Leptodactylus fallax

The mountain chicken has a highly unusual method of reproduction, as unlike most other amphibians which breed in water, this frog breeds in burrows around 50 cm (20 in) deep. The breeding season starts towards the end of the dry season, usually in April when there are heavy seasonal showers, and continues to August or September.[8] At the start of this period, the male frogs compete to gain access to preferred nesting sites by wrestling and making loud 'whooping' calls from forest paths and undergrowth clearings.[3][8] The winning male occupies a nesting burrow and emits 'trilling barks' to attract a female mate.[3] Once a breeding pair is formed, the male and female engage in amplexus and the female is stimulated to release a fluid, which the male makes into a foam with rapid paddles of its hind legs. Once the nest is built, which takes 9 to 14 hours, the male leaves the burrow to defend it from intruders, while the female lays the eggs.[3][12] After the tadpoles have hatched, the female lays up to as many as 25,000 trophic (unfertilized) eggs upon which the tadpoles feed. While the young develop, which takes around 45 days, the female continuously renews the foam, only leaving the nest to feed.[3] Eventually 26 to 43 froglets emerge from the nest, with the timing of this coinciding with the onset of the wet season, when there is an abundance of food.[3][8] The mountain chicken reaches maturity at around 3 years, and has a lifespan of approximately 12 years. Mature females only produce one brood per season, but male frogs may father the offspring of more than one female.[8]

On Dominica, this critically endangered frog is favoured for its meaty legs, which are cooked in traditional West Indian dishes, and it was until recently the country's national dish.[13] Annual harvests were thought to be taking between 8,000 and 36,000 animals before a ban on hunting was introduced.[2] The mountain chicken is particularly vulnerable to such harvesting as it has a relatively small brood size, limiting its ability to recover from heavy losses, while the removal of breeding females is particularly damaging, as the tadpoles are dependent upon the females for food and moisture. The species' large size, loud calls and tendency to sit in the open also makes it a particularly easy target for hunters.[8]

Hunting of the mountain chicken frog was banned on Dominica in the late 1990s, although a three-month open season was declared at the end of 2001, and hunting was not fully prohibited until 2003.[2][8] Public awareness programmes have also been implemented to inform the Dominican public of the threats the mountain chicken faces and to try to discourage hunting.[2]

Perhaps the greatest, and least understood, threat to the mountain chicken frog today is the deadly fungal disease chytridiomycosis.[2] This disease, which has wiped out many amphibian populations across the globe, established on Dominica in 2002, and in just 1½ year the population on the island declined to near-extinction.[1][3] Although there have been indications that the Dominican population possibly is slowly starting to recover from this rapid decline, by 2017 it was still estimated to number less than 200 individuals and this was before Hurricane Maria, which might have negatively impacted the tiny population.[4] Sometime between 2005 and 2009 the fungus was introduced to Montserrat, perhaps via small frogs on imported banana leaves, and it spread southwards from northern ports along river systems. In 2009, there was thought to be only two disease-free mountain chicken frog populations remaining.[5] In 2009–2010, the entire Montserrat population rapidly crashed, with only a couple of individuals known to survive in the wild in 2011,[1] and none have been definitely confirmed after 2016.[4] In 2019, the species was regarded as functionally extinct on Montserrat.[4]

The mountain chicken has also lost huge areas of its habitat to agriculture, tourist developments, human settlements and, on Montserrat, volcanic eruptions. On Dominica, the species is largely confined to coastal areas where there is great demand for land for construction, industry and farming, while on Montserrat, volcanic activity since 1995 has exterminated all populations outside of the Centre Hills.[2][8] Human encroachment upon the species' habitat has also brought it into contact with a range of pollutants, including the highly toxic herbicide Paraquat, which is known to kill birds and mammals. Predation from introduced mammals, such as feral cats, dogs, pigs and opossums, is also a relatively new threat to the species on Dominica.[8]

In February 2010, volcanic activity from Soufrière Hills on Montserrat resulted in ash covering large parts of the frog's habitat on that island, further endangering the species.[14]

Following the catastrophic volcanic eruptions on Montserrat, it became clear that dedicated conservation measures were needed if the mountain chicken frog was to be saved from extinction. In July 1999, the Durrell Wildlife Conservation Trust took six male and three female frogs to Jersey Zoo (formerly known as Durrell Wildlife Park) as part of a captive breeding program. Additional frogs were taken from disease-free areas, and the species has readily bred in captivity, with a number of other zoos achieving further breeding success.[1][15] These captive frogs now form the basis of a safety-net population should the species become extinct in the wild.[15] In addition, since January 1998, the Montserrat Forestry and Environment Division, in partnership with Fauna and Flora International, have been monitoring the species' population.[3]

Since the captive effort based on the Montserrat population was initiated in 1999 by Jersey Zoo, it has been successfully bred as part of an EEP breeding program involving more than twenty European zoos,[7][16] along with five US zoos,[17] and viable clutches are produced each year.[4] In 2019, the captive European population numbered 236 individuals.[7] A number of frogs bred in Europe have been returned to their native Montserrat where released between 2011 and 2014.[18] This is part of a trial program to determine the later chance of a successful reintroduction and these frogs are closely monitored to see potential differences in mortality to the chytrid fungus that is found throughout Montserrat.[1][4] They are in a fenced-in semi-wild enclosure where their water pool is heated to 31 °C (88 °F) by solar power, which is above the temperature where the chytrid fungus can live.[7]

From 2007 to 2017, there were attempts of establishing a local captive breeding program for the Dominica population of the species, but it did not succeed and was finally abandoned when the facilities in Dominica were destroyed by Hurricane Maria.[4]