What's Killing Bats in the Northeast?

Scott Horvath:

Welcome and thanks for listening to USGS CoreCast, I'm Scott Horvath. Today, we are going to talk about bats and white nose syndrome. So without further ado I want to go ahead and welcome Paul Cryan. He is a research biologist with the USGS out in Fort Collins, Colorado.

Paul Cryan:

Hey, thank you for having me.

Scott: And also on the phone from Madison, Wisconsin is Kimberly Miller. Do you want me to call you Kim or Kimberly?

Kimberly Miller:

Yeah, Kim is fine.

Scott:

She is a wildlife disease specialist with the USGS National Wildlife Health Center. Kim thanks for joining us.

Kim:

Hey, thanks for asking me.

Scott:

In the winter of 2007, I believe this is when this whole white nose syndrome started, I guess popping up and I guess it is affecting tens of thousands of bats in the northeastern United States. So the thought was that this was going to probably sort of subside and go away as springtime approached, but then it started coming up again. What I want to know from the two of you is can you tell us just a little bit about what white nose syndrome actually is and sort of you know why is this resurfacing all of a sudden again?

Kim:

Sure, well it first was noted, as you said, in February of 2007 by one of the wildlife biologists in New York and what he was seeing was bats flying outside of the hibernaculum in the wintertime and also bats with this white substance around their nose and that is how it got its name, white nose syndrome.

Scott:

Right.

Kim:

That white substance though is not on every affected bat and it can be seen on other places on the bat other than their nose. Then this year the biologists in New York, but also some other states as well started seeing affected bats. Though we have bats in multiple locations in New York, Massachusetts, Vermont, Connecticut later on in the season and we were then seeing bats displaying these unusual behaviors of being outside of the hibernaculum in the winter, flying in the daytime, and massing near the entrance of the hibernaculum and these are all things that they really should not be doing and they are also seeing bats with the white nose on their face, so that is kind of how it got its name and a little bit of the background. So the disease was seen in many more areas this year as compared to last year and why that is, we do not know. We are not sure whether it is an infectious disease. The white substance on their faces and bodies appears to be a fungus, but we have not been able to consistently culture you know one particular fungus from these bats, so it could just be that that is just sort of something that is not the primary problem, it may be that there is some other thing in these bats are more susceptible and so they are more susceptible to other disease problems and this white fungus that we are seeing on them may not be, you know, the primary cause of why these bats are affected.

Scott:

Right. Now, you said that there are other parts of the bat it can appear on other than the nose?

Kim:

Yeah, it has been noted on the wings, on the body, on the legs, so it has been seen other places other than the nose. The ear tips for example, they have seen white material on the ear tips, but again it is not every bat that appears to be sick has white nose.

Scott:

Okay, only certain bats for whatever reason, yeah.

Kim:

Right, right.

Scott:

Okay, so you know of course you know obviously you know this whole topic is about bats and people always, I won't say always, but they sometimes think of when you mention the word bats or you mention something about a bat, you know a society of like Count Dracula, or you know vampire bats, or you know something like this, something you see in the movies or TV, so they obviously have this fearful reputation, but they are pretty vital to the biological environment. So can you sort of explain what that is about?

Paul:

Yeah, sure. Yeah, most of those popular what we call misconceptions about bats are just dead wrong. Globally, bats play very, very important roles in most of Earth's ecosystems. There is about 1100 species of bats on earth and in tropical areas they play very important roles of seed dispersers, pollinators of plants and you know lots of insects, and here in the US we have about 45 species of bats, the majority of them, about 42, are primarily insect eating. We also have a few that occur in the desert Southwest that play important roles in the pollination of large cone or cacti and Agave Century Plants. But here in our neck of the woods, most of the bats are feeding on insects and they consume tremendous amounts. We are just now starting to get a feel for how much they play a role as insectivores in our environments. But the best example we have is from an area of Texas where there is a large concentration of species that we call Brazilian free-tail bats and there was a study done in 8 county region of Texas and they found that those bats, just in that 8 county region were probably consuming somewhere around 2 million pounds of insects each night during summer when they are in the area...

Scott:

Wow!

Paul:

...eating to about 400 metric tons of insects a year and they extended those results to an economic analysis and in that area the pest control services of bats played probably equated to about 1 or 2 million dollars in the prevention of crop damage and application of pesticides by farmers in that area. So that is just one species of the 44 that we have and you can imagine that these other bats are having a tremendous impact too. We just do not really know how our ecosystems would function if some of these bats are taken out of the picture and that is one of the big concerns with white nose syndrome. We have never seen consistent and widespread die-outs in bats like this. In general, they are not susceptible to epizootic diseases, you do not see these diseases raging through their population and killing large numbers and their population they are very slow to reproduce. They have one young per year here in this part of the world, they grow slowly, they take a long time to get those young up and running, so they don't bounce back from this catastrophic population impact.

Scott:

Right. So they are severely affected by this, I mean it obviously affects their growth and the expansion of their own species I guess.

Paul:

Yeah, some estimates are putting it as hundreds of thousands of bats in the affected area dying of white nose.

Scott:

Well is it only certain species or is it like a certain number of species that so far are affected or...?

Kim:

It has been primarily the little brown bats, but also the large brown bats, eastern pipistrelle, and then the Indianan bat which is an endangered species.

Paul:

Yeah, these are mostly hibernating species. There are other species of bats that occur in that region that live in trees primarily or other types of roof during winter, but we are mainly seeing this in the hibernating species that aggregate in caves and mines.

Scott:

Okay.

Kim:

And also I should say the northern long eared bat as well is involved. One thing I wanted to second that Paul had said is that we really do not get reports of large scale bat mortality. In one of the locations in Vermont, one of the caves, they have been going in and surveying those populations and finding no few thousand bats. Well some cavers that has gone into the cave and moved some of the rocks and found that there is a whole another chamber way you know further back had not ever been accessed by people and so when they went back in there and did population counts they founded like another 20,000 bats. My point being is that we do not typically get the large die-outs of bats, but in the caves and hibernacula combined that people do visit or do surveys we have not historically gotten reports of mortality in those areas. So it is kind of a new finding to have.

Paul:

Yeah, the bat researchers have been visiting a lot of these sites for the past 80 to 100 years and the situation with white nose syndrome was so alarming that there has really been a response by the bat research community and I think the feeling among a lot of us that work with bats that this is something very unusual and very serious stuff.

Scott:

Well and along those lines what is USGS and other federal wildlife agencies doing to sort of learn more about this disease and what is happening in that area?

Kim:

Well, here at the center, we are a diagnostic and research center and our whole focus is on disease prevention, detection, and control in free-ranging wildlife, so we are really kind of unique in that aspect. We received phone calls and things from biologists, both at the state or federal level, regarding wildlife health issues or problems or concerns and oftentimes they are calling about something that dies and that is what happened in this case. Biologists call in, talked to our fields of other wildlife disease specialist here about what they are seeing, bats acting unusual and submitted carcasses to us. They come in to our diagnostic lab where they are worked up by our veterinary pathologist and what they're doing is called a necropsy and that is really like a human autopsy. They are examining these bats inside and out looking for things that less of normal and look abnormal and they collect samples of the skin and the fungus from around the nose or up the body to send to our various labs to look for bacteria, viruses, parasites and they also collect a number tissues to look at microscopically. And the point of all of this is really to try, it is like putting together a puzzle and we are really trying to put all those things together into a coherent picture of what's going on. Some of our lab results are in, but not everything, but the one underlying thing that we have seen is that generally across the board these bats are in poor body condition or emaciated, they're just not doing well, which indicates that either they went in to hibernation, maybe in much healthy condition, and they just did not have enough fat source to make it through or they went in to hibernation in good condition, but for some reason have really used up a lot more of their fat stores and have not been able to get through.

Scott:

Okay.

Paul:

The real puzzling thing here is that these hibernating bats go into winter hibernation in a typical year with adequate fat reserve to survive the winter and when they are down in that deep state of torpor they are burning very little energy and the fat that they accumulate going into a typical winter could last them far longer than a winter. But the problem is that they arouse from torpor they bring their body temperature up to normathermic levels so like our high body temperature like us and those arousals they have to do that for whatever reasons to drink, get rid of their bodily waste, ate, to relocate within the hibernacula and it is no natural arousals that consume that vast majority of energy during winters. And if anything is causing those arousals either to be more frequent or to last longer when the bat is up and burning energy that is going to quickly tip the balance of this tight energy budget towards starvation and so we could have many different things whether it is a contaminant or pathogen somehow increasing arousal frequency. There is a lot of things...it is a very complicated picture and it is amazing that we have all these laboratories and ecologists and many diverse players involved, really working together.

Scott:

And I think the last question that I have for you, both of you is, is there like certain areas that are more perfect for this type of disease?

Kim:

Well, that is something we would really like to know (laughter). It is hard to answer that because it is not clear if this is a disease problem that is primarily an infectious disease problem, meaning is it a disease that the bats are able to spread amongst themselves. So if it is something like that because bats do move around quite a bit in the summer, it potentially could be something that could be transported to new areas. If it is bats there are other factors going on that are not infectious or contagious then you would need those conditions to exist in that new area for it to be a problem for bats. Does that make sense?

Scott:

Yeah, like climate related conditions.

Kim:

Right, if this is related to some other thing and not a contagious infectious disease organism then, yeah, you would need those things to be occurring at that site in order for it to be a possibility to occur in those bats. So that is one of the reasons that we really would like to try and pin down better just what some of the factors are, what causing this because then we can detect and take those next step to determine whether there are things that we can do to minimize that losses or stop this process.

Paul:

Yeah and the worst case scenario is that this is something infectious and I hope that it is not. The bats from the affected areas, in the affected caves that we see in this winter do quite a bit of regional migration in all directions and the areas that these bats migrate to during summer overlaps with areas that are visited by wintering bats from further South. So there is a real fear that this is, if this is something infectious, it will move into the Southern region.

Scott:

Well, let us hope that it isn't infectious and at least limit it to a specific area, that way you can sort of close down where you know have to focus on I guess on the research in preventing this. Well Paul and Kim, I appreciate you taking your time out of your morning to meet with me and discuss white nose syndrome.

Paul:

Thank you, my pleasure.

Kim:

Yeah, thanks, my pleasure also.

Scott:

Great! Well that does it for this episode of the USGS CoreCast. Thanks a lot for listening and don't forget that you can get transcript of this episode related photos and links by going to usgs.gov/corecast. And the USGS CoreCast is a product of the U.S. Geological Survey Department of the Interior. Until next time, I am Scott Horvath saying "keep it cool."

 

 

Dr. Nancy Thomas, wildlife pathologist at the USGS National Wildlife Health Center, conducting a necropsy on a little brown batBat with white nose syndrome hanging from a cave wall. Credit: New York Department of Environmental Conservation.

 

Dr. Nancy Thomas, wildlife pathologist, and Dottie Johnson, technican, collect samples while conducting a necropsy on a little brown bat.

 

Mentioned in this episode:

• National Wildlife Health Center
• USGS CoreCast

Music credit:"action_beds_08_awaiting_the_alarm_L2", dynamedion