Forest Focus Ep 23 Bats.mp3

Paul Wade [00:00:12] Welcome to episode 23 of Forest Focus. I'm your host, Paul Wade, with the Regional Public Affairs and Communications Office. In this episode, we go batty for bats. Each year, bat week is observed the week before Halloween and is used by bat enthusiasts, scientists, conservation groups and others to educate the public, dispel myths and bring attention to the struggles they face. The beneficial impact these amazing creatures have on our ecosystem should be celebrated far beyond the season of spooky ghosts, skeletons and vampires. Joining us to do just that is Ted Weller, an ecologist with the Pacific Southwest Research Station of the U.S. Forest Service, located in Arcata, California. Ted welcome. And let's start with what is a bat? 

Ted Weller [00:01:09] Sure. So that's our flying mammal. So there that they're the only mammal that's capable of powered flight. So there's other things like flying squirrels that kind of glide. The bats are the only ones that are powered flight, so they have wings. They can fly around, they're mammals. What does that mean? That means that they have fur. In the case of bats, they also give birth to generally a single young per year. And then they nursed the mothers and nursed these bats every year. After they give birth, they nursed them up to to the point that these bats can fly on their own. 

Paul Wade [00:01:45] The only flying mammal on the planet? Well, that's a rare distinction. Can you explain a little bit more about their young? Like what? What are they called? 

Ted Weller [00:01:55] The young of the bat is called a pup. And then when they're when they're born, they're actually sort of naked or just have a little bit of slight fuzz on on their sort of naked body. And then they grow up from being this naked, tiny, I'll say tiny, but it's when they're born. There actually can be up to a third of the size of the mother, but they become like full grown back within about three weeks, and then they can start to fly on their own and start to hunt on their own hunt for insects. 

Paul Wade [00:02:25] Let's talk about species because I've looked up bats on the internet and I've read your research papers and there's lots of bats mentioned. So how many species are there? 

Ted Weller [00:02:38] So there's a lot of bats. So in the US, the numbers are now in the low 40s for the number of species that we have. But worldwide and bats are everywhere except for Antarctica. So they're on every continent except for Antarctica. The latest count I looked at today is fourteen hundred and thirty nine species, and basically we're adding a couple of species monthly as as you know, people go into remote areas and touch bats and discover discover new species. And the highest diversity of that's the most the largest number of species are in the tropical areas. So as we go, you know, north of the equator and south of the equator, we tend to get fewer species. So the US has in the low 40s for the number of species. And in Canada, there's maybe like a dozen or 

Paul Wade [00:03:28] So not so far south as in the Antarctic. But what about north as in the Arctic? How much cold can bats typically handle? And is there an Arctic bat? 

Ted Weller [00:03:41] No, there's not really an there's not really Arctic bats there, bats who exploit that environment primarily in the summer. So as some people might know, if you go up to say, places like Alaska, there's a lot of insect activity during the day or in the evening there. So fast can really feed and gain a lot of weight there. The trade off for them is that then they have to figure out what to do for the winter there in in that case, they hibernate and they start hibernating in these northern latitudes a lot earlier than they do in the southern latitudes. 

Paul Wade [00:04:12] Well, you brought up my next question hibernation. Please tell us more. 

Ted Weller [00:04:17] So most of what we know about bats hibernating is from bats that hibernate in caves. So what does that mean? That basically means they they go into these caves that are cool temperatures not below freezing, but is close to freezing as possible. And they basically just shut their whole system down so they can have heart rates that are just a few beats per minute in their actual body temperature drops to just above freezing. And this allows them to save a ton of energy over the winter. So in the winter, as most you know, there's not a lot of insects for them to eat and they they have to do something to survive. So that's what they do. They just use less energy. Then more recently, we found that they do that for periods of maybe three to six weeks and then every once in a while, they have to get up and fly around. Mostly, this is like they fly around inside the cave, and it's an open question in terms of why they do that. Some people would say it's too clear metabolic waste. Other folks say that it's they need to actually drink a little bit of water. So it's often like a humid place and they can drink water or they can lick ice or snow or something like that to get some water intake. You know, most of the bats that we have in in the in the US will start hibernating in the beginning of November, and they'll hibernate all the way through until April. So in other words, like taking these long three to six weeks breaks up doing nothing, flying around for a few hours and then taking another break for, you know, a few a few weeks. And they do that all winter long until April. Some bats will arouse from their hibernation early in April. Some of them might go all the way into May, and it's in the bats that are sort of higher up in latitude. The colder areas tend to start their hibernation earlier and then end it later in the spring. An interesting thing is that the bats that hibernate tend to be the longest lived bats, so the world's record for a bat is 43 years old. And this bats about that hibernating in Estonia I believe. 

Paul Wade [00:06:26]  Estonia, huh? Well, that's one of the Baltic states just south of Finland, and it can get cold there. So what is the typical lifespan of bats? 

Ted Weller [00:06:40] Yeah, it's really difficult to find the the age of bats because it's hard to sort of mock them in and keep track of them. We assume that the average age of the average lifespan of a bat is something like eight to 12 years. So they're very different from, say, rodents that live a year or two and have large litters, you know, multiple multiple young a year. And then they kind of go through the whole life in two years. That's sort of a longer lived have a single young every year and live what they say is they live slower than rodents say. 

Paul Wade [00:07:15] Well, what a fascinating field of study and a fascinating creature. Can you tell us how you got started in studying bats for the U.S. Forest Service? I mean, do you have a cool backstory like Batman? Like you stumbled upon it or something? 

Ted Weller [00:07:30] Right, right. And that's actually sort of sort of how I started. I sort of fell into it. My undergraduate work was in environmental engineering, and I worked as an engineer for a couple of years doing like underground fuel tank spills and cleanup of that. And then what are the change careers and met a person from U.C. Berkeley who was studying coyotes in the field? And I was like, This is really what I want to be doing, sort of matching technology and study of wildlife. We've done that and decided I'm going to become a coyote researcher. But in the in the realm of wildlife research, you can't always go exactly where you want. In the end, the predator research sort of dried up on me, needed a job. There was a graduate student who was funded by the Forest Service working on that project. And basically, I decided to take that job because it paid like 25 cents more an hour than the other jobs that I had available that summer. And then at that point, I decided, Well, I'm going to be doing this job. I should learn something about bad, started reading up on them and realized, Oh my gosh, there's you know, so many things that we don't know about, but I realize there's a number of questions to ask. I came up with some of those and proposed that work to the Forest Service and the university, and they said, Yes, that sounds interesting. And that was sort of the beginning of my career as a researcher with the forest. Sort of. 

Paul Wade [00:08:58] Well talking to you now, it seems like this was a match made in heaven at one point in time. Did you know that you were on the right path? I mean, you, you had the curiosity, you had the interest. You proposed the questions. But was there a certain time when you when you felt OK, this is this is what I was meant to do? 

Ted Weller [00:09:15] Right. So actually, it does kind of remind me of this. This just a story that we were talking about earlier was we were working on a study where we were mainly using these echolocation detectors to sense whereabouts were in the environment. Were they near creeks are far from creeks, et cetera. And then at the same time, we would capture bats to kind of confirm what we are hearing and identifying based on their echolocation calls to see that those species were there. And one evening we were walking along a ridge and we spotted, a spotter, spotted a Spotted Owl that was on the tree and we stopped to watch this animal and it was sitting on the limb of a tree and it just sat right in front of us and we were kind of up on the ridge above it, who were eye to eye with this owl and suddenly noticed that these bats started flying out of the dead tree. With this with this owl was just sitting on the branch and then the Owls are chasing these, these bats down. And then I looked at these bats and I thought, Oh, they sort of have a lighter colored belly than the other bats that we've been capturing ended up capturing some of them. That particular night found out that they were this species called the fringe tailed my. And so my project that I proposed was, where are these bats roosting within the forest? Because at the time, it was understood that they mostly resisted in caves and rocks and buildings, and I was pretty sure that they are roosting in these trees, dead trees. And then later, using radio telemetry, you know, tiny transmitters attached to these bats. We actually tracked bats back to that exact same tree. And that was really successful and also made me feel good that I kind of saw had this observation that actually turned in to be something that was scientifically defensible. 

Paul Wade [00:10:59] Interesting stuff, Ted. And maybe you've inspired a future bat scientist out there. So let's get back to science. And can you tell us a little bit about the scientific term, maybe about their bodies and what they're capable of? 

Ted Weller [00:11:18] Yeah. So that's in the order called Chiroptera. And this basically means hand wing. So if you if you look at about it, you know it just you see a flap of sort of leathery skin out there. But the skins actually supported by some long bones and those are actually modified finger bones and they get really long. So it would be as if our our fingers were sort of trailing all the way down to our knees like that that long and then that supports that leathery wing membrane. Within that, there's sort of two main groups of bats. There's the flying foxes that people have seen these these are large bats that eat fruit so they can have wingspans up to six feet long. And they actually look like little dogs. But most of the bats in the world are are in a group called micro bats or are small bats. These can be as small as your thumb. And then they have a wide variety of diets, so they can be they could eat insects, they can eat nectar, they can be pollinating bats. The vampire bats are members of these, these micro bats, et cetera. 

Paul Wade [00:12:31] Vampire bats. You mentioned it. Well, maybe we shouldn't get into it just yet, and hopefully we will circle back in and maybe you can share an interesting story. But you mentioned sizes. Can we talk a little bit more about that where these bats are located? And then we'll we'll get back to North America. Obviously, we'll get back to the bats that are in this region. 

Ted Weller [00:12:57] Yes. So the bats in the US, the vast majority of these are insect eating bats. And then there's a few species that are in the southern part of the U.S. that are pollinating bats. And these bats, people can even see them feeding at their hummingbird feeders at night in places like southern Arizona. Once we get into the tropics, there's a wider variety of resources available to these batch many different wild fruits and different kinds of flowers and a huge insect diversity. And so in those places, we see a larger diversity of bat species. 

Paul Wade [00:13:31] Well, we do know that they're capable of acrobatic flight where they duck and weave to get insects. What else are they capable of? I'm hearing something like crawling. 

Ted Weller [00:13:41] Yes, they sort of crawl and they can be very accomplished crawlers. And they when they crawl, they're basically using their elbows to propel them to propel themselves. So it's as if their hands are sort of tucked up by their shoulders and then they get up on their elbows and move. The other thing that's that that I've seen or more commonly, is that bats are very good swimmers and they swim in the same way. So a lot of bats drink out of, say, ponds or they forage for insects that are just on the surface of the pond. And occasionally they'll make a mistake, or they will hit a small limb and fall into the water and they swim right across the water surface. And, you know, as a as a human trying to sort of chase them on foot, it's really hard to keep up with them. They're such good swimmers. 

Paul Wade [00:14:30] So you're saying that they do come down to ground level to feed? What about high up? What's their typical like elevation reach? 

Ted Weller [00:14:40] There have been some, some recent work on that. So that's again, they're diverse and they fly at a lot of different elevations. So some of the bats that we have locally here will actually fly very close to the ground and forage for insects that are just on the grass. Others are way up in the sort of lower atmosphere and in forging on moths so they can be 3000 meters, so around 10000 feet up in the air. And they're actually tracking the moths that are that are migrating. And these moths are taking advantage of the lower atmosphere, wind currents and just sort of drifting north northward, say in the bats, know that there's a huge number of moths up there so they can get up to like 10000 feet and go up there and just feast like crazy on these moths. 

Paul Wade [00:15:28] So moths are on the menu. What else is in the typical diet of bats here in North America? 

Ted Weller [00:15:35] The bats of North America as a group are eating or eating insects solely, and then within that there's diversity. So there's large bats who forage for larger insects and then small bats that forage for smaller insects. Bats do consume a large, a large amount of insect prey every night so they can eat sort of up to half of their body weight in insects every night. And when you think about large colonies of bats, they can really do some damage, like on these, on these migrating moths, as I was mentioning. So the main thing that that I like to sort of tell the public when I'm out talking is that everyone's sort of aware that if they go out in the evening, there's lots of insects out there, there's mosquitoes out there. You can see moths foraging around streetlights, et cetera. But if you think about what are the predators of these, of these insects at night, mostly it's bats. So we're really reliant on bats to control the nocturnal insects. 

Paul Wade [00:16:37] When our bats most active, I'm going to guess at night, but is there a reason for this? And also, maybe a little bit more about light sensitivity. I've seen videos of them flying in the daytime, so please tell us more. 

Ted Weller [00:16:52] Yeah. So it's true that that bats mainly come out at at dusk. So some some species of bats come out slightly earlier. You might see them just before sunset, but generally they come out of their roosts about 30 minutes after sunset and they begin foraging at that time. Now the reason they do that isn't necessarily because they're light sensitive because we can't see bats occasionally out flying during the day. It's primarily because they're avoiding predators in that way so that predators might be hawks. And then the hawks will start to have less activity in the evening. And the bats are saying, great, I'm going to take advantage of that. The Hawks are kind of settling in to sleep, the insects that I'm interested in are coming out, so I'll come out at night and exploit these insects. And at the same time, be safe from the predators. So in terms of the light sensitivity? Well, you know, for years, folks, you know, once we discovered that bats echolocate it, we assumed that they were able to navigate basically in complete darkness by using echolocation. We can we could talk more about that later, but basically sending out really loud, high frequency calls of a frequency that humans can't hear. But it's very loud, like rock concert loud and then listening for Echoes. And then when they get these echoes back, they actually sort of have a mental picture of, Okay, there's a tree on my right, there's a tree on my left, there's a moth that's a certain distance in front of me. And for years we kind of assumed this is how bats are navigating. But we're finding that more and more that bats are taking advantage of all their senses. So one of the myths about bats is that bats are blind. Well, they're not. And they can actually see quite well at After Dark. So after dark, if you're trying to navigate just on vision alone, you'd rather be a bat than than a human. Some species probably use their eyes or their vision more than others, but they're taking advantage of the full suite of sensors that they have available. I don't think when we when we capture bats, we're often using headlamps with bright lights. The bats don't necessarily like those those bright lights on them, but it's also probably not harming them as as spokes on them. When they see bats are foraging around a stadium, lights or foraging around street lights. So they're actually taking advantage of these lights not for the light itself, but because those lights are attracting large numbers of insects. And they said, Well, it's sure it's a little bright in there, but I'd rather have a few tasty moths and have to squint for a little bit. 

Paul Wade [00:19:25] OK, you mentioned the word roost. This is a place where they typically rest. Raise their young. Where else do they roost in their natural habitat? And what about adapting to manmade structures? 

Ted Weller [00:19:41] So historically, what we know about bats is about their roosts, which is a place that bats spend their time during the day is that people thought, well, bats roost in caves, bats roost in attics, bats roost in the old churches. And the reason that we thought that about bats is primarily because these were the easiest places for humans to see them. Bats are very secretive. One of the things that we found recently is that we've been able to use radio telemetry, so we put a small radio transmitter on a bat and that can actually follow them. When we do that, we find that in the summer, many of the species, most of the species are actually using trees a lot of the time. So they'll go off and roosting in trees that are damaged in some way. So either trees that are that are dead and have their bark on them and the bats can crawl up into that bark. They can go in little holes that were formed by insects or other animals. And the reason the trees they can roost in rock crevices. There's lots of different places where they're concealed from, from predators that bats can can be roosting during the daytime. There are also bats do get into buildings and and as you were mentioning, there's there's cases where people can say, Well, we know that bats are roosting in here. We want to preserve the bats. So let's just basically turn this building into a bat roost. The bats love you for that because they they chose that building because it has exactly what they need in it. Mainly the temperatures that bats seek. So during the summer, when bats are roosting, they're raising their pups. The moms want to stay nice and warm. They want to have a nice, warm temperatures during the day. They want to have these roosts that are near a water source so they can. They can get out and get a drink near great places to find insects if they've already chosen a building like that. That's really where they they want to be. It has everything they need for them. So when people have the ability to preserve a building as a roost, this is just a a great, great thing that that you can do for bats. Most people don't have that, that advantage. And one of the things that people do is to use a bat box, which is a small wooden sort of container that's just small enough for a bat to crawl up into. And it's an it's an alternative, whether that's use these bat boxes. It's really hard to predict. So again, they're looking for a certain sort of temperature profile. It's like a Goldilocks syndrome. If these bat boxes get too hot during the day, that's not great for the bats. If they don't get hot enough during the day, then that's also not great for them. So looking for something that has just that right temperature? And we often can't. Know that ahead of time. So the places that are generally most successful with their boxes are when you have to tear a roost down. We had a good example of that in our local national forest here, where they knew they had to remove this building because it was a hazard. What they did in that case was they erected six or so bat boxes up around that building and let the bats get used to those bat boxes for a couple of years. The bats started using them, primarily they they use the building, but occasionally they would use this little bat box as an alternative place to roost. Then, when they tore down the buildings, those bat boxes were stuffed with bats who had already become used to it and then were able to use those to roost throughout the summer. 

Paul Wade [00:23:15] The word colonies was used. Bats seem to be very group oriented. Tell us about their social habits and meeting 

Ted Weller [00:23:25] The social habits of bats, right? So a lot of people think of old bats roost in these large numbers in caves. This is absolutely true. Some species do that. There's there's caves that have over a million bats in them. And then the challenge in that kind of environment is what about when those million moms all give birth to pups and how they can find their pups in those situations? So there's evidence that some moms form partnerships and we'll nurse each other young, and then they're also locating their own pups during within these these huge rules so that how are they doing that? We think it's actually by sense of smell because it's they all sort of look alike, et cetera. A lot of these things are unknown at the same time. The Hoary that I study are considered solitary bats, so they actually roost outside. They roost in the leaves or the needles of a of a tree. They just hang there by by themselves. Out out in a tree. So you can imagine how males and female bats that are that like to go into caves. They how do they find each other while they go to a cave in? If you're a male, you can find a female flying around in front of the cave and you can mate then. But then there's the question that that that I'm interested in some of my colleagues are interested in as well. How do these these hoary bats are one? There's also read bats that roost literally in trees. How do they find each other and where do they mate? It's really sort of an unanswered question, especially because often the females will go to an entirely part of the different continents during the summer to raise the young. And then they pass through some area where there's males and they mate during during that fall period. So the when and where of how these bats locate each other is is kind of an unknown. And then one of the studies that we did recently, we were trying to study the migration of the of the hoary bats and we assumed, Oh, OK, these we tracked these bats during the fall. We'll find out that they're sort of moving north to south. Or maybe they're moving from somewhere in the center of the continent where it gets really cold and they come towards the coasts where it's more mild climate during the winter. So we we actually were able to attach this small, you know, tiny little GPS unit to the bat and tracked the bat. So this this unit was called the pinpoint. It was the name of this tag, and the reason it was called the pinpoint date was because it took a total of eight locations from the bat. It wasn't like the GPS in your car, which is, you know, updating every few seconds or something. It was going to take a total of eight locations. And then the other part for us that was was challenging was that then we then had to recapture the same exact bat that isn't flying to a central place like a cave and then grab that GPS unit from the bat to get the data. But when we did, we found something amazing was that this is bat left Northern California. It flew into Oregon. It flew over to Nevada. And then it flew back to our study site like over the course of a month. We were thinking, what in the world would cause a bat to do this right? Couldn't it find some insects that were closer by to eat? Or, you know, why is it flying sort of, you know, northeast and then west again? And the only thing that we could really come up with so far, I mean, this was just the gas was that it's out there patrolling around trying to find some females that it could meet with. 

Paul Wade [00:27:01] So it sounds like they're more than happy to fly for, you know, great distances for the things that they want migrating. Do bats tend to migrate? 

Ted Weller [00:27:12] It's a continuum, but basically when when the winter comes, bats have to do one of two things either hunker down and hibernate, or they have to migrate to somewhere else. And we used to think that that bats would migrate sort of north to south or towards the coast. And the reason that. They would migrate was because they could stay active throughout the winter, and then there was insects available there that they could hunt throughout the winter. But I think more and more we're understanding that every bat sort of makes a migration move from where they are in the summer to where they hibernate. And some of these bats are migrating southward, like the massive roosting trees. They're just moving to a place that allows them to be in a tree and not freeze to death from from the cold, like if they were sitting at a tree in Montana or something, they say, Well, why would I do that when I could roost in a tree in California? 

Paul Wade [00:28:06] Echolocation detectors, GPPs, sonobatches, sonograms, caves. The equipment in the research involving bats sounds pretty fascinating. 

Ted Weller [00:28:21] Yeah. So researching bats is a great scientific pursuit because we really never know what what we're going to find a lot of times for for for many years. Its focus in the past have relied on they could count bats where when they're in sort of a conspicuous place like they were in a cave where they were, you know, in the attic and you would occasionally see bats. But lately, in the past few decades, we've been able to learn a lot more about that because of technology. So we have technology that allows us to hear the echolocation calls of bats, which otherwise humans can't hear then. Then further technology allows us to then translate that into something visual so humans are much better with visual senses than than hearing senses. So we translate that into what's called a sonogram, where we can look at the calls of the bats and then further furthering that there's ongoing work that allows us to identify which species of bats are out there based on the sonograms of their calls. In the same way, we were only able to know about the roots of bats when when they are really obvious. But as technologies developed and we're getting these radio tags that are smaller and smaller and smaller, we're able to put them on bats and see where the bats lead us to. And for the most part, when and when folks have have tried using this radio radio telemetry. They're not led back to to a building or a cave. They're often led back to trees or a little rock crevice or sort of surprising places that the bats roost. In all, this is really reliant on on the latest technology developments. One of the things that we've been able to do studying the horrible, which is one of the largest bats in North America, is we were one of the first groups to put a GPS transmitter on these hoary bats. And then when we get the data back, we're able to see where that that was on a few different occasions. And then and then most recently, I work with. With this bat, which is a larger bat, we're actually able to, as I was talking about these bat detectors or echolocation detectors that folks have and can place on the ground to listen for bats that are flying by, we were actually able to get a micro just the tiniest ever little bat detector and place it directly on the bat. So we could see when this bat was calling what all the different calls were from the bat and know that we were receiving the full signal from that bat because the microphone was, you know, just like a centimeter away from its mouth. 

Paul Wade [00:31:00] These Echo location detectors, we're going to post some photos for the show, and they appear like to be on tripods about six feet high with a small audio devices on top and then placed throughout the study area forests, for instance. 

Ted Weller [00:31:21] Yeah, that's right. So that's that's typically what we do. So there's, you know, different ways you can deploy these things. One of the thing that you might see up on a post there is the tiny microphone that's actually attached to the brains of the operation. And so that microphones just like a microphone that you see on stage or something for a rock concert, except for it's highly specialized to listen to high frequency sounds. But there's a whole number of advancing, again, advancing technology. So there's there's now a tiny microphone that you can actually plug into your cell phone, and it allows you to sense the bats to record the bats coming in. And then a little display on your cell phone itself will provide an identification of this bat in near real time. So it's something that is advancing rapidly and that citizens citizens can get involved in. And we're increasingly sort of taking advantage of citizen scientists to say, Hey, you're out in many places with your phones. If you could listen for bats, we can actually put that to some of those data to use and learn more about when and where bats are flying around. 

Paul Wade [00:32:28] A couple of things here, Ted, I also understand you can utilize a vehicle with a detector on it to drive around and pick up those acoustics from the echolocation detectors. But at the same time, there is a need to keep some of these roosts away from the main public to protect. Obviously, the bat species. Having said about caves, there are cave doors, bat doors, if you will not bat, you know, bat caves. And those are protected certainly on the national forest system with a great or cage that prevents people from getting in. However, it aids bats from entering and exiting and also to stay protected from unwelcome visitors. But in the end, to be able to know where they're located, to be able to set up these detectors and capture this acoustic material, does that aid in the research of monitoring the populations, the species, their movement, their habitat, 

Ted Weller [00:33:51] As for these sonograms and the sonobatch that you were asking about? There's a whole variety of techniques and approaches to actually identifying the species of bats that fly by. So most of these are the technology for detecting bats is is is really well honed so we can make recordings of bats, make high quality recordings of bats, and then the challenge for four bat biologists and even for sort of computer analysts who are looking for different ways to automatically identify these bats is how do we once we have a recording, how do we assign that back to a particular species? So there's a number of of different, different approaches. So some of them involve biologists sitting there and looking at these sonograms, which is basically just a visual representation of the call, sort of looking at those and assigning them to species. And then we can basically train up computers to automatically do that to some extent and then have that vetted by biologists afterwards. It's sort of like it's sort of like facial recognition technology. So that's out there. It's at an airport. They're like recognizing the faces of people. But if they really want to say, are we sure it's that individual person, then you actually have a human go in and look at it and verify what the computer suggests to you. So that's kind of the process that we're using for four bat call identification. Most of these detectors also do produce a representation of the bat sound. So what they're recording is the full sound of the bat, but that's at a high frequency that the humans can't hear. But most of them have some kind of technology that says, like, either slows that call down by 10 times. So it makes it at a frequency that we could hear, or it converted into sort of a series of like clicks like click, click, click, click so the things that you can, you know, say, Oh yeah, there's a bats flying flying by. So that makes it more rewarding for the person who's who's doing the recording. If they're if they're standing there or driving around with their bat detector, they can actually hear when bats are coming by. 

Paul Wade [00:35:59] But it's still possible to hear bats. For instance, you might be under the bridge or in a cave, right? You can still hear something. 

Ted Weller [00:36:11] Occasionally, people around bats when the bats are in their roost, so people might be near bats when the bats are in a bat box or people or under a bridge or in a building enough. And then you can hear about chirping, you know, and this just sounds, you know, like another like a rodents chirping, maybe. Or it's just like tick, tick, tick, tick, tick, tick, tick, tick. This kind of sounds and these are echolocation calls and that these are actually just sort of contact or communication calls between bats. Or it may be like the is communicating with their young or just bats, you know, communicating back and forth to each other. So they're not locating in that case, but they are making sounds that are communicative in nature. So again, just kind of pointing to like the whole variety of things that bats are capable of. So they are capable of making audible sounds and then they're capable of making these high frequency sounds that they're using to navigate around the night skies, but they're also capable of making sounds in the audible range. And as we discussed before, they can see quite well, particularly after dark. They have well-developed sense of smell. So really just a great feature for understanding that the sensory capabilities of mammals. 

Paul Wade [00:37:24] So what is the most prevalent flying mammal here in California or the Pacific southwest region? And how is the national forest and the bat getting along.

Ted Weller [00:37:38] Right, so across the southwest region, which is basically encompassing, encompassing California? I would say that the most prevalent that it kind of depends on what the habitat is, but probably the most prevalent that is the Mexican free tail bat. These are the bats that they'll roost in really large numbers under bridges. They'll be just in case they risk in buildings. They're very comfortable around around humans so that, you know, they'll get into houses a lot. And there's and there's, you know, frankly, there's there's lots of them out there. But as you move up into forested areas, they're not quite as prevalent, although they seem to be expanding their range more into some of the forested areas. And in once we get into the forest and then the most common bat in the national forests of California might be the silver haired bat or the California myositis, a number of species there. There isn't one that really stands out, I would say, in the forest as being the most common bat where the things that we've seen in in California and then again across the across the country is that, as I mentioned earlier, most species of bats will roost in trees and do roost in trees throughout that throughout the summer period. And given that the Forest Service is probably the greatest land manager of trees in forested areas out there, it's really become clear that the Forest Service is providing habitat to a whole suite of bat species and may be providing more, more summer habitat for bats than any other sort of land management agency or any sort of entity, certainly in the US. But but potentially worldwide, just managing the habitat for these bats. And then that relationship that this sort of ecosystem components, the ecosystem services that bats provide are being facilitated by the management of forests, by the Forest Service. 

Paul Wade [00:39:37] Well, Ted, you know that the world isn't a perfect place and. There are threats to the bat population. Can you share those with our listeners and talk a little bit about some of the efforts that are being taken to mitigate that? 

Ted Weller [00:39:57] Bats are threatened like, you know, like a lot of wildlife species, like a lot of mammals by the typical things that we've known about for years, like habitat loss. So converting natural habitats into things that aren't natural habitats anymore. As I mentioned, bats love to roost in trees, so whenever we lose, trees were potentially losing about roosting areas in the past few years in California and throughout the West. One of the one of the things that's that we found is these large wildfires. So in in general, wildfires might actually not be the worst thing for bats if they if they sort of burn in a mosaic of some hot areas in some not hot areas, because the when the fire burns through, it often kills some of the trees. But then these trees actually become great places that bats can roost in. Sometimes it also stimulates a pulse of insect activity so that bats could then forage in these same areas. But as we're seeing these fires get sort of larger and more intense where there's vast swaths of of land where there's just no trees left, this could really have an impact on bats. And a lot of these are then related to climate change. So the other the other thing I mentioned about bats is that they need to have a roost near a place that they can drink water. So this is especially important for the mother bats in the summer. They're nursing their young all day. They're staying in the roost all day, often in a place that's quite warm and they actually get pretty dehydrated, need to get right out and find a source of open water. So in some parts of the country where there's just small ponds and these ponds dry up during the summer, this can be an issue for bats. Some of the other. The other issue that's been facing bats lately is a development of wind energy technology. So there's there's some species of bats that are killed by these large wind turbines. And this is an area that I've been really active in. So it's it's it's an interesting pattern in that the species that tend to be killed at the wind energy facilities are namely or mainly the tree roosting bats. And in particular, they're killed during the fall period, which is when the bats are migrating. So they're sort of maybe out of their normal range of operations. The place that they're spending time and where they may know the location of every tree on the landscape, they're moving through a unique landscape and they encounter these wind turbines. Maybe they're even exploring these wind turbines as a place to roost or potentially meet other bats because the fall is that they're mating period as well, and they're coming into conflict and they're basically being hit by the turbine blades and being killed there. So that's affecting the migratory bats. And then finally, the one that that people might have heard the most about is something called white nose syndrome, which is a fungal disease that's that's killing bats. And this is primarily affecting the bats that they use the strategy of hibernation over the winter. So there's the migratory bats that kind of migrate to the more hospitable climates. And then there's other bats. You choose to sort of stay closer to home, but find a nice cold, cold, wet cave where they can hibernate over the winter. And these bats are then being impacted by white nose syndrome. So white nose syndrome is a devastating disease, so it's one of one of the most impactful diseases ever to hit wildlife populations. So there's three species of bats where we've we've documented over 90 percent declines in their in their populations. White nose syndrome is is now present and I think 38 states and maybe seven Canadian provinces. It was first noted in the northeast New York in 2006, and it's been sort of slowly year by year, spreading south and west from there. And then just in around 2016, we actually had a big jump in white nose syndrome was found in Washington state and several bats have been killed from white nose syndrome in Washington state. So there's sort of multiple fronts of the expansion of this fungal disease, white nose syndrome that's really having devastating impacts on North American bats. 

Paul Wade [00:44:23] And now that this white nose syndrome has been discovered and monitored, is there a silver lining? Is there some sort of approach to slow this spread or to maybe even address it directly? 

Ted Weller [00:44:37] They seem to be sort of stabilizing to recovering. So that's a little bit of a silver lining, perhaps, but it's going to take a long time to get back to their previous numbers. In the US, it's certainly the number one thing. I mean, the main thing that we're doing now is just trying to monitor the progress of the disease. So we're doing that in sort of a multi-pronged way so that the sort of hands off technique and just understanding the impacts on their populations is being done through this North American bat monitoring program. And there's the acoustic monitoring approaches that I mentioned before. So that's done done during the summer. And we can just see, are we seeing changes in where we see certain species of bats? The other sort of component of that is to do surveys during their roosts. So particularly during their their winter roosting or that so-called hibernate column, the place that bats hibernate. And in those cases, you know, trained biologists will go in. We're wearing protective equipment to protect and spreading the disease from, say, one cave to another. And then we're going in taking a look at the bats. They're counting them, keeping an eye on their population. And then in some cases, we're able to just tick a sort of a Q-Tip like swab and get a sample of the bats wing tissue to see later through genetic analysis is the presence of the fungus on these bats? And then what is the sort of progression of that on the animals year to year? What about the lifestyle in the cave? In the caves? Is it bats that huddled together that seem to be most, most susceptible to this disease? Or is it bats that are spread out? What about the temperature of the caves, the temperature, the humidity level of these caves? Is there something that we can do to protect or predict where white nose syndrome is is most likely to be most, most challenging for bats, or whether there's places that seem to be surviving and we can think about how to modify those, modify those areas. There's been a whole number of of different approaches that have been successful in laboratory settings for treating the fungal disease, so people have come up with different anti-fungal type of type of treatments. Beneficial bacteria, things like that that will help to combat the fungal disease on the bats. They work in a laboratory setting. But the challenge is how do we get them onto the bats in the field? So in in large numbers, sometimes large groups of bats in a cave? Or what about when there's just a few bats in many, many, many caves and mines all across the country? Like how would we ever start to sort of have a vaccination program? So this is the big challenge in, and part of that challenge also is to make sure that whatever we might do that to treat the bats, it's not going to have unintended impacts on those cave ecosystems. So let's say we came up with the treatment that required us to sort of spray this anti-fungal treatment on on the bats in the cave might work great for the bats, but might sort of impact other fungal communities in the cave, which have other beneficial, beneficial uses. Again, this kind of concept that there's all these interconnected parts of nature and we only understand little bits, little bits of each of them. So we just need to be really careful about what we might do to treat the bats. There's a couple of places I'd recommend. What if you want to learn more about white nose syndrome? There's a there's a nice website with a with a really easy name. It's called whitenosesyndrome.org. So that's all lowercase. Just one word white nose syndrome, org. And then probably the best place to learn more about bats is the Bat Conservation International website. Again, a really easy website name. It's Batcon.org that explains a whole variety of the kind of studies that bat conservation is involved in, and it provides information on on on bats bats worldwide. Bat Conservation International has been a longtime partner with the Forest Service, so we'll help Bat Conservation International with some of the work that they want to do. And then Bat Conservation International also helps on our projects. And so it's been just a great sort of symbiotic relationship between the Forest Service and our conservation international for for quite a long time. And their website is a great place that the public can go just to learn more about bats and be excited and impressed by bats. 

Paul Wade [00:49:26] Well, there is a week before Halloween called Bat Week that we utilize to educate the public and dispel myths about bats. However, I'm sure it's a constant battle for scientists and conservation groups. You to push all the great things about that against that spookiness side that we've seen in movies and obviously during Halloween. And Ted, you mentioned the vampire bat, which is this iconic vision I think pops up in everybody's head. But can you tell us a little bit more about the real vampire bat? 

Ted Weller [00:50:06] Sure. So as I mentioned earlier, there is over 1400 species of bats and they have a diversity of feeding habits. So like I mentioned, like most of them, eat insects, there's bats that eat fruit, there's bats that actually specialize on eating frogs. And then among these 1400 bat species, three of them specialize on feeding on blood. So there's only three. They're all in the same sort of Central America and South America. That's that's their distribution. So even though folks know about Transylvania in Europe, there's actually no vampire bats in Europe, nor is there vampire bats in Asia or Africa. They're all in in the western hemisphere here in Central and South America. And then these bats, some of them specialize on feeding on birds, and others specialize on feeding on animals. So they'll often like, as you mentioned, you asked earlier about the bats ability to walk or to run. So vampire bats are great at this because often they're approaching the animals that are standing on the ground and they can then crawl up to the animal and they have sort of a numbing agent in their saliva so that the animal doesn't necessarily feel or, you know, have pain from their bite, very sharp teeth. And then they'll make a little nick in the bat and then just lap up the blood of the animal. One of the things about vampire bats that's interesting from a sort of ecological and conservation perspective is that the range of the vampire bats seems to be increasing northwards towards towards the United States, so out of Mexico, into the United States. And one of the reasons for that is because they're feeding on cattle and as cattle production has has become more common in these parts of Mexico. They're sort of following the cattle polls as you will like some bats, follow the mass migrations out of Mexico. Vampire bats seem to actually be following the cattle production northward and that they eventually might make their way into the U.S. So so far, you know, there might have been one or two cases of vampire bats being detected in the U.S., but they haven't established themselves as a species, as a species in the U.S. The other thing to know about vampire bats is they're actually quite small. You know, they're the size of your fist at the at the at the largest. So a lot of people assume that that vampire bats are large. So I did have one experience in Nicaragua where we were capturing that they were coming out of a tree. We were expecting a certain species of tree roosting bats. We weren't expecting vampire bats. But what came out of the bat? The tree was a really large species about this actually a carnivorous bat, not a vampire bat. And and we we captured this. That is a big surprise to all of us, and we were kind of excited about it as bat biologists. But there's a number of this sort of villagers standing around and they were saying, Oh my gosh, look at this vampire bat, vampire bat. And we're trying to explain to them, No, no, this isn't isn't a vampire bat at all. Vampire bats are much smaller, et cetera. And then we sort of, in a way, lost credibility because they couldn't believe it because they were like, I've kind of seen this bat, and I know that that's the vampire bat. 

Paul Wade [00:53:30] So I'm going to guess that during Halloween as a bat. Ecologist, you're both happy and sad, right? 

Ted Weller [00:53:39] Yeah, they OK, there's a couple of cool things here in this that you just I'm glad you brought that up for. For one, you kind of mentioned like from the from the flyer from BatWeek, people saying, Oh, there's like spooky things like bats and spiders that are associated with Halloween, right? And it's it's funny because they're not necessarily associated with Halloween. And this is this is my thought. They're not associated with Halloween from the beginning because they were spooky. It is the time of year when the nights start to get longer, so that's kind of spooky. But it's also the the time of year when you see these huge, you know, pumpkins spiders like setting up their webs. That's that happens in the fall. The tarantula migration that you're just talking about, that happens in the fall. Most of the public to the average person, when they encounter the bats, they encounter these bats during the fall period. So when the bats are moving from their summer habitat to their winter habitat, they they sometimes, you know, in the strange places, so they get underneath your patio umbrella or you might see it underneath your gutter. This is the time of year when aircraft collide with bats. And this is the time when when bats are mostly killed, that that wind turbines. All this is like bats are out of their normal space. They're moving from ones. They're moving from one spot to another and they are finding themselves in weird places. Humans encounter them, and they're sort of associated with this particular season, which is which is interesting. 

Paul Wade [00:55:08] Well, there's also a large fan base that actually wants to encounter them and go see them. So are there places that people can do that and become citizen scientists themselves? 

Ted Weller [00:55:22] There are places that that that people can get out in and see that these are largely actually of the Mexican free tailed bats, so they often have some amazing emergencies from their roosts. So one of them in California is the YOLO Causeway out by Sacramento, and that bridge is providing a roost to, I don't know the number, but hundreds of thousands of bats. And so it can be quite a scene as they as they fly out of that causeway and there are public programs there. Probably the most famous one is in Austin, Texas, the Congress Avenue Bridge, which is which is, you know, crossing the Colorado River there and the main road that you can see the state capital from from this road etc cetera. And there's over a million bats in there, and it's a huge tourist spectacle. So they'll they'll organize kayak trips where people can kayak and sit under the bridge and watch these bats emerge and they emerge in these and these clouds. Starlings are famous for this, and a number of shorebirds are famous for this. It's what they call murmuration. So that'll, you know, they'll sort of almost disappear when they fly at an angle to you and then reappear and make these really amazing sort of smoke like patterns on the landscape. But what's amazing about it is as these clouds kind of fly up over the city, you'll see them, you know, a mile or two miles away. You can still see the cloud and it's sort of bending and twisting against the the buildings of downtown Austin, Texas. So that's a that's a great place. It's really accessible if anyone has a chance to go to Austin, Texas. 

Paul Wade [00:56:56] Well, I'm pretty sure that there's not a lot of mosquito fans out there. But just in case, here's another chance for you, Ted, to explain why should the public care about bats? 

Ted Weller [00:57:11] The main thing that I tell the public is is just to think about the insects that are out at night. So we all know if you go out in the evening, there's mosquitoes out there. You can come to your streetlamp at night and see if there's beetles up there. There's moths out there foraging and to think what is eating those at night? Mainly is bats. And, you know, bats are just a vital part of the ecosystem. They're an important cog. You can't if you remove one part of the ecosystem, if you move one cog like bats. What would happen to those insect populations? So that that's that's the main thing in a lot of cases, we don't actually know the answer to that question because we've always had bats. We take that for granted. They're out there doing amazing amounts of service. They're not doing it for us, but they're they're doing it. And it's allowing us to live in an environment where insect populations don't get really out of control. 

Paul Wade [00:58:06] This is a been extremely fascinating. Ted, I've learned a lot. Hopefully, the listeners have as well. Any final thoughts, any future, you know, projects that are coming up or things that you're really excited about. So, you know, wrap up the show and give us what you're what you're thinking and what you're you're really happy about right now when it comes to the species of bats. 

Ted Weller [00:58:30] I think it's just a matter of us kind of keeping an eye on the bats, trying to do the research to understand what these threats might be and then do, and we can like as a as an agency to promote healthy forests, promote, you know, trees, anyone can plant a tree that'll have beneficial impacts, not just a bad but all kinds of wildlife species. And we're finding even even a single tree can can do a lot of a lot of good. So there are things that you know the average person can do to, to promote bats and to promote wildlife. And so I hope that we're doing that both as individuals and as an agency. So the other thing that I'm really excited about is the potential for a citizen scientist. So I mentioned that there's, you know, microphones that you could get that plug right into your cell phone. So to the extent that the average citizen might be able to go out with their cell phone and walk the same this same path every night to be able to monitor the species, so then that would allow them to sort of have an understanding of that species that are around them to sense the changes themselves and then to be able to contribute these data to the larger cost. You know, you might not know what's going on. You might know what's going on in your neighborhood. But that'll help us to understand like what's going on in your county, what's going on in your state, what's going on across the country and to the extent that technologies are allowing us to do more automated identification of these of these calls and the extent that technology is allowing us to share these recordings easily among different platforms so people might be able to upload all their recordings. And then the next day or maybe within minutes, be able to get some results back that allow us to allow them to say, here's the species that I detected. I think these are things that are going to allow the public to get more involved and then allow scientists to better understand the populations of bats. So there's some really cool things on the future that are really driven by technology and a lot of excuses. 

Paul Wade [01:00:32] Appreciate the information, Ted. And good luck to you and the bats in the future. 

Ted Weller [01:00:38] Awesome. Yeah, I enjoyed it was fun. 

Paul Wade [01:00:40] Thanks to Ted Weller for helping us locate all the good things bats are doing for our backyard, the forests and the world to hone in on more information on the only flying mammal on the planet. Check out the links in the show's description page. Thank you for listening. To learn more about this show. Share it or hear our other episodes, please search Forest Focus podcast. And if you have questions or suggestions on a topic of area of expertize you would like us to feature, please email us at SM.FS.R5FFPodcast.usda.gov. Until next time. Enjoy your public lands. And remember to recreate responsibly, know before you go and learn what you can do to prevent wildfires. Take care. This podcast is sponsored by the U.S. Department of Agriculture, Forest Service and USDA is an equal opportunity provider, employer and lender.