Pipistrelle bats  (Pipistrellus pipistrellus and Pipistrellus pygmaeus)

It was recently discovered that there are actually two species of pipistrelle bat formerly grouped together as Pipistrellus pipistrellus. Both species are very similar but differences in the frequency of the echolocation calls and genetic differences distinguish the two (2), P. Pipistrellus echolocates at 45 kHz, and P. pygmaeus at 55 kHz (2). Research into behavioural and ecological differences between the two species is currently underway. The pipistrelles are Britain's smallest bats (4), are generally brown in colour, and have fast 'jerky' flight. An individual can eat up to 3000 insects a night (2).