Nathusius' Enthusiasts

S1E4 In our fourth episode, Steve joins bat legend Daniel Hargreaves on an autumnal evening in Rye Harbour Nature Reserve on the coastal boundary of Sussex and Kent in the search of Nathusius’ pipistrelle. Dan gives us an insight into the ecology of this migratory species and what discoveries the National Nathusius’ pipistrelle project has had to date in its five year history. Dan is also responsible for setting up the successful ‘TriniBats’ project and describes how that project came about.

The National Nathusius’ pipistrelle project was launched in 2014 with a grant from the People's Trust for Endangered Species, to improve our understanding of the ecology, current status and conservation threats for Nathusius' pipistrelles in Great Britain.

To find out more about the project, including migration maps of individual bats caught discussed in the episode, visit https://www.bats.org.uk/our-work/national-bat-monitoring-programme/surveys/national-nathusius-pipistrelle-survey 

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Transcript

Steve Roe: 0:57

A few weeks ago on an autumnal evening in October, I joined bat legend Daniel Hargreaves at the rye harbour nature reserve on the coastal boundary of Sussex and Kent, which is about as far southeast as you can go in England on the hunt for migratory species of bats. I'm Steve Roe. And this is BatChat. Dan, it's October, it's freezing, the nights are drawing in. And it's quite a dank, miserable evening. Well, what are we doing this evening?

Daniel Hargreaves: 1:24

Very good question. We're hoping to catch Nathusius' pipistrelles on their migration. And we know that they migrate at the beginning to end of autumn. And to the past few years, around this time of year end of September, beginning of October, we've tried to get numerous bat groups down to the southeast of England, and hopefully, spreading out along the cost will be able to intercept bats during their migration.

Steve Roe: 1:54

So how long has that project been running? For now though,

Unknown: 1:57

we started the Nathusius' project in 2013. There were a number of people working on Nathusius' pipistrelles before that. So we're getting towards probably nearly 10 years now of of data, but the actual Nathusius' pipistrelle project project is probably in its fifth year if we include the pilot project here. And why are we so interested in Nathusius' pipistrelles? What was it actually sparked the interest to find out more about It's funny, I think, because it's got the name pipistrelle them? attached to it. We often think of pipistrelles as common species, we've got three species in the UK. And the Nathusius' pipistrelle. In particularly, we actually know very little about it, we know that we pick them up, we know that we find them. We've got lots of bat care records, we've got lots of bat detector records. But actually their ecology in the UK, we know very little. And we're learning more year on year we learn and we find out new information. And hopefully one day we'll be able to say pretty much exactly what the Nathusius' pipistrelle is doing here. So I should say, I mean, we said we're a long way from home, we're actually in the very southeast corner of England right down, a stones-throw from Dungeness in the southeast of Kent, how many of the bat groups are involved in the projects across the UK Across the UK? I should have a count up really! There's 24 groups that are involved. There's three groups now in Wales that are involved. Lots across England, a couple in Scotland, the Northern Ireland Nathusius' pipistrelle project as well. So lots of groups when we started, it was four groups. So it's everybody's jumping on the bandwagon, which is a very good thing for the Nathusius' pipistrelles because they're not really interested in counties or borders or bat groups. They're just interested in the landscape and, and moving across it. So for listeners who might not be that involved in groups, and just general basically members, how are we catching these bats and what are we doing with them once we've got them? Okay, so we've got a methodology setter, which is basically we've got harp traps and mist nets. And we've discovered really, that the catch and the Nathusius' pipistrelles you need to be playing a call. So we need something to be able to lure the Nathusius' pipistrelle in. And we found that the best call to use is a male advertisement call. This is a male calling out to try and attract females. So we've copied his call, and we're playing it from a speaker mounted next to a harp trap or a mist net. And we're hoping that will attract the bats so that we can catch them. Once we've caught them. It's a case of taking over biometrics over data to make sure it is a Nathusius' pipistrelle look at the sex look at the reproductive status. And we put a small metal ring on there, and the ring has got a unique number on it. And that means if we catch that individual again, we know exactly where it came from,

Steve Roe: 4:54

and have have any of the ring backs that we've caught turned up elsewhere.

Unknown: 4:58

Yes, we've had several recoveries, we've had a lot of recoveries from site to site. Last night, for instance, we've caught a nefarious purpose tool that was it was caught at the same site last year. But long distance record. We've had free records of bats leaving the UK and being found forever across Europe, East Europe, Holland, Poland and Belgium, which has been really good and we've had several captures of bats flying here that have been rung in other countries. So namely, Lithuania and Latvia.

Steve Roe: 5:32

So you said that very calmly as if it's nothing, so that clearly means the bats flying across the North Sea? Yes. Presumably more than once a year.

Unknown: 5:40

Yes. Yeah. We were unsure of how many it's, I did say that calmly. But I remember. sat here at Rye several years ago when we got the first bat from overseas and wasn't quite as calm then. But But now that we've had several recaptures, we're starting to understand what these bats are doing. And they are moving on mass across Europe. And it's quite, you know, it's quite remarkable to think of an animal that's, you know, a little larger than your thumb, weighing seven or eight grams being able to fly these incredible distances. And we're quite lucky that they come in head into the UK as well, where we can intercept them.

Steve Roe: 6:19

So I mean, you said bats are moving across Europe, do we know whether they're, what their migration patterns are they spend in the summers here, or the winters here? Or how do we know what do we know about their migration.

Daniel Hargreaves: 6:28

So we think mainly spending the winters here, there are bats that are definitely spending their summers here. But we know that they're avoiding the really cold climates in northeastern Europe. And they're heading on this southwest trajectory. And that's bringing them down into warmer climates like the UK down into France, perhaps as far as Spain. And really, it's a strategy that's probably been going on for years and years and years. And it's a way of them avoiding a harsh winter, and being able to feed here, fatten up over winter and survive, and then most likely heading back in spring, to replaces.

Steve Roe: 7:05

And at the start of the project, people were taking fur clippings of bats for something called isotope analysis, can you just tell us what the purpose of that was and what the results of that were?

Daniel Hargreaves: 7:12

Yes, we were a little bit worried at the beginning that we had to catch a bat with a ring on it would be almost impossible. We were sort of we envisage it we'd have to bring 1000s of bats to get a recovery. That wasn't wasn't the case. But when we first started before, if we could take a fur clipping, and then we could take that to the lab, and the lab could have a look at the stable isotopes that were being put down, for that clipping and that would give us an indication possibly of where the bat's origin was. So where they were, they've been feeding where they've been drinking, what they've been eating would be laid down in the fur clipping in the fur and then we'd be able to sample that and the data came back suggesting that they were coming from North East in Europe. And we were a little bit sceptical when the data first came out before it seems like a long way that these bats could have flown. But what's been really good, it's the ring recaptures have confirmed, that's where the bats were originated.

Steve Roe: 8:11

So we're out in Kent, at this place called dry, how many other people or how many groups are out from another, presumably they're from combat group, or

Daniel Hargreaves: 8:20

that's a mixture as a few groups or combat group have got four sites that they're doing. Sussex are out here at Rye one bat group, and the several back groups that have joined in so we've got people that have travelled from Somerset, you've travelled from Derby Steve, so you've had lots of different groups join in, which is really great, because it's a way of getting bat workers to work together to get people to come en-mass. If it was one bat group, they could probably cover one or two sites, perhaps in a night if they were lucky. But by teaming up, we can cover several sites. And when we did this a few years ago, we were very lucky to have a bat that was caught with one group, then less than an hour and a half later, and if a group caught it further along the coast. So it was a good way of determining the movement of bats and how long it takes them to cover distances.

Steve Roe: 9:10

And what is it about that work in the UK that sparks people interest and enthusiasm and gets them to come out on evenings like this and get involved?

Daniel Hargreaves: 9:16

I think it's just the fascination. It's the fact that any moment any of the people that are out tonight could walk over to a harp trap or mist net, and catch an animal that's flown in from 1000s of kilometres away and learn something new that nobody knows about, or nobody's ever seen before. And I think that gives us a unique opportunity. Often, you know, there's a lot of people that go out bird watching, and they get a lot of satisfaction from seeing different birds or birds move in long distances to be able to do that in settings like this, I think is what appeals to us.

Steve Roe: 9:50

And what was it that sparked your love of bats in the in the first place? What kicked it all off.

Daniel Hargreaves: 9:53

It was a primary school project on bats we had to choose an animal and I can't remember why but I chose bats. And I did a little project on it. And I purchased a book called Which bat is it by Bob Stebbings. I remember paying three pounds 50 for it, I still have that book to treasure it and at the age of seven, I don't know why I was fascinated in the penis shapes of bats over dentition over whiskered or Brandt's bats Perhaps it was slightly unusual. I should have been reading children's books but I was fascinated by this book. And then later that summer, I was asked to rescue rescue a back from the school kitchen or the school canteen. And really I wasn't rescuing a bat I was rescuing the dinner ladies that were all screaming and cowering in a corner. And after that I just fell in love with them. And I've been studying them ever since.

Steve Roe: 10:47

And what can we do as bat groups to inspire younger people to get involved because at some point we're not going to be here. What is it that we need to do?

Daniel Hargreaves: 10:54

Yeah, I think We just need to get them involved, we need to reach out to them really, it's very easy for us that are driving around and working at night to ignore children completely. But if it wasn't, for me, being at school doing small projects on bats, I wouldn't be sat here doing this now. So I think, even sometimes, if it feels futile, or you think the children aren't listening, it only takes one or two individuals to get an interest. And you never know where that's going to lead them. And I think we should always be thinking about young people in the next generation of bat workers that are going to come through and the best time to capture somebody's imagination, is when they've got an open mind. And that's often when they're a child.

Steve Roe: 11:34

And turning away from the UK for a moment, you've also set up a very successful project on the Caribbean island of Trinidad, which you've charismatically called Trini bats. How did that come about? And what made you want to set that project up?

Daniel Hargreaves: 11:45

Yeah, that was an interesting route really. We I went to Trinidad in 2009, with Bat Conservation International on one of their founders circle trips. And whilst there I met Geoffery Gomes and Jeffrey was the bat worker, really, in Trinidad and Tobago, it's it's not like the UK, if you're asked how many people are interested in bats it was just Jeffrey. He was the only member really of what, you know what we wouldn't see as a bat group in Trinidad. And the problem was Jeffrey was saying that bats in Trinidad, they were the regulations stated that they were vermin. And to try to get any sort of funding or money to study vermin was nigh on impossible. And we thought, well, obviously, they're not vermin, there was 68 species of bats in Trinidad and Tobago, and over half of them were pollinators and seed disperses. And you know, not just about what I'm doing is pest controllers. So it was interesting that a country could class something as vermin that they knew very little about. So I spoke to Jeffrey and he said, You know, I'd love to harness some of the energy from the UK from the rest of the world, get people interested in bats. What can we do about it? So I thought, Okay, well, the Caribbean sounds like a nice place to work. And I'm sure if you ask many bat workers do the fancy a couple of weeks on the Caribbean, looking at exotic bats that they'd say yes, that's how it was born, really. We started doing ecotourism trips. And we started a an NGO called Trini bats. And the rest is history, we've been doing that for 10 years, it's been very successful. We've managed to change for legislation. So bats aren't classed as vermin anymore. They are a protected species. But more importantly, we've done a lot of social outreach to people. And we have a big Facebook page. And it's open people's minds about bats, there was mysterious creatures that never, nobody ever saw. And Jeffrey has been very proactive on social media. And that's generated a lot of interest. And people are interested in what we are doing, which can only only benefit the bats.

Steve Roe: 14:28

And out of those 68 species, so there any out there that we would recognise from the UK,

Daniel Hargreaves: 14:34

We wouldn't there's several Myotis species that are as difficult to identify as some of some of our species. But really, a lot of them are doing similar roles to what to what our bats are doing over here. So you wouldn't, there wouldn't be any bats, for instance, that you would find here or you would find in the Caribbean. But the Myotis bats are out there. The rest of the bats are all fruit nectar, sea disperses and carnivorous bats as fishing bats out there. But if you look at what they're doing in their environment, it's exactly the same as what our bats are doing here. They've all found their niche of a wave feed in niche ecology. And you know, it's the same as our bats. We've just got far fewer of the

Steve Roe: 15:15

Presumerably, but it's got the advantage if you don't have to go into hibernation over the winter ever.

Daniel Hargreaves: 15:19

Absolutely. Absolutely. You got food all year round, but you have different seasons. So you have a dry in a wet season. And you've exactly like the bats here, they've got to to be able to change their behaviour to match the season. So they might be eating certain fruits. In the wet season, they might switch to flowers in the dry season. And same for insectivorous bats. So you would get migratory bats through the Caribbean that would need to move to find more food or to find better breeding grounds.

Steve Roe: 15:46

Briefly describe the Islands for us you know, presumably we're thinking it's a tropical place with lots of rain forests, how sort of how large is it? What's what sort of habitats are out there?

Daniel Hargreaves: 15:54

Interesting. Yeah, it's so Trinidad. Tobago is a lot smaller. Tobago is north of Trinidad, but if you look on a map, you've got Venezuela, and then right next to it only seven kilometres off the coast. You've got Trinidad and it's not it's not a big island. Its shape is a bit like Wales, but much smaller. You could probably drive north to south in half a day. It's not a huge island, but it's got lots of mixed habitat and because it's so close to Venezuela, the fauna and the the environment really represent Venezuela. I was in South America than what they do the rest of the Caribbean, it's a unique island 68 species of bats, it's unparalleled in the rest of the Caribbean. And what's what's been good for Trinidad and Tobago, there's lots of lots of hills, lots of ridges, lots of areas that are difficult to cultivate. And I think that's what's really helped protect the forest. And they've got lots of protected reserves out there, and they've got some urban areas mixed in. And that's why you get such a diversity of species.

Steve Roe: 16:57

And just before we go and check the harp traps that we've got set up tonight, what do you say in the future about conservation holds for us?

Daniel Hargreaves: 17:05

Good question really, is often people often think we need to conserve the bats, we need to be helping the bats as much as possible. And really, it's about looking after the environment, looking at what the bats need, and what we can do as individuals to support that. So early days, it was all about trying to see what bats we have working out what bats were. And really what we should be doing is looking at what the bats need from us what they need from the environment, what sort of landscape they need, what sort of scale of landscape they need. And that's what I think we should be, we should be looking at. And there's a few ways of doing that. But one is educating people that, you know, we need to understand what the bats need, and then people need to understand that, but also the damage that we are potentially causing just by the way that we are living. So I think, you know, thinking for the future, I think we're in a very good place at the minute in the UK, there's lots of people that are interested in helping the environment, but they're interested in it and not necessarily taking action to do it. And I think that's the next stage really, is to say if you do this, it's going to benefit these animals by this and I think that's probably what we

Steve Roe: 18:09

Great, thanks better go check a harp trap. Excellent. need to push on. This audible clicking you can hear is the sound of the acoustic lure which is set up at this harp trap. But if we slow it down by 10 times this is what it sounds like. So it's about 20 past 8 and we've just pulled out a third Nathusius' Yes. And what sort of things we're looking for

Daniel Hargreaves: 18:48

detail so to make sure everything's accurate we have a data sheet over teams are following we were looking for biometric data so the weights and measurements the forearm and identification features I'm just weighing the bat and the bag now just 38.5 Quickly, take him or her out of the bag. So it's easy math 28.5 bats weighing 10 grams which is not a lot real if you think about probably the same as what 50 pence piece slightly less

Steve Roe: 19:48

And do male and female parts have different weights for the same species?

Daniel Hargreaves: 19:53

Yeah, we've noticed lately that females are slightly heavier than the males. But I think that's just the time of year. Males are slightly more active. They've got other things on their mind. I think the females are spending a bit more time feeding. I'm just going to measure the forearm. Which is 34.3 and we'll also measure her fifth finger which gives us an indication of the species we know what species it is. It's quite easy to tell a pipistrelle weighing 10 gramss is really quite large. I often think of things like Daubenton's and Natterer's would be a big bat. This pipistrelle is even bigger. Fifth finger measurement 44. So the ratio between the length of the fifth finger in the forearm, often for Nathusius' pipistrelles is greater than 1.25. So we've been collecting that data just to see how accurate that is. So in the future, we can rely reliably say if it's an identification feature or not. But just looking at this pipistrelle Well, it's in my hand, it's much larger than a standard pipistrelle it's got incredibly dense, shaggy fur and the underside is slightly paler. And on the back, it's sort of a white creamy colour, where the dorsel fur is much browner. And you can see it's built for migration really, it's built for long distance flying, got really strong, broad shoulders. And it's really dense fur to keep it warm and the further extend about halfway down the tail membrane. They say it's really dense. But if you look at the back, she's almost all sort of shoulder regions, which means she's built for flying. We can also look at the venation in the wing, where the fibres run. Classic and Nathusius' pip, if we follow the fifth finger down to the first knuckle joint, follow that fibres as a break going across the cell, which is classic for Nathusius' pipistrelle. So we've got a female adult Nathusius' pipistrelle. He's got a little bit of a nipple looks like she's possibly bred before, probably earlier this year. And next thing we want to do is put a ring on her forearm. And we generally ring with ladies on the left, and males on the right. And these rings, it's a small metal band says London zoo at the top, and then a number below it and this one is J 6420. We just place that on the forearm, close it down to a gap of about half a mil. So it slides up and down the forearm but, the fifth finger doesn't catch into it, that ring will stay on her for the rest of her life. And if we're lucky, when she's recaptured, we'll understand exactly where she was caught. And we start to get an idea of the age of the animal. So once we have all the data, we just check, check the sheet that it's all written in correctly. And then we'll be ready to release her. Nice you can start to see just under her skin. She's starting to put a lot of fat on getting ready for the winter. So you can actually see visible fat often round by the tail membrane, and on her back this backfat which is going to see her through the winter months when there's less insects flying. So she's doing really well for herself. She's nice and warm. I will let her go and just follow in our talk like to make sure she's flown away. Nicely. Excellent.

Steve Roe: 24:26

Great. That's it for this week, but a small request from us here at BatChat. If you're listening to us via the apple podcasts app. We'd love to hear your views about the show using their ratings and reviews box. If you're listening via a different platform, join the conversation online using hashtag BatChat. We're back in two weeks time talking to the bat workers of Wales.