ARC's Pool Frog Recovery Project Manager, John Baker shares news of surprise spawning, population growth, testing new survey techniques and more.

The pool frog survey season is well under way.  Frogs at the primary reintroduction site (a confidential location where frogs were originally translocated from Sweden) started breeding early this year.  On the first Saturday in May, during overcast weather, pool frogs were barely active during the morning, but by the afternoon two pairs were in amplexus and spawn produced. Normally spawning occurs during warmer weather and usually after a great deal of calling and jostling among males. This time there were no precursors and the males had not changed into their pale green breeding coloration.  They continue to surprise us.

Song Meter Micros will be trialled in pool frog surveys this year

ARC has welcomed some new pool frog survey volunteers this year who have attended training. An identification guide has been produced to help surveyors distinguish the different life stage of pool frogs (male/female/juvenile/metamorph). Funding from the Green Recovery Challenge Fund has allowed ARC to purchase wildlife sound recording units (Song Meter Micros) which we are testing in the field this year to extend surveys over a greater area. Detection of frog calls is often used abroad but it has not been used before to survey for native British frogs and toads.

Early survey results from the second site, at Thompson Common, indicate that the population there has made a significant increase in numbers this year. The counts of adult frogs have already exceeded those of previous years and pool frogs have spread to additional ponds within the reserve. Julia Mumford-Smith, of Norfolk Wildlife Trust, has found the frogs in an area where they were last reported in the 1970s, by former ARC employee John Buckley.

Amphibian pond and beaver dam on ditch

Work to identify and evaluate additional reintroduction sites continues. Recently this has involved visits to sites where beavers have been released in enclosed areas. It is too early to say yet whether the beavers will shape their habitat in the favour of the northern pool frog, but experience elsewhere (including a beaver release site in Cornwall) has shown that amphibians in general do rather well in beaver ponds. It would be particularly pleasing to see pool frogs established in a habitat restored by beaver.

There is also some sad news to report – the passing of Charles Snell, who died earlier this month. Charles more than anyone else prompted the re-evaluation pool frog status, setting the stage for the reintroduction (e.g. Snell, 1994, The pool frog - a neglected native? British Wildlife 6(1), 1-4). Charles was one of the last people to see northern pool frogs at Thompson Common, in a compartment along the Great Eastern Pingo Trail. A male and two female pool frogs have been seen in these ponds this spring. It would be fitting if they were to breed here for the first time since Charles last saw them at Thompson Common in the 1990s.

If you would like to find out more about ARC’s Pool Frog Recovery Project please visit the project page.

ARC’s Pool Frog Recovery Project is funded by the Government's Green Recovery Challenge Fund. The fund was developed by Defra and its Arm's-Length Bodies. It is being delivered by The National Lottery Heritage Fund in partnership with Natural England, the Environment Agency and Forestry Commission.