The Bedfordshire Bat-by-Boat Survey

In this final episode of Series 7 of BatChat, we go out on a unique paddling journey along the River Great Ouse with the Bedfordshire Bat Group and the Viking Kayak Club. Bob Cornes from the bat group explains how the survey came about and as we embrace the peacefulness of the river we discuss bat behaviours in their environments. The episode showcases community-driven conservation efforts, emphasising the significance of grassroots initiatives in bat conservation. 

As well as recording various people taking part in the survey, your host Steve Roe has two bat detectors strapped to the front of his kayak; one tuned to 20kHz and another at 50kHz to record the sounds of the bats around us.

See what the Bedfordshire Bat Group are up to.

Viking Kayak Club

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Use our voicemail feature to send us a recording so that we can share your bat experience in the next series. It could be the sound of your bat detector or simply a narration of what you’re watching.

We’ll be back with series 8 in the autumn of 2026.

Transcript

Steve Roe

[0:00]Hello and welcome to BatChat, the award-winning podcast from the Bat Conservation Trust. Join us in this episode for an evening of being out on the water, simply messing about in boats on the search for bats. Yes, welcome to this final episode of Series 7. If you're joining us for the first time, the Bat Conservation Trust is the leading charity in the UK, solely dedicated to the conservation of bats and the landscapes on which they rely. Among our many objectives, one of them is to support the 80 or so local bat groups through partnerships as they are critical to our success. The Bedfordshire Bat Group is one such partner group. Formed in 1988, the group works for bat conservation within Bedfordshire and Luton. It carries out a wide range of surveys and one of its most popular events is a survey by canoe out on the river. I heard about these surveys when I was invited to give a talk at a recent AGM of theirs and couldn't resist the opportunity to take the podcast gear out onto the river. As dusk approaches on a launch jetty by the side of the River Great Ouse, we join our team for the evening, a mix of people from both the Viking Kayak Club and Bedfordshire Bat Group.

[1:17]

Canoeing for Bats

Steve Roe

[1:18]Bob Corns from the back group is giving a briefing before we get out on the water.

Bob Cornes

[1:26]We've got a fairly short section of the river to do tonight which is nice because we can be very relaxed and take our time. As Sean said I'd like to wait till it's dark enough for bats to fly otherwise we get a recording set of recordings where the first section of the river looks blank and it's just because we're a bit early. So once we start to hear bats flying around we can set off down the river. We'll be fairly close together so you can shout out if we see a particular the species of bat as usual feel free to ask questions we've got lots of knowledgeable people tonight so you won't need to ask me but ask any of the others that's it i think, oh yeah sorry well the other thing i was going to say i look back at the records it's seven years since we did this section of the river it doesn't seem that long because it's been the covid, business in between when we last did it we recorded five species on this section the usual fall which is common pit, soprano pit, notchal, dolbentans and we had some serratine activity at the Barford Bridge end but there's no cattle there now so we may or may not get that tonight we'll see and you never know we might get something else we shall see. What I'll do after we finish is I'll analyse the recordings and produce a map showing what we heard where. Yeah.

Steve Roe

[2:46]So with that, we got into the canoes and started a slow paddle downstream towards Great Barford.

[2:54]

Kayak Club Insights

Bob Cornes

[2:54]Noctule.

Steve Roe

[3:14]So graham just while we're going down just tell us about the kayak club that you're from and what we're doing tonight then

Danny

[3:21]So we're from viking kayak club in bedford which was set up by a group of friends 60 odd years ago and we were a vibrant club with 200 or so members doing all sorts of different paddling from canoeing and slalom racing boats all sorts of different paddling just enjoying our time on the water and for the last 20 years we've been supporting the Bedfordshire bat group by doing these bat surveys on the river. We provide the boats and the motive force and the members of the bat group have been carrying out surveys as we go and we've been learning about the bats over the years.

Steve Roe

[4:12]What is it that's made you want to do it? You do this free of charge form. What is it that will you get out of it?

Danny

[4:17]It's something that sort of a variety of people have done over the years. Links and friendships have formed from there. But what I get out of it is just to be paddling through in the pleasant evening, just enjoying nature and just seeing something entirely different. At the end of a working day it's lovely to be out on the river in the dark, which we don't do very often. I've seen the bats, learning about the bats, but also the nature around us. We've seen swans carrying the signets behind them and as it gets darker the temperature will suddenly drop and the river will go still and it's quite a magical time.

[4:58]

Nighttime River Safety

Graham

[4:56]Signets have grown so much today.

Danny

[4:58]They've grown, I love watching them Brad.

Steve Roe

[5:02]And we heard you guys give the safety brief another start apart from the obvious falling in what extra things are you guys thinking about coming out at night

Danny

[5:09]This is a navigation the river here is a navigation so there could be canal river boats motor boats sort of traveling at the same time keeping away from the trees because we don't want to get caught to the trees but also there's going to be fishing lines and things hanging down but generally it's quite a benign river it's one of the slowest moving rivers in the country um so so it's for this type of paddle um it's uh it's fairly straightforward for the uh further up the river um when we've been surveys further it's getting a bit more tight and twisty and trees coming down but that just has the uh entertainment for all of us and we've uh we haven't lost anybody yet and

Steve Roe

[5:51]What sort of area do you guys cover is it the whole of bedford or are you certain areas

Danny

[5:55]It's mostly on the the River Ouse. So the official navigation ends at Kempston Mill which is three miles or so north of Bedford upstream from where we are today. And then the Boose goes all the way down to the comes out at Kings Lynn. We usually cover club night paddles and generally weekend paddles. We tend to be sort of going down as far as Great Bartford which is where we'll finish tonight but other times we go out on different stretches of the river and different rivers all around the country.

Steve Roe

[6:30]And if people want to find out more about the club they're interested in joining what's the website for you guys? There he goes. So what we had so far tonight Bob?

Bob Cornes

[6:44]Noctual, very prolonged, so far a bit, common bit, and I did think I heard Dolbenton's briefly but I didn't manage to see one.

Steve Roe

[6:52]Yeah I thought I heard one as well.

Bob Cornes

[6:53]Ah, it was not just me then.

[6:58]

Bats on the Move

Steve Roe

[6:59]Oh, Dolbenton's just gone past.

Bob Cornes

[7:09]Delaying the start was definitely a good move because if we leave earlier as we tended to on these surveys for the first 20 minutes you don't hear anything much what's.

Graham

[7:19]At 40 what would you

Bob Cornes

[7:21]Uh could be common pit could be door benton's back, so we're.

Graham

[7:29]Up to i'm up to four species

[7:34]

Observing Bat Behavior

Bob Cornes

[7:35]There's the top entrance, that's high speed, rapid click.

Graham

[7:47]They're a medium sized bat but they're just off the water so if you see it, if you can find one in the talk light then you'll find that they sort of glow so they've got a light underbelly. I can hear it, it's just where it's gone.

Bob Cornes

[8:15]We've got Dolbentons flying around just in front of us.

Graham

[8:18]Yeah, I saw it a minute ago. I saw it in your right.

Bob Cornes

[8:26]Yep, noc-tor. Well, as a general rule, the dolbentons are going to be very low over the water. The noctuels are going to be really high in the sky, sort of treetop high, and the pipistreels will be somewhere in between. Feeding buzzers, Some nice feeding buzzers going on,

[9:32]

Survey Logistics

Bob Cornes

[9:28]so bentons so.

Steve Roe

[9:32]Bob when did the idea for this start then

Bob Cornes

[9:34]The original thing was a kind of bat walking canoes and that was done for a couple of years it didn't involve the Viking kayak club either at that stage I think it was a different club that was involved but then in 2011 we started doing surveys like this with the aim of systematically recording bats on the river and at that stage it did involve the Viking kayak club as well as the pack group and we've been doing them ever since except for a break when Covid restrictions were happening.

Steve Roe

[10:12]And are you always doing the same bit of river are you doing different bits

Bob Cornes

[10:15]Each time no we've been working our way along the river so we do a different section each time we're now beginning to, duplicate ourselves in the you know this this section we're doing tonight was done seven years ago because we have covered the whole of the great ooze in bedfordshire in the time we've been doing it so you know we want to get as much detailed information as we can about where the different species are on the river. I mean, the pipistrelles can be just about anywhere. The dolbentons are much more patchy. You tend to find those concentrated where there's a lot of trees or shrubs on the banks of the river. So you've got a more enclosed bit of environment. Noctuials, I never quite worked out the pattern with noctuials. They're not everywhere by any means. There are areas that are good for them and areas that aren't, but I haven't quite worked out the pattern and then sometimes we pick up less common species like serotenes but again in in fairly specific places so.

Steve Roe

[11:21]What species have you had so so far on all the surveys then you've had all three pipistrels

Bob Cornes

[11:26]Yes only occasional enthusiasts pipistre but we have recorded them daubentons i think we've had one or two naturas but we rarely hear those yeah, One or two brown longies, but again rarely hear those. Seratines we've had. I think that's it. One I'm slightly surprised we've never heard is Barberstelle. Because there's plenty of them around in Bedfordshire. And traditionally they're supposed to be associated with river valleys, but they don't seem to come out to visit us when we're doing this. Because they are fairly quiet, so you'd need to be quite close to them to hear them anyway. But it's a good range of species.

Steve Roe

[12:14]And just tell us about the kit you're using then you you've got the detectors that are recording the back so you're also using gps to work out exactly where they are when you get back

Bob Cornes

[12:23]Home yes i've got a darmin gps in my pocket which i find very reliable the problem is that the detector doesn't have a built-in gps and you've got the problem of marrying up the two sets of data which is not straightforward. First of all you have to make sure the clocks are as closely synchronized as possible and an error of a couple of minutes can make quite a big difference on the location. So I have to try and synchronize the clocks and then matching up the two sets of data is complex. Fortunately Danny our back group chair who's with us tonight used to work in computing and he's written a program that takes all the sound files from the detector, looks at the time stamp on them and locates the nearest time stamp from the GPS track so it can match the two together and produces a spreadsheet which gives the exact location of each of the sound files so that way we can map fairly precisely where they are along the river.

[13:30]

Data Collection Challenges

Steve Roe

[13:30]And do you notice any different types of behaviour with bats when you're on the river compared to doing stuff on land?

Bob Cornes

[13:38]Well the obvious thing of course is the Dolbentans feeding. They don't only feed over water of course but you know that's the method of feeding they specialise in and we certainly get very good views of that from the river. The other thing that's very noticeable is how localised the bat activity can be. You can go through a section of river and if it's open on both sides, very often there's no bats around at all or perhaps the odd notch you're passing over. But as soon as it starts to get more enclosed, you get a hot spot with a number of pipistrels feeding and often doorbentons as well. So it's not so much that you're seeing different behaviour is that you're seeing how they relate to changes in the habitat as you go along the river. Socrano pit.

Steve Roe

[14:34]And roughly how far are we going downstream tonight?

Bob Cornes

[14:36]About three kilometers from where we started so it's a fairly modest distance we've done I think we did about seven kilometers us once so it varies the constraint really is where we can get into the water and get out of the water and there's also the car parking to think about that we have it has to be a place we can leave vehicles so sometimes you have to do longer sections than others this is one of the shorter ones tonight the seven kilometer one was a bit of a slog we were all very pleased to get out of the canoes by the end of that we.

Graham

[15:13]Do get a lot of the local landowners doing quite

Bob Cornes

[15:17]Positive about the.

Graham

[15:20]The bat surveys and allowing us to get into the river or out of the river on their land and we've had we've had people actually opening their gates to their guard to drive in and take the boats down to the

Bob Cornes

[15:33]River and actually we did that the last time we did this section as i remember Yeah. Was that bloke in Renhold? It was. Who was very helpful. Yeah.

Steve Roe

[15:45]And obviously we're in the middle of NBMP season at the minute. What stuff is Bedford-Shabak Group doing elsewhere in the county?

Bob Cornes

[15:52]We've got a moderate amount of NBMP, so we don't do as much as some groups, I think. One survey that, as a group, we've never really got involved in is the waterway survey, oddly enough. The difficulty with that, if you do it the way that the NBMP protocol says, is you've got to find a section of river that you can walk along the bank of, but be close enough to get to the water to pick up the bentons. We do some roost emergence for the NBMP. Soprano pips, seratines. Not common pips at the moment. The common pip roost that we used to monitor for the NBMP has been deserted by the bats and we haven't found another convenient one to do. So we do those. One or two people have done the field survey but I'm not sure there's anyone doing it at the moment.

[16:46]

Hibernation Surveys Explained

Bob Cornes

[16:47]And the other thing we're involved in in a big way is hibernation surveys in the winter. Perhaps there ought to be a protocol for doing the waterway survey by canoe.

Graham

[16:56]But if you want to be as close to the water as possible, it's difficult to get closer.

Bob Cornes

[17:03]And in a canoe, you can get to parts of the river where you couldn't otherwise get there but because there's no suitable paths, even if you got permission, it would be physically difficult to get to some bits of the river without having a canoe.

Danny

[17:20]It's as simple as one side of the river to the other.

Bob Cornes

[17:23]In a canoe, you can move through, you know, quite long sections of river easily. But the other thing about it i mean we we are doing a serious survey but we're also enjoying it i find it immense fun doing this.

Steve Roe

[17:40]It's ages since i've had this much natural activity constantly

Bob Cornes

[17:43]Well not chills do like rivers i was mapping bedfordshire bat records a few years ago and if you do a map of the county with not your activity on it it really is concentrated along the rivers very noticeable although they will fly some distance away from a river they do seem to be attracted to rivers one of the things i like about well doing bat stuff generally but perhaps the specialist is coming on the river is that because you're not using torches most of the time you you start to develop a different way of perceiving your environment which is really enjoyable, I didn't see it well was it low all right it's very difficult to judge size actually in this situation I can hear door bentons at the moment they're not but they're not particularly big when the big ones are the noctules but noctules are so high it's difficult to judge how big they Graham.

Steve Roe

[18:51]How many boats have we got out tonight and what are the logistics of doing something like this?

Bob Cornes

[18:56]We've got six.

Danny

[18:57]Boats out tonight and usually the logistics problems are getting boats at the start and getting the coming boats at the end.

Bob Cornes

[19:04]Steve, did you hear that?

Danny

[19:05]It's much nicer just to paddle down the river rather than have to paddle back up against the flight afterwards. And there's usually a bit of shuttling, just moving some cars to the end and starting today. This evening some of us paddled up the river which is very pleasant early on as you've gathered and moved the cars afterwards so it's all fairly straightforward

Steve Roe

[19:38]I think that's a ceratine. Is it? Yeah.

Bob Cornes

[19:43]It's really great.

Steve Roe

[19:44]Yeah, really a regular Redden.

Bob Cornes

[19:47]Did you hear the ceratine? There was a brief burst a moment ago.

Graham

[19:52]So, what are the mountains below? Oh, look at the wolves! There are three or four of them, but it's literally little baltons, so I've lost a lot of the scents. Yeah, but that's where Debbie and the new cavern...

Steve Roe

[20:04]So... So Danny, just tell us what other things Bedfordshire Bag Group are up to then at the minute.

Graham

[20:10]So we've got the canoe surveys that we do here. We do various regular surveys, so we do transects, so activity transects, and we do various monitoring of emergence of roosts, so we've got a couple of, we've got a large soprano roost that's recovering from having some work done nearby, that at its height was over 1500 bats, so that gets done every couple of weeks. We also do a Dorbentons count and bat box checks at certain sites to give us an idea of ongoing activity. We've been doing this for years so we can look at the data alongside itself over the years and see trends. We do public bat walks, we do bat walks for various different groups, we do surveys at other sites so for example surveying whipsnade zoo nice which is a bit of an unusual one we've normally got zoo keepers with us as well so we go and see what's there and we we've got hibernation act surveys that also happen at the zoo so it's there's some very interesting stuff going on around there and after that we've had a couple of trapping sessions

Graham

[21:31]So we'll get involved in all the things that I suppose I would expect back roots to do so we'll literally go out and do trapping in various different places some of it's SSSIs, some of it's areas that we're looking at to see what's going on so we might be looking for a small myotis we've got a wood where we know we've got barber stells so we're trying to work out exactly how they're using the woodland and we know we've got a maternity roost there as well, so that's been counted out. So we're quite active on those sorts of things. We also have some static activities going on for a certain rewilding project.

Steve Roe

[22:15]Yeah.

Graham

[22:16]And we're helping gain the baseline data for them. It's one of the landowners that helps us on various bits of areas where we survey that we would like to retain access to. So it makes sense for us to help them. and it also helps us find the scientific information of what's going on in our area yeah so it worked both ways because

Steve Roe

[22:40]On the hibernation stuff you guys for me are quite unusual because you don't have loads of underground sites do you so just tell us a bit about what sort of sites you have got for hibernating

Graham

[22:48]That so we've got some we've got a couple of uh interesting sites we've got an air raid shelter uh we've got a railway tunnel which is our main main site so we get maybe up to 200 hibernating bats on that one.

[23:06]

Engaging with the Community

Graham

[23:06]We've got ice houses, we've got lime kilns, so where that's our closest to a normal sort of an underground site, but we've also got some garden features in sort of large estates and ice houses in large estates, so some of these garden rockery features we've had Barber for example which isn't necessarily what you'd expect but we we get barber cells in this area so it's not overly surprising from our point of view

Graham

[23:41]It's really nice they crop up in in some unexpected places so yeah we've we we cover the bases in a way so there's plenty for members to get involved in all of our stuff's advertised either through our newsletter or on our news group so if you remember you've automatically got access to the news group and that gives you the up-to-date information what's happening and contacts for people getting involved it's it's a nice mix yeah we've got a nice eight range and and a mix of people on the committee and also as members so some people are consultants some people are just enthusiasts and of course they're the mainstay of the backroom the enthusiasts and they're the people with so much knowledge and can help train and bring on other people the ones that are in a way make the back route run.

Steve Roe

[24:39]And what is it about these surveys that you like so much, why do you enjoy doing these particular boat surveys?

Graham

[24:44]Oh they're amazing, it's just so different, I mean being on the water at night is absolutely amazing, you get really close up to Door Benton's at times, it's just really special, it's things that people don't do, you don't normally get the chance to do it and the other thing is you're out with such a great bunch of people I mean the Viking kayak absolutely brilliant they arrange everything for us they sort out all of the the logistics and they're a great bunch we've been working alongside them for years and it's there's a stalwart group it's a normal group and they're just so much fun to be out with there's all the banter and everything else because everybody essentially knows each other so it's just really good I mean you might find that there's no reason why other groups couldn't maybe find somebody within a canoe club that manages to patch things together. I mean in our case it was myself and Sean.

Graham

[25:49]I knew Sean from where I was working and we sort of worked out how to get this to work.

[26:06]

Reflection on the Experience

Graham

[25:59]We started off with an actual club, it was an outdoor centre to work out whether it worked. It was very experimental, it did work and then when they decided that they couldn't carry on, Sean said the Viking had to step in and that's how we started initially and then it came on to doing the visual surveys as well because it was the Viking club saying you know is there other things we can do to help you yeah so it's worked out amazingly well i

Steve Roe

[26:33]Mean this has been great it's been so so interesting to see the backs of this at the river level

Graham

[26:39]Yeah i mean you get the top entrance along right next to you at times you know they're at the same height as you almost you know there's one just went about six foot past you on the line Oh, my God. Are you going to need some help? Are you going to pull it? Yeah, you can lift it over and see if it does.

Steve Roe

[27:15]The day after the survey, Bob emailed the results from his detector and confirmed we'd had five species. Common and Sprinopipstrel, Noctual, Seratine and Dorbentans.

[27:27]

Episode Wrap-Up

Steve Roe

[27:27]A huge thanks to everyone involved in this episode from both the Bedfordshire Bat Group and to the Viking Kite Club, who were great in getting our canoes lined up at various points in the darkness to help with the recording of the different people you've heard from in this episode. And of course, as usual, there are links in the show notes to various resources that you might find helpful, including how to find your nearest bat group.

Steve Roe

[27:52]And that's it for this series of Bat Chats. If you've enjoyed this episode, there are seven series of the show, so go and listen to them if you're new to the podcast. If you're a regular Bat Chatter, you'll be glad to know that recording of Series 8 is already underway and once again we'll be back in the autumn period around the end of October for a new series. Now before I go, I have a request. if you're out watching bats one evening this summer or doing something bat related I'd love you to use our voicemail feature to send us a recording so that we can share your bat experience in the next series it could be the sound of your bat detector or simply a narration of what you're watching you can record and send the voicemail using the speak pipe link in the show notes of this episode you can even listen to the recording before pressing send whatever you send us include the location of where you're recording the bats even if it's just which county you're in. Bat Chat is an original podcast production for the Bat Conservation Trust. Its producer, editor and presenter is me, Steve Rowe. Thank you to every single guest who appeared in the series and of course for your continued support of the show.