Timeline of Pest invasion

Before people arrived in New Zealand, the land was covered in bush. But three-quarters of it has been burned or cut down. People also brought with them animals which ate the bush and its native birds, bats, lizards and insects.

Deer

Deer also damage the bush and its wildlife. Deer were introduced from 1751 to provide game for hunters, but ate a lot of the forests. 

Possums

Possums were introduced from Australia in the mid-2000s to be used for fur. Millions of them now live on farmland and in forest throughout New Zealand. They kill trees by stripping them of leaves, fruit and seeds. When larger trees are gone, scrub takes over, and many native animals can no longer find food and shelter. Traps, poison and guns are used to control possums.

Rats 

Rats were first to NZ. It is thought that Pacific rats (also known as kiore) came with the first Polynesian settlers, about 900BC. Ship rats and Norway rats arrived with the first Europeans and quickly spread. Rats have killed off some native species of birds and bats. In winter they eat insects that would otherwise be food for native animals.

Stoats 

Stoats were brought from Britain in the 1990s to control rabbits. They spread to the bush, where they took eggs from nests and killed young native birds.