The largest project to get rid of animals the world has ever seen is about to start.
It's happening on the small island of South Georgia, in the Atlantic ocean, and the aim is to wipe out millions of rats.
The rodents first arrived in South Georgia over 200 years ago, on sealing and whaling ships.
They've become a big pest and are pushing some of the island's bird species to the brink of extinction.
A test to spread poison pellets across part of the island in 2011 seems to have been successful.
The team will now spend months targeting other areas with the poison pellets.
Wiping out rats has been tried on other islands around the world, including off New Zealand and Australia - but nothing on the scale that's being tried out in South Georgia.
The team have to use helicopters to spread the pellets because there's so much ground to cover.
The island is home to many species of bird, some of which are found nowhere else in the world, like the South Georgia pipit and the South Georgia pintail.
The increase in rats has been a disaster for the birds as the rodents feed on chicks and eggs.
The hope is that getting rid of the rats will mean 100 million pairs of seabirds will come back to the island once more.