The audio journal about getting into the wilderness.
The WildeBeat edition 109 & 110: Creatures of the Night
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Halloween is coming up. What kind of spooky things might you see in the wilderness at night? This edition of The WildeBeat; Creatures of the Night.
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News from the Wildebeat, the audio journal about getting into the wilderness.
This is a combined version of program numbers one oh nine and one ten.
I'm Steve Sergeant.
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STEVE: What kind of small, furry mammal hides in dark places, in caves, in tiny crevasses and cracks in the rock, or under flaps of tree bark during the day, and then gets out and rules the skies at night. Many of you probably know already; I'm talking about bats. To most of us, bats are pretty mysterious. To a lot of people, they're creepy and scary. For example, Dave Smith, who we heard from in our edition number eighty, is an expert on staying safe around dangerous animals like grizzly bears, bison, and mountain lions. But none of those beasts creep him out as much as bats.
DAVE SMITH: Ha. Yeah, I'm one of those people. [laughs] I know I'm supposed to say they're good and they eat insects, but it gives me the heebie-jeebies every time I see one flying around.
STEVE: Last summer, at a nature sounds workshop, I met a guy who's right at home with bats. Curt Black lives in the Seattle area. Some people call him the Bat Man, though he dismisses that nickname as silly. I talked to Curt remotely from his bat cave, I mean, his home in the Seattle area.
CURT BLACK: I actually greatly enjoy interacting with them, and have done so since, I don't know, sometime since the nineteen seventies. But probably unlike most people out there, I've had my pre-exposure rabies inoculations since sometime in the nineteen seventies. There's a piece of me that wants to get across that you shouldn't handle bats if you don't have those pre-exposure rabies inoculations, ...but that it's great to admire them from afar. Anytime they're flying by, that's just a great thing to appreciate.
STEVE: So, how did you get started?
CURT BLACK: I used to be a very active caver, so cave explorers end up encountering bats in caves. Certainly bats live lots of other places as well, but the place that people and bats seem to interact a lot is cave passages... But eventually I kind of transitioned; I was kind of helping bat researchers, telling them where we were seeing bats. You know, talking to them about their caving techniques, and things like that, and eventually started hanging out more with the bat researchers than the cavers. And so, finally this transitioned to mostly bat research type stuff. I'm lucky enough to live in an area that has a local organization; in this case Bats Northwest, in Seattle, and we take kind of an educational role, and so Bats Northwest does a lot of education and outreach, gives talks, in schools and public presentations. We also try to get people who are interested in bats folded-in, through a bat ambassador training program, and those folks then become kind of a center of the training activity.
STEVE: So, it being almost Halloween here, bats are scary, scary creatures. Is that opinion people have of them warranted?
CURT BLACK: I'm usually pretty reluctant to reinforce the creepy, spooky, halloween-ee aspects of bats. I mean, I spend a lot of my time trying to overcome that stuff. But it still does give us an opportunity to talk about bats, at least once a year. Although I spend a lot of my time talking about them, and I'm happy to do so, pretty much anytime.
STEVE: A lot of people when they see pictures of bats they think of them as really scary and quite ugly. They're pretty tiny things with these ...really large wings, and these mouth wide open with all these teeth, and these odd-shaped ears and noses. They're all pretty terrifying looking.
CURT BLACK: There is a reason that they're flying around with their mouths open, at least the bats around here need to do that in order to get the sounds out, so that they can start getting those echos back and figure out where they are. But it's not an agressive thing. It's just the way they have to do it. ...They are very, very skilled fliers. And they're doing amazing things with that acoustic energy that they're using to image the environment. I mean, just like you do amazing things when you glance around the room, ...you're creating a three-dimensional picture of where everything is, and they're doing exactly the same thing except that they're painting the space around them with sound, and then building that picture, and then flying through it at a high rate of speed, and probably in pursuit of an insect. They're just amazing.
STEVE: So that open mouth isn't scooping insects out of the air?
CURT BLACK: No, they don't actually eat that way. Our insect eating bats up here are actually using their wings and batting the insects down into their tail membrane, and then they reach down there and get it... When you look at a swallow or a nighthawk or whatever, those birds have lots of specially adapted quills... around their mouths that give them lots of information and about how close they're getting to insects and allow them to capture insects with their mouths, but bats just aren't doing that kind of thing. They actually reach down, knock it into their tail membrane, ...crunch it up a little bit, maybe take the wings off, disable it, make it possible for them to eat it. It's a pretty different approach.
STEVE: Dave Smith's heebie-jeebies aside, people seem to have a lot of reasons why they think bats are scary and creepy.
CURT BLACK: I think most people think bats are blind, and flying rodents, things that get tangled in your hair, agressive with their little open mouths, some kind of modified bird or something. I don't think people think they're mammals. And that they're probably all blood-sucking vampire type creatures just waiting for you to expose a part of your neck.
STEVE: But almost none of these things are true. For example, you'd be seeing pretty well if you were as blind as a bat.
CURT BLACK: Yeah, it turns out they can see about as well if not maybe better than we can in low light.
STEVE: While some bats about the same size as some rodents, they're no more closely related to rodents than humans are.
CURT BLACK: They're definitely not rodents, they fly, but they are not rodents. They're in their own order of mammals, ...the Chiroptera, the handed, winged mammals. ...I think the thing that distinguishes them most from rodents would be their reproductive rate. And these are the mammals that have the lowest reproductive rate for size. And they're the longest-lived animals for their size. So like one young per year, contrasted with a litter every, ...like a white-footed deer mouse or something, at what twenty four days of age, and then every thirty something days they can have a litter of like eleven. So I mean in one year you could have like a million animals if you had unlimited resources for that mouse. And in that same your, your two-bat parents would have produced one offspring.
STEVE: So, how do I keep them out of my hair?
CURT BLACK: If you don't like having a bat in your hair, ...all you have to do is shout "Cut," because you are clearly in a movie. Bats just don't do that in the real world. They're very skilled flyers. ...So they'll get close to you, but they are not trying to get tangled up in you. Usually, you are a big, prominent thing in the environment, and these bats are insterested in using like the insects that circling over your head or have been attracted to your carbon dioxide or the moisture or just the warmth of your body. And lots of time there's big clouds of insects that are above you that are like mating and having a great time up there but this bat finds that a very rich foraging habitat.
STEVE: And where did that vampire thing come from?
CURT BLACK: Well, these bats are certainly not vampires for the most part. Out of the thousands of species of bats in the world, some three of them are actually vampires... But they definitely don't suck blood. They just make little divots out of you and lap-up the blood that comes out because of the anticoagulant that they're using in their saliva.
STEVE: But we're going to find them in the Rocky Mountains in Colorado, or in a forest in new England?
CURT BLACK: Definitely not. So you'd have to go down almost to central Mexico, and then on south as far as northern South America, is kind of the range for those vampire type bats. Pretty much all of the bats in North America are just eating insects except for just a couple down in the southern end of Arizona and Texas, where you get a couple of nectar-feeders, and then one species that gets up into pretty much southern Florida that's a fruit-eating bat. Everybody else, out of the forty five species north of Mexico, is all about eating insects, which most people should like because if you don't like insects, you really ought to like bats.
STEVE: One way Curt fights the undeserved, creepy reputation that bats have, is to lead bat-watching walks in parks on the outskirts of Seattle.
CURT BLACK: OK. Well, I'd be happy to start if people would like. I think it's about the appointed time. So why might tonight be a pretty good night for doing a bat walk? Any ideas?
AUDIENCE MEMBER: It's not rainin'.
CURT BLACK: Yeah, OK. So there's no rain. And that does actually interfere with the ability of, first, insects to fly through the rain with, you know, these missiles going by. So on a scale of thinking like an insect; big rain drops, it's scary. And it's not been a really warm day but it's sunny enough that we've probably had, what, some insect hatch today. Yeah, like right above us here, at least, we've had differing numbers. But usually, you wind up with a cloud of insects above your head. And that might explain one reason that people encounter bats more, or at least notice them, is that you're getting these insects around you.
CURT BLACK: The bats are really busy right now, they're trying to get enough food to get their young raised to the point where they can fly. The young are flying. They're putting on enough weight that they can make it through this next cycle of either hibernating or migrating out of the region, because all of our bats eat insects.
CURT BLACK: How about, where we are in the cycle with the moon? Does that -- Anybody have a sense of how that might affect bat activity?
AUDIENCE MEMBER: More bats on a full moon? [off-mic]
CURT BLACK: That's actually the opposite, they're kinda -- So, she said "more bats on a full moon," and it's actually, they're kind of luna-phobic. A lot of bats are more reluctant to come out when the predators for bats can see them.
CURT BLACK: I'd like to talk before they start actually start talking to us about echo-location. So, bats are doing something different from us. I mean, when you look at a picture of a bat, there's stuff going on with sound. So we use bat detectors now which have little microphones on the front, and they listen to the ultrasonic range, and they take things that are outside of our range of hearing and bring them down low enough to where we can actually hear hear it coming out of the speaker.
CURT BLACK: So I just heard a bat fly by. Well, I mean, I heard the bat detector saying that a bat flew by. When it starts to get hard to like read a newspaper, whatever, that's kind of where I start thinking we're about the right place for bats.
AUDIENCE MEMBER: Right there!
CURT BLACK: OK. So, did you hear that buzz there?
CURT BLACK: That was a nice performance! Oh, he's back.
CURT BLACK: OK. Feeding buzz. Feeding buzz.
CURT BLACK: A buzz.
CURT BLACK: So I guess you're seeing that bat pretty well. So the question is, do you see bats on bat walks. I think you do see bats on bat walks. Was that at all threatening?
AUDIENCE MEMBER: No.
CURT BLACK: I sampled that sound as it went by with this time-expansion detector, and this is what it sounds like in time-expansion. So it's sweeping through a range of frequencies, that sounds like a chirp. And what we can do is feed it into this computer and we've got some call analysis software that we can bring up other bat calls, and figure out what kind of bat it is. That little guy is a silver-haired bat. So a Lasionycteris noctivagans.
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STEVE: Back at Curt's home, he talked about how we can watch bats on our own wilderness adventures.
CURT BLACK: Well, bats are almost everywhere. Especially our more wild places, still. But they're challenging to watch. So it takes some energy. There's almost no overlap in our activity periods... So just about the time that swallows and things stop swooping over water bodies and pulling out insects, when that shift closes down, the bats pop out and do exactly the same thing. So if you're hiking or camping or out there in the wilderness and you're, especially over some water body, if you can orient yourself in such a way to maybe be on the eastern side of something, looking to the west or the northwest where the setting sun is still illuminating the sky, a lot of times you can see the bats out over the water body, out over the clearing, harvesting insects. And they're backlighted by the sky, and it's a beautiful thing to watch... Once you get an eye for it, they're definitely there. But, like when we give these bat walks at Green lake, we sit on one side of the lake, looking across through this gap in the trees, and through that gap just pour hundreds of bats... This lake is a magnet for wildlife... in this case they're coming down here in the first thing, to get a drink of water, and then to harvest the insects that have been hatching out through the day, if it's a warm day, and that's the resource we're trying to get a look at.
STEVE: Curt points out that trying to see bats is not really the best way to appreciate them, because they don't really live in a world of light. They live in a world of sound, and to get to know them well, we've got listen instead.
CURT BLACK: It's pretty hard... And a bunch of them look almost identical, actually a couple of them, a professional cannot tell them apart in the hand... They're nothing like birds... We don't identify bats by going out with binoculars and things and looking at them. So that's really just a whole different approach. We sit out there with these acoustic monitoring devices, these time-expansion recorders, and we record little chunks of their calls as they go by, and then analyze those calls on a laptop, and figure out which bats are going by. There's lots of ways to eavesdrop on the ultrasonic echolocation calls that bats use to orient and hunt. And they don't have to be horribly expensive. I mean there's no upper bound pretty much to how much you can spend for a time expansion bat detector. There's some up in the I think eight and ten thousand kind of range. But there's much less expensive ones in the maybe two-hundred dollar kind of range. And then if you're willing to build things, I mean, there's lots of plans, stuff on the Internet and stuff for taking say the transducer, the little microphone that an old Polaroid camera used to use... and actually make your own, and so it's not too complicated.
STEVE: How many of our North American bats are audible without any electronic aid. Are there any?
CURT BLACK: Yeah, you definitely can hear several species. I'm mostly familiar with the ones in Washington State. So the spotted bat is probably the best example, because actually it's echolocation calls are predominantly down there about twelve kilohertz, twelve thousand cycles a second. You can definitely hear those bats. A lot of our bats, during the last stage of catching an insect, there's a feeding buzz; they produce a series of pulses and they make a new pulse every time they get the echo back, so as they get really close to the insect, the pulses get quite close together, and it's a buzz type sound. And the ends of those feeding buzzes a lot of times get down lower in frequency than the rest of the calls, so you can actually hear the end of the feeding buzz... Then a bunch of bats give off kind of social calls. Palid bats especially in eastern Washington, a lot of times we can hear them going by. Because they're kind-of honking at each other. They're talking about something.
STEVE: So you don't have to wait until Halloween to go bat watching. They could be around most any time. Just watch for them in silhouette over a body water, or listen for them in the still of the night.
STEVE: My thanks to Curt Black, for providing all of the location-recordings for this show.
STEVE: We'd like to hear about your experiences with bats, or any comments or suggestions you have for our show. You can call our toll free comment line at 866-590-7373, or send e-mail to comments at wildebeat dot net.
STEVE: WildeBeat members can download a complete recording of one of Curt's evening bat-watching walks from our WildeBeat Insiders web pages. For a limited time, become a WildeBeat member and get up to five books as thank you gifts, courtesy of Wilderness Press.
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Our official website is WWW dot WILDEBEAT (that's W-I-L-D-E-B-E-A-T) dot NET. You can help us help more folks to appreciate our wild public lands, by clicking on our support link to become a member. The WildeBeat is produced by Steve Sergeant, with help from Jean Higham, as a nonprofit educational project of Earth Island Institute.
This has been The WildeBeat, combined program numbers one oh nine and one ten. Thank you for listening.
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