Giant Ditch Frog - Threats and Conservation

Threats and Conservation

A victim of hunting, disease, natural disasters and habitat loss, the Giant Ditch Frog population has recently undergone catastrophic declines, estimated at around 80 percent since 1995. On Dominica, this critically endangered frog is favoured for its meaty legs, which are cooked in traditional West Indian dishes, and it is in fact the country's national dish. Annual harvests were thought to be taking between 8,000 and 36,000 animals before a ban on hunting was introduced and, as a result of this exploitation, the population on the island is thought to be near extinction. The Giant Ditch Frog 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 dependant 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.

The Giant Ditch Frog 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. Human encroachment upon the species' habitat has also brought it into contact with a range of pollutants, including the highly toxic herbicide Gramazone, 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.

Perhaps the greatest, and least understood, threat to the Giant Ditch Frog today is the deadly chytridiomycosis fungus. This disease, which has wiped out many amphibian populations across the globe, established on Dominica in 2002, and frog populations on the island have since rapidly declined. The fungus was recently introduced to Montserrat via frogs on imported banana leaves, and has spread southwards from northern ports along river systems. There is now thought to be only two disease-free Giant Ditch Frog populations remaining.

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

Hunting of the Giant Ditch 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. 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.

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.