Ep 72 White-Nose Syndrome: How deep is your torpor?

00:00:02
Speaker 1: I'm doctor Winnifred Frick, and I started studying white nose syndrome when I was a post doc. And I had been interested in population ecology and conservation biology of bats, but had not worked on hybrid and eating bats. And I got introduced to the topic of whiteness syndrome by doctor Tom Koontz, who is really the godfather of that biology in North America. And he was a professor at Boston University, and he invited me to be a post doc with him, and I went to visit him in the summer of two thousand and nine, and he had basically been studying little brown bats and in Massachusetts and New Hampshire for decades. Really had a whole system of a set of maternity colonies, which is where females come to raise their pup that he had trained graduate students and also had a field camp with undergraduate students. So these were like, you know, this was his system, and really these colonies were part of his life and in his study system and really like old friends. So this is the summer of two thousand and nine, uh, and so it was really early on in the in the WS epizootic and we went on a tour. He took me on the tour of all these maternity colonies, and every time we would show up, instead of being thousands of bats chattering and these are like an old barns and atticts and things, and they should have you should have been able to hear little chitters and chatters of the females doing their social calls while raising their pups. It was just silence and there were no bats there, and and we'd get to the next site and they'd be the same thing, and it was just it was so heartbreaking. And I could see on Tom's face just the the loss of these bats that he knew and had this long term relationship with and that they were gone. And a couple of years later, I was working in Virginia and doing underground surveys there and it was sort of a similar thing where we would go underground with Rick Reynolds, who's the state biologist in Virginia, to these sites that he knew, and he knew all the bats that should be in there, and we'd get in there and you know, the main cavern where there should have been, you know, thousands of bats, was just empty. And it was that same look of just kind of disbelief and a sense of personal loss for these folks who had a relationship with these sites and with these bats and seeing them just be gone.

00:03:25
Speaker 2: Wow. I just can't imagine the devastation.

00:03:30
Speaker 3: I know, it's so horrific.

00:03:34
Speaker 2: You just heard from doctor Winifred Frick, and we are very excited because this is not the only time in the episode that you will hear from her. She actually was kind enough to spare some of her time to chat with us about white nose syndrome, which is the topic of today's episode of this podcast, Will Kill You.

00:03:56
Speaker 3: Hi, I'm Erin Wels and I'm.

00:03:58
Speaker 2: Erin Alman Updike, and we did that completely backwards.

00:04:04
Speaker 3: I love it.

00:04:04
Speaker 4: Actually, that was fun. It's fun to do things a different way sometimes, I know.

00:04:08
Speaker 2: I was like, I don't know where we're going anymore with this. It's great, but we know where we're going with the topic of today's episode, which, as we mentioned, white nose syndrome. It is a wildlife disease. It's one of our first this season.

00:04:23
Speaker 4: I think it is our first one this season. Yeah, We've only done a few like in our history thus far, so I'm life exclusive.

00:04:32
Speaker 2: Yeah. Yeah, but I'm very excited because you know, this is the kind of thing where in grad school we learned about this as like a developing issue, right, and it still is very much developing.

00:04:46
Speaker 4: I know, it's I remember hearing a lot about it back in like twenty thirteen when I first started grad school, and I feel like I haven't been hearing about it as much lately. And so it was really great to do a nice deep dive and I learned so much that I never knew, Like all I knew was, oh, the bats are dying.

00:05:05
Speaker 2: Yeah, exactly. It was really cool to do this deep dive. And I'm really excited to hear what you have to say.

00:05:11
Speaker 4: Oh, I'm excited to hear what you have to say. And I'm also excited, Aaron, like you mentioned to speak with doctor Winnifred Frick, who is incredible and a true expert on white nose syndrome and bats. So yes, yeah, very exciting.

00:05:24
Speaker 2: Before we get into all of that, we have some business to take care of.

00:05:29
Speaker 4: The most important business. It's quarantiny time.

00:05:32
Speaker 2: It's quarantiny time. What are we drinking this week?

00:05:35
Speaker 5: We're drinking weigh in it, weigh in it because as we sat down to record, we kind of realized that we had forgotten to name this quarantini.

00:05:46
Speaker 4: We forgot. It's fine. We wung it, we wung it.

00:05:51
Speaker 2: Yeah.

00:05:52
Speaker 3: I like the name though, I love it. It's perfect.

00:05:55
Speaker 2: And I also like what's in the quarantini, which.

00:05:59
Speaker 4: Is tequila, of course, because Aaron tell us why we had to choose tequila.

00:06:05
Speaker 2: Because without bats, tequila wouldn't exist.

00:06:09
Speaker 3: It wouldn't exist.

00:06:11
Speaker 2: Bats pollinate the agave plant, which is what is used to make tequila, so bats are crucial.

00:06:17
Speaker 4: Crucial for tequila. Yeah, but it's not just tequila, you know.

00:06:21
Speaker 3: We spiced it.

00:06:22
Speaker 4: Up a little bit, added some peach green tea, some orange liqueur, some lemon juice. It's like really quite tasty and refreshing.

00:06:30
Speaker 2: Yeah, super refreshing and the most important thing about this And I don't know if it actually adds that much to the flavor. It might detract. But you rim the glass in powdered sugar for white nose syndrome. And we will post the full recipe for this quarantini, as well as the non alcoholic placeba Rita on our website This podcast will Kill You dot com, as well as on all of our social media channels all right.

00:06:55
Speaker 4: Other business that we always have to mention. We have a really great website, this podcast.

00:07:00
Speaker 3: We Kill You dot com.

00:07:01
Speaker 4: On it, you can find a link to our Goodreads list, our bookshop dot org affiliate account, our music by bloodmobile, transcripts of every episode non alcoholic episodes, all of our merch Oh my gosh, there's just so much.

00:07:16
Speaker 3: Go check out our website.

00:07:17
Speaker 2: Yeah, I think I think that about covers it. So can we learn about white nose now?

00:07:24
Speaker 3: I would love to.

00:07:25
Speaker 4: Let's take a quick break and then dive into the biology. So white nose syndrome sometimes in the literature also called white nose disease, but we're gonna call it white nose syndrome. This is a disease of hydating bats that is caused by a fungus named pseudo Gymnoascus destructans.

00:08:08
Speaker 3: It's very I think appropriate name.

00:08:11
Speaker 2: I'm just calling it. Oh yeah, I think I just call it PD because I saw that pseudo and was like, I'll attempt that once if I have to. But that's it.

00:08:21
Speaker 3: Yeah. Called p D for short.

00:08:24
Speaker 4: It used to be called geomic's destructance, but it's a different genus anyways. P D for short and I know that aarin, you're going to talk about the discovery of this fungus and this fungal infection, but suffice to say it is a very recent discovery and has since been the cause of mass fatalities among hibernating bats in North America. This fungus is what's called a psychrophilic fungus, which means it's cold loving, so it grows at temperatures generally between ten and fifteen degrees celsius, and it really maxes out at like twenty celsius, so it can't really grow above that, which for those of us in the US is like fifty to sixty eight degrees fahrenheit. And that aspect is really important. But I'm just going to put a pin in it for now and we'll talk more about it later. So white nose syndrome was first noticed and named. I hope I'm not stepping on your toes erin in a picture, because this fungus literally grows on the skin of the muzzles, which are the tiny little bat noses, as well as their ears and wings, and it looks like a little white, fluffy Santa Claus beard kind of yeah right, yeah, yeah. At least one paper described it as quote the delicate, exuberant white filaments that obscure the muzzle.

00:09:57
Speaker 2: Wow, that's like so much. That's like such a cute description for such a horrible, like horribly devastating fungus.

00:10:05
Speaker 4: I know, it makes it sound really adorable. It's not on the wings, where it also can grow. It looks kind of like a tacky white film almost, but it also can present a lot more subtly with just kind of a loss of you know how bat wings are kind of a little bit shiny looking, so infected bat wings can just kind of be a little less shiny or maybe just have small little tears in them that you wouldn't necessarily see unless you were looking very closely. And like we mentioned, as fluffy and cute as it might look in some pictures, this fungus is nothing of the sort. It's a lot more sinister. It doesn't just grow on the fur or on the skin where you see it. Histologically, if you look at the skin underneath a microscope, what you'll see are these fungal hiphi, which we've talked about this season earlier in our cocsidioid O micosas episode. It's the tree like branching fungal form, and so if you look under the microscope, you'll see these little tree like fungal structures that invade the epidermis the skin of the bat and form these little cup like erosions, these little ulcers that erode down into the underlying connective tissue. These fungal hiphie will invade and essentially can like replace hair follicles. They can invade sebaceous and apocrine glands. So these are like glands on skin like we have them too, that secrete oils and sweat and things like that.

00:11:48
Speaker 3: Around the muzzle.

00:11:49
Speaker 4: And and on the tips of these hiphi are one of the things that can distinguish them from other species of fungus. They have these conidia, which are spores the like reproductive structures of fungus, and their little curvy little nugs. They kind of remind me of like a malaria parasite without the tail.

00:12:10
Speaker 3: I feel like that's what.

00:12:10
Speaker 4: They look like under the microscope, kind of like a little boomerang shape.

00:12:14
Speaker 1: Right right.

00:12:15
Speaker 4: Okay, So bats who are infected with white nose syndrome during hibernation. These are hibernating bats that are infected by the end of their hibernation season. They generally appear very, very emaciated, they're starving, and very often they'll die. Infection intensity in affected hibernacula, which is a new word I got to learn.

00:12:40
Speaker 2: I noted that in mind too. I was like, I love this word.

00:12:44
Speaker 4: Hibernacula is like where bats hibernate, like their caves and things. Infection intensity often reaches one hundred percent by the end of a winter hibernation season, but actual mortality rates vary greatly by species, which we'll talk a lot more about. Right, So that's like the fungus and the symptoms. It's like we've covered a lot of ground in a short amount of time, and we now know that the end result is massive, massive die offs of hibernating bat species. So the question that I want to get at in more detail in this biology section is how in the heck does this happen? Like why are bats so susceptible to this pathogen? What bats are we even talking about?

00:13:35
Speaker 3: Because the thing is the.

00:13:37
Speaker 4: Skin lesions that I just explained, like, it's it's just a mold that grows on the wings and the nose. That doesn't sound that pathologic. But that's just what you see. It doesn't explain how these bats end up emaciated and dead. Right, So to understand that, there's two main questions that I'm going to try and answer. One is why these bats are susceptible to the fungus to begin with, and the second is what's going on within this infection that causes these dramatic effects. So first to answer the question of why are these bats susceptible, We'll focus on the biggest piece of the puzzle, and that is that white nose syndrome is a disease of hibernating bats.

00:14:18
Speaker 2: Right, So we get to talk about hibernation Aaron, which is very thrilling because I, similarly to you, went on like a little bit of a deep dive into the evolution of hibernation and I just just like, and as I was putting my notes together, I was like, I don't know where to put this, So I'm just going to put it in a parenthesis somewhere, a fact section, Yeah, exactly, my gosh, the history section. I'm yeah, just going to be sprinkling some fun facts in there because it's such a short history. So anyway, I love it. I'm excited.

00:14:55
Speaker 3: I'm excited too.

00:14:56
Speaker 4: Let's talk about what hibernation actually is, because I think a lot of us probably don't really know, right. You think of like a bear that eats a lot and then goes into a cave and hibernates.

00:15:07
Speaker 3: What does that mean?

00:15:09
Speaker 4: All right? So, during times of scarce food supply aka usually winter, some endothermic animals so like birds, mammals, not lizards and snakes, animals that control our own body temperature internally. That process requires quite a lot of energy. So one way that some endothermic animals cope with this food scarcity is by entering a state called torpur. I'm learning so many new words, it's so fun. And torpur is when these animals can decrease their metabolic demands substantially. Often body temperature drops substantially, and then heart and respiratory rates drop. Energy expenditure massive drops. So animals can then survive these periods a very very low food supply just by living off of their stored fat. Essentially, these torper phases can last anywhere from six to forty days depending on the species, and hibernation makes up these torpor periods, interspersed with a few hours or maybe up to twenty four hours of quote arousal periods where the animal often will bring their body temperature back up to normal or just move around be a little bit more aroused than during torpor.

00:16:38
Speaker 3: But this is important.

00:16:41
Speaker 4: During these torper phases, especially small mammals that hibernate, body temperature can drop as low as ten degrees celsius or lower.

00:16:53
Speaker 3: That's fifty degrees fahrenheit.

00:16:56
Speaker 2: It's amazing that's that these.

00:17:00
Speaker 4: So not normal for most mammals.

00:17:06
Speaker 2: Well, it's also interesting. Well anyway, I'll get into the evolution of it later, but.

00:17:14
Speaker 4: Oh, I love it. It's really really fascinating. So just to kind of put that in context, Like what range are we talking about human body temperature we know is like thirty six celsius ninety seven ninety eight fahrenheit. Little brown miotis, little brown bats normally their roosts are like around one hundred fahrenheit thirty eight. See, although I've seen some studies that say their body temperature can hop all the way up to fifty three celsius one hundred and twenty nine fahrenheit, So they can be really hot and happy. But during hibernation, their body temperature drops down to within a couple degrees of their hibernacula where they're hibernating, which is usually between two and ten degrees celsius.

00:18:04
Speaker 2: Right, which is right in the range of little PD. Oh, say that again, it perfect setting, perfect setting for PD.

00:18:17
Speaker 4: Okay, so that's hibernation, torpor, etc. So how does that altogether make that so susceptible?

00:18:28
Speaker 3: You already said.

00:18:28
Speaker 4: Strike one, right, that that is the perfect temperature for PD to grow. It is the temperature at which that fungus is most happy, right, strike one, Strike two. In addition to the depression of a lot of different metabolic features like respiratory rate and heart rate, there's also a lot of evidence that among many animals, overall immune response is drastically lessened during hibernation.

00:18:58
Speaker 3: And this makes sense.

00:18:59
Speaker 4: Because most bacteria and other pathogens can't replicate very well at low temperatures.

00:19:05
Speaker 1: Right.

00:19:06
Speaker 4: Yeah, So in general, animals that have been studied during hibernation have up to a ninety percent reduction in circulating white blood cells.

00:19:17
Speaker 2: I think I also remember reading somewhere that the hibernation this like basically the rabies virus goes quiescent, like you can, it'll just stop during hibernation.

00:19:28
Speaker 4: That is fascinating. It just stops replicating entirely.

00:19:32
Speaker 2: That's what I remember reading. And this is like where I'm putting a citation needed to myself to go back and check, but I think I remember reading that.

00:19:41
Speaker 4: Yeah, I mean, yeah, it makes sense like that it would just persist but not still be replicating.

00:19:46
Speaker 2: Right, It's like, actually, you know what a cryogenesis? Right?

00:19:52
Speaker 4: Yeah, Oh my god, so much interesting work about hibernation. It's a totally separate engine. But so so, while these animals hibernate, even though there are periods of arousal during that time, you do see white blood cell counts rise. But even during those arousal periods during hibernation, those white blood cell counts don't tend to rise back to like summertime normothermic levels. So that strike two, right, Strike one, we're in the perfect temperature zone. Strike two, we already have a depressed immune system. Strike three, though, is the clincher. White nose syndrome affects the status of hibernation itself, and that is how it has the devastating effects on these bats that we see. Right, So now we can answer that second question, how does this skin infection what seems to be just a skin infection cause emaciation, starvation, and death.

00:20:56
Speaker 3: Spoiler alert.

00:20:57
Speaker 4: We don't fully know the mechanisms of this, but there's a lot of hypotheses and there's a lot of support for some of these, So I'll kind of go through what we know so far. First of all, bats that are infected with white nose syndrome arouse a lot more frequently during torpor than uninfected bats. During these arousal periods, their body temperatures also increase to a greater degree than uninfected bats. Both of these things, more frequent arousals and body temperatures shifting at a greater rate likely lead to an increase in metabolic demand. And the thing is, we don't fully understand exactly why it is that these bats are arousing more frequently when they're infected with white nose syndrome, but it's thought that it's very likely due to an increase in water loss. Oh okay, right, So, even though this is called white nose syndrome because of the white, fluffy mold on the muzzle, it turns out that the major player in terms of infected area is actually the wings. So wings in a bat besides being absolutely gorgeous. Oh, the structure, it's so cool. But besides that, they're also a lot more than just skin. There are a lot more than just a bat's mode of transportation.

00:22:26
Speaker 3: They're a very.

00:22:26
Speaker 4: Physiologically active structure. They're involved in gas exchange, they're involved in fluid balance, and so it's thought that fungal damage in the wings leads to an increase in evaporative water loss, which then leads to dehydration, fluid losses, electrolyte imbalances, and then increased arousal because of this water loss, which then that increase in arousal leads to an increase in overall metabolic demand, which then leads to eventual starvation and death. Right, Yeah, there are other potential mechanisms at play. There's a lot of hormone changes that are seen with white nose syndrome infection. There are behavioral changes that are deemed sickness behavior where bats that are infected are more likely to hibernate differently off to the side and alone instead of clustering.

00:23:19
Speaker 2: Which is interesting in itself because of like transmission.

00:23:24
Speaker 4: Exactly right, And so it's thought too that is this somehow like is it a protective behavior for the bat where they're like trying to not get more infected from others who might be around them kind of a thing. There's a lot of kind of behavioral research on it. But they also when they do arouse, even though they arouse more frequently, their behavior is different when they're aroused. They have like reduced activity. They appear sick when they do arouse, And it's not really clear whether this is what exactly is kind of the cause of this, but we do know kind of this overall picture that this infection leads to increase in arousal increase, metabolic rate, premature fat depletion, starvation, and death in a lot of species.

00:24:13
Speaker 2: Of bat, in a lot of species, but not in.

00:24:17
Speaker 3: Every species, but not.

00:24:21
Speaker 4: And that is where this story gets so interesting and so complicated.

00:24:27
Speaker 3: M HM.

00:24:28
Speaker 4: So. In North America, where white nose syndrome is a problem, at least as of today, twelve bat species have been found to be susceptible to white nose syndrome, and at least six other species have been found colonized with the fungus, but without any real signs of disease or impacts on their population densities, and way back in our chytrid episode we talked with doctor Tagan McMahon about how this is also true in amphibian Some species of amphibians seem to be very tolerant of the chytrid fungus while others are really massively impacted. Right, And the same is true of white nose syndrome. So while we can say right off the bat that of course it has to be hibernating bats like hibernation is a big part of susceptibility, and not all bat species hibernate, although a lot do. In North America, more than half of the forty seven species of bat rely on hibernation to get through the winter. But it's not just that, because the fungus responsible for white nose syndrome has been found kind of all over Europe as well as the northern reaches of Asia, and not only does it exist in caves in hibernacula, but also on bats. And it also causes a very similar white, fluffy, moldy beard, but no disease, no white nose syndrome, just white noses. So the question of what makes some bat species very susceptible and some bat species not so susceptible is still a very open question, but there's a lot of people really trying to do the work to figure out what is the difference not only between the bat species in Europe and Asia that are very tolerant of this infection, but also even in populations in the Americas that have survived infection, that have you know, resisted this infection. There's a lot of potential theories out there. There's things like the specific microhabitats of hybernacula and little itty bitty differences between bat species in like the temperature of their hybernacula. There's a lot of cool work on the specifics of the physiology of torpor, so like how deep is your torpor or like exactly what temperature do you get down to? Things like that I'm.

00:27:02
Speaker 2: Gonna in my head is now how deep is your love? But how deep is your torpor?

00:27:09
Speaker 3: That's really good and that's our that's really funny.

00:27:18
Speaker 4: And also differences in immune response to kind of get at you know, how are these different bat species reacting to this infection, are they fighting it off, are they.

00:27:30
Speaker 3: Just existing with it, etc.

00:27:33
Speaker 4: But what's so interesting is that there's also some studies from bats in Europe that suggest that the infection doesn't result in as much tissue damage because the fungal hyphe don't invade as deeply into the connective tissue, so literally doesn't cause as much damage to the wings, but the fungus does invade around the muzzle, and it's not a difference in the fungus itself because PD strains from Europe are just as virulent in North American bats right as PD strains from here. So it's really interesting and there's a lot of like very open questions still as to like what are these real mechanisms of tolerance and resistance in these bat species, because if we can get at that, then we could know more about maybe how to help protect other species.

00:28:25
Speaker 2: It's really interesting because I think that like it once again shows how little we know not just about our own immune system, but the immune systems of animals.

00:28:36
Speaker 3: Right, what the heck.

00:28:38
Speaker 2: It's fascinating, Yeah, yeah, And I feel like one of the most exciting things about this. I mean, it's like horribly devastating, but I think it's really exciting because this is all happening right now, Like there are studies going on right now to answer these questions.

00:28:58
Speaker 4: Yeah, speaking of studies going on right now to answer these questions, I think one of the biggest questions is like, what can we actually do about this? Right And we'll talk a lot more about that in the current events section with our expert, doctor Winnifred Frick. But I do want to just mention that people are doing so many different things to try and prevent the spread of this fungal pathogen. So there are groups that are working on vaccines oral like virally vectored vaccines that are actually not dissimilar to the Johnson and Johnson and Astrozenica covid vaccines that are using a raccoon pox virus that expresses some proteins from this fungus.

00:29:42
Speaker 2: Interesting.

00:29:43
Speaker 4: Yeah, it's very interesting. It seems to induce an immune response, so that's very promising.

00:29:48
Speaker 2: How practical is the logistics of the distribution?

00:29:53
Speaker 4: That's I think the biggest thing is the practicality of it. People are also working on the application of probiotic bacteria, real treatments, using bacteria that we use for other like agricultural applications to help suppress fungal growth. Also the use of UV lights. Oh yeah, at these entrances isn't that so interesting? It turns out that this fungus has a mutation in its DNA that makes it highly susceptible to UV light, which is why it only grows inside of caves on bats living inside of caves. So people have thought if we put UV lights at the entrances and exits of Hybernacula, that'll kill fungal spores on the bats as they fly.

00:30:37
Speaker 3: In and out.

00:30:38
Speaker 4: Yeah.

00:30:39
Speaker 3: Yeah, so there's a lot of potential.

00:30:41
Speaker 4: I think there's a lot of creativity in how people are trying to tackle this massive problem that is devastating North American bat populations and has been for over a decade.

00:30:51
Speaker 2: Yeah.

00:30:52
Speaker 4: So yeah, that's the biology. I didn't let you ask any questions, Arin, I.

00:30:58
Speaker 2: Feel like I mean, I feel like you covered a lot of ground, and I think that the unusual thing about this particular topic is that, because it is so new, we probably read all of the same papers.

00:31:10
Speaker 3: Oh I'm sure.

00:31:11
Speaker 2: Yeah, because like the literature is only at most like fourteen years old, right, yeah, mostly like thirteen years old.

00:31:21
Speaker 4: So okay, well take us through that thirteen year history, Karon.

00:31:24
Speaker 2: Would I will? Okay, let's take a quick break first in the late winter of two thousand and seven, biologists from the New York State Department of Environmental Conservation set out to visit some caves near Albany, New York, for just a routine survey of the hybridating bats that were there in the area. You know, things like how many bats are there, what caves are they in, where are they in the caves, how the hibernation seems to be going you know that sort of thing. And you know, one of the things they were looking out for, of course, is whether there was anything unusual that seemed to be going on with the bats. And I'm sure that the biologists conducting the survey expected it to be no different from the countless other surveys that they had done in previous years. But the scene that greeted them when they first entered the caves and turned on their headlamps was unlike anything that they had ever seen before. Maybe the biologists knew some thing was up during their approach to the caves when a few bats flew shakily out of the cave's entrance into the snowy landscape, when instead they should be snugly hibernating inside. Or maybe the bodies of a few dead bats that dotted the ground a few steps outside of the cave's entrance gave them some indication as to what they might find on the inside, But I'm sure nothing could have prepared them from the scene that awaited them inside the cave. Absolutely piles and piles of dead bats on the floor of the cave, others moving around seeming to look for food, despite the fact that this was deep in hibernation season and that there were no insects in the cold landscape for the bats to eat. And when the biologists moved on to other caves in the area, they learned that, unfortunately, this was no fluke. At at least three more of the caves where they surveyed they saw similar devastation, with mounds of dead bats on the ground and more flying in the winter sun where they would not find any food, but rather would be easy pickings for birds of prey.

00:34:09
Speaker 4: I really can't even imagine how horrific a scene that must have been.

00:34:15
Speaker 2: No there are so in one of the books I read, or in one of the chapters of the books I read, there's a picture of it.

00:34:21
Speaker 3: That is, I saw that picture, you saw it.

00:34:24
Speaker 2: I mean, we saw it. We read all the same stuff, the same stuff.

00:34:27
Speaker 4: It was, Yeah, it was. It was really really awful, especially because before that I had only seen individual bats.

00:34:36
Speaker 3: Right, No, it's with white nose.

00:34:38
Speaker 2: I mean, like just to give you some idea over that, Like, in those four caves, biologists estimated that between eight thousand to ten thousand bats had died as a result of whatever was making them wake up from hibernation prematurely, But at that time they didn't know what it could be. Was it an infectious disease, Was it some sort of pesticide, Was it habitat disturbance by humans. At the time that these first bat die offs were recognized, the world was no stranger to massive unexpected wildlife or plant losses, colony collapse disorder and bees, kittrid and frogs, Tasmanian devil, facial tumor disease, even the chestnut blight, among many other things. By the way, a lot of those are fungus, not all.

00:35:30
Speaker 3: Of them, but a lot of them fungus. Yeah.

00:35:33
Speaker 2: Interesting, And each one of these enormous mortality events illustrated just how interconnected the world is. Not just in observing the cascades within an ecosystem, but also in highlighting the roles that humans play both as perpetrators of disturbance or as disseminators of infectious agents, but also as victims themselves. Things don't happen a vacuum, as we are very fond of saying on this podcast, and the role that any organism plays in an ecosystem is never negligible, and the impact that a loss of a species, or at least a loss of a population, can have on an ecosystem can be very difficult to predict. And if anything, these mortality events have highlighted how wildlife or ecosystem conservation isn't just some altruistic venture to preserve the charismatic megafauna of our planet. It's necessary for our own survival. So the discovery of thousands upon thousands of dead bats in some caves outside Albany was not just this tragedy that took place somewhere in New York. It ranging some very big alarm bells across the globe. As we've talked about before on this podcast, bats are often unfairly scapegoaded as pests, as bringers of disease, as whatever. But what is often not talked about enough is the absolutely integral role they play in the ecosystem, in our economy, and of course our health. There are over fourteen hundred species of bats worldwide.

00:37:22
Speaker 4: I was hoping you were going to list these numbers because I get so excited hearing about how many bat species there are.

00:37:29
Speaker 2: Plus one to subscribe to batfac there's going to be a lot of them here we go. These bat species occupy nearly every environment that you can think of, and they display an incredible diversity in body size, in food preferences, in hibernation, activity, in lifespans, social behavior, and so much more. And I want to give a shout out also to the amazing bat researchers who taught me so much about bats at strut some Soni and Tropical Research Institute in Panama.

00:38:03
Speaker 4: You know, it's it's very thrilling. I had a line that I didn't say in my little writing here. I was like, we're not that biologists, but we have a lot of friends who are we do.

00:38:12
Speaker 2: I was just gonna say you heard from one on the podcast before Alex Trio provided a first hand account for Dangay. Yeah, there are so many amazing bat researchers that I have encountered was really? I mean, I still remember my very first year in Panama back in twenty thirteen, learning from a presentation by Rachel Page that there are more bat species on Borrow, Colorado Island, at least seventy four species, which is this like kind of smallish island in the Panama Canal than there are in all of North America.

00:38:47
Speaker 3: Yeah, like what, it's so cool?

00:38:51
Speaker 4: Do you know what I learned researching this episode? There are no bat species in North America that are also in Europe.

00:38:58
Speaker 1: Who woo.

00:38:59
Speaker 2: That's interesting, isn't it. Did you know that some bats are incredibly long lived, like some live over thirty years? What the oldest?

00:39:09
Speaker 4: Yeah?

00:39:10
Speaker 2: I think like at least six species live over thirty years, and the oldest recorded bat lived forty one years.

00:39:16
Speaker 4: Stop, it's adorable. Did you know that the little brown bats are so little? They're only like five to seven grams.

00:39:26
Speaker 2: Oh, they're so cute. They're so cute, and hold on. I also I also looked up the etymology of the little brown bat, and I gotta find out what it is real quick.

00:39:36
Speaker 3: I love this.

00:39:37
Speaker 2: Okay, So the etymology of the little brown bat, which the species name is miotis lucifigus. Lucifigus means it's from the Latin light and to flea, so it's like it's a little light fleer, like to flee the light.

00:39:52
Speaker 3: That's so cute.

00:39:53
Speaker 2: It's very cute. Oh, what are some other bat facts? I guess I don't really have. That's like, there are some more batfacs. But I also want to shout out a Kentucky fact, which is that Mammoth Cave in Kentucky is the world's longest cave system, with more than four hundred miles of documented caves and probably much like more extensive. It's also the only national park in Kentucky, and it was also hit by white nose starting in twenty fourteen, bringing.

00:40:23
Speaker 3: It back, bringing it back, okay.

00:40:26
Speaker 2: Bringing it back. But also I'm not done with batfacs.

00:40:29
Speaker 3: Okay.

00:40:29
Speaker 2: Good articles about colony collapse, disorder and bees often talk about like the number of foods that would be lost to us without bee pollination. But did you know that there are also many foods that bats pollinate.

00:40:44
Speaker 3: I did, but tell all our listeners.

00:40:49
Speaker 2: Bananas, avocados, mangoes are among over three hundred fruit species that depend on bats for pollination and many others rely on bats to help help spread their seeds, like figs and cacao, and bats also play a hugely important and often overlooked role in agriculture. Yeah, through insect control.

00:41:12
Speaker 4: Pest management, pest You should pay them, I know.

00:41:17
Speaker 2: I read an analysis from twenty eleven that estimated that bats provide insect suppression services to commercial agriculture in the US that is valued at on average twenty two point nine billion dollars per year.

00:41:33
Speaker 3: That's a billion with a B.

00:41:34
Speaker 2: Yeah, that's a lot. That's a lot lot. And if you've listened to some of our COVID episodes before, you know how we've talked about the importance of bat conservation for preventing spillover events, and we'll get into more of that later in our episode with our amazing guest. But the bottom line is that these bat deaths in New York would have far reaching consequences. What exactly those consequences would look like or how intense they would be, dependent, of course, on what on Earth was responsible for the deaths, And once that was figured out, then the scope of the problem could be estimated and a plan for mitigating the spread could be developed. When the biologists had stepped into those caves, they noticed something striking about the dead bats that lay in piles on the cave floor, not just the sheer number of them, but also that many seemed to have this fuzzy white growth that was covering their nose, and some had patches like they're on their wings or torn wings. And it looked like it could be a type of fungus that could be the source of all of this death. But how would you even go about figuring that out? The identification was not necessarily an easy one because the places where these bats hibernate, the hybernacula are full chock full of fungi, and probably most of them not fully characterized or never even like isolated before.

00:43:04
Speaker 3: Yeah, that's a good point, And so culturing.

00:43:06
Speaker 2: Any one swab, even if that swab is directly from the muzzle of a bat, is likely to get you a lot of different fungal species. How do you know that you have the right one or the one that is causing the disease? Essentially, you follow cox postulates. Number one, you have to find the pathogen in just the disease, but not the healthy individuals. Number two, you have to be able to culture the pathogen from an isolate collected from a diseased individual. Number three, you have to be able to take that cultured pathogen and inoculate a healthy individual with it and then have disease result. And number four, you have to be able to then re isolate that pathogen from that inoculated individual and cultureate.

00:43:55
Speaker 4: It was pretty exciting to read papers that did those things. Yes, I never get to read those papers.

00:44:04
Speaker 2: Yeah, and so that's exactly what they did. So they actually tested this with these hibernating little brown bats and so finally, then pretty soon after it's not really a final a type of moment, they had the culprit, which, as you mentioned first, was Gomic's destructans. Now it's P. Destructans or PD. The fungus that was causing this growth. PD hadn't been described previously, but as you mentioned, it did appear to be related to other fungal species that are also cold loving, and in the group it seems that some are pathogenic, but to plants and not to animals. So it seems that this one is the only one of the group, at least from one of the papers I read so far right, that is pathogenic to animals. Okay, So now that researchers had nailed down the pathogen responsible for this massive bat mortality, what were the next steps? Well, one was to figure out just how bad this was. Was it only those four caves outside Albany, or were their bats dying all over the country or all over the world. Understanding the current distribution of this fungus would help characterize the scope, but it's also just a snapshot, you know, what's happening here at this moment in time. With mortality rates in the ninety percent range, Understanding how this pathogen spread and where it came from was crucially important. White nose syndrome, as it came to be known, was an emerging infectious disease. But an emerging infectious disease can be newly emerging, as in, it's existed there before, but a recent mutation or a change in the environment has led it to increased transmission in a way to make it more lethal or something like that. Or it's brand new introduced into a naive host population that has no evolutionary history with it. So why is it so important to make this distinction between whether a pathogen is introduced or re emerging, and it's important for predicting how it's going to behave and how we try to control it. For instance, if the North American PD had been around for a long time in North America and a new mutation had led to these die offs, then introducing it to Europe, for example, like somewhere it didn't exist, could be devastating for bat species there who were presumably naive to that strain of the pathogen or the pathogen itself. But if instead it was introduced from let's say Europe to North America, that could tell us about how the European bat species cope with this fungus. And in terms of management, understanding whether a pathogen is introduced or has existed before is also super important. So if the pathogen had been present in North America before, then management practices might focus on the factors that influence the virulence of the pathogen because you're not going to control its spread. There's nothing you can do to control it spread because it presumably already has spread. Right, But if it was new, then management techniques focus mainly on controlling the agents that spread the disease. But in the case of white nose, that would mean controlling the bats themselves, which is all but impossible.

00:47:25
Speaker 4: Yeah.

00:47:26
Speaker 2: Okay, So there are many different ways to test whether PD was introduced into the US from somewhere else or whether it had just evolved to be more deadly. And I'm not going to go into all these different ways, but i will list the results or the evidence that points towards this being a newly introduced pathogen into North America. Excellent, And I'm taking these points from a Nature paper by Zoo call at All twenty sixteen. By the way, just to give credit where credit's due, we will shout out all of our sources at the end.

00:48:03
Speaker 3: Okay.

00:48:04
Speaker 2: So Number one, none of the fungal communities associated with the North American bats and the places that they hibernate the Hybernacula are closely related to PD. Number two, the isolates of PD in North America seem to be all clonal from one single genotype, suggesting yeah, suggesting one introduction. Wow, So if it had been here a while, if it was something that had changed recently, we would see a lot more diversity. Number Three, since the first known instance in North America, which as you mentioned, was actually traced back to two thousand and six in a photo of bats with white nose. The distribution of white nose syndrome has followed a very clear invasion path, and there's one exception to that. So asterisk number four. PD has been found in many European and some Asian countries, as you mentioned, including on bats, but without the super high mortality that we see here. Number five, experimental infection of North American bats with PD samples from Europe leads to disease or death. And number six there's additional evidence that goes into like the fungal biology of it. So basically like there's the existence of different mating types of the fungus in Europe compared to just one in North America. What it again, Yeah, it suggests an introduction, and so all of these bits of evidence put together, it's pretty suggestive that this fungus was introduced into North America from you know, most papers say Eurasia, and they estimate that because of the diversity of the fungus in different sites in Europe and Asia, and the fact that there appears to be either tolerance or resistance in the bats to the fungus there, it has probably existed in those places for millions of years.

00:49:55
Speaker 3: I'm just I have so many thoughts.

00:49:57
Speaker 2: I know, yeah, I know, I mean, and it's like this is such an ongoing area. It's like you can only almost dig so far down the rabbit hole in some way, or down the bat cave.

00:50:09
Speaker 3: Ooh, that's good.

00:50:13
Speaker 2: The oldest specimen of PD at least that I came across, was a nineteen eighteen museum specimen of a bat that had been collected in France.

00:50:22
Speaker 4: Wow.

00:50:22
Speaker 2: Okay, so yeah, So how did it get to North America. We still don't seem to know, and it's possible that we'll never know the exact sequence of events. There are several different possibilities, from the transport of an infected bat from Europe to the use of contaminated field equipment in North American caves, from tourists with contaminated clothing or shoes, to maybe even I saw one paper suggest the import of European specialty cave aged foods like some cheeses.

00:50:57
Speaker 3: Wow.

00:50:58
Speaker 2: Yeah. Yeah. So, while all this research was going on in terms of understanding where this fungus came from and how it's being spread and what are we going to do about it, the pathogen continued to work, It continued to spread, it continued to kill millions and millions of bats. And that's actually the wrong tense, of course, because research is still going on and the pathogen is still continuing to spread. Since that first photo showing white nose syndrome in New York from February two thousand and six, the disease has spread to thirty nine US states and seven Canadian provinces. And while most of this spread is likely due to bat movement, some has been caused by humans, such as when it showed up in western Washington State, thirteen hundred miles or twenty one hundred kilometers away from the closest known contaminated site in Nebraska. Showing up in Washington State, it has continued to spread out from there. Is there a limit to the spread? Yes? There does seem to be, partly because hibernation, which is a key factor in the severity of disease, is not, as you mentioned, a trait shared by all bat species. Here's my rabbit hole insertion of the evolution of hibernation. Yes, I want to shout out a really interesting paper by Lazaroni at All from twenty eighteen and in this paper, they talked about how the earliest bats, which evolved sometime in the ECNE around fifty to sixty million years ago, they weren't necessarily hibernators, like they probably weren't hibernators, but rather daily heterotherm, so they practiced this daily torpor. Wow, and that is sort of this midway between an endotherm and an ectotherm, meaning that like with this this heterothermy or daily heterothermy, you can regulate their temperature themselves but also allow the rounding environment to regulate it.

00:53:02
Speaker 3: Right, So it was only.

00:53:03
Speaker 2: Later that hibernation and homeothermy evolved. And so this is also this this long time belief that the earliest mammals were homeotherms, when in fact it might actually have been at their heterotherms because that's sort of more in between. Yah. Yeah, like yeah, reptiles like reptiles and amphibians and homeothermy.

00:53:27
Speaker 4: Absolutely, And I never even thought about that as like hibernation as a kind of way of doing that too, oh my gosh.

00:53:35
Speaker 3: Wow.

00:53:35
Speaker 2: Well, and it's so cool because all of these things too have been looked at as discrete traits, but they're not like this exists on a spectrum, the way that like body temperature regulation is managed.

00:53:48
Speaker 4: I went on a deep dive of bear hibernation and they barely even drop their body temperature. So they're able to do this amazing metabolic reduction without really reducing their body temperature very much. Ooh, it was really fascinating.

00:54:02
Speaker 2: And then there's like regional heterothermy so like different body parts. I mean, it's incredible. There is so much more to explore down these rabbit holes, I down these bat caves. I love it anyway. Okay, but not only do not all North American bats hibernate, which would reduce their susceptibility to the fungus, but also the environmental preferences of the fungus may prohibit it from establishing in some southern parts of the continent, for example, So like it hasn't shown up in Florida despite showing up in nearby states for at least seven years, but the worst may still not be over. More than half the bat species in the US are severely declining or are endangered, and other parts of the world where PD hasn't yet spread are certainly at risk, such as Australia. Even though some bats are displaying resistance to the pathogen. Population recovery will take a very long time because this is such a new disease, Like there's not really much more to the history than this. It's still being written, and so I'm very excited for our guests this episode since she's one of the ones doing a lot of that writing.

00:55:21
Speaker 3: Yeah, So I will stop.

00:55:23
Speaker 2: Here so that we get to hear what the expert has to say about the ecology and status of white nose syndrome today.

00:55:30
Speaker 3: Excellent.

00:55:31
Speaker 4: We'll let her introduce herself right after this break.

00:55:58
Speaker 1: Yes, I'm doctor Winifred Frick, and I the chief scientist at That Conservation International and an Associate research professor in ecology and evolutionary biology at the University of California, Santa Cruz. At Back Conservation International, I lead our science department that's really focused on trying to use science and research to understand and solve the threats to bats and protect bats worldwide. So BCI is a nonprofit organization dedicated to ending bad extinctions worldwide. We implement endangered species interventions to try to protect critically endangered species around the world. We also work on habitat protection and restoration, and we work on research and development of scalable solutions to find conservation actions that can help.

00:56:44
Speaker 4: Thats awesome, Thank you so much for speaking with us. We're really excited. So we wanted to kind of start just by getting a sense for the status of white nose syndrome in the world today. So could you kind of tell us the geographic districytribution of white nose in North America and the overall effects that we've seen on bat population so far, like the number of species that have been impacted, and maybe some numbers in terms of population declines.

00:57:12
Speaker 3: Yeah, so white nose syndrome.

00:57:15
Speaker 1: Has spread from where it was originally emerged in Upstate New York across North America. It is currently in over thirty US states and seven Canadian provinces, and it's actually really coast to coast. So about five years ago the disease was detected in Washington State. But there's still some areas in which the pathogen that causes white no syndrome, which is a fungus Pseudogymnoascus destructings, has shown up and invaded certain areas, but we have yet to see the manifestation of disease. But the impact that the diseases had has been really severe. So it affects hibernating bat species, and we have research that has just come out showing that across the range of some of these speceis, the declines have been greater than ninety percent for some of our hibernating species, meaning that nine and ten bats that we know about have died from this disease over the past decade.

00:58:11
Speaker 2: Yeah, it's hard to even, I think, imagine the scope of it or picture the scope of that. And so I don't have to tell you, but bats are integral in any ecosystem and declines in their numbers could have very widespread and cascading effects. So could you talk about what we've seen so far in terms of the impact that these bat declines due to white nose syndrome have had in the areas that have been hardest hit.

00:58:37
Speaker 3: Yeah.

00:58:37
Speaker 1: So here in North America and in temperate latitudes, almost all of our bats are insectivorous. So bats are voracious consumer of nocturnal insects, and a lot of those insects are actually agricultural pests. It's well documented the value that bats have to farmers. In fact, bats are eating insects that otherwise farmers would have to apply pesticides for bats have been documented to increase crop yields in places. So one of the things that's been so intense about white nose is that we lost really common species, species that were highly abundant, right, and so we've seen a dramatic decrease in the number of bats that are out in the night sky, consuming insects and performing their ecological services. It's hard to quantify that kind of impact because of just the complexity of the ways that we collect data that can kind of measure the interactions between that abundance on the landscape insects and their impacts. So at this moment, there aren't studies that really demonstrate the economic impacts from the loss of bats, but the logic experiment of that is true.

00:59:48
Speaker 3: Yeah, that makes sense.

00:59:50
Speaker 4: And as you mentioned, we've seen such massive declines in bat populations, but we've also seen some populations stabilize or even show i think the beginnings signs of recovery. Maybe, So what do we know about the mechanisms of how these populations have persisted. And I'm also wondering how has that been informed by what we've seen in Europe and Asia. Is there any reason for hope in this story, or might we see a permanent reduction in population size?

01:00:20
Speaker 1: Yeah, those are great questions. And what we've seen is in certain areas there seem to be colonies that seem to have stabilized, although they have declined precipitously. It's easy to kind of generalize across species, and I should clarify that. You know, there's three species that have been most heavily impacted by white now syndrome in North America, the little brown bat, the northern long eared bat, and the tricolored bat. And then there's a fourth species, the Indiana bat, that's actually was already listed endangered in the United States, and in some places that species has seen you on average, eighty percent declines and colonies. But there are a few places where there still are very large colonies, and so some of the research that's been done on stabilization and maybe evidence of the starts of resistance had been on little bround back colonies in New York, where there are still a few very large colonies, although they're not as large as they once were, And so I think there's still active research going on trying to understand both the mechanisms of resistance and or tolerance of populations persisting but still getting infected. You know, one of the things that makes whiteness syndrome from a disease ecology perspective so pernicious is that the fungus that causes the disease can persist in the cave and mine habitats where bats are hibernating, and so when the bats return to their underground refuges to hibernate, they get re exposed to the fungus. So it has an environmental reservoir, right, And so pathogens that have an environmental reservoir can have a more serious impact on populations because once you see a big decline in the number of individuals, the pathogen is still there and available to infect the remaining individuals at the site. So that's to say that we're still trying to investigate what the long term impacts will be. We have there's some hope that there'll be environmental limits to the impact of the pathogen, meaning that we know that the disease affects bats when they're hibernating, and it takes a long time for the fungus to grow on their skin. Tissues and cause the physiological disruption that leads to mortality. And so in places where bats aren't hibernating for as long, we may see less mortality, although we're still seeing high levels of mortality across the range of where the fungus is currently spread. What we do also know is that the fungus is widespread throughout Europe and Northern Asia and there and that's also do get the disease, meaning the characteristic lesions, But we don't see the same level of high mortality rates in those places. So it could be that those populations have evolved some kind of resistance or tolerance, and there's been a number of studies that have kind of tried to investigate those different mechanisms.

01:03:22
Speaker 2: Gotcha, And so, looking maybe ahead a bit in the future, what do we know so far about how things like climate change or this increasing land use change are likely to affect the distribution of white nose syndrome And are there any concerns for it's spread beyond North America in places that are still naive to the pathogen.

01:03:47
Speaker 1: Yeah, well, in terms of the spread, yes, there's been quite a bit of concern about other places that have temperate hibernating bats. And so there's been some surveys that have gone down in temperate South America, Chile and places. There's been some research trying to understand what the risk to Australian bats might be. And you know, we first discovered that the fungus is actually widespread in Europe and that's where we assumed that it had come from. But then doctor Joe Hoyt also did an extensive amount of work looking at presents for the fungus and evidence of the disease in northern Asia and actually and also working with a set of collaborators kind of through basically a very extensive survey effort to understand both the dynamics and the environment and on bats in Asia and into Europe. So I think it's very important to be monitoring in these these other places and be able to act quickly if signs of the fungus get there. We know that the fungus can persist on people's clothing and boots and the things. That's quite possible that I mean, that's how we assumed that it got here was through you know, some human activity. And then you know now that the fungus and the disease are in Texas and in caves where Mexican f retail bats, which are capable of sort of you know, getting the fungus on them. They don't seem to be very likely to have high levels of mortality because they don't hibernate for extensive periods of time. But they're migratory and they migrate into Mexico. So there's Mexican collaborators, doctor Rodrigo Menin who's working on doing surveillance for the fungus in Mexico.

01:05:31
Speaker 3: As you move.

01:05:32
Speaker 1: Into more tropical latitudes, it's really it in mountain areas and high elevations where you might get that's that might hibernates will use torpor periodically, but it's probably long term hibernation that is really the risk factor. To go back to your question about climate change, you know, thats are choosing in temperate latitudes, that's are choosing underground environments that are are very stable, that are thermally stable. I'm not sure how much climate change will influence underground conditions. Although we've looked a little bit at the relationship between surface temperatures and underground temperatures. We know that temperature and humidity affect the fungus and may also affect the hibernation energetics of the bats. But I think probably where there's the intersection between climate change and disease impacts has to do with both the extreme weather events that disrupt ecology of species in various ways. We saw huge mortality event in Texas during the big freeze this winter. So you've got these other stressors, right, these other big events that cause mortality or disrupt the food base, and if species are sort of at the limit and trying to persist and survive this devastating and difficult disease infection, to then have the extra whammy of a big, unseasonal storm that may delay spring or have some other kind of knock on effect.

01:07:00
Speaker 3: Yeah, that makes sense.

01:07:02
Speaker 4: So kind of as you've been saying, and as we talked about through the whole episode, this is a very ecologically complex pathogen. So what about other things? How do things like colony size or even social behavior, How do these kind of big picture things play into infection or extinction risk for different bat species?

01:07:25
Speaker 1: Right, So, a little bit about the ecology of winter, ecology of hibernating bats in most of eastern North America, our hibernating bats are aggregating in large numbers and in multi species aggregations, meaning you've got multiple different species using the same cave or mind to hibernate. So these are really communities of bats that are in these underground spaces, and there's a lot of there's variation in the social behavior during hibernation. There's certain species that form dense clusters where there are actually tightly packed together, most likely for thermoregulatory reasons, and then other species that are more solitary where they roost individually throughout a site. So within one site you might see tricolored bats that are sort of dotted throughout the cave or the mind, and then these dense clusters of something like an Indiana bat or a little brown bat. And what we found when we were first doing work on sort of the transmission ecology of this disease is that the sociality, whether they were in dense clusters or not, didn't seem to have a big impact on the disease, and most likely that's because of the role, the important role that the environmental reservoir plays that there's a lot of contacts between bats in between species in these underground environments and so you can't necessarily predict the contact rates based off of the roosting behavior.

01:08:58
Speaker 2: Yeah, that's very interesting, And so now comes the question of well, what do we do about it? And I know that there's been a lot of research on potential interventions, from things like vaccines to bacterial control to using UV lights to combat white nose syndrome. So could you walk us through what interventions have the most support or have shown the most promise and what are people doing on the ground right now to control or manage the spread of this disease.

01:09:28
Speaker 1: Yeah, that's a great question. So from the very beginning, there's been a really earnest attempt to try to find solutions to this disease. And I think it's one of these a really powerful example of researchers and managers coming together and working together to try to solve a difficult problem. There's an active research community trying to explore different solutions, and so Tony Rookie at the nationalide Life Health Center is working on a vaccine to see if that might help improve survival. There's been very different research and different kinds of treatments of things that you could actually spray on bats that might reduce the infection or reduce mortality from infection. And there's also been a set of research that's focused on environment what we call sort of environmental treatments or environmental cleaning, which is ways that are focused on reducing the pathogen in the environment. You know, there's different pros and cons to different types of approaches for treatments that require actually treating the bat. You've got the difficulty of trying to access a high en f proportion of the population that could be treated. Thats are incredibly sensitive to disturbance while they're hibernating and so and their torpid they're not metabolically active, So you have to have a treatment that will work and also that doesn't require lots of application, and that also doesn't super disruptive, and so you know, thinking about treating the environment opens up some other kinds of opportunities because you could potentially do it before the bat's return to hibernate and knock down the pathogen load. Of course, that's only going to be feasible in certain kinds of environments, because if you're trying to do something that could reduce the fungus, it might have non target effects, and that's not going to be appropriate in cave ecosystems, but minds that are human made environments, it might be possible, and lots of mats hibernate in minds. There's some folks that are working and trying to change the microclimate conditions underground because there's evidence that suggests that bats that are in cooler, dryer hybernacula have higher survival rates. And so if we can maybe make the environmental conditions in terms of the microclimate less conducive to fungal growth and better for that hibernating energetics, that that could improve survival at that conservation International we've been involved in a number of different studies that have tried some of these different approaches over the years, and currently we're working on a different type of approach that we have nicknamed our Fat Bat Project, which is focused on using some underlying research that shows that bats that are still surviving in places where whitness has been for a long time show an increase in their body condition. They basically get fatter prior to winter, and then they have the fat reserves to basically withstand the infection and the metabolic costs that come with it, and so we've been looking at ways in which we can help. That's fatten up before winter with the idea that increasing foraging efficiency. So that's do this thing where they go through this period of hyperphasia right before they hibernate, and the most energetically intense time for female bats is when they give birth and they lack tate, so they're ending the summer sort of having just gone through a really intense energetic period and then they've got to rebuild and put on fat mass before being able to survive the winter. So they basically go on this feeding frenzy for a couple of weeks during what we call the false warm, and they just pack on the fat. And so we're trying to target that time frame and we're building them bug buffets with using UV lights to attract nocturnal insects that they can feed at near their hypernacula. And it is pilot results. We're still working it out, but the results, the pilot results promising, were really excited and the nice thing about it is that it could point to long term solutions of helping increase habitat quality in doing things to improve the underlying prey base that could benefit. That's at the target areas where they want to improve their body condition before hibernation.

01:13:45
Speaker 2: That is so cool. Bug buffets.

01:13:48
Speaker 1: I love the project is fat bats at the bug buffet.

01:13:52
Speaker 2: Yeah, that's incredible, that's so cute.

01:13:56
Speaker 4: I also just love picturing bats like getting extra chunky for going into hibernation.

01:14:01
Speaker 1: The bats are the baths, like they're so they put all their fat on their butts and like so chub Yeah.

01:14:09
Speaker 2: Oh my gosh, I love it.

01:14:13
Speaker 4: So speaking of how adorable bats are, I'm sure you're aware how bad of a rap they often get unfairly in popular culture. And I think it's probably in part because they do have these associations with a lot of pathogens that can potentially spill over into humans, including of course coronaviruses. And I saw at least one paper with some evidence that bats that were infected with white nose syndrome actually had higher viral loads of some coronaviruses. So could you talk about bat diseases like white nose syndrome and how the health of bats can be actually directly related to human health in the context of bat conservation or it's.

01:14:57
Speaker 1: Important underscore that we still don't know how the virus that causes COVID nineteen got into the human population. What we do know is that bats can be of ancestral hosts for coronaviruses, so they carry closely related stars like beta coronaviruses. Although the closely related virus to SARS COVID two probably diverged forty or fifty years ago, and so there's still a lot of investigation as to how the virus that causes COVID nineteen got into the human population. One of the things that's fascinating though, is that bats are kind of like superheroes when we think about their immune systems. They are capable of carrying a bunch of different viruses and don't appear to get sick from them, and so there's lots for us to learn in terms of what sort of superpowers bats have in terms of their immune systems. And I think that was one of the reasons why white nose syndrome was so shocking and upsetting, is that there aren't that many diseases that we've seen really negatively impact bat populations in this sort of way. There's a lot of research about bats and disease, but from all the viral research. It's more about how well they can sustain viral infections and not be pathogenic. Right, But you know why nos is caused by a fungal pathogen, and we've certainly seen other kinds of fungal pathogens decimate wildlife, like the kittrick fungus and amphibians. I think one of the big lessons that we have learned from the covid pandemic is just how understanding ecological integrity and protecting wildlife and protecting ecological systems is part of global human health. There's a growing body of evidence that shows that it's a disruption and degradation of ecological systems that increase the chance for spillover. And that's true across the board, not specific to bats, and so I think it's really important that we recognize and understand the ways that we can predict and prevent spillover events through conservation and protection of intact natural ecosystems.

01:17:07
Speaker 6: Yeah.

01:17:07
Speaker 2: Absolutely, And so white nose is obviously one enormous threat to bats in North America, and I was wondering if you could speak more generally about some of the other biggest threats to bats, both in North America and maybe globally as well, and what can we do to sort of combat those threats.

01:17:30
Speaker 1: Yeah, So we recently did a review of the global threats to bats and what we find is that so that's an incredibly diverse order right there, the second most diverse order of mammals with over fourteen hundred different species and a lot of that biodiversity. It occurs in tropical latitudes. So iconically we think about bats roosting in caves, but actually at about forty percent of the bat populations are cave roosting, but many many species live in force environments. Back many of our cave rousting species also depend on forests for foraging and habitat. And so the top number threat globally debts is habitat destruction through deforestation, right and then land conversion from agriculture, So land use the intense impact that we have on the planet in terms of just habitat destruction and degradation globally. Other threats include hunting, unsustainable hunting, So events are hunted in parts of Asian and parts of Africa, and if those hunting practices are done in a way that are unsustainable. We've seen certain species actually get hunted to extinction and then here in North America and really start of growing around the world. One of the major threats that's been identified as the impact of wind energy. So unfortunately, wind turbines kill bats and kill large numbers of bats, and so trying to determine ways in which we can support renewable energy in ways that does not cause biodiversity loss is really important. And luckily there's really great research that shows that there are things that we can do. We can actually prevent the turbines from spinning at low wind speeds during the seasonal migration and that dramatically reduces the amount of fatality. But getting some of those solutions adopted and part of standard practice remains a challenge. So lastly too, like we know, climate change is also an impact, so increase of severe storms, roost disturbance is another threat. So going back to thinking about our bats that roost in caves, they can be really vulnerable to people coming in and either disrupting them on purpose because they are trying to like harvest guanto or do other things, or not being aware that they're disrupting those populations. So in terms of what people can do, the thing. You know, it's wonderful when people share just how valuable important bats are. There you can also support groups that are working on that conservation. And then I like to also promote that anything that you can do to lower your footprint on the planet helps bats. So things that you can do to lower your carbon footprint or and other things, is that you know, we're sharing the planet with other creatures, and if we can lower the type of impact we have, that benefits. But if it's bats.

01:20:23
Speaker 6: Too, well that was just fantastic.

01:21:04
Speaker 4: I I'm still fangirling. I absolutely, really, really thank you so much, doctor Frick for taking the time to speak with us. I have never gotten to speak with someone that I've read so many of their papers, except maybe Peter Hotez, Like.

01:21:20
Speaker 2: I was just about to say, Peter, maybe Peter Hotez. Anyway, that was absolutely wonderful. Thank you so very much. Well, should we go right to sources?

01:21:32
Speaker 3: We certainly should, so I shouted.

01:21:34
Speaker 2: Out a couple in the history section, but I will shout out just a couple more that I thought were super great. So there's an entire book called bats in the Anthropas scene that is great, not just for information about white nose, but about like other ways in which bats have been affected by humans, and so on and so forth. And then I also want to shout out a very very recent paper from March of twenty twenty one by Hoite at All called Ecology and Impacts of White Nose Syndrome on Bats. Tons of great info there, and also I have a bunch more sources all post it on the website.

01:22:11
Speaker 3: Excellent.

01:22:12
Speaker 4: I want to mention that the white nose Syndrome in Bats chapter from that book was written by none other than our guest doctor Winnifid Frick, along with several other authors, so thrilling. I also want to give a shout out to the whitenosyndrome dot org website, which is coordinated by the US Fish and Wildlife Service. Not only does it have a ton of very digestible information, they also have a RefWorks page that has links to over five hundred peer reviewed articles on white nose syndrome and related things, so it's far more comprehensive.

01:22:48
Speaker 3: I opened so many.

01:22:49
Speaker 4: Papers that I didn't even get to from that refwork site. But I will also post all of the papers that I actually did use for this biology section on our website, Like Erin mentioned, this podcast will kill You dot com you can find the sources for this episode and every single one of our episodes.

01:23:06
Speaker 2: Yes. Well, thank you again to our wonderful guest for taking the time to chat with us about white nose syndrome.

01:23:14
Speaker 4: Yeah, and thank you to Bloodmobile for providing the music for this episode and every single one of our episodes.

01:23:20
Speaker 2: And thank you to the Exactly Right Network, of whom we are a very proud member.

01:23:25
Speaker 3: And thank you to you listeners. We hope you enjoyed this animal episode.

01:23:29
Speaker 2: Yeah, thanks for listening.

01:23:32
Speaker 4: Yeah.

01:23:33
Speaker 2: Well, until next time, wash your hands.

01:23:36
Speaker 4: You filthy animals. Eight