An island located halfway between Antarctica and New Zealand was declared rat-free Monday, some 200 years after rats arrived there by sealing and whaling boats.

　　Campbell Island had the largest population density of rats anywhere in the world, eradication project manager Andy Roberts said. They had reduced the island's shearwater seabird population to a handful“which will take hundreds of years to recover,”he said in a statement.

　　Other unique birds like the flightless Campbell Island teal and the tiny Campbell Island snipe had only survived eradication because they were removed from the island by environmentalists.

　　“After 200 years of rat occupation, Campbell is now a safe haven for the millions of seabirds that breed there,”New Zealand Environment Minister Chris Carter said in a statement.

　　Tons of rat poison pellets were dumped on the uninhabited 27,900-acre island, 440 miles south of New Zealand, by helicopter two years ago to kill the Norway rat.