Grantham Ecology

We were carrying out a building inspection earlier this week, looking into nooks and crannies to see if we could find bats, or evidence of their presence. To reach these features safely, a cherry-picker was hired to lift us into place. The operator was very friendly and interested in what we were doing. When I asked him to take me up to a crevice above a window, he said;

‘You’ll never get a bat in there’

‘You will…’

‘No way… how small are they? I thought they hung up in the rafters?’

The ‘hanging bat’ stereotype is very widespread but really not true of many of bat species in this country. The two horseshoe species will always be found hanging upside-down in the classic pose and some other species will also hang upside down, including the brown long-eared and some of the myotis species. However a number of UK species, including the common pipistrelle – the species you are most likely to see flying in gardens – prefer to roost in crevices where they wedge themselves in quite tightly. Other species falling into the ‘crevice dwelling’ category include the other two pipistrelle species – soprano and Nathusius – the Daubenton’s bat, the larger noctule, serotine and Leisler’s bats, and the rarer woodland dwelling barbastelle bat.

The common pipistrelle bat is often found roosting in crevice-type features in houses, such as beneath lifted hanging tiles or roof tiles, in gaps around windows, in gaps in brickwork or underneath lifted flashing. The gaps they can squeeze into are really very small – 2cm is quite enough for them to get inside.

Last week I was lucky enough to spend a few days climbing trees and inspecting potential roosting features up in Cumbria where we found a common pipistrelle bat roosting in a hollow in a tree limb over a stream. The video quality isn’t fantastic because it is filmed using an endoscope – this invaluable piece of kit is a camera and light mounted on a long flexible ‘snake’ attached to a hand-held screen which you can feed carefully into potential roosting features and look for the bats in places you could never otherwise inspect. Although the quality isn’t great, I think this clip gives a nice insight into the kind of places these bats will choose to roost.

For many more video clips of bats roosting in trees, I would recommend you to check out the Bat Tree Habitat Key page on Facebook.