Pelophylax lessonae - formerly Rana lessonae

Where to find them

Pool frogs were presumed extinct in the wild in 1995, but have since been reintroduced at two sites in Norfolk. The first was established using frogs collected in Sweden under special permissions from 2005 to 2008. The second population is being created by transferring frogs from that first population, starting in August 2015. For more information on the second release, please see this leaflet:"Re-introducing the northern pool frog to NWT Thompson Common Norfolk


Pool frogs are extremely variable in colour, although the type reintroduced to the UK are predominantly brown with dark brown or black blotches over the back and a lighter, often yellow, dorsal stripe.

Pool frogs are around the same size as common frogs, typically up to 6cm in length, with females slightly larger than males. During the breeding season the males have a loud call generated by a pair of inflatable pouches (vocal sacs) each side of the mouth; a feature absent from the common frog Rana temporaria.


Pool frogs breed much later in the year than the common frog. Breeding coincides with the onset of warm nights in May/June. The spawn ‘rafts’ are typically smaller than those of the common frog, and individual eggs are brown above and yellowish below. Pool frogs (and other members of the green frog 'complex') are known to bask in the sunshine on even the hottest days.


The pool frog has full protection under UK law. It is an offence to kill, injure, capture or disturb them, and to damage or destroy pool frog breeding or resting habitat. It is also illegal to sell or trade pool frogs. This law applies to all life-stages.