabies. Think bat and you likely think dirty bat or bat as vampiric bloodsucker. Think bat and you likely think evil harbinger of doom and destruction. (Okay, that last one’s a tad over the top … but you get the idea.) Bats have fewer defenders than fear-laden critics.

But bats, the only mammal structurally capable of sustained flight, are just creatures with significant ecological — and economic — roles. Hate mosquitoes and other insects? They’re on the nighttime menu for bats. Like bees, many bats pollinate plants and spread seeds. Bat shit (sorry; bat guano) is rich in nitrogen and is a profitable fertilizer. Bats’ ability to navigate in the dark (echolocation) is a subject of significant scientific study.

But in the past five years, up to 6.7 million bats are estimated to have died in 16 states and Canada, the U.S. Fish and Wildlife Service said. Three species face extinction — the little brown bat, the northern long-eared bat and the tricolored bat. A malady called white-nose syndrome is killing them.

Researchers gleaned the estimate by counting bats in winter trips to caves. Bats roost densely, reports Darryl Fears of The Washington Post. So researchers take digital photographs of bats snoring through winter and literally count noses of bats. In 2009, researchers estimated bat deaths at about 1 million. The new figure has alarmed scientists. Says Mylea Bayless, conservation programs manager for Bat Conservation International in Austin, Tex.:

We’re watching a potential extinction event on the order of what we experienced with bison and passenger pigeons for this group of mammals, The difference is we may be seeing the regional extinction of multiple species. Unlike some of the extinction events or population depletion events we’ve seen in the past, we’re looking at a whole group of animals here, not just one species. We don’t know what that means, but it could be catastrophic.

White-nose syndrome, reports Fears, is caused by a fungus called Geomyces destructans. The fungus eats through the skin and membranes of bats. The syndrome was first observed in in 2006 in Howe Caverns near Albany, N.Y., a popular tourist destination down the road from me. Reports Fears:

Since then, biologists in Virginia, Pennsylvania, New Jersey, Vermont, Indiana and other states have returned to caves and mines during the annual winter hibernation of bats and reported alarming numbers of fresh dead to wildlife and gaming agencies.

The extensive demise of bats threatens forest health — and segments of the economy based on forests.

The paper products industry could also be hard hit if pests such as the emerald ash borer proliferate in the absence of bats. Loggers in states such as Vermont “ought to be concerned, but I don’t think the word has really gotten out to these folks,” said Mollie Matteson, a conservation advocate for the Center for Biological Diversity in Richmond, Vt.

“It certainly behooves people concerned about the health of forests — loggers or ecologists — to pay attention,” Matteson said. “But it’s hard to make a direct connection between 7 million bats dead and what happens to forest pests.”

I still don’t like bats. I’ll still duck when they flit over my deck. But none of us should be happy that nearly 7 million have died with no apparent recourse to a cure. The potential extinction of any species — even one that fills many of us with fear and loathing — must concern us.

More on bats:
white nose syndrome
the economic cost of losing bats
the science of bats (video)
Bat Conservation International
Organization for Bat Conservation

photo credit:
• vampire bat by Michael & Patricia Fogden/Corbis

7 replies »

  1. People would be amazed if they knew how many mosquitoes and other bugs a typical bat takes out. I don’t have the figures at my fingertips, but the figure is astounding. They make great insect control.

    I find bats fascinating. I even bought a book once, long ago, on how to build bat houses (sorta like bird houses, but for bat) so I could do my part to encourage their place in the ecology. Rabies freaks me out, but otherwise, the more bats the better.

    Thanks for this piece, Denny. Really interesting stuff.

  2. My wife and father in law tell stories about their trip down to the bottom of the Grand Canyon and the bats that kept them bug-bite free overnight. Cool stuff (but in case she’s reading this, I’ll let her tell it properly).

  3. Yes, an actively flying mammal is a curious and unusual species, and in the US we pretty much only have insectivores, so all of them are beneficial. And they don’t carry rabies any more than skunks, at least in Northern CA., or other varmints.

    Losing bats evokes our loss, even more dangerous, of honey bees. Hives are collapsing. Diseases, killer Africanized bees, pollution, constant transport across the county, there appear multiple issues. And their loss would be devastating. We don’t need bats as badly as we do bees to keep eating and harvesting many foods efficiently. I wonder if there are overlaps, to wit, pesticides and pollution and warming, are lowering immune systems, making bats vulnerable to diseases they would have fought off better. Or is this just a pandemic somewhat separate from human activities? Theories?

  4. Thanks for your comments, folks. Robert, I’d forgotten about the hive collapses. Thanks for bringing that in here.

    • Saw a story recently on bees. They think the culprit is a smaller bug that lays its eggs in them – a killer parasite, sort of. Which sucks, but curing a disease is a lot easier once you actually diagnose it.

  5. I didn’t get to the bat house project this summer, but i’d like to install one on the house … even if the deck is high enough off the ground to keep most bugs from being annoying. At the very least i’d have bats around to indulge my childlike glee that comes from tossing pebbles into the air and watching them dive bomb them in the dusk and pull away at the last minute.

    Good for the garden too, like keeping toads around. (I bought a toad house last summer, but all the toads i imported were way too fat for it and found more spacious lodgings in the yard.)

    This news is sad and discouraging, much like the honey bee collapse. On that it should be noted that the colony collapse is affecting non-native honey bees and so mostly affects our non-native food crops. Not that that makes it any better, given that most of our food crops are non-native species. I’d build a hive in the yard, but i’ve heard far too many stories of home hives killing dogs, of which i have one and all my neighbors do too.