As my plans to set sail across the Bay of Biscay with ORCA this year have been paused due to the pandemic, I have found myself a new wildlife fix in which to sink what seems a copious amount of free time into... Bats!
This summer I have been working as a seasonal Bat Surveyor, conducting emergence surveys in the evenings across Yorkshire. Emergence surveys involve keeping a keen eye on your designated building(s) whilst listening out (heterodyne detector in hand) for any bat activity. During these evening escapades, I have developed my survey skills and have started to fine tune my ears to distinguish different bat calls – it’s quite a tricky business for newbies! For the first couple of surveys (much to my relief), the main goal was to differentiate bat from bird… You laugh but it is actually very difficult if the bats aren’t echolocating!
Image: Nina Herbert. North Yorkshire. 2020.
Interestingly, bats make up one fifth of all mammals (they are the only flying mammal) and there are between 1100 and 1300 different species worldwide. 18 of these reside in the UK, of which 17 are known to actively breed here. Yorkshire is home to 11 species of bat, including the whiskered bat (Myotis mystacinus), common pipistrelle (Pipistrellus pipistrellus), noctule (Nyctalus noctula) and brown long-eared bat (Plecotus auritus). For anyone who doesn't know, bats are protected in the UK under the British Wildlife and Countryside Act (1981) and European law. This means it is illegal to harm or displace bats from roosts. They are protected because their numbers have declined so rapidly in the last century due to a number of factors such as habitat loss and fragmentation, a falling number of insects to feed on and disruption to their natural roosts through the clearing of trees and woodland. Listed below are the 18 species of bat you can find in Britain – the greater mouse-eared bat (Myotis myotis) is classed as a vagrant species and is the only species not actively breeding here. It was officially recorded as extinct in 1990 but in 2002, a single individual was recorded residing in the South of England and has remained in the region year on year.
Alcathoe bat (Myotis Alcathoe)
Barbastelle (Barbastella barbastellus)
Bechstein’s bat (Myotis bechsteinii)
Brandt’s bat (Myotis brandtii)
Brown long-eared bat (Plecotus auritus)
Common pipistrelle (Pipistrellus pipistrellus)
Daubenton’s bat (Myotis daubentonii)
Greater horseshoe bat (Rhinolophus ferrumequinum)
Grey long-eared bat (Plecotus austriacus)
Leisler’s bat (Nyctalus leisleri)
Lesser horseshoe bat (Rhinolophus hipposideros)
Nathusius’ pipistrelle (Pipistrellus nathusii)
Natterer’s bat (Myotis nattereri)
Noctule (Nyctalus noctula)
Serotine (Eptesicus serotinus)
Soprano pipistrelle (Pipistrellus pygmaeus)
Whiskered bat (Myotis mystacinus)
Greater mouse-eared bat (Myotis myotis)
Quick Fire Characteristics
As the sun starts to set, it can be quite difficult to define what species you have encountered by eyesight alone. Noctules are one of the largest UK bat species and often emerge around this time. They typically roost in trees and are distinguishable by their fast, high flying and 'chip chop' popping noises. Noctules are usually mistaken for swifts because of this characteristic. Common pipistrelles are generally the next species to emerge. In contrast to noctules, these bats are one of the UK’s smallest species, so much so that they could fit into a matchbox! Common pipistrelles have a loud, clicking call that peaks at around 45kHz and sounds like a slapping noise (very technical description… you’re welcome). Soprano pipistrelles have a similar call but peak at around 55kHz and sound slightly higher pitched, hence the name, 'soprano'. These are also very small and dart around catching insects mid-flight. Both pipistrelle species can eat up to 3000 insects per night! My favourite UK species however, is the brown-long eared bat. These fuzzy brown mammals tend to emerge later in the evening, usually around half an hour after sunset on a clear night. Their calls peak at 35kHz and sound like a soft, fluttering noise. (I have definitely seen a brown long-eared bat before I have heard it!) When resting, brown long-eared bats tend to tuck their large ears under their wings. Sounds cosy, right?
I have been lucky enough to encounter several species during my surveys including the above mentioned common pipistrelle, soprano pipistrelle, noctule and my favourite, the brown-long eared bat. I can now confidently distinguish each of these species by their calls - it takes practice though! This photograph (left) shows a colony of 8 brown long-eared bats roosting on a beam which we were fortunate enough to see during one of our surveys. The photo was taken by a licensed ecologist and an infrared lens was used on the torch as to not stun the bats. Believe it or not, it is quite a rare sight to see bats grouped together like this in the open – usually they are roosting behind tiles or in between insulated roofing!
Image: Brown long-eared bats (Plecotus auritus). Photo credit to Emily Ramsden, a licensed Ecologist. North Yorkshire. 2020.
Ways You Can Help
If you are interested in encouraging your local population of bats then there are some simple ways you can help. Bat boxes are one of the easiest options – these are different to bird boxes as they have a narrow slot at the bottom to allow easy entry. Bat boxes act as safe places for bats to roost and have small indents inside for them to hold on to. These should be located at least 5 metres above the ground as bats often drop when they emerge. You can also plant trees or shrubs if you want to encourage bat activity. This will help because insects thrive around shrubbery and hedgerows, and bats thrive on insects! Planting night-scented flowers such as honeysuckle (Lonicera periclymenum) and evening primrose (Oenothera biennis) and building a pond can also encourage bats – again, this increases insect numbers which means more testy meals for the bats. If you are interested in learning more about our British bat population then check out the sources below. They provide very useful information including species factsheets and echolocation sound clips for each species.
Thanks for reading!
Sources
Bat Conservation Trust
Hampshire & Isle of Wight Wildlife Trusts
Yorkshire Wildlife Trust