| Teresa Dapp |
King Edward Point, South Georgia (dpa) – The island of South Georgia used to be home to up to 100 million seabirds in one of the richest breeding areas of the world’s open seas.
King penguins, wandering albatross, cape petrels and a host of other species once thrived undisturbed amid the teeming South Atlantic waters – until the HMS Resolution dropped anchor in 1775.
As Captain James Cook claimed the island for Great Britain, the ship’s rats also disembarked.
More swam ashore from the sealing and whaling ships that followed.
Devouring eggs and chicks across the South Georgia and the South Sandwich Islands for two centuries, they took over all but a few small islands off the coast.
The former bird paradise is a “a shadow of its former self in terms of the wealth of its wildlife”, says Tony Martin, habitat restoration professor at the University of Dundee in Scotland.
“They wiped out in excess of 90 per cent – it could be as much as 98 per cent – of all the birds that were there when Captain Cook found the island in 1775.”
Martin heads ‘Team Rat’, which the South Georgia Heritage Trust has engaged to wipe out the island’s scourge of brown rats and mice using poison.
If they are successful, the rodent population may vanish as soon as this spring, although it will take two years to know for sure, given the tenacity of even small numbers of rat survivors.
In 2011, Team Rat distributed the first bait laced with the poison brodifacoum on part of the 3,900-square-kilometre territory.
In 2013, it littered a second region with the lethal treat. The final phase should ensure the total eradication of the invaders.
But it requires a major logistical operation to work. Three helicopters and fuel must be shipped through rough seas to South Georgia, and the bait laying plan must be stringently followed across the entire target area.
“The idea is that every single rat on the island has to have access to at least one bait pellet,” says Martin.
Strewing tonnes of rat poison across this largely unspoiled wonder instantly sounds alarms.
Will it kill birds and other wildlife too, is the immediate question?
“Yes,” Martin says. “But the populations of birds bounce back, whereas the populations of rats do not.”
There is no native human population on the islands, which are inhabited by a few dozen scientists and administrative staff sent from Britain.
The British authorities here had to sign off on this collateral damage, and accepted that “the benefits of rodent removal to the island as a whole far outweigh any short-term impacts on the small number of species affected”.
How effective the first poison bait runs were can now be gauged, since the island is divided by glaciers which prevent the rodents from resettling in cleared areas.
“The results were great,” says Martin. Not only have the rodents gone, but birds have now resettled, including the yellow-billed pintail, Anas georgica, which is only found in these isles.
Rare species would also be able to survive on South Georgia’s smaller islets, he believes. The worry though, is that global warming will melt the glaciers enough for the rat population to spread again. It only takes one pregnant female to survive eradication to rekindle the species, Martin warns.
South Georgia is not alone in its
struggle against the rodents. On the uninhabited island of Booby Cay in the Bahamas, black rats – with help from feral cats and dogs – have ravaged the iguana population. On Australia’s Lord Howe Island they now threaten 13 indigenous species.
But an ongoing five-year programme has almost eradicated rats on the tiny Canadian islands of Murchison and Faraday in British Columbia. And the Hawadax island in the Aleutians is now recovering after being rat-ruled for many years.
Tony Martin and the South Georgia Heritage Trust hope for the same results from their 10-million-euro operation, which is funded mainly through private donations.
On February 24, the team is due to leave Port Stanley in the Falkland Islands by ship and begin the bait dumping over several weeks from mid-March.
Whether the pests are really eradicated can only be judged in two years’ time. If so, then it will become equally important to prevent a re-invasion.
Rats can swim about a mile, and according to Martin, the main danger without Cook-style landings is from ships wrecking on or near the shore.
If all goes well, the birdlife may thrive again and eventually hit their former 100-million mark.
“It will literally be decades – perhaps more than a century – before the island’s wildlife gets back to where it was before the rats and mice came in. But frankly, in my lifetime and even my children’s and grandchildren’s lifetimes, not all of the birds will be coming back in a big way.
“But we are absolutely confident that they will come back as fast as they will, because the main threat to their existence will have been removed,” Martin says.