Part 1: Batty for Bats! 13th May 2022
A small but enthusiastic group set up in Springfield Quarry armed with bat detectors. We used two different types: Magenta heterodyne detectors and an EchoMeter Touch which connects to your phone or tablet. As most bats navigate using ecolocation, in sounds usually too high-pitched for us to hear, these detectors pick up the sounds and convert them to a sound we can hear. We learned more about bats in this country, and which bats we are lucky enough to find in the South-West. We were curious about what bats we might find that live in or use the quarry: would we find the elusive lesser horseshoe bat?
All bats in the UK are heavily protected and are threatened by human activity such as roost destruction or disturbance, or land use change when we build cosy houses on the fields and woodlands in which they used to hunt. Even roads and streetlights can harm bats! It was really important to find out what bats might use the quarry, if any, because it helps us work out just how good the habitat is. Luckily, much to our relief, just as we had finished learning about bats and how to use the detectors out came the bats!
We encountered the smaller pipistrelle bats (probably common pipistrelle) first of all, as one wooshed over our heads feeding on the smaller insects such as midges. We learned that they can eat up to 3000 insects a night! We don’t know where they were roosting, perhaps in cracks in the side of the quarry, but it’s more likely they have a maternity roost in a nearby house or church. This is the time of year that bats begin to give birth, so it’s a good job that there were lots of insects around the quarry to fill their bellies, as this will help the mothers to produce enough milk to feed their babies.
Later came an unexpected surprise, what we think is a serotine bat. There were at least two of these larger bats, but the real surprise came that they weren’t just flying over en route to a feeding ground: this was their feeding ground! Serotine bats usually roost on the outskirts of towns and prefer open habitats, rivers and lakes, so it wouldn’t have been unusual to find them at Entry Hill Golf Course, or further up towards Horsecombe Vale towards Tucking Mill. I really hadn’t expected them to stop off in the comparitively small quarry, but there were at least two flying low over our heads feeding for a lot time. Serotine bats are especially fond of eating beetles such as dung beetles, and from an earlier visit to Springfield Quarry I knew that there are dung beetles there.
(Above videos were not ours, but the graphs are from our own bat walk, analysed in AnalookW)
Alas, we saw no sign of horseshoe bats, lesser or greater, and so we discussed why this might be. Firstly, the quarry may not be the right habitat for them. We didn’t know how far back the “tunnel” barred by a metal door (with bat exits included) goes, so that might not be the right place for them to be. Secondly, we do know that bat populations have been struggling, so maybe there might have been some there once, but no more. Finally, we were out early in the night: some bats are happy to come out earlier in the night because they don’t mind the dusky-light or streetlights, such as pipistrelle bats. Horseshoe bats, however, are less keen on light so tend to emerge later in the night. This means that while we may not have seen any, it doesn’t mean there aren’t any around at all! Better luck next time, perhaps.
We didn’t find out if any bats are actually roosting in the quarry, either to hibernate in winter or to breed in spring. What we did learn, however, is that Springfield Quarry, a hidden wilderness in a sea of housing estates, is actually a really important feeding ground for bats. This means it must be host to a fantastic number of insects, and so I left with a sense of buoyancy having seen and heard some bats, and excitement for the bioblitz the following morning.
If you want to find out more about bat detecting, or bats in general, the Bat Conservation Trust website has lots of information on all topics bats!
– By Cat Baker