Pioneering work on Cavan’s newest bat

RESEARCH Nathusius’ pipistrelle was first ringed in the Republic in Killeshandra

A Virginia based expert is amongst a group of researchers carrying out pioneering work on the Republic’s newest species of bat.

While the Nathusius’ pipistrelle has been resident in Ireland since the 1990s, it was only trapped and ringed south of the border for the first time in September 2018. The location for that significant event was Killeshandra, and Dr Tina Aughney from Virginia is among those undertaking the delicate work. She is a member of the Nathusius’ Pipistrelle Working Group, a small voluntary team of bat experts who have all been specially trained to handle and ring the protected mammal.

“Bat ringing is very rarely done,” explains Tina. “We got a licence for the Nathusius’ Pipistrelle Working Group, and it’s one of the few ringing projects in the country.”

Six Nathusius’ pipistrelles were caught over a couple of nights in Killeshandra - three males and three females.

“Nathusius pippistrelle are very gentle to work with – when ringing them, they were very patient with us. It’s a bat species I’m only getting to know because I’ve only been working with them for the last few years.”

Research ground to a halt with the arrival of the pandemic so they have not had been able to chart the extent of the bats’ terrain.

“Because of Covid-19 we weren’t able to go out and retrap in 2020. So unfortunately we won’t know until we are able to go back out and start trapping again.”

Nathusius’ pipistrelles weigh between 6-10g, which may sound minuscule, but they are by no means the smallest Irish bat.

“The smallest ones are the soprano and common pipistrelles - they are about 5g,” says Tina. “That’s the thing about bats - people think these are giant mammals flying at night-time, but they are very small mammals. The biggest one we have, the Leisler’s bat would fit into the palm of your hand, but it’s just they do have big wings, and in the hours of darkness our imagination flies away with us.”

Stronghold

Now established with a resident population Tina assures Nathusius’ pipistrelle doesn’t pose concerns for our biodiversity or other bat populations.

“Each of the bat species have their own niches and they are not in competition,” explains Tina. “It’s been on the island for about three decades. It was first recorded in Northern Ireland in the early 1990s. It’s primarily associated with large water bodies, so its stronghold is Lough Neagh.

“Cavan, with the Lough Oughter complex, is an amazing habitat. So we are getting records further and further south, but the stronghold seems to be Northern Ireland and the border counties.”

What attracts them to large lake water bodies?

“It is the volume of insects associated with lake water bodies, it primarily feeds on aquatic insects.”

While they are relative newcomers to Ireland, they are widely dispersed across Europe.

“They are an extraordinary migrant species in mainland Europe,” she says of the bat that can travel up to 2,000km. “They tend to have their winter residence in Eastern Europe, and their summer residence in Western Europe. So they have been known to travel hundreds of kilometers in between the two seasons. But they consider that the population that emigrated to Ireland has stayed here, because we have summer roosts and we have winter roosts - there is a population all year round. So for some reason, they arrived and thought: no, we’re happy out here.”

Asked if it is possible we have a year-long resident population, but numbers are swollen by migrants, Tina is circumspect.

“There is quite a lot of ringing in the UK and we haven’t seen any of their ringed bats turn up in Ireland. The answer to that at the moment is: we don’t know, but we don’t have any evidence to say yes or no. That’s the whole point of these exercises - to gain that information.”

She adds: “It’s quite a rough sea to be crossing back and forward to be honest – between the North Sea and the Irish Sea, so I think, once they are here, they are here.”

Hunting calls

Once permitted to conduct surveys again, Tina is confident of finding populations in Cavan due to regularly ‘hearing’ their ultrasonic hunting calls on bat detector devices.

“Each bat species has their own characteristic hunting call,” Tina outlines. “The Nathusius’ pipistrelle has a peak frequency at 38khz – to put that in context, our hearing is at 20khz. We are picking up that 38khz Nathusius’ pipistrelle, and we have been consistently picking it up in Cavan. I have picked it up down here in Virginia around Lough Ramor.

“We had a student working on the lake in 2015, and he regularly picked up Nathusius’ pipistrelle, so they are there, it’s just that we don’t know information about what the population is like. That’s why we decided to start this working group, because similar work is being done in the UK. We decided to try to get a handle on where the species is on the island of Ireland, and to document that. Literally this is very much the pioneering efforts. It’s an unknown for us so we’re looking forward to seeing what happens over the next few years.”

The Celt notes there’s no reason they wouldn’t be in Sheelin as well.

“They are a relatively big bat and because they are a migratory bat, they are well able to fly. Each of our bat species have a particular distance they can fly in the night, but the Nathusius’ pippistrelle can cover quite a distance. So they could easily have their roosting sites in one place but head off 20km to feed in a really nice lake nearby.

“That’s the thing – it’s establishing their range. We have a lot of unknowns when it comes to this particular species, so it is quite exciting to fill in those gaps.”