In Britain, the common toad population is "seriously threatened": natterjack toads have declined by 75 per cent in the past century, and since the 1960s the number of great crested newts in the country has dropped by 60 per cent.
Now, 50 leading researchers are now campaigning for £200m to protect endangered species. The Amphibian Survival Alliance would involve monitoring, research, disease management and captive breeding of amphibians.
Tony Gent, the chief executive of the Herpetological Conservation Trust, said decline in amphibian populations was often seen as an early indicator of environmental change, because the creatures rely on two habitats, leaving them vulnerable because they can be affected by changes both on land and in water.
"We are certainly aware of large-scale decline globally, and there sometimes seems no hope for their survival," he said. "The biggest threat to amphibians in the UK is the impact from habitat change."
Since 1980, up to 122 species of amphibian have become extinct worldwide. Another 32 per cent of the world's amphibian species are considered at risk.
Amphibians have existed for more than 300 million years, predating the dinosaurs, and their dramatic decline has alarmed many researchers. Professor Andrew Blaustein, from Oregon State University in the US, one of the first experts to document amphibian decline 20 years ago, said: "This is part of an overall biodiversity crisis, and amphibians seem to have been hit the hardest of all vertebrate species."
A key problem is a fungus that causes an infectious disease called chytridiomycosis. In places where it has appeared, amphibian populations may be wiped out within six months, the researchers said in a report published in Science. Global climate change and pollution are thought to increase the fungus's spread.
Victoria Micklewright of Froglife, a charity concerned with conservation of amphibians, said the fungal disease was identified for the first time in Britain last year in an American bullfrog in the wild. The fungus kills toads and frogs that have recently turned from tadpoles. The charity is calling on the public to report any dead toadlets and froglets that they see.
She said that the amphibian population was also being severely threatened by overdevelopment. "They may be small, slimy and not pretty to look at, but the common toad is quite obviously in serious decline. Toads migrate up to one kilometre to get to their breeding ponds," she said. "But increasing development of rural areas means that ponds get destroyed, or that the toads - whichtend to migrate at dusk, which coincides with rush-hour - get run over on busy roads."
Ms Micklewright said that the natterjack toad, which previously inhabited all coastal areas of the UK, was now the rarest amphibian in the country and could now only be found in Norfolk, the north-west of England and in north Wales. "It is a coastal species that tends to live near sand dunes, but habitat destruction means that it can now only be found in isolated areas in the country," she said.
Amphibians at risk worldwide
Harlequin Frogs
There were 110 species of harlequin frog in Central and South America but, between the 1980s and 1990s, almost two-thirds of the known species became extinct. The fungus chytridiomycosis is believed to be the cause. Scientists believe climatic changes are leading to outbreaks of disease due to the fungus. Dr Alan Pound, who studied the harlequin frogs, has said: "Disease is the bullet killing frogs, but climate change is pulling the trigger."
The Painted Frog
Found only in the remote Boyaca region of South America, the frog was believed to be extinct for more than a decade. But in May this year, scientists sighted it for the first time since 1995. Conservationists believe the fungal disease chytridiomycosis was responsible for wiping them out.
Natterjack Toad
The natterjack population in the UK has declined by at least 75 per cent in the past century. The loss of habitat is the main reason. They like very short vegetation and very shallow ponds. But, as land use has changed with urbanisation and commercially grown vegetation, they suffered.
Strawberry Poison Dart Frog
The bright red colouring warns predators away from the highly poisonous creature. But the frog, found in Costa Rica and tropical forests of central America, is vulnerable to habitat change, and the destruction of rainforests has made them rarer.
Mountain Chicken
An edible species of frog that lives on Montserrat in the Caribbean. The volcanic eruptions of the late 1990s have devastated the population and hunting also threatens them. The future looks uncertain, but a captive breeding programme in Jersey is hoping to secure its survival.
Golden Toad
This creature lived in Costa Rica but become extinct in the past 20 years. The disappearance was sudden, as the abundant species dropped to extinction within three or four years. Scientists have concluded global warming may have been the cause, triggering disease and fungi.
Great Crested Newt
The population has declined by more than 60 per cent in the UK since the 1960s. This is almost entirely due to loss of habitat. The change to intensive agriculture and the loss of ponds have contributed to its decline, which has led to it becoming a protected species.
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