We have a big problem. We have more than 800 native species that are threatened.
If we don't take immediate action, we're going to lose a lot of them.
This isn't just a potential problem. One of our native parakeets, the kakariki, has just become extinct in the Northland region.
"The very bird whose name means green is no longer present in most of New Zealand," says Dr Luis Ortiz-Catedral.
"Introduced browsers compete with kakariki for food and shelter and they feed on the eggs, nests and incubating females – if you combine those thing you have a recipe for disaster."
Dean Baigent-Mercer walks the forests for his job, and doesn't like what he sees.
Watch the video for the full Story report.