This month, a conservation "hit squad" will visit the Galapagos Islands to try and save their unique wildlife by eradicating the invasive species. Julian Fitter, chairman of the Galapagos Conservation Trust, said: "Unless something immediate and drastic is done, there will be nothing left of the island's endemic plants and animals. The land is being grazed away to nothing."
The Galapagos Islands, 600 miles off the coast of Ecuador, are invaluable in providing the world with a living laboratory of evolution. Darwin was the first of many scientists to study the unique ecosystem, where biology and geology have gone to bizarre and wonderful extremes.
There are 15 main islands and 106 smaller ones, created by volcanic eruptions out of the ocean some 3 million years ago. There are active volcanoes there even today. Because the chain of islands was never attached to any other land mass, all the resident species are descended from ones that flew, swam, drifted or were carried there.
Ninety-five per cent of the reptiles, 50 per cent of the birds, 42 per cent of the land plants, 80 per cent of the insects and 17 per cent of the fish cannot be found anywhere else in the world. They include the Galapagos tortoises, marine iguanas, flightless cormorants, blue- and red-footed boobies and 13 species of Darwin's finch, whose variously shaped beaks were used to illustrate his theory of evolution.
The threat to these endemic species comes from overgrazing by goats that have run wild, and from non-native predators, such as rats, killing the defenceless indigenous animals.
Alcedo Volcano on Isabela Island is home to more than a third of all Galapagos giant tortoises. It faces ecological collapse as a result of an infestation of goats and burros. The enormous goat population, numbering more than 80,000, is eating the vegetation the tortoises depend on, and they cannot compete.
Dogs have eaten most of the land iguanas, and black rats have discovered how to chew through the shells of baby tortoises, which are soft until they are about three years old.
On the neighbouring island of Santiago, conservationists at the Darwin Research Station say all the endemic plants and most of the unique animals could be wiped out in five years by goats and pigs. For example, Scalesia trees, which look like giant sunflowers, until recently formed an entire forest across the island. These have been devastated by goats, leaving only a few sparse clifftop clumps. And pigs have developed a taste for the world's rarest seabirds, the dark-rumped petrel. The pigs can smell out the petrels' burrows and kill them easily when they surface, as they are too clumsy to escape.
The Galapagos National Park has had some success ineradicating goats from the smaller islands, like Santa Fe, Espanola and Pinta, but the problem on the larger islands like Alcedo is now unmanageable. Simple hunting techniques are no longer effective, as the goats are reproducing so rapidly the rangers cannot keep up, and the situation is out of control.
Mr Fitter explains that with these numbers, you need to destroy them rapidly before they get a chance to reproduce.
The Galapagos Conservation Trust has asked Brian Bell to examine the problems facing Isabela and Alcedo. Mr Bell, an expert on the eradication of invasive or introduced species, is the managing director of Wildlife Management International, a small private company established to make available to other countries New Zealand's expertise in island management.
His company has been asked to undertake projects by governments and agencies such as the Royal Society for the Protection of Birds, and Birdlife International. One of his recent projects was eradicating brown rats and black-naped hares from Gunners Quoin in Mauritius last September.
Mr Bell explains that cleaning up islands requires the investment of many resources and much time and money. He says: "I don't enjoy killing, but I accept it as an essential way of preserving rare forms of life. People get uptight about what they see as cruelty to animals, but they don't know how harsh nature is. Look at seabirds - most of them die in their first year due to lack of food. It's sad, but if they all survived we'd be overrun by birds."
Mr Bell is visiting the islands this month for three weeks, and his report will ascertain howbest to carry out the eradication and what methods to employ.
Julian Fitter says: "One possible recommendation is the use of helicopters as a vehicle to shoot the goats from. This has the advantage that the goats cannot get away, and the terrain and vegetation will not impede in the same way as a ground operation. With luck, once Brian and I have discussed his report, we can implement the programme in November."
Mr Fitter adds: "I have high hopes for the future of the Galapagos - it is a priceless jewel that must be preserved, not just for the rest of the world to come and visit or study, but because it is of incomparable economic value to Ecuador. If Ecuador loses its unique wildlife and tourists no longer visit Galapagos, then the whole Ecuadorian tourism industry will suffer."