Nick Upton / Rescued Serotine bat (Eptesicus serotinus) having its recovery and ability to fly tested in a flight cage by Samantha Pickering before release back to the wild, North Devon Bat Care, Barnstaple, Devon...

Nick Upton / Rescued Serotine bat (Eptesicus serotinus) held in a hand performing a threat display while having its recovery and ability to fly tested in a flight cage before release back to the wild, North Devon...

Nick Upton / Serotine bat (Eptesicus serotinus) with a numbered ring fitted a year earlier held with a wing spread during an autumn swarming survey run by the Wiltshire Bat Group, near Box, Wiltshire, UK, Septembe...

Nick Upton / Serotine bat (Eptesicus serotinus) with a numbered ring fitted a year earlier held during an autumn swarming survey run by the Wiltshire Bat Group, near Box, Wiltshire, UK, September. Model released.

Nick Upton / James Shipman inspecting a Serotine bat (Eptesicus serotinus) with a numbered ring he fitted a year earlier, caught during an autumn swarming survey run by the Wiltshire Bat Group, near Box, Wiltshire...

MYN / Paul van Hoof / Comparison of bat droppings. Brown long-eared bat (Plecotus auritus) left, Common pipistrelle (Pipistrellus pipistrellus) top, Serotine bat (eptesicus serotinus) right. The Netherlands, September, Mee...

MYN / Paul van Hoof / Serotine bat (Eptesicus serotinus) female, The Netherlands, May. Meetyourneighbours.net project

MYN / Paul van Hoof / Serotine bat (Eptesicus serotinus) female, The Netherlands, May. Meetyourneighbours.net project

Eric Medard / Serotine bat (Eptesicus serotinus) flying low over water, taken at night with infra-red remote camera trap, France, July.

Michael Durham / Big brown bat (Eptesicus fuscus) in flight at night, Sulphur Springs, Central Washington Desert, USA, June.

Michael Durham / Big brown bat (Eptesicus fuscus) portrait, Central Washington, USA, June.

Michael Durham / Bat bug (Heteroptera) ectoparasite feeding on part of the wing of a Big brown bat (Eptesicus fuscus) Arizona, USA, July.