Little Brown Bats Could Disappear In The Northeast

Reporting in Science, researchers write that little brown bats, or Myotis lucifugus, are likely to disappear from the Northeast over the next 16 years. Study author Winifred Frick discusses white-nose syndrome, which is associated with die-offs and caused by a fast-moving fungus.

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IRA FLATOW, host:

This is SCIENCE FRIDAY from NPR. I'm Ira Flatow.

You know, species die out all over the world in remote places we never heard about, but there is one species that is dying right before our eyes, in our lifetime. We've been talking about it for years on this program, and now a group of scientists writing in the journal Science says there's a 99 percent chance little brown bats, once a very common species, may be extinct in the Northeast within the next 16 years.

What's killing them? Is it this fungus we see on the bats, the white-nose syndrome? Or is that just a symptom of some deeper problem? Scientists have spotted infected bats as far west as Oklahoma now. Could this infection soon threaten bats all over the continent? That's what we'll be talking about at the beginning of this hour, our number, 1-800-989-8255. You can tweet us, @scifri, and join the discussion on our website at sciencefriday.com.

Let me introduce my guest. In fact, we have up on the Web page a bat video, a tour of a bat cave where the bats were falling victim to white-nose disease, up there on our website. You can take a look at that. We did a couple years ago. That's how long this has been around.

Winifred Frick is a post-doctoral fellow at the University of California Santa Cruz and Boston University. She joins us from the studios at Boston University today. Welcome to SCIENCE FRIDAY, Dr. Frick.

Dr. WINIFRED FRICK (Boston University, University of California-Santa Cruz): Thank you, Ira.

FLATOW: What is the situation today with the bats? Where has the white-nose syndrome been found so far? I say it's as far out as Oklahoma?

Dr. FRICK: That's correct. You know, it was first discovered in Albany, New York, in 2006, but this - and every year, we've seen a huge increase in its distribution, but this year was really the worst.

It made it up to Quebec and Ontario Provinces in Canada and as far west as Oklahoma, as you mentioned, as well as as far south as Tennessee. So we've seen it spread halfway across the continent.

FLATOW: And how fast do you think it could make it over the Rockies to the West Coast?

Dr. FRICK: Well, that's a good question. Faster than we would like, I'm sure. The - one of the distressing things about the record in Oklahoma was that it was found on a new species, Myotis velifer, which is the cave myotis, and that species happens to have a more western distribution. It makes it all the way to California.

So we could very likely see it into the Rockies this winter and even further west than the Rockies.

FLATOW: And in your paper, you're predicting that there's a big chance these bats may be gone in 16 years, at least from the Northeast. How do you come up with that number?

Dr. FRICK: Yeah, so what we did was we took two very extensive data sets, a 17-year record of mark recapture, which is, Scott Reynolds went out and captured little brown bats in a maternity colony every year, starting when he started his Ph.D. here at Boston in the early '90s.

And so we had a really good record of the annual variability before white-nose hit, of the survival of little brown bats. And then we also looked at historic records collected by New York Department of Environmental Conservation and Pennsylvania Game Commission of counts of bats at hibernating sites and sort of meshing those two data sets to look at the natural variability in the populations before white-nose hit.

We learned that the populations were actually doing fine. They were healthy and thriving before the disease was discovered in 2006. And then we took the information from caves that have been infected since 2006 and looked at the mortality, the empirical evidence of the mortality at those caves.

And we put all that data together in population models and asked the question, okay, if given the natural variability in the system and the known mortality that we've seen, if those population dynamics continue - if the mortality and the spread of the disease continue the way we've seen for the past four years -what will be the chance that these bats will be on the landscape in 20 to 100 years? And that's where we got that very dire prediction.

FLATOW: Yeah, well, you see the fungal infection, the white-nose on all the bats, but you're not sure if that's the cause or possibly just a symptom of the problem, right?

Dr. FRICK: Well, we're scientists, and we like to be very careful and not be definitive, but - until something's really proven. But, you know, we have very strong evidence at this point that the fungus, Geomyces destructans, is strongly associated with white-nose syndrome.

It is what's growing on the bats. It grows on their wings and causes the necrotic and scarred wing tissue, and the bats are waking up too frequently during their hibernation, and they're starving to death.

So we refer to it as the putative pathogen, because we have to satisfy Koch's postulates before we can say for sure that this pathogen causes the disease, and that work is ongoing and being done right now.

FLATOW: So it's not the fungus. They're not being shred to death by the fungus. They're waking up in their hibernation period, going out, freezing and starving to death is what's happening.

Dr. FRICK: That's what we think, yes. Yeah.

FLATOW: And why would they wake up from the fungus?

Dr. FRICK: Well, we're still working on some of those details, but we have what's called the scratch and - the itch and scratch hypothesis, which is perhaps the fungus growing on them irritates them.

You know, as anybody who's had athlete's foot knows that those kind of fungal infections, skin fungal infections, can be very irritating. And so perhaps that.

It could be that their, you know, they need to mount immune response, and their immune systems aren't active while they're hibernating, and so perhaps they know they need to try to mount their immune response, so that's why they're waking up.

A lot of researchers are working on these sort of mechanisms-of-death questions.

FLATOW: So they wake up, they fly out, they starve to death, and I understand that this is not the first case of this kind of bat death, that it occurs in Europe, also.

Dr. FRICK: Well, we have confirmation that the fungus, Geomyces destructans, the same species of fungus, has now been documented on a handful of species in a number of countries in Europe. But what we're not seeing in Europe is the symptoms of the syndrome, so the aberrant behavior, flying around in winter, the scarred and necrotic wing tissues, the loss of body fat, and then we're not seeing the massive die-offs in Europe, either.

FLATOW: Isn't that interesting?

Dr. FRICK: It's interesting, and it may be a ray of hope. I mean, if this fungus has been around a long time in Europe, and the bats there have, you know, evolved with it and learned to coexist with it, then that could be a big ray of hope for us here.

FLATOW: Last year, we talked about the possibility of building warm bat boxes inside the caves so that the bats wouldn't freeze after losing their fat. Has that been tried?

Dr. FRICK: Yes, so Justin Boyles and Craig Willis, who are the authors of that paper, tried that this winter, and unfortunately, the bats didn't use those boxes.

And this is the case where, you know, where because we're facing such a major crisis, people are really sort of thinking outside the box, if you'll excuse the pun, and trying to come up with as creative options as possible.

And so I applaud Dr. Boyles and Dr. Willis for thinking, you know, putting an idea out there, but at this time, it doesn't look like that's going to be the saving grace.

FLATOW: Let's go to the phones, Ken(ph) in Alfred, Florida. Hi, Ken.

KEN (Caller): Hi. Thank you for taking my call. I've been following this for a couple of years myself, and it's really worrisome indeed. My understanding is that the white-nose fungus is an opportunistic, and that what I'd heard is that there's a problem with the bats' digestive systems, something about key enzymes showing up missing or not showing up, as it were, and that they were burning through their fat stores much faster and therefore waking up and trying to eat.

It would be nice to keep them warm during this time, but what they really need is something to eat. Can you speak to this research about the lack of enzymes, and is there anybody actually coordinating the research? Is there - is the funding adequate?

FLATOW: Okay, good questions.

Dr. FRICK: Yeah, those are great questions. In terms of whether the fungus is opportunistic or not, there's very compelling evidence that this was a novel introduction of this fungus to North America, because we don't have any record that this fungus was growing on bats in North America beforehand.

We actually have very good data on that, because people were taking photographs of bats in hibernating caves for years prior to this, and people have gone back and looked through those photographs.

And you would expect, if this is opportunistic, you would see it sort of flare up from time to time. And we also have a very clear pattern of spread, that it really has spread from an epicenter and radiated out, which is another good indicator that there was a point source of introduction.

So, you know, early on, people weren't sure, and that actually motivated our work to try to understand how the populations were doing before 2006, because you would expect that this was already present in the system, and somehow the bats were just sort of succumbing to it now, that there would be other indicators that the bats were in poor health. And that data has showed that they were doing fine, prior to 2006.

FLATOW: Do these bats eat mosquitoes?

Dr. FRICK: They do. Their diet...

FLATOW: And then that's a huge problem, if you lose all these bats, and what happens to the mosquito populations?

Dr. FRICK: Well, that's true. I mean, we're basically in the middle of a terrible natural experiment about what happens when you remove a very abundant species that plays an important role in terms of ecosystem services.

They don't eat exclusively mosquitoes. They eat a wide variety of insects, and some of those insects are agricultural pests and forest pests, as well as some mosquitoes in the diet.

FLATOW: There are frogs dying all over the world from a fungal infection. You have bats dying now from fungal infections. Could there be some kind of link between the two?

Dr. FRICK: Well, there's no link between the two fungi, that are the chytrid fungus that's attacking amphibians and this Geomyces destructans that's attacking the bats. But it does, you know, speak to the broader problem of wildlife disease and pathogens creating significant risks to species. And in the case of white-nose, the potential role of humans moving pathogens around.

FLATOW: And there had been talk about using fungicide on the bats. That hasn't worked or is not practical, either.

Dr. FRICK: That's not practical for a number of reasons. One is - you know, maybe - as anybody knows who's had athlete's foot, to use that analogy again, a lot of fungal infections require multiple treatments. And so the idea of trying to treat bats with an anti-fungal, say, as they're entering a cave would be very difficult.

The other thing is we can't just go in and mass-spray inside these caves because these caves themselves are valuable ecosystems with other rare or endangered species. And we can't just go in and mass-spray inside a sensitive ecosystem.

FLATOW: All right. We'll just have to wait and hope for the best and keep track of what's going on. Thank you, Dr. Frick, for joining us.

Dr. FRICK: Thank you very much.

FLATOW: Winifred Frick is a post-doctoral fellow at the University of California-Santa Cruz, and Boston University.

We're going to take a short break, switch gears and talk about cooking for geeks. Yeah, are you a geek who likes to cook? We're going to have some interesting ways that you can cook, how to turn - well, there's so much to talk about. I don't want to give it away. So stay with us. We'll be right back with Jeff Potter, cooking for geeks and your questions, 1-800-989-8255. Or you can tweet us, @scifri, @-S-C-I-F-R-I. We'll be right back.

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