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Barbastelles at Paston Great Barn

November 17, 2021 Bat Conservation Trust Season 3 Episode 25
BatChat
Barbastelles at Paston Great Barn
Show Notes Transcript

S3E25 This week Steve is on the Norfolk coastline in the East of England visiting Jane Harris from the Norfolk barbastelle study group. Paston Great Barn dates back to 1581. It’s a huge thatched barn made of flint, brick and stone measuring 50 meters in length and about 10 meters wide. Despite it’s size, driving south along the coast road it’s very easy to miss as you pass its end flint wall and not until you glance in your rear view mirror do you get a feel for the expanse of the structure. Hidden away inside this SSSI and SAC is an important roost of rare barbastelle bats which emerge from the barn at night and either head off down the country lanes or to the cliffs along the beach to forage. Jane and Steve discuss the work done by the research group to discover more about barbastelles in Norfolk as well as this important roost where it all started back in 1996.

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Steve Roe:

Well, as promised your next episode in series three of BatChat is here, and today we're heading to the East of England. I'm Steve Roe, a BCT trustee. If you're a returning listener, it's great to have you back once again. And if this is your first time, welcome along, episodes are released every second Wednesday from now until the spring, and you can join the conversation online. Use the hashtag BatChat. that's all one word. As we meet each of the guests in this series, you'll hear stories from people working to make a difference in the world of bat conservation. You'll hear from people who care about individual species, people who concentrate on one particular part of that ecology and people who are working with bats at a landscape scale. As well as keeping up with the latest news and hearing from people in the world of bats. We hope that you'll be inspired to get involved because bats need our help. Today we meet one of those people who is interested in one particular species, the barbastelle. Jane Harris is part of the barbastelle study group in Norfolk on the east coast of England. Back in May, whilst I was on holiday in the area, I drove down to Paston Great Barn which is right on the coastline, dating back to 1581. It's a huge thatch barn made of flint brick and stone measuring 50 metres in length and about 10 metres wide. Despite its size, driving south along the coast road, it's very easy to miss as you passes and flint wall and not until you glance in your rearview mirror to get a feel for the expensive the structure. I first got to visit Paston as a teenager when I was getting interested in bats, and whilst on the family holiday met with a surveyor who was undertaking regular counts of the colony. And I can still remember being taken inside this huge structure and being shown the colony of barbastelles tucked away above one of the doors and staying to count them as they flew out over the side and down the dark country lanes listening to their distinctive castanet echolocation calls. 20 years later, and then back and you join me inside the barn with Jane Harris who is describing the space we stood in.

Jane Harris:

Well, we're in the mediaeval thactched barn, which is I think, one of the biggest in the country. It was used by the the famous Paston family in the past. And it's a huge barn with adjoining cow sheds. That was, I think, really, it came to prominence when sheep and will farming were important in Norfolk, and it's a brick and flint, and thatch with something like 20 trusses that go up different levels to the roof. So it's full of timbers, which have more disjoint sets and gaps in them right up to the roof. So it's in many ways a bat heaven, because for crevice-living bats, there are lots of opportunities here.

Steve Roe:

So Jane, we're here to talk about the unusual pneus of the site because it's used by barbastelles. Why is so unusual for that species,

Jane Harris:

Well barbastelles are primarily regarded as a woodland species. And at the time the roost was discovered here. It was the first one a known in a building. I think there may be more now but it's certainly the most significant one at the time. And the reason it seems to be used by barbastelles is the fact that it functions like a surrogate woodland with all these timbers with crevices. So within it, they can undertake their normal behaviour of roost switching, without going elsewhere. And that's what they do. Although we do find they're a little bit more faithful to some of the lintels, and staying in them for a long time, which probably isn't quite the same as you would get in the woodland where they switch more often. But I think now they've been faithful to this barn since about 1996. They come back every year. The barn is obviously undisturbed because Natural England have it on lease, and it's an NNR. And it's managed very carefully and the colony is monitored annually. So they're in safe hands here. And there are anecdotal reports of them being around way before the barn was taken over by Natural England.

Steve Roe:

And it's quite unusual to have a building designated as a national nature reserve isn't in his own right.

Jane Harris:

That's right. Yes, I think so. It was it was under threat because it was it's owned by Norfolk buildings Preservation Trust, and they were hoping to convert it to a visitor centre as they had done wax and burn it isn't very far away from here. And Norfolk bact group, John Goldsmith, you may remember he did some surveys discovered the colony. And from then on, it was quite a long procedure to work out what would happen and in the end it was designated as an NNR an SAC. And SSSI obviously, and the lease was going to Natural England for 50 years.

Steve Roe:

And it like you say it's unusual to have barbastelles in the building because they are normally considered a woodland species. I mean, what's the woodland situation in Norfolk? Because looking at the map, it's quite an arable area.

Jane Harris:

That's right. When it was always considered that this roost was unusual, not because just because it's a building because it's a building in an arable area. And after the roofs was discovered here, interest in barbastelles grew in Norfolk, the Norfolk barbastelle study group was formed that was 2007. And that really was partly spawned by Ash Murray, who was site manager here for Natural England and Keith Zeeland, who was manager of some of the big woodlands, National Trust's woodlands at Felbrigg, Sheringham Park and Keith knew from the BCT monitoring woodland monitoring protocol that they were barbastelles at Sheringham. So he and Ash formed the group and we started looking at those woodlands, initially the ones mainly in North Norfolk, but also some privately owned in West Norfolk. And we've gone on to look in South Norfolk where they're the interesting thing there is the woodlands are much smaller and more isolated, but where they have suitable roof trees, we're almost certain to find barber cells. So we're now getting a picture throughout Norfolk of what barbastelles need, and where they will actually use the woodlands for maternity.

Steve Roe:

How have you found all that out? Have you actually tracked these batsbows.

Jane Harris:

Right. But when when the group started, we were mainly looking at distribution using transects and building up the methodology for that. But we very soon realised that if we want to find out more about where the breeding colonies where we had to radiotrack. So initially, we had Chris Vine from Cambs [Cambridgeshire] group, helping us until they got chained up to track and radio track. And we've been doing that ourselves since 2012. I think. So we've been targeting all this woodlands. We started the National Trust ones showing them Park, Blickling Felbrigg. And then at the Ken Hill Estate over in the West, which is an interesting one, because their now rewilding. So we hope to go back there and see how the barbastelles are doing. And then various other woodlands, close to Paston. Because we wondered whether it was an isolated colony. Were there any other viable cell maternity routes within sort of an interactive area, and we found one about six kilometres away to the south, and the foraging ranges overlap. So that started to tell us something about potential interactions between colonists perhaps passing isn't quite so isolated, and another one about 10 kilometres to the west. We've also started with looking in different habitats, different woodland types and South North at the woodlands are slightly different, more hornbeam in ash, but there is Oak amongst them. Some of them are heavily coppiced, but most of them have some non intervention areas and we were finding about the styles in those. So we find them in South Norfolk as well. The gaps at the moment are the broads. We don't know very much they've got the wet woodland, but there is some oak in some of them Calthorpe Broad which is another NNR we've looked at and there's maternity colony there that stone southeast of here more towards the coast not so far away. We don't know much about West Norfolk yet.

Steve Roe:

So I mean, it sounds like you found quite a lot of colonies across Norfolk, do you know roughly how many you've found?

Jane Harris:

I think we the groups and 15 maternity colonies by radio tracking, and another three where we've caught post lactating females and the root potential of the woodlands is high. So we're pretty sure they're there as well. If you add the ones that have been found, by example, the Norwich Distributor Road, ecological surveys, the Northwest link, and one or two other sources were up in Norfolk at least 24 barbastelle maternity colonies scattered from north to south, but as I say, with a bit of a gap to the west, apart from Ken Hill, on the edge of the wash, and the Broads, I don't know much about the Broads.

Steve Roe:

Thinking about sort of 30 years ago when we didn't know much about barbastelles at all, you know, actually, it seems like the population density here in Norfolk seems pretty healthy compared to what we used to know about them at least.

Jane Harris:

It does. There are historic records of barbastelles in hibernation sites in the past. We rarely see them in hibernation sites now I think probably because the winters aren't cold enough. But it was always thought from, for example, Frank Greenway's work and so on that barbastelles would be in heavily wooded river iron landscape. So what were they doing in Norfolk? So that's really what the group was setting out to look at. And we find that if they've got a suitable rousse woodland, or which there are quite a few, they are able to feed in the associated call arable mosaic, particularly weather, a lot of good hedgerows tall hedgerows, hedgerows, I think are really important. And sometimes you get tributaries or ditches with a lot of woody vegetation along them, they'll use those a bit of rough pasture mainly. But also, if their colonies are within about five kilometres of the coast, particularly where their cliffs cliffs are important. They will visit them for example, from here past and very often, the first place they'll go to forage is the cliffs at monthly and if the weather is right, and there are insects and I think it's the shelter, that's the important thing. They will stay there all night. But if they get there, and maybe it's an onshore wind and there are no insects, they'll come straight back, go back down south to back to the woods. So the coast is important where the colonies are near the coast, the Felbrigg colony forages at Cromer on the cliffs, they're further west, it's more sand dune, and salt marsh, we get some visiting, and barbastelles on the coast, but not not so much as where we have cliff. So I think it's the shelter, that's really important.

Steve Roe:

I was gonna say, because if they're in a natural or more normal woodland environment, you expect them to be on the shelf side of the woodland. So you think that's to do with the weather do you

Jane Harris:

Yeah weather influences where they forage.

Steve Roe:

And for listeners who have never seen a bat being tagged before, can you just describe what a radio tag looks like and how it sits on the bat.

Jane Harris:

It's basically the top of the tag, it has the battery in it, the electronics, the workings. And then the antenna is a very, very fine antenna that's usually 15 to 20 centimetres long, depending on what you want. There are different weights of tag, but the ones we use are usually about point three, six, or point four, five, because the guidelines are that the weight of the tag, and the adhesive, which is a medical glue mustn't be more than 5%, the weight of the bat. So with barbastelles, we really want them to be over eight grams to take tags like that with comfortably. So once we've caught them, we clip a little bit of fur off from between the shoulder blades, but little glue on on where we've clipped on some on the bottom of the tag. When that goes tacky, you put the tag on, and just gently firm the hair around it and leave it put the bat back in the bag and leave it until the glue has confirm and then want make sure that's warm and release it again. And then it's long nights after that.

Steve Roe:

I mean, we take glue and it's it's a special glue, isn't it that it's not like a normal? It's not like using super glue or anything like that, is it?

Jane Harris:

No, it's medical. There were various ones. Medical adhesives, often used for colostomy bags, you know, that type of thing. So the tags fall off eventually. Sometimes they come off quite soon. And I think that can often be if that's being working its way into a crevasse or sometimes they stay on longer than that.

Steve Roe:

And how long how long does the battery lasts usually on these things.

Jane Harris:

That depends on how the tag is set up the number of beats per second the length of the pulse. We go for about two weeks that you can get longer but then the pulse rate will be slow. So it depends what you want. If you want to track a moving that you don't want the pulse gap too wide, particularly barbastelles they move so fast.

Steve Roe:

You say they move fast. You know what sort of foraging area how many kilometres from the roost will

Jane Harris:

Well the core sustenance zone is six they forage? kilometres radius from the roost and we found that that's about right. But bear in mind we're new to tracking either pregnant and early pregnancy females or post lactating ones so they have an affinity to the maternity routes, they're probably not going as far as the males would go for instance. So we find they go on average about five kilometres certainly from Paston we haven't had any go any further than that. But you know we only track a certain small percentage, but I know in the past males have been recorded by the people going 15/20 kilometres.

Steve Roe:

And is it just barbastelles you've got here in the barn or are there other bat species here?

Jane Harris:

No there is a significant Natterer's roost as well. Mainly in all the mortise joints with many mortise joints. And they they arrived earlier than the barbastelles. So they should come anytime now because they give birth a bit earlier. And all the lining papers down under each of the trusses helped me to know where they are. And then I can use the cameras to try and get a count of how many bats.

Steve Roe:

So I mean, Jane's just said lining papers. So there are what looks like white wallpaper rolled out underneath each of these, these trusses and weighted down and the one that were stood next to has got a scattering of Natterer's bat droppings on.

Jane Harris:

Yes looks like the first visit. Yes, and that's in truss five. All the trusses are numbered, so we know which ones so they should, the numbers should start to build up soon, no sign of the barbastelles yet, but I would expect they were back end of May beginning of June.

Steve Roe:

And scattered around as well. There's a number of what look like security cameras.

Jane Harris:

They are there. The roost here is monitored by different cameras in the past, but things have improved. And what we're using now are basically security infrared security cameras, which don't give that good quality video, but they're really flexible in that you can set them up to record because they're linked to a recorder whenever you like. You don't have to come in and keep disturbing the roost. And they are linked to a recorder with a monitor in the barn next door so the cables feed through and you can see what's happening from that. So I can I get a count every night. And I can see what's happening the colony right through the maternity period.

Steve Roe:

Nice. and they're on little tripods as well so you can move them around and follow them.

Jane Harris:

Two fix ones under the two big door lintels where the barbastelles above spends most of their time and for roving ones that I can use on the Natterer's if I can work out where they are.

Steve Roe:

And in terms of the woodland roosts you've found elsewhere in Norfolk, what I mean the trees that you find in roosting, what sorts of features are those roosts in are they in woodpecker holes or bits of?

Jane Harris:

No, loose bark, loose bark, there are they will use splits as well splits and cracks. But loose bark seems to be the most predominant type. And we get that a lot on oaks and sweet chestnut, probably in that order. Those those two really important but you get you can get loose bark and other species. And they will use them I think the maternity colonies seem to go more for the outcome sweet chestnut, when they kind of dispersed and you get a bit more variety. But those that type of roofs, the oak and sweet chestnut with lots of blue spark is what we have in the colonies north of Norwich where the Northwest link is supposed to go the road that joins the NDR with the A47. And there are so many wonderful roost trees there. And the work that's going on has shown that there is a really big barbastelles colony, which is going to be definitely impacted by the road. So the work is going on studying that at the moment.

Steve Roe:

And you say a larger share what's what's the average size for a barbastelles maternity colony and these words.

Jane Harris:

Right, I think it varies a lot for what we've found in the sort of trees, we've been looking at sort of woodlands is probably up to about 25. Sometimes you get them in a bark collar, round an aerial bough, and then we make 20/25. If it's more of a bark slab, which might make it bigger, you might get up to 35 something like that. I think the big colony in the woodlands north of Norwich is something like over 100. But it's a very large tree with many potential roosting places. So it's hard to answer that. I think it depends what space the feature allows probably

Steve Roe:

nice and diplomatic. And you touched on earlier. We talked about, you know, a bit of interaction between the roost what what have you found out about the interaction between the different colonies Is there is there definitely interaction or we we still not sure?

Jane Harris:

That's interesting. I mean, we found this some overlap between foraging areas of different colonies. We found that for passing with one about six kilometres to the south, we found that with one at Blickling with another one nearby in terms of whether the bats move between them, we don't know. But another strand of our work was came out of this question of whether Paston was isolated because it's in an honourable environment. And by chance really We built up collaboration with Dr. Alan Edwards, at the John Innes Institute in Norwich. And we thought it was feasible to start trying to look to see if we could get enough good quality DNA from faecal samples to look at the cytochrome B on a gene on the mitochondria and see what the haplotypes were, because there was already work on those published. So that's what we've been doing. Collecting faecal samples from colonies all over Norfolk, including Paston. That work is just about coming to fruition. I think it may have some interesting results, which may give an indication of the status of barbastelles colonies in Norfolk, whether they are in good condition in terms of the genetic variability or maybe not, but that's all I can say. We are now teamed up with somebody at UVA, because the analysis is quite complicated, I think so watch this space for that. But that was a standard I work that came out partly because of the Lorton review and thinking about colonies and landscapes being interconnected. And were they vulnerable? Or was that good gene flow, which would help them be more resilient in the future? So that that was one strand of what we do? And hopefully, we'll get something useful out of that.

Steve Roe:

And what do you see the next steps for the project being into the future?

Jane Harris:

I think we need to look at the areas we hadn't looked at before, are the roads important, and also the West West Norfolk, one of the things that Ash Murray, particularly apt tried to do is where you have so many multiple routes within a woodland to try and do synchronous counts, to get an idea of Colony size and use that for monitoring in the future. So that's something we want to try to improve on. Although also in the the woodlands north of Norwich, we are looking at meaning there as well, more long term monitoring. So monitoring is an important aspect, the genetic work, we might follow up, if that looks to be interesting, and then filling in filling in the gaps. And also, of course, trying to influence the new land management schemes to try to improve habitat, particularly hedgerows, and linking up for bad spells. So there's lots of things we would like to do.

Steve Roe:

So I mean, a lot of work has gone on gone on in the last few years. And the picture of ourselves has changed quite a lot from what we used to know, what sort of sense do you get for the conservation of barbastelles bats in here in Norfolk and the rest of England?

Jane Harris:

I find that hard to answer, because I don't know if there's any work that looks on it on the sort of geographical scale that we've looked at. I mean, we're looking not at one colony in perhaps one woodland or two woodlands, but we're trying to get an idea of the of the status right through the county. So I don't know how to answer that. All I will say is, I think, I think they're extremely vulnerable still, because of Land Management, because of infrastructure schemes, particularly the Northwestern link, I think that would be a disaster, if that colonies is lost, or it declines, as we know, already already from the northern distributor, the first bit that the colonies have gone from there. So I think that is really something that's very important to try to influence.

Steve Roe:

And in terms of the future of this place, you know, this, I mean, it looks very solid, you know, I mean, what sort of ongoing restoration or maintenance,

Jane Harris:

Yes, it's, that's natural England's responsibility. It was thatched some years ago. And various bits of maintenance work are done. Obviously, when the barbastelles aren't here. It's also a hibernation site as well. So I did mention them an actress but we also have pipistrelles soprano and common pipistrelle and long-eared's, it's not breeding, but they're hidden away often. So it's quite an important hibernation site. So the work is always done very sensitively. Any work outside you see there's quite a lot of vegetation to keep clear that's done with an electric strimmer now to keep the noise down and all that sort of thing. And the structure of the barn is I have to keep the walls clear so they can monitor whether any cracks or subsidence or anything like that. So that's ongoing all the time. At the moment, I think the thatch is in good, good condition. So I don't think anything is planned.

Steve Roe:

And if people want to find out more about the group and the work you're doing, have you got a website?

Jane Harris:

We have go to website. Yes, Norfolk barbastelle Study Group. And of course, We've built up all our work, which we were very pleased to be able to do and get it in British Ireland Bats because it pulled together everything from 2007 up to 2019. So maybe the next 10 years will produce something more

Steve Roe:

Great stuff. Jane Harris, thank you very much.

Jane Harris:

Thank you.

Steve Roe:

And thank you to Jane for meeting me on this fantastic site whilst undertaking about survey work that week over the border in Suffolk. And thank you to you for listening to this episode. I hope you've enjoyed it. If you take a look at the show notes, you'll find links to a newsletter article following the history of the bats of Paston and the work of the barbastelle study group. You can follow the bat groups of Norfolk on their social media sites. The links are in the show notes. Now we've got some exciting news for you. We're launching BatChats first ever competition. Two of this series future guests, children's authors Angela Mills and Emma Reynolds have kindly donated prizes. Angela has donated a copy of Bobby the brown long-eared bat signed by both Angela and Chris Packham. And Emma has donated a copy of her newly released book Amara and the bats to enter the competition. To win one of these brilliant books. All you have to do is write as a review about the show, and the two winners will be picked at random at the end of this series. Not all podcast apps allow you to leave reviews. So if you're an Apple device user, leave us a review on the Apple podcasts app which is already installed on your device. If you're an Android user, you can leave us a review on the podcast addict app. And if you don't listen to the show on a mobile device, you can write your review on the pod chaser website. instructions of how to leave your review in each of these places can be found in the show notes of this episode. Remember, we need to be able to contact you if you win. So when you leave your review, make sure you give us your twitter or instagram handle in the review. If you don't use these drop us an email to comms@bats.org.uk with a copy of your review, we're only able to post the prices to addresses in the United Kingdom. If you've missed any of that it's all in the show notes of this episode. We'll be back in two weeks with one of those authors, Emma Reynolds and I'll leave you with a taste of what's to come in that next episode. I'll see you then.

Emma Reynolds:

I just absolutely love bats. I've always loved them since I was a kid. And I just don't think there's that many books about them. There's there's obviously a few really good ones but nothing compared to how many books there are about bears or rabbits or a lot of the popular animals. And I just felt like they're a bit of an underdog really, and I just really wanted to show everyone how amazing they are. And in doing the research for the book, I fully came to understand you know how vital they are to all life on Earth. I wanted to show people what microbots were like up close the bats are most likely to see flying above their heads.