World first for Critically Endangered frog

In a world-first attempt, 27 Critically Endangered, captive-bred mountain chicken frogs have been released into a semi-wild enclosure in their native home of Montserrat, with the aim to restore a population of this once-abundant species to the Eastern Caribbean island.

Despite surviving hurricanes, volcanic eruptions and being hunted for centuries on their native islands of Montserrat and Dominica, the mountain chicken frog was driven to the brink of extinction by a deadly microscopic fungus, commonly known as chytrid.

This pioneering release is the first stage of a project that uses environmental manipulation techniques in an attempt to protect the species from the deadly fungal pathogen, believed to be the cause of over 500 documented extinctions and declines of amphibians worldwide.

A collaboration of experts from The Mountain Chicken Recovery Programme, including Durrell Wildlife Conservation Trust, are now working to establish a chytrid-free refuge for the mountain chicken frog, using first-of-its-kind environmental manipulation techniques. As chytrid cannot survive in temperatures above 30°C, the semi-wild enclosure was designed to contain artificially heated areas, which should ensure the pools remain free from the pathogen. Made up of forest floor clearings, basking sites, and heated water pools, this ‘safe haven’ uses green heating initiatives such as solar-powered smart ponds that regulate their own temperature, making it uninhabitable for chytrid.

Dr Mike Hudson, who leads the project for both Durrell and ZSL, says: “Currently, there is no known method for eradicating chytrid from the wild. We have had to think outside the box and come up with a mechanism for enabling frogs to survive alongside the fungus in their natural environment. In this world-first attempt at using environmental manipulation to mitigate the disease in the wild, we are hoping to not only make steps towards saving the incredibly threatened mountain chicken frog, but also to provide a model system that can inspire conservation action for hundreds of other species affected by the disease globally.”

The newly released frogs brought to Montserrat from Durrell’s headquarters at Jersey Zoo and ZSL London Zoo, are being closely monitored and regularly tested for signs of infection. Their use of the semi-wild enclosure compared with their natural unmanipulated habitat is also being assessed in order to evaluate the effectiveness of this method in countering chytrid fungus. The next two years will be spent tracking the presence of the pathogen to see how it responds to the manipulated environmental conditions.

If successful, this project could be expanded to create a connected network of ‘safe havens’ for mountain chickens across Montserrat. The success of this project will see the establishment of the first breeding population of mountain chickens on the island in 10 years. It is hoped that the techniques developed in this ground-breaking project can be applied to amphibian conservation globally as a way to protect species from the deadly chytrid fungus.

Ben Tapley, Curator of Reptiles and Amphibians at ZSL London Zoo said: “It’s an enormous privilege to be part of such a ground-breaking project that really demonstrates the importance of conservation breeding in zoos in response to chytrid mediated amphibian population declines. The solar-powered ponds were trialed with mountain chicken frogs in carefully designed facilities within zoo settings before the release – and so far, it looks promising!”

The project is a collaboration between Durrell Wildlife Conservation Trust, Zoological Society of London (ZSL), Chester Zoo, Bristol Zoo Gardens, Nordens Ark and the Government of Montserrat.