The hunt is on to catch a stoat believed to have scaled Orokonui Ecosanctuary's $2million perimeter fence, threatening juvenile kiwi and other native birds.
A specially trained dog was being used to hunt the stoat, which had evaded traps, ecosanctuary general manager Chris Baillie said. Another dog was helping to find the young kiwi.
If a stoat killed a kiwi, it could be the first of many deaths, she warned.
''Stoats don't just kill to eat, they just kill. Our concern is it will get one kiwi and then just mow them all down.''
Staff found footprints of an adult stoat in the snow inside the perimeter fence on Friday, Ms Baillie said.
Hardened snow was suspected to have helped the stoat scale the fence, she said.
The fence had a stainless steel curved hood to stop predators climbing over, but the snow could have allowed the stoat to obtain a foothold and scale the fence.
The stoat could kill any of the native bird species in the ecosanctuary, Ms Baillie said.
Stoats inside the fence were usually caught immediately in one of the permanent traps, but this time footprints in the snow revealed the stoat had walked past two traps.
''This one is shy of traps.''
Earlier this year, two stoats were trapped inside the fence.
They were believed to have scaled the fence by gaining footholds on joins in the fence.
The 150 joins have since been replaced.
A trained terrier-cross dog was searching the ecosanctuary yesterday.
The dog was not expected to catch the stoat but could isolate it in an area in the 307ha of protected habitat so it could be trapped.
Ms Baillie expected all the juvenile kiwi would be found yesterday.
They would be taken to Rona Island, in Lake Manapouri, and Centre Island, in Lake Te Anau, by Department of Conservation staff.
The stoat's invasion was a ''big setback'' for the ecosanctuary, she said.
''It is not the end of Orokonui's kiwi creche. Other juvenile kiwi will be brought into this site later in the year, as long as the habitat is safe.''
A stoat was capable of killing a kiwi under 1.2kg, she said.
An adult kiwi could defend itself by using its strong legs to fight off the attacker.
Ms Baillie doubted anyone was releasing stoats in the ecosanctuary ''It's a possibility, but I don't know why someone would do that.''
