My First Bat Walk: What I Learned About Our Local Bats
I recently went on a bat walk here in Northern Ireland with BTO. It was my first time seeing bats properly and I want to share some of the amazing information I learnt.
We walked along a greenway that was lined by trees just as the sun was setting. The whole group was interested in bats and multiple bat detectors were given out. I actually wasn’t expecting we would see any bats as I had not really before, the shock of seeing bats almost instantly manoeuvring through the air, targeting their prey, left my mouth wide open.
Ireland's Bats
Bats are mammals and belong to the Order Chiroptera. They are the only mammals capable of true flight. They comprise of around 20% of all classified mammals species worldwide.
In Ireland we have 9 bat species in total, eight from one family and one from another.
Family Vespertilionidae
Vespertilionid bats have a plain muzzle, and a flap of skin outside the ear called a tragus, this flap is important for knowing the vertical position of prey when foraging.
On the walk we mostly heard pipistrelles, but Ireland is home to a wider variety of bats than you might expect:
- Common pipistrelle (Pipistrellus pipistrellus)
- Soprano pipistrelle (Pipistrellus pygmaeus)
- Nathusius’ pipistrelle (Pipistrellus nathusii)
- Leisler’s bat (Nyctalus leisleri)
- Brown long-eared bat (Plecotus auritus)
- Daubenton’s bat (Myotis daubentonii)
- Whiskered bat (Myotis mystacinus)
- Natterer’s bat (Myotis nattereri)
Family Rhinolophidae
Compared to the Vespertilionid bats, Rhinolophid bats have a more complicated muzzle, with flaps of skin called a noseleaf. These bats also focus their echolocation through their nose. The bat below is the only bat to hang from its feet in Ireland.
- lesser horseshoe bat (Rhinolophus hipposideros) - Not found in Northern Ireland
If I had to pick a favourite from the above it would have to be the Nathusius’ pipistrelle as it's just so adorable and cute, and there are a lot of them local to me.
Life Cycle
Most Irish bats start to become active around early summer. Also in early summer female bats get together in a nursery, this is called a colony.
In a nursery the mothers start to give birth around late June or early July and each mother will only give birth to a single pup. By 6-7 weeks the pups will be independent after feeding on the mothers milk.
Around mid august mating will start to take place, this happens in a swarming site or in a roost protected by a single male called a harem. Females retain sperm throughout the winter and do not ovulate until spring.
In Ireland, bats and hedgehogs are the only mammals that truly hibernate. Currently very little is known about bat hibernation in Ireland and where they go.
The average lifespan of a bat is around 7–8 years and some can live a bit longer. This is pretty long compared to other similarly sized creatures.
Roosts
One of the most fascinating things about bats is where they choose to live.
Bats typically rely and roost in buildings. Think of attics, bridges, crawl spaces etc. They mostly stay here in summer months then go elsewhere to hibernate for the winter.
Near me in Antrim we have a roost of Nathusius’ Pipistrelle which is the one of rarest species of bat in Northern Ireland. From this paper The status of Nathusius' pipistrelle (Pipistrellus nathusii Keyserling & Blasius, 1839) in the British Isles we can see in 1997 a roost was confirmed at Antrim Clotworthy Arts Centre - "1997 Roost Antrim, N. Ireland Clotworthy Arts Centre JMR/JKO Russ et al. (1998)"
There are a lot of Nathusius here in this roost, this report in 2015 estimates around 500 roosting here! I have also walked around here and heard them in the roosts myself!
From that same report it shows that it is also a Nursery roost which is mentioned above, these are usually the largest roosts.
Protection
It's important to know that bats both in Ireland and Northern Ireland are protected by law. It is illegal to disturb, injure, kill or disturb their resting place. When going near a roost, or dealing with bats, it's very important to contact and get advice with the corresponding agencies:
- Ireland - National Parks & Wildlife Service
- Northern Ireland - DAERA
Echolocation
Firstly, there is no such thing as a blind bat! All bats can see, and most use a form of sonar to help them navigate in dark environments. They use this form of sound to bounce of object and listen so that they know where it is.
You can hear this with bat detectors that measure this in kilhohertz. When walking around with a detector the bats sound like they are making squeaks and pops. You can hear them zoning in on their prey which is awesome.
When listening on the bat walk, you can hear a series of clicks from the detector and you can tune into certain frequencies, we were able to hear common pipistrelles and a soprano pipistrelles. The feeling of seeing and hearing their echolocation at the same time was brilliant, they were zooming over our heads eating away.
More can be read about echolocation here What is echolocation & how do bats use it?. I really liked this article and they are lots of interesting facts about some of the bats above.
Reflection
This first bat walk has shown me how amazing and important our local bats are. They play a vital role in our ecosystem, helping to control insect populations and providing food for other predators. I was surprised to learn we have more species than I ever imagined, and that on some nights you might even encounter several in the same spot. I’ll definitely be going on more walks to test this out, and I plan to get a detector so I can contribute even more to my growing list of citizen science records.