Bats waking up mid-winter

This Common Pipistrelle (Pipistrellus pipistrellus) appeared in our neighbours living room a couple of nights back and chatting to Rob Colley it's apparent that there have been a number of sightings of active bats recently.

There's no obvious explanation why bats should emerge mid-winter, but an interesting coincidence was that they appeared around the same time that Winter Moths (Operophtera brumata) were noted on the wing in good numbers. It's tempting to speculate that bats are able to coincide their winter activities with those of the Winter Moth?