Rats have invaded a bird sanctuary near Stewart Island.
Ulva Island is home to some of New Zealand rarest birds and rats have now been found breeding there.
It's 13 years since rats were found in significant numbers on the island.
The Department of Conservation says 12 rats have been caught since Christmas, which indicates they are breeding.
More than 200,000 people per year visit Ulva Island, which is an unrestricted off shore sanctuary island.
It's thought the rats travelled on boats, with the public.
DoC says a baiting programme will now get begin.