Big Brown Bat (even though he looks quite little)

Big Brown Bat (even though he looks quite little)

Bats have lived in North America since the dinosaur age. The only mammals capable of flying, these creatures are often misunderstood as aggressive, blood-sucking predators. But bats are critical to the ecology of the United States because of their appetite for eating insects and ability to pollinate flowers and plants. In the past four years, millions of bats have died from a skin disease called white-nose syndrome. First detected in New York, the disease has all but wiped out the bat population of the northeast and has quickly spread to sixteen states. Diane and guests discuss concerns over the declining U.S. bat population.


  • Cynthia Moss Professor, University of Maryland; director, auditory and neuroethology bat laboratory
  • Dan Ashe Director, U.S. Fish and Wildlife Service, Department of the Interior
  • Mylea Bayless Conservations programs manager, Bat Conservation International
  • David Blehert Microbiologist, U.S. Geological Survey's National Wildlife Health Center


  • 10:06:53

    MS. DIANE REHMThanks for joining us. I'm Diane Rehm. It's estimated that bats provide $22 billion of pest controls for American farms every year. Now, the entire U.S. population of bats is threatened with extinction by something called white-nose syndrome. It's a skin disease that's killed more than 1 million U.S. bats in just four years. Joining me in the studio to talk about why this is happening and what it means for the U.S. economy and the environment: Mylea Bayless of Bat Conservation International, Dan Ashe of the U.S. Fish and Wildlife Service, and Cynthia Moss of the University of Maryland.

  • 10:07:58

    MS. DIANE REHMShe's here with a tiny friend whom we'll hear from and see just a little later. You can join us, 800-433-8850. Send us your email to Join us on Facebook or Twitter. Good morning to all of you.

  • 10:08:26

    ALLGood morning.

  • 10:08:27

    REHMMylea, let me start with you. Give us a brief description of bats in the U.S. and around the world. Which species live here and elsewhere?

  • 10:08:41

    MS. MYLEA BAYLESSSure. Bats make up about 20 percent of the world species. They're the second most diverse group of mammals. They occur worldwide every place on the globe, except the coldest and hottest regions. They pollinate plants and disburse seeds throughout the rest of the world. But here in the U.S., all of our bats, or most of our bats, are insectivorous. That means they primarily eat night-flying insects. Many of those damage forests and eat crops and are pesky. So they are really, really valuable to the U.S. economy and to our society as a whole.

  • 10:09:21

    REHMDan Ashe, we hear so much that's negative about bats. Why are they so critical here in the U.S.?

  • 10:09:30

    MR. DAN ASHEWell, you're right, Diane, bats have a stigma about them. But as you mentioned before, bats provide very important eco-system service to the people of the United States, particularly in the agriculture sector, providing more than $22 billion a year in economic benefit related to pest control. And if we were to lose that, then we would have to replace that service with greater pesticide application. So that would be more costly, and it would also incur more environmental damage by the application of more pesticides, so...

  • 10:10:04

    REHMGive me an idea of what one bat can do.

  • 10:10:10

    ASHESome of my colleagues may be able to better put that into context. But, you know, a single bat can consume more than its weight in insects on a single night. So those would be mosquitoes. For instance, when my wife and I are sitting on our patio during the summer enjoying an evening meal, we'll see bats flying overhead, and they'll be consuming insects like mosquitoes.

  • 10:10:33

    REHMAnd I gather one little brown bat can catch what, Mylea?

  • 10:10:39

    BAYLESSAbout a thousand insects an hour. We estimate they can eat about four to eight grams of insects...

  • 10:10:45


  • 10:10:46

    BAYLESS...every night. And many of those are pests, and many of those are agricultural pests and forest pests, a lot of moths.

  • 10:10:54

    REHMAnd isn't there use of fertilizer from bats as well, Mylea?

  • 10:11:01

    BAYLESSYeah, absolutely. Bat guano has been a fertilizer for thousands of years. And it's been used for all sorts of other things, too, like making gunpowder in World War II and some other really interesting applications. But it's very high in nitrogen and most of the other things that go into making high quality fertilizer. At Bracken Bat Cave in Central Texas, they mine the guano when the bats aren't there, and they sell it for the price of coffee, you know, eight or ten bucks a pound at organic farm stores.

  • 10:11:32

    REHMAnd to you, Cynthia Moss, I gather at the University of Maryland, you study how bats behave. So tell us, how do bats behave?

  • 10:11:46

    MS. CYNTHIA MOSSWell, as Mylea mentioned, bats are nocturnal. They operate at night, and they use -- many species use echolocation to find their food and to avoid objects, so one focus in my lab is the study of echolocation behavior. We have a large flight room equipped with high-speed video cameras, sound recording equipment, which allows us to study this very specialized behavior in great detail.

  • 10:12:15

    REHMHow do they exercise this echolocation?

  • 10:12:22

    MOSSSo the bats produce very high frequency sounds, sounds that are largely outside the range of human hearing. So when someone sees bats hunting insects from their back porch at night, they don't hear the sounds that they're producing because they're out of the range of human hearing. But these very high frequency sounds bounce off of objects, even tiny insects, and the echoes that return to the bats' ears provide information about where the insects are. The bats can localize with very high accuracy.

  • 10:12:54

    MOSSIn some ways, there are parallels with our ability to use vision to localize very accurately, and the bats can track and intercept insects very rapidly using this form of sensing called echolocation.

  • 10:13:09

    REHMDo they talk with one another?

  • 10:13:13

    MOSSThey do that, too, and they tend to use different sounds when they talk with one another, typically a little bit lower in frequency and with different characteristics than the echolocation calls.

  • 10:13:25

    REHMI think you've got some sounds for us on your computer.

  • 10:13:29

    MOSSI do. These are sounds that were recorded from a bat that was catching an insect in the laboratory. And what we've done is slowed down the sound so that it brings it into the audible range that humans can hear. So I'll play it now.

  • 10:13:45


  • 10:14:10

    MOSSAnd that's just when the bat caught the insect. So you could hear the bat is producing sounds at a higher and higher rate over time, and that's corresponding...

  • 10:14:20

    REHMAs it closes in...

  • 10:14:22


  • 10:14:23

    REHM...on the insect. Now, in your cage here, you have a tiny little brown bat. Why did you bring the bat?

  • 10:14:37

    MOSSWell, for general interest. This is a big brown bat I have.

  • 10:14:41

    REHMBig brown bat, which is a different species from the little brown bat.

  • 10:14:46

    MOSSRight. But the big brown bat is not all that large. It's actually quite small, the size of a small mouse and -- would you like me to take it out?

  • 10:14:56

    REHMI'd love to see it.

  • 10:14:57


  • 10:14:58

    REHMAnd it's -- I gather, one of the common misconceptions about bats is that they have rabies, but they don't.

  • 10:15:14

    BAYLESSWell, a small percentage of bats do carry rabies, but the misconception is that all bats have rabies. There's not-very-reliable estimates about the actual true number, but, in actuality, it's very, very, very small and highly unlikely.

  • 10:15:30

    REHMAnd I'm hearing the sound that...

  • 10:15:31


  • 10:15:33

    REHMPut it closer to the microphone.

  • 10:15:36

    REHMAnd those are the sounds of a large brown bat, who couldn't be larger than a little mouse.

  • 10:15:43

    MOSSRight, right. And the sounds that you hear are not this animal's echolocation calls, but social calls. This bat is probably a little scared...

  • 10:15:54

    REHMI'll bet.

  • 10:15:55

    MOSS...and is letting us know that with these sounds. So these are not echolocation sounds. The echolocation sounds we would not be able to hear. I have with me a device called a bat detector that picks up the very high frequency sounds that bats produce and transforms them into sounds that we can hear. So if this bat calms down in a minute and stops making these social calls, I can try to use the bat detector and let you hear the output through this device.

  • 10:16:27

    REHMI'd love to. I'd love to. That poor little thing is frightened.

  • 10:16:31

    MOSSYeah. I think I'm going to feed this bat a little insect, see if that helps her settle down.

  • 10:16:39

    REHMThere is also, Mylea, this common misconception that all bats drink blood. Talk about that.

  • 10:16:51

    BAYLESSYeah. That is a common misconception. There are bats that feed on blood. But they are vampire bats, and they only occur -- there's only three species in the world, and they only occur in Central and South America. So they actually don't drink blood like Dracula, like you think. They lap it like kittens. They make a small incision, and they have an anticoagulant in their saliva. So they make a small incision, and they lap the blood. And that anticoagulant has actually been used to discover new medicines for stroke victims and anticoagulants that we're using in the medical field right now.

  • 10:17:26

    REHMHow interesting. Cynthia Moss, does that bat recognize you?

  • 10:17:33

    MOSSWell, that's hard to say. I -- this particular bat and I have not had a lot of interactions. But, over the years, I have trained bats in behavioral tasks, and I think in the situation...

  • 10:17:49

    REHMLike what?

  • 10:17:51

    MOSSWell, to make discriminations between different echos that return from objects at different distances. And so those bats I would handle on a daily basis. And I think the bat did come to recognize me as the person who would provide food, and we didn't interact in the same way I might interact with my dog. But this bat I haven't had that much interaction with, so I don't think...

  • 10:18:19

    REHMDo they have a sense of smell?

  • 10:18:20

    MOSSOh, absolutely.

  • 10:18:22

    REHMInteresting. Cynthia Moss of the University of Maryland. She's director of the Auditory Neuroethology Laboratory. Short break, we'll be right back.

  • 10:20:00

    REHMAnd I've just had the rare opportunity of seeing inside that tiny large brown bat's mouth and looked at its tiny but extraordinarily sharp teeth, which I don't know why it surprised me, but it did. And joining us now from an NPR studio in Madison, Wis. is David Blehart (sic). He's head of the U.S. Geological Survey's National Wildlife Health Center. Good morning, David. Thanks for joining us.

  • 10:20:42

    MR. DAVID BLEHERTGood morning.

  • 10:20:43

    REHMI gather you've recently identified a fungus as the cause of this deadly white-nose syndrome. What's it called? How does it kill bats?

  • 10:20:57

    BLEHERTThe fungus was a new species when we initially discovered it -- or a previously unknown species that we named Geomyces destructans. And although we're still doing research to learn more about exactly how it kills bats, we believe that it does so based on the extreme amount of damage that it causes to the wings of the animals.

  • 10:21:17

    REHMHow many bats have died, Dan Ashe, from white-nose syndrome here in the U.S.?

  • 10:21:26

    ASHEWell, since the syndrome was discovered in 2006 and 2007, the estimate -- conservative estimate is that over 1 million bats have died as a result of the white-nose syndrome.

  • 10:21:38

    REHMExplain what happened. I gather this first was located in a cave in New York State. Is that correct?

  • 10:21:50

    ASHEIt was. The -- and it has spread now to -- has been either caves or bats with the white-nose syndrome have been identified in 19 states now, so it has spread extremely rapidly, which is the cause of concern, really, that it's not just a localized threat to bats but really a threat to populations of bats nationwide.

  • 10:22:13

    REHMAs you think about this, David Blehert, that could really have a major impact on bats all over the country with the kinds of caves in which bats hibernate.

  • 10:22:34

    BLEHERTAbsolutely. That's our concern. I don't know if you, Diane, saw the movie "Contagion" that came out a while ago. It was a...

  • 10:22:40

    REHMNo, I didn't. But I do want to.

  • 10:22:44

    BLEHERTSo it was a very realistic, although nonetheless fictional, story of the affects that an emergent infectious disease could have on people when there's no treatment or other means of prevention. But white-nose syndrome is really a non-fictional real world, happening right now, example of an emergent infections disease spreading rapidly through a wildlife population.

  • 10:23:05

    REHMTell me how exactly it affects bats, David, and what they do when they get this particular infection?

  • 10:23:21

    BLEHERTSo, despite the name for the disease, white-nose syndrome, which comes from a common presentation of the growth of a white fungus on their noses, what we found is that the fungus also colonizes the wings of bats. And the skin of bat wings is a very delicate organ that's actually more important to the bat than just providing a barrier function like the skin of our hands.

  • 10:23:42

    REHMI just viewed that bat wing for the first time in my life. It's really very delicate and beautiful.

  • 10:23:52

    BLEHERTAnd so one thing you also probably appreciated is how large it is. A bat has about eight times more skin on its wings than it does on the entire rest of its body.

  • 10:24:00

    REHMRight, right.

  • 10:24:02

    BLEHERTAnd so in addition to needing that skin in order to fly, that skin also plays an important role in preventing the loss of water while that bat is hibernating all winter long and not otherwise drinking water. It -- they can exchange gas through their wing membrane, so they can passively get rid of carbon dioxide when they're hanging upside down hibernating and only taking a couple of breaths per minute. And that wing skin is also important for controlling blood pressure and heat exchange with the environment and many other functions.

  • 10:24:33

    BLEHERTSo as this fungus colonizes that wing skin, it not only destroys the wing and the ability of the bat to fly but it also disrupts these other critical functions that are important for that bat to be able to survive hibernation and beyond.

  • 10:24:48

    REHMSo if the bat is infected with this particular fungus, what does it do? How does its behavior change, Dan Ashe?

  • 10:25:04

    ASHEI think that question is better handled by David. But the bats have been observed with aberrant behaviors like leaving caves in the middle of winter so that the belief is that the fungus is disrupting them or causing them irritation, which is causing them to wake up in the middle of winter. And when a bat wakes up in the middle of winter, it's expending a lot of energy. And any animal that's hibernating, energy is a premium. Conserving energy for that species during hibernation is a premium.

  • 10:25:35

    ASHESo if they wake up, they fly around. Then they want to go out and eat. And so bats have been identified -- have been seen outside of caves in the middle of winter. So it causes aberrant behavior. It causes them to use energy at a time of the year when they really don't want to use energy.

  • 10:25:51


  • 10:25:52

    BAYLESSYeah, you know, there's one interesting figure I've read where researchers working on little brown bats have shown that when a little brown bat wakes up, just one arousal burns through the same amount of fat that that bat could use to hibernate for an entire month. So when Dan says costly, bats enter the winter hibernation season with a very discreet amount of fat. And if they wake up too many times, they literally starve to death before the winter is over. And that's what's causing a lot of this mortality.

  • 10:26:24

    REHMAnd I gather then, David, what you're doing is finding lots of diseased and deceased bats.

  • 10:26:35

    BLEHERTThat's correct. And those bats are then collected by state biologists and sent to the National Wildlife Health Center in Madison where we perform disease investigation or diagnostic work.

  • 10:26:46


  • 10:26:48

    BAYLESSYeah, I'd like to give you an example of just -- when you say finding a lot of bats, what that might mean. Aeolus Cave, which used to be the largest hibernacula in all of New England -- bat hibernacula used to have about 300,000 bats.

  • 10:27:02

    REHMAnd where is it?

  • 10:27:03

    BAYLESSIt's in Vermont.

  • 10:27:04


  • 10:27:05

    BAYLESSAnd now it's almost vacant. The main hall where you walk into the cave, where you go into the cave to begin with, used to have 4,000 little brown bats roosting along its walls in the winter. When Scott Darling, who's the Vermont bat biologist, and his team went in last year, they counted 35 -- 35 bats. And it's been called the poster child of WNS. In 2009, when it hit, Scott described to me walking through the carcasses of literally 10- to 20,000 bats...

  • 10:27:35


  • 10:27:36

    BAYLESS...on their way to do the survey. And he told me at that time -- and I wrote this quote down 'cause I thought it was so powerful. He told me, the walls of this cave used to be covered with hibernating bats and their chattering voices. Now, it is a quite death chamber. It's simply depressing. And that example for me really describes what a tragedy this is for bats in North America and for all of us.

  • 10:27:59

    REHMAnd you got another problem, which is that lots of people like to explore caves. And this could be a real problem, Cynthia Moss, for bats.

  • 10:28:15

    MOSSWell, when people go into caves in the winter when the bats are hibernating, they disturb them, and they become active. And when there's no food available, 'cause the insects are not out, they can use up their fat stores very quickly. And so people have begun to put up gates in front of caves so that humans will not enter and disturb the hibernating bats. But this is separate from the white-nose syndrome.

  • 10:28:43


  • 10:28:44

    ASHEI think that's why the importance of a show like yours, Diane, is to -- the caving community has been a great partner for us in conserving caves and protecting caves because they are where they like to do their form of recreation. So it's really important to begin to educate people who are cavers about how they can help us to prevent the spread of white-nose syndrome. And there are techniques that are available to -- for them to, number one, be aware that they can transmit the spores from the fungus from cave to cave, and how they can take measures against that.

  • 10:29:19

    ASHESo education is going to be a key for us in dealing with this white-nose syndrome.

  • 10:29:24

    REHMDan (sic) Blehert, what about European bats? Are they infected with the same fungus?

  • 10:29:34

    BLEHERTSo a group of European researchers has found that the same fungus, Geomyces destructans, is actually quite common on bats of Europe, present in numerous countries. Interestingly, it doesn't seem to affect those bats in the same way as it affects North American bats. And there have been no reports of unusual bat mortality caused by the fungus.

  • 10:29:58

    REHMSo what does that tell you?

  • 10:30:01

    BLEHERTSo some of the epidemiology work that we've done for this disease leads us to the idea or the hypothesis that this fungus may have been accidentally introduced to an initial site in New York State which sparked the epidemic of white-nose syndrome in North America among a naïve population of bats. In other words, the fungus is behaving like an invasive species or an exotic invasive species among bats that didn't co-evolve with it to be resistant by some means.

  • 10:30:31

    REHMSo as I understand what you're saying is that the European bats, though they may have been exposed to this fungus for a long time, have somehow developed a resistance to it. But having that same fungus introduced, perhaps by a European tourist, to the U.S. bat population has created now this large problem.

  • 10:31:07

    BLEHERTThat's one of the possibilities that we're looking into.

  • 10:31:11

    REHMOne of the possibilities. What else are you looking at?

  • 10:31:16

    BLEHERTWell, there's other means that it could be introduced, but I think that global travel and trade is recognized as perhaps the largest driver in the emergence of infectious diseases worldwide. With air travel, we've effectively eliminated barriers that used to prevent spread of pathogens around the world, such as mountain ranges and oceans. And there's almost no place on this planet that any of us, if we set our minds to it, couldn't be within 72 hours. So it does lend credence to the possibility that it was introduced through travel or tourism.

  • 10:31:49

    REHMAnd that those European bats somehow have had it for such a long time that it's not doing the same sort of disaster as it is here in this country.

  • 10:32:04

    BLEHERTThat's right. There are some other differences with regard to the environment inhabited by these bats. So, in Europe, average bat hibernation populations are smaller. And so you could imagine that if there's fewer bats, there's less chance for growth or amplification of the fungus, if it grows faster on bats, and there's less chance for the fungus to transmit between bats. And so that may be part of the reason that it's less lethal or not lethal to European bats.

  • 10:32:35

    REHMIs there any way to stop the spread of this problem?

  • 10:32:42

    BLEHERTWell, one of the things that the Fish and Wildlife Service -- and Dan may want to speak more about this -- is doing is instituting what are called universal precautions for the prevention of spread of infectious diseases. And that includes restricting human access to sites used by bats, requiring that people decontaminate their shoes and clothing when they move between sites, and even requiring, in some instances, that people have dedicated caving gear for sites so that they don't inadvertently track the pathogen.

  • 10:33:13

    BLEHERTThe work that we just published did show that bats can spread the disease agent, the fungus, between themselves. But one might argue that even 1 million bat-to-bat transmission events of the fungus between, say, New York and Massachusetts where the disease already is known to exist, might be less significant than a single accidental human transmission of the fungus from New York to Seattle or from New York to Australia, moving it -- humans have the capability of moving the fungus greater distances than the bats.

  • 10:33:45

    REHMAnd that's the voice of David Blehert. He's head of the U.S. Geological Survey's National Wildlife Health Center. And you're listening to "The Diane Rehm Show." And it's time to open the phones, 800-433-8850. First, to Syracuse, N.Y. Good morning, Ray.

  • 10:34:16

    RAYGood morning, Diane. And you keep me company every morning.

  • 10:34:20

    REHMI'm glad.

  • 10:34:21

    RAYI have a statement and then a question. I live on a small lake in the summer in northeast Pennsylvania in the Endless Mountains, which I purchased in 1991. And up until last summer, I never had a mosquito bite. I have bats that live inside different channels of my house, and I would just sit and watch them come out at night. And, you know, if you crossed the road to my neighbor's house, you couldn't sit out without bug spray on. But down by the lake, no problems.

  • 10:34:55

    RAYAnd last year was the first year that I noticed no bat activity around my house and my neighbor's house. So, you know, I lament that loss, and I don't think people realize just how -- you know, how docile they are and what a wonderful enhancement they are to the environment. Is there anything that I can do to help nurture the development and the safety and bring bats back to my environment? What can I do as an individual to make a difference?

  • 10:35:27


  • 10:35:28

    BAYLESSWell, unfortunately, you're not alone in noticing that bats are missing from your summer skies. Although they're dying in the winter caves, that means they're absent in the summer. And you're not the first person I've heard to tell the story about not seeing bats in the summer skies. My friend Al Hicks used to play this game on his front porch with his son where, every time they would see and hear a bat, he would tickle his son in New York on his front porch. And he told me, last year, they tried to play this game with his son.

  • 10:35:59

    BAYLESSBut they gave up because it wasn't any fun because they sat for a long time, and nobody ever got to tickle. So it's just it's -- your story is not the only one I've heard like this. And it's really, really tragic. There are some things you might consider doing. You might consider putting up a bat house. Although bats are dying in their winter caves, they do have to find someplace to live and find food during the summer. So in places where their natural habitat maybe is not as plentiful as it once was, bat houses are a good solution for summer...

  • 10:36:30

    REHMHow large are bat houses?

  • 10:36:31

    BAYLESSYou know, there are a lot of bat houses on the market, and the big ones are better. So there are some guidelines on Bat Conservation International's website about dimensions.

  • 10:36:40

    REHMAre they communal creatures? Do they like to be with other bats?

  • 10:36:45

    BAYLESSAbsolutely. They like to be packed into those bat houses real tight.

  • 10:36:47


  • 10:36:48

    BAYLESSAnd the crevices are really only about three-quarters of an inch wide. So if you think about that big brown bat you just saw...

  • 10:36:53


  • 10:36:54

    BAYLESS...they back into the crevice, and they like to be very, very tightly packed for safety and for warmth. And the young don't thermoregulate very well, so that keeps the young warm as they're growing and learning to fly.

  • 10:37:05

    REHMSo a bat house. Dan, any other?

  • 10:37:09

    ASHEI think there are many things that people can do around their homes. I mean, and one is to be aware and, as you've tried to point out today, Diane, that bats -- you don't need to be afraid of bats. And many people probably have bats roosting underneath the shutters of their house or underneath gutters or in the bark of dying trees. So when that tree trimming company comes by and wants to take off those dead limbs, maybe think about not doing that.

  • 10:37:35

    REHMDan Ashe, he's director of the U.S. Fish and Wildlife Service. Short break, right back.

  • 10:40:02

    REHMYou may be wondering why we're doing a program on bats this morning. But surely, from what I've heard, it's an extraordinarily important subject. These bats of a number of species are so important to the ecological health of not only this country but the world in general. There is a large brown bat here in the studio which is actually a very tiny brown bat by my standard. Cynthia Moss, describe that wing for us. It's so beautiful. It looks like silk.

  • 10:40:50

    MOSSWell, the wing membrane is very, very thin. And it contains muscle and vasculature, and it supports very agile flight. So the bones in the wing correspond to the fingers of the human hand. There's a thumb, pointer, middle finger, ring finger and pinky. And the membrane is spread across these bones and allow for very agile maneuvers in flight. Bats that feed on insects will take the insects into their wings and then transfer the insects to their mouth. And so the wing is a very important part of the animal's natural behavior.

  • 10:41:31

    REHMAnd how durable is that wing?

  • 10:41:35

    MOSSWell, it's very delicate and...

  • 10:41:39

    REHMVery delicate...

  • 10:41:40


  • 10:41:41

    REHM...yet what is the lifespan of a bat?

  • 10:41:45

    MOSSWell, bats actually live a very long time for their size. In general, there's a relationship between the size of an animal and how long it lives. So elephants live a very long time, mice a very short time. But bats don't fall onto that scale. And there are bats that have been caught, banded and re-caught 35 years later. So they're really off the scale in how long they can live.

  • 10:42:10

    REHMBut, see, that's why I was asking about the fragility or the strength of that wing. It looks so fragile.

  • 10:42:19

    MOSSWell, it can become damaged. And sometimes bats get small holes in their wings, but they do heal. I think the fungus that's invading the wing has a more serious effect then a small puncture.

  • 10:42:35

    REHMAnd that's exactly what I wanted to ask you about, David Blehert, whether, in fact, this fungus could somehow inhabit enough of these bats so that it then becomes incorporated into their whole genome and they rebound.

  • 10:43:04

    BLEHERTWell, I don't think that it would integrate like you're suggesting. But the fungus has a very interesting property in that it can only grow in the cold. Bats hibernate at about 45 degrees Fahrenheit, and that's close to the optimum temperature at which the fungus grows. The fungus cannot grow at the temperature of a bat's body during the summertime when it's active, which is about the same temperature as our bodies, 98.6 degrees. And so we completed a study where we brought in bats from a hibernation site that were heavily infected with the fungus, and their wings were heavily damaged.

  • 10:43:41

    BLEHERTAnd by taking those bats out of hibernation, providing them with food and water, found that, within a matter of five to seven weeks, they made a remarkable recovery once they were able to warm up their bodies, activate their immune systems. They could clear the fungus at that warm temperature and completely regenerate their wing membranes in a manner that was really quite remarkable.

  • 10:44:03

    REHMInteresting. All right. Let's go back to the phones to Ann in Franklin, N.J. Good morning, you're on the air.

  • 10:44:13

    ANNGood morning.

  • 10:44:14


  • 10:44:15

    ANNI -- that's lovely what I just heard about the regeneration...

  • 10:44:19


  • 10:44:19

    ANN...being possible because, when I lived down the street from one of the largest bat caves in New Jersey which is located in Rockaway, the correlation seemed to be that when they were working on a bridge -- they were reconstructing a bridge just a few -- about a 100 yards from their cave -- that's when, I guess, they were stressed. And I just feel like stress has a lot to do with it. Like, if people with psoriasis, eczema, those kind of diseases, their diet, their environment, their sleep -- stress is a big factor in them getting better.

  • 10:44:54

    ANNSo is there any way to -- I mean, maybe fracking has some kind of possible connection there, too. Is it too close to the bat caves, and it disrupts their hibernation? I didn't know whether that had been discussed by the people who were trying to help the bats.

  • 10:45:14


  • 10:45:16

    BAYLESSBoy, I know -- I think David Blehert might be the best person to answer that question since he's been involved in those investigations from the beginning.

  • 10:45:23

    REHMBut what about, first, the bridge, David?

  • 10:45:29

    BLEHERTWell, of course, having an undisturbed habitat is critical to bat survival. And so, while we believe that the fungus alone or what we've shown that the fungus alone causes the disease, certainly, anything that disturbs these critical habitats that bats rely upon in order to survive the winter is detrimental to them. In terms of the recovery, the bats that we saw recover, remember, were brought in under the care of a licensed wildlife rehabilitator and were provided a warm and safe environment in which to heal.

  • 10:46:06

    BLEHERTAnd in nature, with habitat disturbance, the likelihood for bats to recover is probably not going to exhibit the same high success rate that we saw under captive and -- captive conditions where they were provided some care.

  • 10:46:21

    REHMAll right. Here's an email from Dennis. He's in North Carolina who says he saw an educational TV special on bats. "The producer stood in the entranceway to a New Mexico cave at sunset. Amazingly," he says, "not one of the millions of bats exiting the cave for their evening meal struck the man. I've wondered ever since how that could be. Are a bat's sounds and signals, used for navigation and hunting, that personalized that it can be differentiated from millions of others around it?" Cynthia?

  • 10:47:10

    MOSSWell, yes, bats do show small differences. To us, they seem small in the sounds they produce, which mean that they have their individual voices. And they can make adjustments in their voices to minimize interference with the calls and echoes of neighbors. And so we've done some direct studies of that in my laboratory. We've taken pairs of bats and put them in competitive foraging situations, and we've noticed, we've observed that they change their calls in response to the presence of another bat.

  • 10:47:45

    MOSSAnd the changes that they produce depend on how similar the calls are of the bats to start with. So we fly bats individually, let them catch insects, record their sounds, and then, when we put them together, we can look at the adjustments they make. And so when they're closer together physically, when they fly closer together and when their calls are more similar, they make bigger adjustments in their call frequencies.

  • 10:48:11

    MOSSWe also found that often times one bat would stop vocalizing when it was in the presence of another bat. And, here again, the prevalence of this silent behavior, depending on how similar the bats calls were to begin with, so if they were very similar to begin with, then one bat would stop vocalizing, listen in on the other bat. But if they were very different, then they didn't bother to produce or to stop vocalizing as much. So they have a lot of strategies to...

  • 10:48:42

    REHMAre these bats all blind?

  • 10:48:46

    MOSSNo. So bats can rely entirely on their echolocation to navigate and forage in darkness, although I should add that not all that species echolocate. But those that do can rely on it exclusively without using vision. But bats do also have eyes and can rely on vision that may -- that can provide information that compliments the echolocation.

  • 10:49:12

    REHMSo that large brown bat was probably frightened to death when he saw my face.

  • 10:49:18

    REHMYou never know. Here's a tweet from Kay who says he or she went to Mammoth Cave last year. "Park staff had us rinse our shoes in Lysol solution before the tour." David, is that something that's happening around the country?

  • 10:49:44

    BLEHERTThat's one of the procedures recommended by the United States Fish and Wildlife Service that they've co-developed with the National Park Service for that site, for example. And...

  • 10:49:54

    REHMAll right. And how much does that have a salutary effect on what's happening inside the cave?

  • 10:50:07

    BLEHERTWell, thankfully, white-nose syndrome has not yet been discovered in Mammoth Cave. And so the park service together with the Fish and Wildlife Service are working to prevent the disease...

  • 10:50:16

    REHMI see.

  • 10:50:17

    BLEHERT...from being introduced by a human visitor.

  • 10:50:20

    REHMAnd here's an email from Wesley who says "I'm a recreational caver from Virginia. It appears Virginia's not been as impacted quite as severely as other states in the Northeast, likely due to our caves higher ambient temperature, 55 degrees Fahrenheit and shorter hibernation. It still has prompted a caving moratorium. Please ask Dan Ashe why that is."

  • 10:50:57

    ASHEWell, we don't have any kind of national caving moratorium, as David has suggested. What we have is a universal set of precautions that we're asking people to consider. In the U.S. Fish and Wildlife Service, we manage 150 million acres of national wildlife refuges. We have closed all of our caves and mines on national wildlife refuges as a precautionary measure. The Park Service and the Forest Service and the Bureau of Land Management are taking a park by park or forest by forest approach as was mentioned for Mammoth.

  • 10:51:33

    ASHESome states, like Virginia and New York and others, are putting prescriptions in place in caves and on state lands and other areas, so we're asking all land managers to be aware of the potential problem of white-nose syndrome and to take measures to try to reduce the potential for spread by human means.

  • 10:51:53

    REHMAll right, Mylea.

  • 10:51:55

    BAYLESSI think that I hear the concern that the -- that your listener has represented, and I think a lot of people in the caving community are concerned about this. And I just wanted to mention that people in the recreational caving community have been advocates for conservation for many, many years and involved in the white-nose syndrome effort from the beginning. And so, although there's some frustration about these restrictions, I think that community has been overall very supportive of this white-nose syndrome investigation.

  • 10:52:22

    REHMAll right. To Humble, Texas. Good morning Bobby.

  • 10:52:28

    BOBBYGood morning. I heard it said that a very small percentage of bats were rabid. I think the listeners need to be cautioned that if they see a bat in a time and place where they shouldn't see one, that it is likely the bat is rabid.

  • 10:52:44

    MOSSI think that's a very valuable point, although it's a very minute percentage of bats that are rabid. If you can approach a bat on the ground and pick it up and it's acting sick, my guidance is to leave it alone. And if you do come in contact with that individual, you should probably seek some medical attention.

  • 10:52:59

    REHMWhy should you pick it up at all?

  • 10:53:02

    MOSSAbsolutely, you should not. People should leave bats and all other wildlife alone as just a general rule of thumb.

  • 10:53:10

    REHMAnd you're listening to "The Diane Rehm Show." Dan Ashe, do you want to add to that?

  • 10:53:16

    ASHEI would just say that bats have no more incidents of rabies then other forms of wildlife, like a raccoon or opossum or any other kind of wildlife that people would come into contact with. And the main thing is if you see an animal that is exhibiting aberrant behavior, to not pick them up.

  • 10:53:34

    REHMBut what is aberrant behavior in bats, Cynthia?

  • 10:53:37

    MOSSWell, typically, bats will hang upside down, from our point of view, and fly around. They would not typically be on the ground. And, therefore, that would be a sign that the bat is sick and...

  • 10:53:53


  • 10:53:54


  • 10:53:54

    REHM...don't pick the bat up if the bat is on the ground. To Madison, Conn. Good morning, Jay.

  • 10:54:04

    JAYHi, Diane, thank you for taking my call.

  • 10:54:06


  • 10:54:08

    JAYIt's kind of beside the point. I do have a question. But when you were playing the audio of the echolocation of the bats in slower time, I had some chickens in the car, and they got very excited.

  • 10:54:28

    REHMThat's very interesting.

  • 10:54:30

    JAYYeah. (unintelligible)

  • 10:54:31

    MOSSMy dog also reacts to these sounds when I play them.

  • 10:54:36

    REHMGo right ahead, Jay.

  • 10:54:38

    JAYBut I'm a visiting nurse in Middletown, Conn., and I have occasion to frequent a lot of brick buildings in the area. And, on several of those buildings, I've noticed bats living in the eaves. Like, you know, this is during the summertime, so I don't know if they roost there during the winter months. But, on occasion, I've discovered bats clinging to the side of the building during the day and not wishing to disturb them or hopefully no one else wishing -- you know, no one else disturbing them.

  • 10:55:19

    JAYI was wondering if that in and of itself was a sign that they might be suffering this white-nose fungus? And what if anything, besides not touching them, should I have done? You know, maybe letting the Connecticut DEP know or...

  • 10:55:37

    REHMSure, David Blehert.

  • 10:55:40

    BLEHERTSo it's not unusual for bats to inhabit eaves of buildings or spaces in the walls. When it comes to infectious diseases like white-nose syndrome, all diseases involve an interaction between a host -- in this case, the bat -- a pathogen -- in this case, Geomyces destructans -- and an environment. And with bats, we think that the most important environment towards development of this disease are underground caves and mines in which they hibernate.

  • 10:56:07

    BLEHERTIt's my hope that the conditions in the walls of houses, for example, are environmentally less stable and perhaps less conducive to the growth of fungus. It's interesting that different bat species tend to frequent eaves of houses and wall cavities...

  • 10:56:26


  • 10:56:26

    BLEHERT...then those that prefer caves, and so it might be that bats that occupy buildings are actually protected to some degree from progression of this disease.

  • 10:56:34

    REHMAnd David, one last quick question. We only have a few seconds. Can these bats, once they are infected, be cured, or is it a sure death sentence?

  • 10:56:51

    BLEHERTSo some of the work that we've done has shown that a bat can naturally recover from the disease. In wildlife conservation, we're careful to avoid using terms like cure, especially for a disease like white-nose syndrome where we know that the fungus can persist in the environment. And so even if a bat recovers, it could get re-infected from the environment.

  • 10:57:12

    REHMI see.

  • 10:57:13

    BLEHERTSo it's not likely that tomorrow we'll be able to stop this disease in its tracks, but, hopefully, we will be able to moderate its effects and reduce its frequency of spread.

  • 10:57:24

    REHMAll right, David Blehert of the U.S. Geological Survey, Cynthia Moss, University of Maryland, Dan Ashe, director of the U.S. Fish and Wildlife Service, and Mylea Bayless of Bat Conservation International.

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