Are hot weather events harming roosting bats?

Whilst the recent hot weather has been a welcome relief for some and an opportunity to dust off the BBQ again this year, the heat is causing problems for some species including bats.

During the day, bats shelter in dark places (roosts), such as in hollow trees, in loft and attic spaces, under tiles and behind soffits, or in splits in the trunks and branches of trees, moving at different times of the year between roosting places that are used as daytime roosts and maternity roosts.

Bats known to frequently move between roosts to find the right temperature – not too cold and not too hot. But if the roost is too hot the bats become heat-stressed at which time bats can be in danger because a few degrees change can make a difference as to whether they live or die.

In periods of hot weather bat boxes and confined roosts, such as those in cavities, can be especially dangerous to bats. Scientists are now discovering that in a rapidly warming climate, overheating bat boxes and some roost spaces can be a death trap. When bats roost in an a loft or attic they can move inside the space to avoid high temperatures. However bats can’t do this as easily in a small cavity or some bat boxes and they become more vulnerable to overheating and dehydration.

During periods of high temperatures bats may even be found roosting outside of a roost space, such as these bats that were found over the weekend roosting behind a patio umbrella on the wall of a building. The bats were close to the entrance to a known roost of pipistrelle bats. Often when bats are found outside there is some concern, however these bats were found to be healthy and the umbrella was quickly placed back. 

Bats roosting outside can be an indication that not all is well within a roost and the bats within it. Dehydrated and underfed bats can sometimes be found close to roost entrances or on the ground, but there are experienced & independent volunteers who can help.

 Sometime bats found on walls aren’t in any danger and are simply roosting outside due to temperature, such as these bats that were found following the hot weather a few days ago. The bats were observed and were not in any danger and eventually returned to the nearby roost during the day. 

 Many thanks to Neil and family for the photos. 

#bats #batsonthewall #batsinhotweather #ecology