The UK’s rarest amphibian is taking a huge leap forward thanks to scientists behind a pioneering breeding programme.

The pool frog (Pelophylax lessonae) became extinct in the UK in the 1990s but it was reintroduced to a site in Norfolk between 2005 and 2008 by Amphibian and Reptile Conservation (ARC).

Now the wildlife charity has carried out a ground-breaking scheme to increase the animal’s population. 

The ‘head-starting’ project uses a conservation technique for endangered species in which spawn or young tadpoles are raised in captivity and subsequently released into the wild.  This allows a greater proportion to survive the riskiest part of their life-cycle away from predators or losses to other natural causes.

Spawn was collected from the original pool frog site in June 2019.  The resulting tadpoles were reared in laboratory conditions over the summer and released into ponds at Thompson Common, the last-known refuge for pool frogs before their extinction and a site where previous experimental releases have shown promise. Norfolk Wildlife Trust, which owns and manages Thompson Common, has created fantastic conditions for pool frogs by restoring ancient ponds. ARC hopes that the programme will succeed in building on the first reintroductions and increase the number of pool frogs living in the wild.

Jim Foster, ARC’s Conservation Director, said: “This is a hugely exciting but painstaking project.  In 2018 we had a record number of pool frogs recorded at the first reintroduction site, while successful breeding occurred at the second reintroduction site for the first time since extinction of the original native population.

“These encouraging early signs indicate that this form of reintroduction is a viable means of re-establishing pool frogs in the UK.”

John Milton, Head of Nature Reserves at Norfolk Wildlife Trust, said: “I’m especially excited to see pool frogs returning to Thompson Common as I was lucky to witness the spectacular vocal display of the males calling there on one balmy evening in June in the 1980s, before the population was sadly lost. It could become one of the UK natural wonders once again.”

The ARC team included staff and volunteers with specialist expertise who set up the head-starting facility, collected the spawn, monitored and maintained seven large tanks as the tadpoles developed to a size ready for release into the wild.

Alice Pawlik, who worked on-site, said: “I’ve been captivated by this reintroduction project for years and thoroughly enjoyed spending the summer surveying, rearing, and translocating this amazing species.”

The DRAHS (Disease Risk Analysis and Health Surveillance) Project, a partnership between ZSL (Zoological Society of London) and Natural England, carries out health surveillance on the pool frogs before and after release. 

Dr Tammy Shadbolt, Wildlife Veterinarian at ZSL (Zoological Society of London), said: “It's important to ensure that the pool frogs are in a good state of health and free of non-native parasites at the time of release and we were delighted to work with ARC to achieve this aim.”

ARC is grateful for donations, grants and resources offered in kind that have made the head-starting facility possible: Amphibian Ark; Anglian Water Flourishing Environment Fund, a charitable fund managed by Cambridgeshire Community Foundation; British Herpetological Society; Keith Ewart Charitable Trust; Natural England; Forestry England; Zoological Society of London and individuals who have donated via ARC’s sponsor the pool frog appeal.  ARC is especially grateful for the long-term financial and in-kind contributions from Anglian Water , Natural England, and Forestry England which have been instrumental in turning around the fortunes of the pool frog.

Video (c) ARC/Alice Pawlik