Located some 1,800 kilometers off the coast of South America, South Georgia Island has no permanent human residents – but millions of rats. The rodents first made their way to this south Atlantic island on whaling boats in the 18th century and, feeding on sea birds, proliferated quickly.

No one can say exactly how many million rats currently live on South Georgia, which is 167.4 km (104 miles) long and 37 km (23 miles) at its widest point. Whatever the figure, it’s too high in the view of the South Georgia Heritage Trust (SGHT) because of the danger the rats represent to the millions of birds who make this island their home. The rats feed on young birds and eggs.

[Millions of browns rats are proliferating on South Georgia - Photo: National Park Service]

So the SGHT has embarked on a course to free the island of the rodents in what is the greatest extermination of rats the world has ever known.

In early 2013, helicopters are due to inundate parts of the island with grain bait containing two to six-and-a-half kilograms of brodifacoum per hectare. No one doubts the collateral damage of this action – including the deaths of some of the very birds the extermination aims to protect -- but the SGHT sees no alternatives as the rats will soon cover the entire island including areas that until now have been safe for birds.

Stefan Ziegler, a WWF biologist, told Süddeutsche Zeitung that from a natural conservation point of view he supports the planned action, but "the question is whether or not it will be successful. All you need is a couple of rats surviving and in a couple of years’ time you’re back where you started.”

Project leader Tony Martin of the University of Dundee says he and his team will consider the extermination a success if in two years’ time there is no sign of rats on the island. A trial conducted on a section of the island in the past year has so far proven successful.