Fungus devastates 'chicken' frog

Richard Black, BBC News 17 Mar 09;

"If this was killing mammals or birds in the same way it's killing amphibians, millions and millions would have been spent on it."

Montserrat's "mountain chicken" frog has become the latest victim of the killer fungal disease that is devastating amphibians worldwide.

UK researchers say that only two small pockets of the animals on the tiny Caribbean island remain disease-free.

The mountain chicken (Leptodactylus fallax) is one of the world's largest frogs, and appears on the coat of arms of neighbouring Dominica.

Conservationists plan to take surviving frogs into captive breeding programmes.

They suspect the chytrid fungus entered Montserrat on small frogs stowing away in consignments of produce from Dominica.

"We've always been afraid that frogs coming in banana consignments from Dominica would bring chytrid and that it would then spread into the centre of the island," said John Fa, director of conservation science at Durrell Wildlife Conservation Trust.

"The northern populations are closer to the port, and the disease appears to have spread southward along the river systems.

"Essentially, all populations to the north and north-west of the centre hills have been decimated, and there are just two remaining populations of seemingly healthy animals in the south-eastern corner."

An expedition in 2005 found no sign of fungal infection.

Clean sweep

The frogs are so called because their meat tastes like chicken. In both Caribbean islands - the only places where they naturally occur now - hunting was already impacting populations before the arrival of chytrid.

Most of the Montserrat populations were also affected by the volcanic eruptions that began in 1995, although the creation of an "exclusion zone" around the volcano's slopes has provided some help to wildlife by freeing it from human pressures.

Events on Montserrat now appear to be mimicking what happened on Dominica in 2002.

Within 15 months of the fungus arriving, about 80% of the island's mountain chicken had been wiped out.

First identified just over a decade ago, the fungus (Batrachochytrium dendrobatidis) has spread through hundreds of amphibian species on different continents.

It sweeps some to extinction in a matter of months, while others are apparently immune.

"We still don't know how chytrid kills frogs, and there's some very basic stuff about the biology of the fungus that we need to understand," observed Andrew Cunningham from the Zoological Society of London (ZSL).

"We've known about it for 10 years, but so little money has been spent on it.

"If this was killing mammals or birds in the same way it's killing amphibians, millions and millions would have been spent on it."

In captivity, chemicals can be used to rid amphibians of the fungus, but as yet there is no way to cure them in the wild, or to cleanse infected water bodies.

As a result, many conservation groups are focusing their energies on establishing captive populations.

Durrell and other conservation organisations already have mountain chicken in captivity, and will be taking more from the apparently healthy Montserrat populations in the coming weeks.

In contrast to some other operations, though, it plans to treat and return some frogs to the wild within a couple of years, placing them in areas that appear to be free of chytrid.