ARC's Pool Frog Recovery Project Manager, John Baker shares news of early indications of breeding success at Thompson Common after last years challenging weather

ARC’s pool frog recovery project is much of the way through another busy round of seasonal work. The drought during the summer of last year raised concerns over its impact on the wild populations. The pool frog is a warmth-loving species, and although it generally fares well in warmer summers, it cannot survive without water.

During last summer’s drought several breeding ponds dried out at both of the pool frog sites before tadpoles could complete development. In the remaining ponds water levels dropped to leave perimeters of bare mud around ponds rather than vegetation. Normally, at metamorphosis, and for a few subsequent weeks throughout August, newly emerged northern pool frogs live in the vegetated edges of ponds, basking on floating vegetation and gradually moving onto land. The loss of this microhabitat is likely to have made life difficult for last year’s metamorphs and presumably all amphibians faced further challenges once they had left the water, as the extreme aridity of the environment must have limited opportunities to forage and increased mortality due to desiccation.

Surveys undertaken earlier this year indicated that both populations had decreased in size, with counts of adult frogs more than halved at both sites. The common frog population had also taken a hit but the greater numbers of common frogs at both sites means that its populations are likely to make a recovery. Immediately prior to the drought the pool frog population reintroduced to Thompson Common seemed to have become thoroughly well-established – the counts of breeding adults had increased, and frogs were extending their range within the reserve.  Although it is sad to see the frog numbers taking a backward step, it is hopeful that the population has been sufficiently large to withstand environmental impacts - such as drought. 

Early indications of this year’s breeding success at Thompson Common are as positive as can be hoped for. The frogs have bred in four ponds. Tadpoles have grown well and development has been faster than usual, presumably hastened by the record-warm June; the first metamorphs were seen on 11 July.  We will not be able to fully assess this year’s breeding success for a few more weeks when metamorph numbers are expected to peak, but the early signs give hope for a productive year, which will be essential if the population is to recover from the recent crash in numbers.

This summer Nick Jowett and Rachel Haynes have been undertaking ARC’s head-starting, which involves rearing tadpoles in captivity to boost the numbers of young frogs above the survival levels seen in the wild. Rachel and Nick hope to release approximately two hundred well-grown tadpoles back into the wild over the next few weeks, which will provide an important boost to the wild populations.

We are extremely grateful to the Douglas and Joanne Chapman Animal Trust and Forestry England for supporting head-starting work and the following funders of this year’s pool frog recovery work; the Beveridge Herpetological Trust, the William Dean Trust and The Chapman Charitable Trust.