Projects Promising news for northern pool frog populations By Emily Jordan - Pool Frog Recovery Project Assistant & John Baker - Pool Frog Recovery Project Manager Following on from our releases of captive-reared tadpoles in July, the pool frog recovery team has been busy surveying for emerging ‘metamorphs’. A metamorph is a young amphibian that has just completed metamorphosis; it has developed hind and fore-limbs, and has absorbed all or most of its tail. Once the tail is completely absorbed pool frog metamorphs look like miniature versions of the adult frog. The numbers present are an indicator of breeding success in that year. This August we were able to find a really promising number of pool frog metamorphs at Norfolk Wildlife Trust’s Thompson Common, the highest count since they were introduced to this site in 2015! Metamorphs were present at wild-breeding ponds as well as ponds where we had released captive-reared tadpoles, indicating that the frogs multiplied well naturally in addition to receiving a boost from head-starting efforts. At the initial reintroduction site, in a confidential location, the population is likewise continuing to spawn successfully and we have observed emerging pool frog metamorphs across multiple ponds, some of which were also supplemented with head-started animals. This is great news for both of the populations and hopefully we will continue to see increases in future years. The Institute of Zoology has carried out regular health examinations of pool frogs (and other amphibians) at both reintroduction sites since the species was reintroduced to England, with the latest examinations conducted during August this year to coincide with metamorph emergence. No significant health or disease problems have been found at either site and the pool frog recovery team and the rest of ARC hopes the results of this year’s examinations will be no different. Even though northern pool frogs are currently hibernating, project staff have been busy identifying, assessing and visiting potential future reintroduction sites and meeting with landowners and managers. Northern pool frogs are fussy about their habitat so a guide to what they require has been produced to help future potential partners decide whether their sites might be right for the frogs. This is available as a document or brief video clip, both of which can be downloaded from the project web page (below). Several ponds at the first reintroduction site have been restored. In practice this means that ponds that have become overgrown with vegetation have been opened up, allowing in more sunlight. This will also benefit a range of other species, including all sorts of rare aquatic life that shares ponds with pool frogs. We have been reviewing the various head-starting (captive rearing and release) methods used for northern pool frogs over the years. Head-starting this year has been particularly successful, producing the greatest quantity, and highest quality, of tadpoles so far. Five hundred and fortytwo tadpoles were released, exceeding our target by over 80%, with tadpoles growing up to 70mm long! We have recently enjoyed hosting an international workshop with experienced amphibian conservation experts from across Europe, to assess methods for increasing the numbers of northern pool frogs in the future.
Above and top right: Pool frog metamorphs © John Baker (ARC).
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You can read more about the project at www.arctrust.org/recovering-the-pool-frog-englandsrarest-amphibian
This 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.
