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The WildeBeat edition 110: Creatures of the Night, part 2
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Did you see any bats on Halloween? If not, don't worry, they're probably still around, and we'll tell you how to find them. This week on The WildeBeat; Creatures of the Night, part 2.
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News from the Wildebeat, the audio journal about getting into the wilderness.
This is program number one ten.
I'm Steve Sergeant.
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STEVE: Last time, we heard from Curt Black. He's a technical advisor for the nonprofit group, Bats Northwest.
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.
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... 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.
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... 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, program number one ten. Thank you for listening.
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