The Serotine Bat (Eptesicus serotinus) is a fairly large European bat with quite large ears. It has a wingspan of around 370mm and often hunts in woodland. It sometimes roosts in buildings, hanging upside down, in small groups or individually. Its population is believed to be in decline.
The frequencies used by this bat species for echolocation lie between 25-55 kHz, have most energy at 31 kHz and have an average duration of 8.8 ms.