Pool frog  (Rana lessonae)

The pool frog is found across much of central Europe, as far north as Sweden and Norway (isolated populations only), and east to Russia. In the UK, they have only been recorded as possibly native from one site in Norfolk in recent years, with the last wild sighting in 1994. There has been much speculation as to whether the pool frog was native to the UK or an introduced species. Whilst there have been documented introductions in the past, recent evidence strongly indicates the species was in fact native to some areas. Evidence comes from genetic, vocalisation and fossil studies; taken together the information suggests that British pool frogs are most closely related to the Scandinavian pool frog populations. It was likely to have occurred in certain habitats in the east of England. Introduced pool frogs from central/southern Europe do occur at a few sites in England.

Pool frogs tend to prefer permanent, un-shaded ponds which can warm up quickly. The pool frogs at the last known possibly native site were found in pingos, which are a special type of pond formed by depressions in the ground as relics of the last ice age. The species seems to thrive where there are many ponds in close proximity. Pool frogs also spend part of the year away from the breeding pond, dispersing across grassland and woodland.