Scientists are hoping that one of the world's largest frogs is singing songs of love on the tiny Caribbean island of Montserrat and not just singing in the rain.

Mating calls would mean the so-called mountain chicken frogs are looking to breed and hopefully dodge extinction. But scientists say the whooping calls they make by night could also be due to the rainy season.

The mountain chickens are the offspring of dozens of frogs weighing up to two pounds (0.9 kilograms) that were airlifted to Britain and Sweden in 2009 in hopes of saving them from a deadly fungus that has killed nearly 80 percent of the species.

In the past year, scientists have brought back nearly 100 more frogs and released them into a rocky valley filled with small ponds where they like to hide. Breeding season has started, and scientists are anxiously waiting to see if the frogs actually mate.

"We were entering a very difficult situation three years ago," Andrew Terry, field program director with British-based Durrell Wildlife Conservation Trust, said Friday. "A species we knew well, that was already under pressure, was brought to the very edge of extinction."

Durrell is one of three institutions abroad that helped rescue the frogs and created a breeding program that has resulted in dozens of offspring. Frogs also were sent to The Zoological Society of London, Chester Zoo and Parken Zoo in Sweden.

The whooping calls on Montserrat is an encouraging sign, and the male frogs also have started to grow a black spur on their legs used to hold females during mating, said Sarah-Louise Smith, project coordinator with the island's Department of Environment.

But challenges remain.

Twelve of the 33 frogs released earlier this year have died, and the batteries of the radio transmitters inserted into the surviving frogs have lost power after transmitting data for three months, making it harder for scientists to track them.

Of the 64 other frogs released last year, nine have died from the fungus and the last one was seen in November, but Smith said she believes the others have moved elsewhere because they can cover great distances in limited time. One frog traveled 900 meters (3,000 feet), or the equivalent of nine football fields, in only a couple of hours, she said.

The chytrid fungus also remains a potent threat. Cane toads and tree frogs in Montserrat are still carrying the fungus but are not affected by it.

"Their population remains high, and so does the fungus," she said.

Scientists are awaiting lab results to determine the prevalence of the fungus compared to 2009, when it killed hundreds of frogs by causing the skin they breathe through to thicken. Chytridiomycosis also causes lethargy and convulsions. Eventually the frogs die of starvation or cardiac arrest.

Terry said Durrell will continue to breed the frogs that were flown to the institution and release the offspring into the wild.

"It was a contentious and very carefully thought through decision to release animals back because we knew that the disease was still present in the environment," he said. "We had to expect that some of the frogs would succumb to the disease."

The fungus already has devastated the mountain chicken frog in nearby Dominica, whose coat of arms bears the amphibian's image and where the frog's chunky legs were long considered a local delicacy.


On the net: www.mountainchicken.org