Pelophylax lessonae - formerly Rana lessonae

Where to find them

Native pool frogs were presumed extinct in the wild in 1995, but have since been reintroduced at two sites in Norfolk. Northern clade pool frogs are found only in very restricted areas of Scandinavia, Estonia and England. The first reintroduction of pool frogs to England was established using northern clade pool frogs collected in Sweden under special permissions between 2005 to 2008. The second and most recent reintroduction was carried out using stock from the first successfully established population. For more information on the second reintroduction please see: "Re-introducing the northern pool frog to NWT Thompson Common Norfolk

Identification

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 which is generated by a pair of inflatable pouches (vocal sacs) each side of the mouth; a feature absent from the common frog Rana temporaria.

Lifecycle

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.

Protection

The pool frog has full protection under UK law, including The Wildlife and Countryside Act 1981 and the Conservation of Habitats and Species Regulations 2017. 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.

ARC’s pool frog conservation work

Amphibian and Reptile Conservation – and its predecessor The Herpetological Conservation Trust - has been at the forefront of pool frog conservation since concerns about the species first arose. In collaboration with English Nature (now Natural England), we investigated the status of the pool frog and helped to determine that it was in fact a native species. We worked on the first Species Action Plan, which guided early work on the species, as well as more recent action plans and a reintroduction strategy. In practical terms, this planning has led to the first two reintroduction projects in Norfolk, as explained above. We have been central to the actual reintroduction projects – securing the permissions and funding needed, organising habitat management, undertaking releases and follow-up monitoring. We work with government to ensure that pool frog requirements are taken in to account in biodiversity planning and strategies. Most of this work is done in partnership with other others, including Natural England, University of Kent, Brighton University, Forestry Commission, Norfolk Wildlife Trust, Zoological Society of London, and independent herpetologists.

We are especially grateful for the long-term financial and in-kind contributions from Anglian Water and Natural England, which have been instrumental in turning around the fortunes of the pool frog. Other funders have also generously supported our pool frog work at various points, including Heritage Lottery Fund via the Breaking New Ground project.

Photo Gallery

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