ALL of New Zealand’s native frog species could be extinct within two years, warns one of the country’s leading frog experts. His gloomy prediction follows the discovery of a fatal fungal disease in one of the country’s “living fossil” frogs.
Bruce Waldman of the University of Canterbury in Christchurch fears that the disease could quickly spread to other native species. “This is really scary. There’s a real possibility that these unique frogs will disappear,” Waldman told 91av.
New Zealand’s four species of native frog belong to the ancient genus Leiopelma and differ little from the earliest frogs, which lived 200 million years ago. All four are nocturnal, lack ears and don’t croak. They hatch from the egg as fully developed froglets, missing out the tadpole stage.
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The chytrid fungus, Batrachochytrium dendrobatidis, was discovered in the late 1990s in the skin of dead and dying frogs in Australia and Central America. It has recently reached the US and Europe. Infection is usually fatal and the disease is implicated in a rash of recent extinctions.
Waldman found the first known case of chytrid disease in New Zealand late in 1999 in the southern bell frog, a species introduced a century ago from Australia. Bell frogs on both South and North Island are now infected. Waldman suspects the fungus came to New Zealand in frogs imported for the pet trade.
Now the disease has struck the endangered native Archey’s frog. Dead and dying frogs from three separate populations have tested positive for the fungus. Biologists have noticed a decline in these terrestrial frogs since 1996, and at some sites 80 per cent of the frogs have gone. “Once one population is gone, extinction is just over the horizon,” says Waldman.
The fungus seems to be spreading at an alarming rate, and clearly not just via waterways. Ben Bell, a herpetologist at Victoria University in Wellington, thinks hikers and pig hunters carry the disease deep into the bush on their boots and clothes.
“It’s possible that every species of native frog has the fungus,” says Waldman. Hochstetter’s frog, the most widespread native species, shows signs of decline but so far no infection. More worrying is the threat to the two species that live on islands in the Cook Strait. The Maud Island frog is down to a few thousand individuals. Hamilton’s frog lives on a small rocky patch at the summit of Stephen’s island, and there are fewer than 300 left.