Andrew Cunningham
Deputy Director of Science
One of the largest frogs in the world
The mountain chicken (Leptodactylus fallax) is not a chicken. It is a frog. Officially named the Giant Ditch Frog and locally known as a mountain chicken possibly because of its large drumstick like legs which were once eaten for food. The mountain chicken is one of the largest frogs in the world and can weigh over 40 times as much as a European common frog, reaching up to 1kg in size. They eat a variety of animals, including insects, snakes, small mammals, and even other frogs. These frogs currently occur in Dominica and Montserrat but were once far more widespread.
An epidemic of the fungal disease amphibian chytridiomycosis almost wiped-out mountain chickens forever. Since one of the pathogens that causes the disease arrived in Dominica in 2002 and in Montserrat in 2009, the mountain chicken population declined by over 90%. There are now fewer than 100 wild individuals left in Dominica and the species is likely to be extinct in the wild in Montserrat.
We are a part of the collaborative mountain chicken recovery programme, which is leading cutting-edge mountain chicken conservation. Together we are researching possible routes to help the species recover, such as heated water baths for a population managed in semi-wild conditions on Montserrat, and genomic investigations of disease resistance in Dominica. We also hold a population in biosecure facilities at London Zoo, which will act as a source for future population recovery in the wild. Returning an animal which is as much a key part of the eco-system as they are loved by local people.
Mountain chickens are a culturally significant species in both Montserrat and Dominica. Mountain chicken was the national dish of Dominica until their decline, and were widely eaten in both Dominica and Montserrat before the chytridiomycosis epidemic. The mountain chicken even features in the Coat of Arms of Dominica, and local people on both are islands hope their numbers can be recovered.
Mountain chicken threats
Mountain chicken populations on both Dominica and Montserrat have been devastated by the arrival of the fungal disease, amphibian chytridiomycosis, caused by the fungal pathogen, Batrachochytrium dendrobatidis. This disease has caused the decline of an estimated 500 amphibian species, and mountain chickens are especially susceptible.
New methods to control the disease are currently being trialled, including solar-powered heated pools for mountain chickens because the fungus cannot survive warmer temperatures; when infected frogs bath in these heated pools they may reduce their infection burden. Although historically mountain chickens have been hunted, there is now an understanding that everyone needs to work together to save them from extinction.
Mountain chicken conservation
Our population at London Zoo supports translocations back into the wild. To ensure our captive frogs are ready for release into the wild, we worked together with UK zoos to develop the first validated body condition score for an amphibian and pioneered a dietary comparison between captive and wild frogs. By advancing captive husbandry techniques, we hope to improve the success of mountain chicken conservation translocations.
We have helped establish a conservation breeding facility for mountain chickens in Dominica while also releasing frogs back to the wild in Montserrat from our biosecure facility at London Zoo. Through this captive breeding and reintroductions to the wild, we are working to slowly recover chicken frog populations and prevent extinction. Our research has advanced captive husbandry and pre-release health screening of mountain chickens.
Mountain chicken breeding
Mountain chickens breed in a unique way and take proactive care of their tadpoles. Males call from within a chamber to entice females where they produce a foam nest into which the eggs are laid. The eggs are guarded by the male and female frog, and the female frog feeds the tadpoles infertile eggs once a week for around a month until the tadpoles metamorphose.
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Mountain chicken future
In Montserrat the species is now almost certainly extinct in the wild, while in Dominica we’re working with local partners to conserve and monitor the remaining mountain chicken populations. This collaborative project is guided by scientific research which has underpinned decisions on surveys and interventions required to ensure the long-term survival of this species. There is ongoing research on the emergence, epidemiology and impact of chytridiomycosis in mountain chickens. In Dominica, this work is assessing the current size and infection status of the remnant mountain chicken population and other local amphibian species.
Mountain chickens are the perfect model species from which to learn about the impact, epidemiology and treatment of chytridiomycosis. The results of our research have the potential to guide conservation measures for many other amphibian species that are impacted by this and similar diseases.
Mountain chicken conservation key achievements & goals
Our goal is to have healthy populations of mountain chickens as a flagship species for the natural and cultural heritage of Dominica and Montserrat.
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Rapid response to population declines attributed to the fungal disease, amphibian chytridiomycosis.
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Established a conservation breeding facility for mountain chickens in Dominica.
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Developed a molecular diagnostics laboratory in Dominica.
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Capacity building: trained in-country personnel in mountain chicken husbandry, field survey and laboratory techniques.
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Conducted research into the emergence and epidemiology of chytridiomycosis in the mountain chicken.
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Worked with partners to develop a 20-year conservation action plan for the mountain chicken.
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Key partner in the ex-situ conservation breeding programme.
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Maintaining a population of mountain chickens in a biosecure facility at London Zoo; frogs have been bred in captivity and released in Montserrat.
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Undertaken research to improve the captive husbandry and pre-release health screening of mountain chickens.
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Trialled the treatment of amphibians in the wild for chytridiomycosis for the first time.
ZSL mountain chicken research
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January 2016: A study co-authored by the Institute’s Professor Andrew Cunningham and PhD student Michael Hudson tested the in-situ treatment of individual mountain chicken frogs using the antifungal drug, itraconazole. They found increased probability of survival and loss of the fungal infection for treated frogs compared to non-treated animals. Results suggest that in-situ treatment of individuals with the drug could be a useful short term measure to reduce the chytridiomycosis-induced mortality rate and to increase opportunities for other conservation actions, including facilitating population survival in the wild during periods of high disease risk.
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August 2016: Findings from research co-authored by IoZ’s Professor Andrew Cunningham and PhD student Michael Hudson suggest that the decline of the mountain chicken across its range is amongst the fastest recorded for any species, with island-wide population collapses due to chytridiomycosis occurring within 18 months on Dominica and under one year on Montserrat. There’s an urgent need to build mitigation capacity where amphibians are at risk from chytridiomycosis and to prevent the spread of the disease to new areas.
For more than 20 years, we have been at the forefront of research on amphibian chytridiomycosis, a disease which has devastated amphibian populations globally.
