Feb 26 2011
Testing for the biggest rat eradication programme in history is beginning on a remote UK island in the south Atlantic.
Scientists are preparing to drop poison in a limited area of South Georgia in a bid to save the world’s most southern songbird from extinction and restore tens of millions of seabirds to the island’s breeding grounds.
Millions of bird-eating and egg-eating rats are estimated to be living on the island, which Captain James Cook claimed for Britain in 1775. The clearance project is intended to kill all of them within five years.
Two helicopters have been transported to South Georgia to take part in the extermination programme and will from Tuesday begin dropping poison pellets on the island.
The first drops will take place in a limited area to test whether the techniques used by the extermination team work. They will return in 2013 and if the rats have disappeared from the test area, drops will take place over the rest of the island.
Researchers have calculated that they need to clear rats from 800 square kilometres (80,000 hectares) – making the project almost 10 times bigger than the previous biggest rat eradication programme on Australia’s Macquarie Island.
Prof Tony Martin, of the University of Dundee and the South Georgia habitat restoration project director, said: “Killing any rat on an island like South Georgia is a hell of a challenge. If you underestimate their ability to survive and stay away from danger you will fail. “The vast majority of birds that should be breeding on South Georgia have been displaced by the presence of rats. Rats have gone virtually everywhere except the very cold southern coast. We are looking to restore millions, possibly tens of millions of sea birds to the island.
“The exciting thing for me about this is there are few things you can do to revert the impact of human activity on the planet but what we are going to be doing will reverse two centuries of human impacts on the island.”
Brown rats reached the island 200 years ago on sealing and whaling ships and wreaked devastation on the bird population by eating countless eggs and the chicks and fledglings. The ground-nesting birds have little defence against rats seeking to eat the eggs or their young.
Once rats have been cleared from the the island, however, scientists hope tens of millions of seabirds will return to South Georgia each year.
Moreover, they are confident it will save the South Georgia pipit from the threat of extinction. The pipit is found nowhere else and is the world’s most southerly songbird. It has been driven from virtually all of South Georgia, surviving primarily on about 20 small offshore isles. Ten years ago it was estimated that 3,000 to 4,000 pairs were left but since then rats have invaded more of their territory.
Martin said: “The pipit is the flagship species. It’s probably the one which will respond the most quickly to the removal but it’s only one of about 18 species we estimate will be positively affected.”
Other birds that should benefit are the South Georgia pintail, a duck endemic to the island, Wilson’s storm petrel, the South Georgia petrel, the common petrel, and the white chin petrel which has “mostly gone” from the island despite it being its main breeding ground. Numbers of Wilson’s storm petrel have slumped by up to 95% because of rats.