Thompson Common in Norfolk was the last refuge of the Pool Frog, one of the two native frog species to the UK, which went extinct in this country in the 1990s. Following the Norfolk Pingo Mapping Project in 2008 and an initial release of Pool Frogs, this project created more suitable habitat and released huge numbers of young frogs with the aim of re-creating a self sustaining population.
Practical conservation work was undertaken by volunteer work parties, led by Norfolk Wildlife Trust to restore the pingos to a suitable state for Pool Frogs to live in. 28 pingos were restored by means of removing scrub of various age structure and removal of hydra from the pingos themselves. Initial surveys identified Youngs Covert and Oldhouse Yard Covert in Hockham as linked sites to be restored which would eventually allow Pool Frog to spread to and create a stronger population. Landowners and managers were trained in pingo management and the reintroduction created a lot of media interest. Two interpretation boards were installed on the pingo trail and leaflets produced to educate visitors to the area.
After considerable time analysing the genetics of remaining Pool Frog populations in Europe, the most genetically similar individuals to those who used to exist at Thompson Common were found to reside in Sweden. ARC Trust carefully planned the capture and breeding of Pool Frogs from Sweden with EU and ZSL consent and advice. 590 frogs were released during 2015-16 and early monitoring indicates that 2015 individuals over-wintered. It will take up to 10 years to know for certain if the population has been successfully established but ARC and NWT will be working together to achieve that goal through habitat management and the release of more tadpoles and froglets.
"An amazing event for me personally, it's the culmination of a huge amount of work by Norfolk Wildlife Trust, restoring areas of Thompson Common…."
John Milton, Norfolk Wildlife Trust, on the release of Pool Frogs at Thompson Common
A pingo is a periglacial landform which occurs when ground ice freezes and pushes the earth above it to create a bulge or small hill. When the ice retreated and the Brecks thawed out at the end of the last Ice Age, the pingos collapsed, leaving behind the inverse of a hill - a depression. These depressions, commonly mistaken for ponds, filled with water and fluctuate with groundwater levels. They are found in large numbers, scattered across the North East of the Brecks, most notably at Thompson Common. They are found in Siberia, Canada and Norway but nowhere else in the UK.
The project was delivered by Norfolk WIldlife Trust and Amphibian & Reptile Conservation
Pingo Management course attendee