British and US scientists used poisoned bait in the largest rat eradication project of its kind, which cost 10 million pounds (11 million euros, $14 million), lasted a decade and covered 1,087 square kilometres (420 square miles).
“Invasive rodents have been successfully eradicated from the island,” Mike Richardson, head of the South Georgia Heritage Trust project, said in a statement.
Rats and mice arrived with the first humans starting in the late 18th century and had “a devastating effect” on the local bird population, the statement said.
The rodents threatened the survival of two species found nowhere else on Earth — the South Georgia pipit and pintail, the conservationists said.
The South Georgia Heritage Trust said these birds were becoming increasingly confined to rodent-free small offshore islands in the remote archipelago, located in the southern Atlantic off the tip of South America, near Antarctica.
Three dogs were also used to monitor for rats and mice, covering a total of 2,420 square kilometres.
Scientists said they hoped the rodent eradication programme would prove a model for similar projects around the world to eliminate invasive species.
The island is the burial ground of the Antarctic explorer Sir Ernest Shackleton, who died there in 1922, and is home to two scientific research stations run by the British Antarctic Survey.