The Hoffman Kiln: Where Bats Reclaim the Dales

North of Settle in the Yorkshire Dales lies the Hoffman Kiln, a relic of the industrial revolution. It's now an important site for bats of the Dales all year round. In this episode we chat to Dave Anderson and Dave Fisher who on Friday afternoons, in a term they've coined as Fieldwork Fridays, they spend 90 minutes surveying the kiln for bats. And they've racked up an impressive collection of data in studying bat behaviour such as crevice fidelity. We also address the challenge of balancing public interest with conservation efforts, emphasising the importance of educating visitors about the bats’ presence.

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Discover more about the Hoffman Kiln

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Chapters

• 0:04 The Hoffman Kiln: A Bat Haven
• 0:35 Journey to the Yorkshire Dales
• 1:34 Meet the Bat Ecologists
• 5:32 The Importance of Data Collection
• 8:16 Understanding Bat Behavior
• 11:35 Challenges of Public Engagement
• 14:26 Balancing Conservation and Tourism
• 15:43 Insights on Bat Species
• 17:43 The Mystery of Swarming
• 23:00 Internal Surveying Techniques
• 24:47 Future Research Directions
• 30:15 The Resilience of Natteras
• 34:59 Rediscovering the Lesser Horseshoe
• 35:54 The Legacy of Bat Research
• 42:06 Reflections on the Kiln Experience
• 42:29 Final Observations and Updates

Transcript

[0:04]
The Hoffman Kiln: A Bat Haven
Steve Roe
[0:00]Picture stepping inside a vast vaulted tunnel carved from brick and stone. The gentle echo of your footsteps, the faint mustiness of damp stone, arches receding into dim light, and overhead the low curve of the vaulted roof. That's the scene inside the Hoffman Kiln in the Yorkshire Dales. This isn't just a relic, it's one of the best-preserved lime-burning kilns in the country, and you're about to find out why it's also an important site for bats, in this episode of Bat Chat. Bat Chat.
[0:35]
Journey to the Yorkshire Dales
Steve Roe
[0:36]Welcome to another episode of this brand new series of the Bat Conservation Trust's award-winning podcast, Bat Chat. I'm Steve Rowe, your host, and this is the third episode of Series 7, which means from now until the spring of 2026, a new episode is being released every other Wednesday. Last time we were in the Brecon Beacons with the Vincent Wildlife Trust, and this week we're in another of our national parks, the Yorkshire Dales. In June last year, I made the journey up to the Dales to meet a couple of bat ecologists who have been visiting this site on a weekly basis to try and understand how bats are using this large lime kiln. So let's travel to the road heading north out of Settle. Close to the River Ribble, we take a turn right and drive behind some industrial units before coming into a public car park. The kiln looms on the hill in front of us, covered in yellow hawkweed, making the kiln look as though it's been draped in sunlight, even though it's a cloudy day. The flowers cling to every crevice and ledge, blurring the kiln's hard edges and softening its industrial geometry.
[1:34]
Meet the Bat Ecologists
Steve Roe
[1:35]Inside we find Dave Anderson and Dave Fisher who are here to tell us more about the work that they've been carrying out.
Dave Anderson
[1:44]Okay so i'm dave anderson i'm a former museum curator and now freelance ecologist and between me and dave we run what we decided to call the yorkshire dales back project which is kind of an evolution really from when we were involved and ran the east lancashire back group and did a lot of work up in um particularly in the forest of bowland it's that's the work that kind of influenced where we are today.
Dave Fisher
[2:10]I'm dave fisher i'm sort of semi-retired now but um you know it takes bats take me out most days i think um i still do a bit of consultancy which i've done for 15 20 years but i got involved with this place about it was about 2008 um we were dave and i were working in bowling together fridays it was always a friday afternoon wasn't it so we called it a field work Friday and we started exploring all the lime kilns in the Forest of Boland and we found, we were looking at maps, we were going through historic records, I think we found 100 and
Dave Fisher
[2:51]I was sort of serious at trying to see how many were sort of still existing, because we were finding the odd bat in some of the kilns. One kiln we found in particular, sugarloaf, it was really attractive to bats, whereas normally you'd find one or two. This particular kiln, small field kiln, very, very small, like sort of porch size, we were finding 20 or 30 natteras bats in the autumn. This project has sort of evolved from from boland and we started looking at lime kilns on the edge of the yorkshire dales and so on i think there's about 800 in the yorkshire dales 800 kilns but this one kiln sort of has it all and it's got bats all year round so that's that's where my interest came in and we for the last five years we've been coming here fairly intensively as
Dave Anderson
[3:43]You say really the other the other thing about this is that the kiln has some history because it It was a study site for Leeds University when they were doing a lot of, when John Altercombe had his study group. The whole idea, the whole concept of the Yorkshire Dales BAT project sort of came out from a meeting myself and Dave had with Anita Glover when she was still at Leeds University. Because she kind of realised that, you know, there was a lot of overlap in what we were doing in Boland to what needed to be done in the Yorkshire Dales. And there's a lot of similarities between the two areas. The forest of Boland really is almost like an extension of the Yorkshire Dales to an extent apart from it's in lancashire it'll probably upset a lot of lancastrians to say that but landscape wise it's very similar it's got underground sites and and like dave says it had these field kilns so we had a we had a pub meeting with anita where we came up with a plan for how we'd run a back project in the yorkshire dales and then almost unfortunately anita got the job down at vincent wildlife trust and disappear but we carried on so the yorkshire dales is a bit unusual as a national park because it's within the county of North Yorkshire.
Dave Anderson
[4:54]The majority of north yorkshire bat group really are located you know north yorkshire is a massive county and a lot of the people who are involved in the bat group are located sort of york and and sort of over to the east and west yorkshire have always had a little bit of sort of nibbling into this area from back here it's right on on the border of east lancashire as well and surprisingly it's been quite understudied apart from you know there's all this groundwork and this amazing work that that Leeds University did and then nothing afterwards so we've got a national park that's.
[5:32]
The Importance of Data Collection
Dave Anderson
[5:33]Area in in britain it's got the most underground sites of a national park and yet there's no one there was no one looking at it and that's really really attractive obviously if you're interested in bats and interested in hibernation and swarming so that's why we uh we sort of upped up sticks and.
Dave Fisher
[5:53]Moved over i mean you could say it's data deficient there was nothing here really was there i think uh the university they they had about 10 10 bats that they trapped here and rained and that was about it wasn't it yeah um but what we did we started going into caves as well didn't we we're doing a lot of caves and looking at lead mines grassington area yeah and we've again you're doing a lot of leg work it can take a whole day just to walk to some of the mines which are you know four or five hundred meters up on the hills um and you're spending a huge amount of time for with small results. So that's another reason why the Hoffman kiln was just so good, because we can get here, we can both get here in three quarters of an hour. We can survey in an hour and a half. We've got a standardised way of checking it, and it doesn't matter what the weather is. So it's the absolute perfect all year round survey site.
Dave Anderson
[6:48]And the other thing is it kind of follows on from Dave, Dave has mentioned Sugarloaf kiln in particular, where we saw these groupings of bats coming in. But it was very hard to record where they were. We had an idea, an inkling, that the same crevices were used time and time again by the same bats, but we didn't have an easy way of measuring it there. The good thing about the Hoffman Kiln, because it's a man-made structure, is that it's very regular. It's a huge structure, so it's 244 metres long. There's plenty of doorways in where people used to load the interior with limestone and coal to get these fires going and rocks to produce the lime and the fuel tubes in in the roof are just perfect sized areas for bats going to really they're about 125 millimeters in diameter and they vary in their depth from maybe 10 centimeters to to beyond a meter deep so there's there's you know there's up to um six in a row and there's 101 rows of them around the kiln all together so it was obvious with this site that we could number those rows we could label the tubes you know from the outside to the inside and we had an easy measurable way of seeing exactly where the bats were and what they were doing here and what's interesting is that we've found that there is a pattern of behavior.
[8:16]
Understanding Bat Behavior
Dave Anderson
[8:17]Where some tubes are used far more regularly some tubes aren't used at all we've got five years of data now that's showing these patterns up really well and we think it's probably one of the few swarming sites where we can actually see what's happening inside where you know the majority of research that gets done on swarming sites you put a heart trap up at the entrance way and you're catching bats that are coming and going either going into this site or coming out of it whereas here we can actually see what they're doing inside which is uh which got to be fairly unique i mean we can't do it in any of the caves that we go to they're so vast you know there's such vast systems the lead mines we're looking at some of them have five kilometers of tunnels.
Dave Anderson
[8:59]And they're not all accessible because where you get stopes that go up into the, into the roof of the system they're just inaccessible they can be sort of 20 meters 30 meters high and you can't record necessarily what bats are doing in there but here we've just got this like beautiful setup where it's very easy to to survey record what's going on and we're very lucky as well that i mean there wasn't a lot of ringing done here originally but the ringing that happened in sort of 2003 to 2006 we're still getting bats from that ringing turning up today which is really interesting so we know we know for certain that we've got one individual that comes that's 21 years old at least because it wasn't a juvenile when it was caught so and it's always found in the exact same location and it's always found just with one of the bat it doesn't visit anywhere else in in the system which is really interesting you've got this amazing well we've stolen the term from a German researcher, it crevice fidelity so they're they're incredibly loyal to these locations and the interesting thing now is trying to work out why what's going on.
Steve Roe
[10:09]When you invited me up and you said kiln that's sort of where i come from kilns are tiny things this is not that this is a huge structure um you know if i put my arms above my head you can't touch the ceiling but it's it looks still fairly intact has there been much management of this from like historic society to try and keep it intact and obviously visitors are going around today is you know how many visitors does it get on a daily basis you know well
Dave Fisher
[10:32]It's an archaeological site i would think it's getting it's getting a lot more visitors than it used to four or five years ago because we've you'll notice as we walked along there's a new development here new offices craven district council developed that site so and and then a sign came up on the road said hoffman kiln so that's highlighted the whole place because We were coming here 40 years ago, and I used to just drive right by. I had no idea this kiln existed, and very few people do. Then the Yorkshire Dales started highlighting it, putting it in the newsletters, and they started having archaeological walks around the site. So it's raised its profile quite a bit. We're now in a bit of a tricky area, aren't we? Because they want to promote the office spaces here and the workshops.
Dave Fisher
[11:26]They've also been talking about, with Yorkshire Dales National Park,
[11:35]
Challenges of Public Engagement
Dave Fisher
[11:30]the possibility of bringing more visitors in, possibly even having a cafe. So it's going to highlight the whole place even more. Uh last year i was doing some we were doing some monitoring of the old buildings the old warehouses before they pulled them down uh looking at mitigation and so on i was coming into the kiln here and i one day i brought some councillors in well one of the councillors he just thought it was a great idea we'll just put lighting all the way through here you know interpretation boards he just thought this was a fantastic opportunity he'd never been here before so we took him and we showed him just one of the tubes. I think it had about 24, 25 naturas in there. He said, we could do, you know, we can open this up to the public. They can see the wildlife and so on. So we told them, you know, this is, it's gotta be well thought out. We still haven't got a lot of baseline data. Craven Council now has been absorbed by- North Yorkshire. North Yorkshire Council. So they've had big changes and it's a much bigger authority.
Dave Fisher
[12:35]But they've just applied for a grant, I think, for 365,000 to develop the potential for public recreation here, public access, tourist trails and so on. So we're in a really interesting period with possible change on the doorstep. What are they going to do with a kiln like this? At the moment, you may get a couple of dozen people during the daytime. School holidays we've found a few more events people bringing kids in here because halloween is a good place to bring kids here and so on but really it's still fairly unknown by by most people i would think in the yorkshire dales it's not directly on the tourist trail just yet is it no
Dave Anderson
[13:17]It's very low key there's a there's a popular footpath that runs past the hoffman for people who are sort of staying further up towards sort of Horton in Ribblesdale. There's a loop that you can do that walks down to settle and back up again. And you get people who are on that walk sort of popping in. But like Dave says, it's very low key, very low. There is a level of disturbance at the moment, obviously with people walking through, but it seems to be tolerated by the bats there's a balance at the moment and yeah the challenge we've got is to how to balance that in the future so that we keep this sort of site and and you know, the importance of it while allowing people to come and sort of exp i mean it's you know it's a an amazing visitor experience to come in it's you know it's very dramatic it's part of the attraction of coming here you know besides knowing what else is going on backwise it's it is a beautiful place to visit as a structure but yeah the challenge will be to sort of keep that balance of the two.
[14:26]
Balancing Conservation and Tourism
Steve Roe
[14:27]But it is really nice to hear you both talk about the challenges and it being
Dave Anderson
[14:30]You know an.
Steve Roe
[14:31]Interesting proper position rather than saying oh my god we can't do this you know clearly you understand that there is a need for the public to want to see this as they should because it's an archaeologically interesting sight just give us an idea then of potentially what disturbance could take place how many bats are we talking and of what species well
Dave Fisher
[14:48]We've got two main two key species that are here naturis are the most obvious and dolbentons we also get from time to time pipistrels but it's it's very sporadic isn't it and long-eared bats this year has been really curious because we haven't had a long-eared bat all year. I think the last long-eared bat was probably November. We've got the tunnel outside and we found long-eareds in there. There are also three triple kilns about 100 yards from here and long-eareds go in there. But curiously this year, nothing at all. So it's really the myotis that specialise. Occasionally we've had brants. And occasionally, very occasionally, we've had whiskered as well. That's about it, isn't it? So they're the key species.
[15:43]
Insights on Bat Species
Dave Anderson
[15:44]Yeah, the interesting thing really is what's, I don't know if it's the same in sort of your area, is that we've seen a real drop in long-eats in hibernation sites this winter because we suspect because it's so mild, they just haven't been interested in coming in at all. It seems to take quite a sustained period of cold, freezing weather before they'll bother to come in to hibernate within this structure.
Dave Fisher
[16:11]In terms of how many bats, a good day would be 20 or 30 bats that we can see. So we've got these tubes on the roof. We've got 462 of them. We can check them all, like I say, within an hour and a quarter, hour and a half. We can just put a light on very, very quickly and scan them. Today, we'd probably, if we checked every hole, we'd probably find about 15, 14, 15, 16 bats. Which is pretty regular at this time of the year the best time would be autumn when the numbers go up we get some clusters then of 20 possibly 25 30 bats um so it's that sort of that sort of number that you'd expect
Dave Anderson
[16:54]It's difficult to estimate how big the population is because obviously there's different you've got different things happening in here there's well do we use the word resident there are bats that are resident within here and then there are bats that are in and going all the time i always try and describe it as the the kiln's in almost a constant state of flux no matter which season it is so even in hibernation season bats are coming and going all the time here some are resident but others are just choosing to they'll they'll come in and use the tube for a couple of weeks sometimes like six weeks and then suddenly they'll disappear for a couple of weeks and then they'll be back again in the same location again the number of bats kind of follows what you'd expect so there's an increase in bats in autumn as swarming happens yeah.
[17:43]
The Mystery of Swarming
Steve Roe
[17:43]Now i'm going to interrupt here because the term swarming or autumn swarming is used a number of times in this episode some of our uk bat species have a specific mating strategy in a phenomenon known as autumn swarming it happens in and around the entrance to some underground sites where bats also hibernate in the winter, but it takes place late after sunset during the autumn months and Dave explains what it is in more detail.
Dave Anderson
[18:07]So I'll use the one that I use with the visitors there. So this site's very much like the nightclubs in skipton in that um young young male bats, arrive here from all over the district possibly up to 70 kilometers away judging by previous uh research again by by leeds uni so it's calling bats in from 70 kilometers away from lots of disparate roosts and populations they fly in the woodland at the back of the kiln possibly using the cliff face as well and then we were really lucky last year that we saw the end result of that courtship where a pair of bats we watched them through thermal cameras fly back into the system back into the kiln system go into a tube and begin mating so yeah i think it i think it's a first sort of voyeuristic a voyeuristic first if ever there was one we actually managed to document and the natter is returning and mating within the tubes.
Steve Roe
[19:13]Right, let's get back to it.
Dave Anderson
[19:17]We get these clusters of bats coming in to use the same tube which is unusual most of the time there'll be like individual bats in in in the fuel tubes but in in autumn as you'd expect you suddenly get these clusters of of of bats and where we've managed the beauty the other beautiful thing i should mention is that um from a research point of view it's very easy to isolate a tube with a hand net yeah with decorator poles we tend to use so that we can like we can basically block one off and we can catch the bats as if they emerge from the tube um and the ones that we've we've caught in the past have all been young of year so that's an interesting thing that we're noticing and it mirrors research that was done in i think it was newfoundland with little brown bats which are other myotis species where there seems to be a mechanism where the young of the year are brought here and then they dis what we suspect is that they then disperse within the system, and that's a pattern that we're seeing the other thing that we've noticed the last couple of years probably is there seems to be smaller clusters in spring and add almost.
Dave Anderson
[20:32]Do we want to do we want to say it it looks as if there's a very strong indication that in natteras there's potential for spring swarming as well i'd say because that's what we're seeing within the system it's definitely not bats i know from research that's been done in south wales there was a suggestion that you get that increase of activity because bats are leaving the hibernations but we're not seeing that here what we're seeing is bats arriving into the system in spring and then again the numbers drop again so in late april early may there was an increase in naturas and then it dropped and then it's it unusually it's it seems to be higher than previous years at the moment and.
Steve Roe
[21:17]You get are you doing that through trapping surveys you're just noticing that through the visual
Dave Anderson
[21:21]Stuff that's just through visual that's just literally through um yeah walking around with a torch counting bats in in in the system yeah um i.
Dave Fisher
[21:30]Was gonna say in terms of disturbance um i think most people that come in here that they really wonder what we're up to sometimes don't they we just sort of you know and say what are you looking at they think we're just looking at the architecture um so most people are surprised at bats but i think the majority just wander through and have no idea that bats are here it's only maybe in june time when you've got 20 or 30 in a tube there's lots of droppings on the floor which the children can see and uh and you can hear them as well but for the
Dave Anderson
[22:00]Most part.
Dave Fisher
[22:00]I don't think bats really are getting a great level of disturbance
Dave Anderson
[22:04]And the other thing really is i mean we're we're probably the most disturbing factor in in the counts that we're doing well yeah but but from from using infrared, and then comparing it to using you know hand torches, doesn't appear to be any disturbance but i think partly that's because we're quick when we do it we rely on photo photography a lot we've got cameras you know i've got a camera just for surveying this site basically so it's set ready so where we get numbers of bats in a tube we can just take a quick photo and then we'll do all our identification and and and counting from that afterwards so the impact of our of our surveying doesn't seem to have an impact on on the bats there's no sort of desertion of tubes after they've had a light shone on them and especially at this time of year they're quite active anyway you're not bringing them out at all but there's no evidence for that at all.
[23:00]
Internal Surveying Techniques
Steve Roe
[23:00]And are you guys doing any trapping for Swarman or is it just the internal stuff that you guys are doing?
Dave Anderson
[23:04]With this site it's purely internal because we wanted to try and answer the question about crevice fidelity basically, about what was going on inside the system. The problem here for trapping is there's so many entrances it would be difficult to select it. It kind of shows in that Leeds never had a return from their ring bats here when they were harp trapping. But we've probably got 20 returns from from one bat and we suspect this there's at least, two other ring bats that come in that we haven't managed to read the rings on yet one's got a very distinct bent he's got like a kink in the ring so we know that it isn't the other bat and then there's another bat that's turned up when our knowns individual is in so we we know there's at least three that are still coming back and.
Steve Roe
[23:55]Those ring bats do you know where they've originated from where they were originally
Dave Anderson
[23:59]Ringed they were ringed here okay yeah well at least the one that we've identified so far was ringed here yeah it was one of john's john altergan's rings.
Steve Roe
[24:07]So pretty faithful to the site then so it just shows the importance of the conservation of these types of sites doesn't it
Dave Anderson
[24:13]Yeah i mean beyond faithful to the kiln is faithful to one tube yeah we've just never recorded him anywhere else which is which is the really interesting thing, I mean, it kind of hints at the idea that they've got a defined territory that they use for breeding and the bat doesn't just come during the swarming season, which is the other important thing to mention. It comes throughout the year, it's constantly coming and checking that location, spending a couple of days here, disappearing off out to wherever again.
[24:47]
Future Research Directions
Steve Roe
[24:44]So you've collected a large amount of data already, where do you go from here? What are the next steps for you guys?
Dave Fisher
[24:51]We have got a lot of data now.
Dave Anderson
[24:53]We've got a lot of data on what we've got. What we'd like to do next is a combination of two things. One would be to do DNA analysis, to look at how related the bats are to each other and potentially link them to maternity sites. I know that Central Science Labs, James Agatha's done work on that, so that would be an interesting thing to look at here. And the other thing would be to do a ringing scheme. Because we get so much data. i mean we haven't we haven't done any ringing here at all but the data that we're getting from that you know 2003 episode has been invaluable and we can only add to that now really yeah yeah when.
Dave Fisher
[25:34]We check the caves and mines the key species are still the naturas and the door bentons aren't they yeah and on higher ground the brants
Dave Anderson
[25:42]Yeah i mean that's that's another really interesting to point out actually is that all the brants hibernation sites that we found in the yorkshire are above 400 metres. In altitude and they all seem to be quite remote lead mines that they're choosing to hibernate in yeah so that yeah and.
Steve Roe
[26:00]You mentioned the term crevice that
Dave Anderson
[26:02]You got there.
Steve Roe
[26:04]Do we know if there's anybody else in the uk looking at the same sort of stuff as that or is it just you guys
Dave Anderson
[26:08]I think it's just us at the moment we've not heard of anyone else because it was quite a new concept it was a conversation on mastodon funnily enough where i think i was chatting to john alteringham about about what we're finding and then yeah one of his followers jumped in he's looking at it in i think mainly mouse ear bats in germany but yeah i'm quite looking forward to seeing what his research shows so we've got a contact there so keep sharing information.
Dave Fisher
[26:34]We've thrown at quite a few sites haven't we that are just really quite interesting there's another one in bowland we've got a little cave it's only 30 meters long gets six to seven six or seven species of bats in there yeah again it's roost fidelity that we we've it's on private land so we've got access to it uh it doesn't get a lot of low level of disturbance so we can mark where all the crevices are can't we yeah and time and time again they're using exactly the same feeding perches exactly the same crevices for for roosting and i've got to mention it now and that and we found the lesser horseshoe back there uh it was about 2006 wasn't it yeah we haven't seen it since 2012 uh but it's again it's just one of those sites that we i visited it about 200 200 odd times and we've probably had the lesser horseshoe to 15, 20 times maximum over the 20 years. But again, it's just one of those sites. Have you got time to visit? They're only we're a very small team and we've you've just got to maximize your efforts haven't you
Dave Anderson
[27:47]But but those efforts are rewarded i mean that's the thing that you know it's all i always try and bang on about is that it's what first got me started in bats when i when i was a museum curator we used to run all sorts of public events because you know most of your collections are, stored away ten percent if you look is out on display so we used to spend weekends getting all the moth collections out and then five individuals had come in who were massively interested in moths and you'd get some a few families wandering through and then in the year it was the year that the big bat night came out we said we'll we'll run a we'll run a bat walk because we were we were lucky that we were in a big um park on the edge of town we had woodland ponds the works so yeah we'll we'll run a bat walk so we ordered two sky instruments bat detectors that's how long ago it was and we i think it went in the local paper and on the night we had 200 people turn up for the first bat walk and i was amazed and it was just like there's this massive interest in something that no one really has an idea about because you can't hear them so you don't know they're there, So I thought, all right, I'll see what species are known in East Lancashire, because we were the biological records centre for East Lancashire.
Dave Anderson
[29:11]And there was a blank map. There was no idea of what species were there. And that's what fired up that interest to start off with, is there's a question there and it needs answering. And then everything that we've done since then is the same, really. And the interesting thing with bats is that there's a lot of assumed knowledge about them. If you read books about hibernation it'll tell you you know the majority of things that you read if you go onto the website or google search on how bats hibernate it'll tell you that they hibernate in they go into hibernation in late october november and they emerge again in march and people have this idea that the bats spend the whole winter occasionally waking up to drink and to urinate but they're in one place all winter and what you find when you actually you know do to do a study like we've been lucky to do here, where we can visit every week, is that very few bats do that. There are a few individuals that spend the full winter in here, but the majority of them are coming and going. And I think Natteras in particular.
[30:15]
The Resilience of Natteras
Dave Anderson
[30:15]They're quite a tough little and controversially i'll say this again upland bat we find them in a lot of upland sites here and if they get an opportunity to feed through the winter if you get mild nights they'll be out and they'll feed because there's plenty of insects there for them still to feed on and then they'll come back in and we suspect if they've had a really good autumn and they've put on enough brown fat then they'll quite happily hibernate in one spot until that brown fat has gone they use up their fat storage if you've had a wet autumn like we have done for years they don't have the opportunities to put all that brown fat up on so they're out at every opportunity to feed or like the long ears they might just have milder winter sites where they can react better to the change in temperatures that seems to be what this site's telling us what our data is telling us and when.
Dave Fisher
[31:13]We come on consecutive days they've changed
Dave Anderson
[31:15]They've changed daily yeah except.
Dave Fisher
[31:18]For two or three that are there for two or three months at a time yeah we ought to go and have a look at one that we expect to see it there
Dave Anderson
[31:25]Today oh yeah yeah he's really interesting yeah we should definitely go and have a look i see 3b 3b.
Steve Roe
[31:29]Let's go have a look
Dave Anderson
[31:30]Yeah just.
Steve Roe
[31:31]While we're walking then just talk to people about the significance of that lesser horseshoe i know what that's significant why is it significant
Dave Fisher
[31:38]Well, I remember the day we went up there, I took a colleague. She was really interested in getting to know more about bats. I said, well, I'll take you up to the cave. We'll have a look around and you know what you're going to find. You're going to see long-eared natras and maybe adormentons. I said, well, you go in first. I'll just get my gear on. So she went in. I said, it's only a few yards long. She came out and said, there is a bat in there. It's just hanging free. I said, oh, that's interesting. she said it's got its wings wrapped around itself
Dave Anderson
[32:08]I said really uh because.
Dave Fisher
[32:11]We don't have lesser horseshoes in lancashire i think the last record we had in lancashire was probably 1920 1920s or 30s uh so i went in and there it was one lesser horseshoe just hanging freely 30th 30th of october
Dave Anderson
[32:30]2000.
Dave Fisher
[32:31]And did i say six or
Dave Anderson
[32:33]Seven yeah so.
Dave Fisher
[32:34]Um dave then started looking at some of the records for museums was it york museum you went
Dave Anderson
[32:41]To yeah so they were recorded in well i think that was when we first made contact with john altringham yeah we'd sort of talked to anita a bit about naturist but i got in touch and i was like i think this is probably quite significant that we found a lesser horseshoe is it an individual that just happens to have turned up you know it's been transported somehow to get here or could it be that there's been a remnant population from the north you know up until the second world war there were bats still found in the north of england so i started putting the feelers out to all the museums with collections that might have bats in them including natural history museum.
Dave Anderson
[33:22]And tracked down some individuals that had been collected in Helmsley and they were in York Museum collection and then we managed to get a sample from our lesser horseshoe in Boland and when the analysis was done it came back as a more ancestral lineage than sort of contemporary populations which was really interesting so then to try and balance to try and match that, i i had to um i had to ask museums about the possibility of what's called destructive sampling because effectively you want to take a museum specimen and take material from it and eventually we got permission to to get a sample from one of their helmsley uh lesser horseshoes which i went across and took a a tissue punch basically through it to try and get as much material try and get to get some organs if I could, it was a 1920 specimen.
Dave Anderson
[34:22]It was a slim chance and unfortunately when we sent it off we couldn't get any any dna to replicate out of it it was too old so we never proved that but it was one of the it's one of those tantalizing rabbit holes that we've we've left since then since then there was a disturbance event unfortunately at the cave and after that we didn't see the lesser horseshoe again although we had droppings that we collected in 2013 where they came back so you know it's still it's potentially there are still lesser horseshoes coming and going from that cave but yeah we've
[34:59]
Rediscovering the Lesser Horseshoe
Dave Anderson
[34:55]we've not gone back to revisit that one at this step at this stage we did have.
Dave Fisher
[34:59]A record from something like the 19th late 1940s for nidderdale as well
Dave Anderson
[35:04]Didn't yeah and.
Dave Fisher
[35:05]We checked some of the caves at steam gorge in that area
Dave Anderson
[35:07]Didn't we yeah that.
Dave Fisher
[35:09]Was the a remnant population yeah that hasn't been heard of for 90 years 80 90 years
Dave Anderson
[35:15]I mean the interesting thing is to see is with climate change whether they'll recolonise. I mean, you suspect that it was probably more habitat loss that affected them in the first place in the north of England, but there's still potential there. It's something that we still, We still keep an eye on, but we're not putting a lot more. We kind of came to the end of what we could learn, really. So we left that research and then became focused on this instead.
Steve Roe
[35:45]And at the time when you found that bat, where was the other known nearest record for Leicesters at the time? Can you remember?
Dave Anderson
[35:50]Yeah, it was North Wales. It caused quite a lot of questioning, shall we say.
[35:54]
The Legacy of Bat Research
Dave Anderson
[35:55]I can remember meeting a... I met a bat worker from the south of England on a training course it was on one of the roost visitor training for training courses who when I said where I was from I said I'm from the East Lancashire bat group he said oh they thought they had a lesser horseshoe didn't they I said it was really nice because I had my phone with me I said no no no no it look it was in my hand right I've got an in the hand record it did you know so I think a lot of people because it was so such an outlier from the population, just thought that we'd misidentified it. But yeah, you don't mistake one when you've got it in your hand really. It's a difficult species to confuse with anything else.
Steve Roe
[36:37]So we're stood underneath one of these fuel hole crevices.
Dave Anderson
[36:41]Still there? Yeah, is it? Yeah. So this is quite a conundrum. You can see in this, it's quite exposed. It's not actually in one of the fuel tubes. It's just wedged behind a flake of rock. A little natter is about just here. The interesting thing is it was here fairly solidly throughout winter, so we thought it was going to be a... We thought it was an unusual hibernation site then, because they do tend to tuck themselves into the tubes rather than be quite as exposed as that. It's a dead one to see that one. But then the surprise was it suddenly turned up again in May. So what's going on there? Why is a bat coming into what's quite a cold sight in May, when you're expecting it, that is a typical hibernation sight for this bat, and yet it's utilising it other times of the year as well? So there's something more going on here. So you can see it goes back away it's just about you can still just about make out the right the original before we started numbering them was this this was one mn and then the r is for ringed with an arrow and then the tube here this is 1a and this is he's not there today unfortunately but this is where y6147 one of john altringham's bats regularly turns up.
Steve Roe
[37:54]And all the tubes roughly the same depth of these about 30 40 centimeters do they
Dave Anderson
[37:59]They all vary yeah so the there seems to be a preference for tubes that have bricks wedged in them obviously because they create a little crevice but not always you know bats will just happily sit on the wall, of the of the fuel tube and they'll sit at different depths as well, We've done data logging, Tuts or USB data loggers in all the way around, and there doesn't seem to be any variance in the conditions, so it doesn't seem to be that that they're choosing.
Dave Fisher
[38:31]Except this is a darker side.
Dave Anderson
[38:33]Yes.
Dave Fisher
[38:33]And it's probably about one degree cooler here than on the west side.
Dave Anderson
[38:37]So, yeah, the other thing to notice is the doorways at this end of the kiln, a lot of them have been bricked up, or were not opened again, we should say, because in the 90s a lot of these doorways were bricked up and there was less access and then it was it was opened up the interesting thing is the very bottom the sort of northernmost, point on the kiln is predominantly bricked up which fits with everything that someone will tell you bats need for hibernation right if you're going to create a hibernation site oh yeah, everyone says it about railways ones yeah brick them right up leave a little vent at the top that's what's happening down here it's the least populated part of the kiln the bats predominantly seem to like this east side of the kiln which is darker potentially, it's a little bit more stable slightly and.
Dave Fisher
[39:33]The northwest side the weather scene comes in on the yeah the northwest
Dave Anderson
[39:37]Yeah and they definitely select that side so the it is warm yeah they're They're either choosing somewhere that's very stable or they're choosing somewhere where they can respond much quicker to where the temperature change is happening.
Dave Fisher
[39:51]There's a door bentons here. This was here yesterday. So we've got all that we've got the 460 tubes, but we've also got these crevices as well. So your brick crevice there with the door bentons just there.
Steve Roe
[40:04]Are you guys planning to publish any of this data or present at a conference in the future?
Dave Anderson
[40:09]Yeah, so I did a presentation for the last Northern Back Conference. I think we're getting to the point, yeah, we're definitely getting to the point where we need to start looking at the Excel spreadsheet of DOOM, to, yeah, to manipulate that data. So we've got an anecdotal, but based on our data recording, we can fairly well predict what's going to be happening in here. So I think we're safe at the point where we can start actually publishing our work, which we need to do. And yeah, I think we're at the point as well where it would be worth going to the National Back Conference and sharing this information because it does it's don't.
Dave Fisher
[40:55]We need a phd student
Dave Anderson
[40:56]We could do with it ideally a phd student we've got enough data to support one i mean this.
Dave Fisher
[41:01]Is a glorious spot for somebody isn't it very few bat workers still very limited information in probably the best cast
Dave Anderson
[41:09]In britain.
Dave Fisher
[41:10]And uh it's just under investigated
Dave Anderson
[41:13]Isn't it it is yeah so.
Dave Fisher
[41:15]It's the potential is huge i think
Dave Anderson
[41:17]Yeah i mean I think it was quite a blow really it was quite a blow that when John retired that work didn't continue at Leeds University that was quite a loss to the area really, it's like an honour really to be able to build on that, that work that happened it is yeah it's great I mean we met up with John he loves it doesn't he we met up with John last autumn he very kindly donated all his caving gear for us so we have sort of a facility now to take more people with us because we've got more equipment yeah and like i say we're keeping regular touch because he's always interested to hear when
[42:06]
Reflections on the Kiln Experience
Dave Anderson
[42:00]when his bats turn up still even though he's not as active as he used to be well.
Steve Roe
[42:06]It's been fantastic to finally come and see the place so dave fisher Dave Anderson thank you very much
Dave Anderson
[42:10]Okay thank you for coming we.
Dave Fisher
[42:13]Could just do a quick check afterwards couldn't we and I'm just interested to know whether that group of adults
[42:29]
Final Observations and Updates
Dave Anderson
[42:30]Are they right up? They're still tucked right up aren't they? Yeah they're up here. They're active though. So they're in this. Right in the back.
Steve Roe
[42:39]Up in this, right here.
Dave Anderson
[42:44]Because it's gone cool they've tucked themselves further I think.
Steve Roe
[42:48]Thanks again to Dave's Fisher and Anderson. I've been in touch with Dave Anderson this week who tells me that last week's cold snap saw an influx of natural bats coming into the kiln and going into torpor. Before that, it was all still in flux with swarming bats arriving and leaving. As usual, bats are turning up in the same tubes and showing crevice fidelity, but the big news is that they now have four ringed Senaturas bats recorded and each one is over 21 years old. I'll be back in two weeks' time chatting to a long-standing bat group member in the south-west of England.
Edward Wells
[43:21]And I can just about figure out how you might live in a world where you get the echoes back from 30 kilohertz, 45 kilohertz. A world in which you're echolocating at 112 kilohertz. You can't hear anything more than about a foot away from you. And yet you're finding your food, you're avoiding obstacles, you're avoiding people. Unless a horse will fly to within about a foot of you and then whip around the side of you. But what kind of world is that? It's our world, but my goodness, it's a different view of it.