麻豆传媒

DEAD freshwater crocodiles in Australia鈥檚 Northern Territory were once a rare sight. But since the invasion of the cane toad, it has become commonplace for tour guides and helicopter pilots to spot crocodile carcasses rotting on river banks.

Now a team led by Mike Letnic of the University of Sydney has put a figure on the loss of croc life. A massive 77 per cent of some populations of 鈥渇reshies鈥�, as locals call them, have died since the arrival of the toads. The team surveyed crocodiles in four regions of the Victoria river before the cane toad front arrived in June 2005, and after, in July 2007.

That鈥檚 particularly worrying, says Letnic, because removing top predators like freshwater crocodiles can trigger a cascade of difficult-to-predict changes to an ecosystem as numbers of prey species explode.

Cane toads, which are native to the Americas, were introduced to Queensland in 1935 to control sugar cane pests, and have been steadily marching across the country ever since. They are toxic to most species that feed on them, and have decimated populations of goannas and certain species of snakes.

Grahame Webb, director of Wildlife Management International in Darwin, is saddened but not surprised by the findings. 鈥淚t was a disaster waiting to happen, and if it had been whales, or some species with big brown eyes, everyone would have been up in arms.鈥�

Endangered species 鈥� Learn more about the conservation battle in our comprehensive special report.