The sonic success of David King; Inventor of BatBox detectors

S5E53 This week we join David King who created the BatBox III and BatBox Duet detectors amongst several others for four decades. David tells Steve of how it all came about and they delve into the history of bat detecting, how the Bat Detective book and CD was created and we get an insight into his views on the future of technology used by ecologists and conservationists alike.  

• Find David on twitter and Instagram
• BatBox Ltd for their range of bat detectors
• The Bat Detective book and CD
• Want to find out more about bat detecting? Take a look at our guide.

Got questions, thoughts, or curious bat queries? Text us—we’d love to hear from you!

Transcript

Steve Roe: 0:07

Hello, you're listening to BatChat, the podcast from the Bat Conservation Trust, where we take you out into the field to discover the world of bat conservation. Welcome back, folks. And as you know by now, this is the podcast for anyone with a fascination in the amazing nocturnal mammals that fill our skies at night. I'm Steve Roe professionally, I'm an ecologist and in my spare time, as well as doing this podcast, I'm a trustee for the Bat Conservation Trust. Well, as you can hear, I'm surrounded by evening birdsong. I've just called the distant call of a turtle dove and the first part of the evening is going to make an appearance at any moment. I'm on a fleeting visit to Sussex because in the morning, I'm off to meet our guests are about to hear who lives not too far from here. So before I turn into the night, I'm having an evening walk around the Napa State with my trusty bat box three detector is the only back detector I actually own which was bought for me by my parents when I was 12. I've had the chance to use most detector models out there over the years, but it's this particular detector, which is special to me. It's been there with me for countless nights in the dark for nearly a quarter of a century. And for most species. That was the first time I heard their calls. In the morning, I'll be chatting with the guy who invented it, and how it became one of the best selling bat detectors of all time. It's just gonna pass the summer solstice in June, and I'm sat in the garden in West Sussex with the mentor of probably one of the best selling bat detectors, David King. David, thank you for coming on that chat. I guess the first question is, where did it all start? How did you get into bats?

David King: 1:49

I was a musician, originally. And I used to make transducers for guitars. So I was involved with electronics. And I've been interested in electronics since I was 11. Since it started, really, I think I started because my ex wife was a zoologist. She was interested in bats. And she became interested in the mid 80s. And there was a handful of people that used to go around looking at bat roosts and things and it wasn't like it is nowadays. And she wanted something that would translate the ultrasonic calls, she knew they were ultrasonic calls into audio. And a few of her friends had these converted radios. And so I thought, well, you know, went back to first principles. And I thought, well, I could probably make something similar. And I tried. It was in two parts. At first, there was the detector part and the amplifier part. You had to connect it with a cable between the two was quite loud. And some people thought we might disturb the bats. But she wasn't very impressed with it. And so I went back into the workshop and came up with the first MacBooks three are, which was actually the best books to I think, because the first one was the prototype, right? Yeah. And again, she said, Well, it doesn't tell you what kind of best it is. And I thought, well, that's a bit advanced. So I was quite down in the mouth about it. I took it along to a back group meeting. And we went outside. This is the Cornwall Wildlife Trust site. And we listened to bats outside and everybody came over to me said what's that? What's that? It's picking up all the bats and, and mine isn't. And that was the backbox, two at the time. And they became really interested in one person was going up to the first one of the early back groups of Britain meetings in I think it was York at the time. And she took her back detector with her. And I thought, well, you know, she's they're not going to be very impressed up there. But she came back she said, Oh, I wanted to have the detector back. But she said I left it with Phil Richardson because he wouldn't let it go. He said No, please can I have it please can I borrow it? And he was so impressed with it. You wrote a little article in back chat. And after that, check started pouring through the letterbox for similar devices. And I I tried to keep the teaching. I was a music teacher at the time. Tried to keep that going at the same time. But it became too difficult after a while and I had to swap Horses.

Steve Roe: 5:01

Yeah, David, just before we started recording, David just passed me a excerpt from 'Bat Chat', which was the newsletter of the, back then, NCC. And we we had known that was about that long ago. So yeah, it's quite nice to to know that it's continuing now, that company became stuck electronics just talk about how the name came about them.

David King: 5:22

It was an abbreviation of St. Agnes where I was living at the time that was in Cornwall. So it was the first four letters really S T, a G, so I couldn't think of a better name at the time. So called it Stagg electronics. And we we sold hundreds and hundreds of these backbox threes. And I tried to modify it and improve it each version. But in the early days, I, I tracked the circuit boards with tape and pads and etched them myself. Yeah. Which obviously is done by computers. Now it's so easy. But the first ones were actually done by hand. And I used to have acid baths and things to make the boards. And I assembled them all myself. They there were there was no as it was a kind of sideline, I wasn't buying vast quantities. And all the time. My ex wife was saying, Do you think do you think it's worth investing in? Because I was trying to persuade her that we should buy a lot of components and start making them big scale? Yes. She said No, sir. So I, I did. I did the opposite. How I am. And we bought lots of components and made lots of them. And I couldn't make them fast enough, really. So I had to give up the teaching. I kept it going. Part time I used to teach it Tura school. I really enjoyed that. It's great fun, but it wasn't so lucrative. So I carried on and thought about developing the next kind of bat detector, which I think was called batty is which was a detector built into headphones. You could switch switch from a centre frequency of 25 kilohertz and 45 kilohertz, okay. Yeah, so there's a little toggle switch on one ear, and you just flicked from 25 to 45 kilohertz. So you could pick up most bats that way, or the low frequency bat Sarah teens, not chills, social cause of longhaired. And 45 pips would come up louder than 55 pips because there will be higher frequency. But in those that was before Gareth had defined the difference between the two. But it was interesting that I could have let him hear from Gareth, talking about just about starting work on the two, the two types of phones or types of pipistrel. And this was a Bristol University, a comparison of different detectors at the time.

Steve Roe: 8:35

And this is dated 1919. They weren't split up all the way back until about 92. So this is this is January 1990. And God says, I certainly think that making a tape about workers will be a good move. The quality of your recordings is excellent Tibetan anything that's been so far produced in the UK. So is that where the idea of doing the back detective the tape and then the CD came from?

David King: 9:02

Yes, yeah, I had one of the original tapes that Phil produced, Phil Richardson produced. And they all sounded pretty much the same. In practice, when I went out with mine, I could hear differences. So I thought, Well, why not try recording, building a tape of them. And the first tape I produced was like an upgraded version of the one that was available and more species. I think, after that, I decided to do a CD. That was quite a lot later. But that one, I was able to spend more time collecting recordings. They were all heterodyne there. It was possible to you know, get some differences between bats quite easily. So I was focused on getting the hearing better, you know, people's ability to listen better and rather than nowadays, it's you trust the technology that I was liked the idea of trusting the person. An example here is to use it talks. Oh. Look at that. Yeah, that's bits of information. But if I said, Look at the giraffe

Steve Roe: 10:25

out on a scrap piece of acetate with black printing on it's a circle about the size of CD, and inside the various random shapes, and I can't see any draughon that I Yeah. So

David King: 10:41

your ears will give you some information that you have to sort of your brain has to process. And it can do a lot more than you think it can. And that's kind of an optical illusion. But as soon as I mentioned, giraffes, some people say oh, yes, of course. Because you put together the bits in your brain fills in the gaps.

Steve Roe: 11:07

That's amazing. I was going to ask about just going back to the battery is Yeah, you think about it now. And it was a hands free bat detector, which is free ecologists. And that work is great. Yeah. Why? Why did hands free never catch on? Because they just don't make them anymore? Do they? Nobody's done anything. So

David King: 11:24

I found them an economical it was. I really did it for the love of it. And because I wanted a bat detector that where I could carry a torch and not trip over in the dark. The I had to buy headphones from Sennheiser. And they were pretty expensive. I still Yeah, they were they had to be comfortable because you'd be walking around for hours, these things on, and they had to be light. So I couldn't get any old pair. And they weren't cheap ones available. But I chose the Sennheiser ones for the best quality. But modifying those wasn't economical, really. And so I couldn't sell them at a price that people would say, oh, that's reasonable. And it's just a question of scale again.

Steve Roe: 12:13

So you've honed down that box three, which is still the only detector I actually own is my first bat stack. So when I got into that to the age of 12, use lots of others through work and through the back group. And it's a fantastic little detector. When then did the technology frequency different division come out? And when did the really popular detach with the Dirac come about them? I

David King: 12:34

was persuaded by Colin Catto from BCT. To make a frequency division detector, I thought well, why not incorporate hips nine as well. And so put one channel frequency division one channel heterodyne. And it came out quite well. So that became the duet. The backbox three was better at heterodyne because it had a massive speaker in there. And it was you could run groups of people. I've got letters from people saying I had two or 300 people in my back walk and only one detector. It was about books three, but they could all hear it you see. So that was very good for walks and talks and things. But for closers study people needed to record frequency division so they could look at the thing and actually evidence the fact that they'd seen a 45 Pip. Because with a recording, because if you've tuned into about detecting you've got no way of registering where you're tuned in. So you could say well, that's a 45 kilohertz pitch, we can say it's a 55 It couldn't prove it. But with frequency division, however crude it was, you could say you could show a sonogram of the different pitches. So that was the first time people could prove what they saw. And it started being adopted by more professional bat interest people.

Steve Roe: 14:07

And was that overall before you sold stock electronics? Was that the most popular detector that you're making at the time?

David King: 14:15

Yeah, it was the stagger looked electronics evolved into backbox. Limited. Later on, I thought well, I can't call it stag electronics if I'm not in St. tagless. So when I moved to Sussex who became backbox limited, same detectors we were carried on selling the black box threes, I think must have been 10 or 12,000 of those worldwide and they used to go to every corner of the planet really. I was constantly surprised by how many how many people from remote places heard about it and asked about it but Get the blackbox three, then was replaced by the duet or not replaced, I kept them alongside one another for a little while then then stop the three. The duet came out. Then somebody said, Well, after doing lots of bat walks, somebody said, Why don't you produce one for children. So I produced the micro bat, which was based on the same technology as the bat is where you could just switch from one centre frequency to another, which made it easy. And then you didn't get people breaking off the tuning knobs, which they did on bat walks. And it was more of my own. I didn't, although I was earning a living doing it. I was more interested in doing it for the benefit of the people that were interested in bats. And most of my own survey work because I started surveying at 990. Really, I was first licenced in 89. I got some Bob Stebbings correspondence here. This is when he first saw the bat box three. And

Steve Roe: 16:13

like say, he says, I saw the instruments at Liverpool. So they really were flying around the country about them when they at the moment I have all of the bat detectors I need, including the new mini two, and stress that will be getting reviewed by experts. It's really nice to see all this history here, isn't it? So I

David King: 16:30

think I must have sent him one to look at. Because he did ask to review one. He was kind of the guru at the time. So I I was quite keen on his opinion of it. And there we are. There's a letter from Phil, who talks about the QM C's Well, QM C stands for Queen Mary College. Pi Professor Pi was building them the the famous professor pi, because before that they were all huge, great devices that you had to close down somewhere. Hold gates and things like that.

Steve Roe: 17:09

Go Yeah, I was gonna say we've last series, we went over to the British Library. They've got an exhibition out at the moment. And part of it is Batson. They've got Holgate on display. It's a massive thing. This is really interesting. So this review from Phil is saying the latest QM C mini Scott's a transparent purse best disc with all the frequencies printed on that rotates over small elite led and this is where he suggested replacing the black twist knob with a combined disc which is the version I've written this BB three I've got here has a transit a small transparent desk with all the frequencies printed on ingeniously

David King: 17:48

you can think feel for that.

Steve Roe: 17:50

Yeah, we use those minis in douche bag away quite a lot for backlogs and they went down really well. It was dead easy to say switch between the red, the red, I have the notch on the green light to the pitch light. It was really simple. microbots on the micro batch. Really simple design. Yeah. Yeah, they went down really well.

David King: 18:08

I was gonna say, because when you do bat walks, you have to introduce people who've never heard about before, to what they sound like and what they do. And the kind of detectors that are around now are more focused on recording and not producing a sound for people to listen to, like,

Steve Roe: 18:31

like you say the technology is moving on that it's all based on a visual cue. What, what's your view of that? And does it matter that we're going to lose that field skill over time?

David King: 18:43

Well, my view is that we, we shouldn't lose that skill. Because it comes along with other things, the cheers of bats and things like that. So if you rely totally on technology, you're you're as vulnerable as the battery. Basically, if your battery went flat, you're not a surveyor anymore. So just somebody's looking at black things coming out of a race. But you can identify a lot of bats by ear with heterodyne and even time expansion. But you can identify bats quite easily with that, because you hear frequency division in one year. And immediately after that time expanded episode. And I could go around and recognise a lot of species apart from some of the migratory species and of course, just just with time expansion, because you do get your ear in and you can hear the difference between four and a half kilohertz and five and a half kilohertz by ear quite easily.

Steve Roe: 19:54

So what's your view of the current batch set to market them?

David King: 19:57

Well, I hope it gets better. I think the sound quality has gone down, you know, because people are more interested in the the visual experience afterwards and in the office or whatever. Or even worse than that. They're interested in what the computer tells you.

Steve Roe: 20:16

That I mean, it's always a contentious question, what is your view of auto ID, then?

David King: 20:21

Well, it's getting there, it's a little bit better I use it myself for where I'm teetering between one or another species. I think, well, I'll run it through this and see what they think. Yeah. And because they're drawing on lots and lots and lots of increasingly more examples now, coming down with decisions between pecota sororitas and Curtis austrack. Yes, and those are the things I think I'm a bit sceptical about, you know, I can't believe that there is a clear cut. And you see on the screen, it says, one minute, it's Lakota authorities. And the next call is awestruck. Yes. And you think well, if they're able to overlap like that, it's going to be difficult. So for running through a whole 1000 files, is going to give you a pretty good idea of what's the

Steve Roe: 21:19

what's your favourite bat call or bat encounter when you've been recording bats over the years if you've got a favourite memory.

David King: 21:28

There are so many of them. Yeah. The one of my favourites was, I stopped at a petrol disused petrol station in corn on the way to Cornwall, and I could see Sarah teens catching me bugs just in the canopy. And so I stopped and got the detector out. They weren't deterred at all by that. And watch them really close catching these may bugs, you could see the Beetle in the mouth as they flew off because they came out quite early to catch these. And that stuck in my head because it was quite an experience. It was like a display, especially for us, which we just sat there and watch them doing this. Really close quarters, I suppose in Africa, in the Kruger National Park, we caught some giant horseshoe bats. We had a look at them as well. This was early on and I had the backbox three there. So we were able to hear what they sounded like. And they were echolocating. At some distance, you couldn't pick them up with the with the backbox. Three, but that was a very sensitive detector. Anyway, that one. Yeah. I used to test it in the early days, but by dropping a pin up the path and a garden. And you could hear it right by the back door.

Steve Roe: 22:56

I remember on a field trip a man to graduate degree we went to Borneo for a couple of weeks and took this detector out with me. And it was still shooting to fortify for UK. pipistrelles and switch this detector on and within seconds could hear a horseshoe. And it was that was like

David King: 23:14

Oh, which which horse he was, I don't

Steve Roe: 23:16

know I need to go. I've never looked at the book I need to kind of look I can't remember and didn't know at the time. But it's quite a few out there seem to remember. Luckily,

David King: 23:25

in Britain, if you're making a bat tape, it's easy, because we've only got a few species. But you go somewhere like Africa and or the tropics recently went to Costa Rica. And there are so many bats there. I'd have no idea what they were listening for them. I

Steve Roe: 23:46

mean, that bat tape and CD did the bat detective, again, got a copy of that. And that's how I learned back calls. And you did and like you say it was about the sound and listening to the rhythm and the tonal quality that's an that was really useful for me when Brian come into the story.

David King: 24:05

Brian and I used to do talks and early back detector workshops in the 90s, early 90s. And I talked about the detectors and he talked about the biology etc. And we then we go out and do listening. So that's how I got to meet Brian

Steve Roe: 24:24

making bad sectors then and and your background as a musician has taken you all over the place. Really I guess you've specialised in handheld devices technology now means that we've got static remote recording detectors that go out and record 1000s and 1000s of backdoors. How do you deal with the storage of backhauls at the moment?

David King: 24:42

I don't collect them anymore because they're, you know, I haven't got that many years left in my life to look through them all. I mean, it's like my record collection. I've got CDs, music CDs, so many of them And I think that, you know, even if I sat down now and listened for the rest of my life, I wouldn't get through them. Yeah. So you've got to prioritise. And so I don't, I don't I don't collect calls anymore, except if they're special, you know, if it's something really unusual, we're currently

Steve Roe: 25:19

seem to be in an era of night vision, thermal, and AI is the hot topic of the moment. technology's changing at such pace. How do you think that's going to influence how surveys for bats are done? And we're just going to become technicians as these technologies put up a barrier and put up a barrier between us and the bats? I guess? Yeah,

David King: 25:39

well, they already, surveyors are dividing into two types, really, you get the type that the ecologists that are interested in the biology in the, in the, the actual animals, and you've got the professionals that just want to do the job, you know, just find out how many bats are there and what species they are and, and what they have to do. So you can approach it either way. But I prefer the first because you actually experience more. But you can be sat in front of a computer all day. Otherwise, I've put back detecting in, in to perspective now because I do so many other things. In France now. And that detecting is just one of the things but I'm pleased when people come and say, Oh, tell me about the bats and they can talk about them.

Steve Roe: 26:36

Okay, we haven't even touched on the fact that you've got house over in France and you go there all the time. What sort of stuff you got over in your garden there.

David King: 26:43

We've had up to 11 species going through the garage alone. Great horses greater mouse heated, less a horseshoes, long pluck Otis orators and austrack es Jeff Roy's three three kinds of pips, but they don't have the soprano where we are Barbra styles sells quite common. Yeah, that's with the bats. But other creatures. We we've had a black stork in the field next door. Golden Orioles. Regular hoopoes. That's right. Turtle there. turtledoves. Owls, all sorts of owls, badgers foxes. And we've got Ragon down in the river at the bottom of the garden. So we do get to see a lot of stuff there. And every time we go, we think wow, look at that moth. Giant emperor. And, and we get 1000s of moths. 1000s. But I love it there. It's like It's like England that it's in Normandy, but it's it's got a lot more wildlife a lot more insects.

Steve Roe: 28:05

One final question I have, why are bat detectors always in black cases make them really hard to see why did no one ever make something that was in a different colour? Is it just what was available at the time?

David King: 28:17

No. Well, when you sell a detector, you sell it in the daytime. And, and all that all the sophisticated equipment was black in those days.

Steve Roe: 28:30

It's been fascinating talk to you, David became Thank you very much.

David King: 28:33

You're welcome.

Steve Roe: 28:36

A huge thanks to David for taking the time to give us that fascinating history and insights. And David, if you're listening that bottle of French wine you sent me away with was delicious. We've put a link in the show notes to the BakBox detectors website as well as the detector advice pages on our own website. So if you'd like to find out more, check out the links. We'll be back in two weeks time with the landowner of the largest number of bat roofs in the country. Catch them