The deliberate cutting of a hole in a predator-proof fence has shocked staff at Wellington's urban ecosanctuary.
Zealandia is home to rare and threatened species like kiwi, hihi and tuatara.
Zealandia director Danielle Shanahan said that over the weekend someone with a power tool cut a hole big enough to let predators in.
"We're absolutely gobsmacked and dumbfounded as to who could have done this."
A member of the community found the hole and reported it on Sunday morning.
A check had occurred on the fence the day before, Dr Shanahan said, so the best case scenario was the hole only existed for a few hours overnight.
"It really is a hugely impactful thing to do. Of course, we're mounting a major predator incursion response just in case a predator did get in.
"The potential impact of an intruder is absolutely huge on the rare and threatened species that are inside the sanctuary."
If just one stoat got inside, it could wipe out one of the species, Shanahan said.
The birds are particularly vulnerable at the moment, as breeding season begins.
Shanahan said it was the first attack like this since the fence went up 20 years ago.
"People really love this place, it's become a hub for our volunteers and members but it's had a huge impact on our city. Kaka, which were previously extinct from this region, can now be found all over the city.
"It's hard to understand what sort of person would have done this," she said.
Staff are now being strategic in placing traps and lures, and she is asking locals to report any suspicious behaviour or damage.
The sanctuary is also considering upping its security measures around the site, including extra CCTV.
Police have been notified.
RNZ
