
A dead stoat was found in the middle of a track earlier this month.
The discovery was concerning, Department of Conservation southern South Island operations director Aaron Fleming said.
A member of the public walking on the Great Walk track on July 12 reported the dead stoat to DOC, which retrieved it the next day.
The stoat's skull was crushed indicating it had died instantaneously from either a trap or similar blunt force before being found on the track.
"Rakiura is known to be stoat-free," Mr Fleming said.

"We need to know if we are dealing with a new significant threat to Rakiura’s native species, or if this stoat has been transported from elsewhere and planted deliberately. Both scenarios are disturbing. We are taking this seriously."
Southland district councillor Jon Spraggon, who represents the Stewart Island ward, said when contacted that considering the stoat was found in the middle of the track with clear footprints, he felt it may have been done tongue in cheek.
"The fact that it was in the middle of a track with its head crushed, it would tend to be that perhaps someone's trying to be humorous," he said.
"I have never heard of anything like that before. With everything else happening on the island in relation to the 1080, [it could be] just someone ... sort of highlighting, ‘yeah, there's pests anyway, so why are we bothering with 1080?’."
DOC is spreading 1080 across more than 40,000ha to kill predators in an attempt to save the endangered pukunui/southern dotterel. This has upset hunters, residents and tourism operators.

"It's sort of settled a wee bit at the moment but I know there's still angry feelings, definitely. I'd love to see them sit down and talk and share information and everything, but it doesn't seem to always work that way."
The dead stoat had been sent to an expert to see what further information could be obtained, Mr Fleming said.
Samples were being sent for genetic testing to try to determine where it had come from.
"It would have devastating implications for native wildlife if stoats were to take hold on Rakiura," Mr Fleming said.
"If stoats were to establish on Rakiura they would threaten efforts to create a predator-free space for kākāpō to be returned, and they would quickly decimate other native species on the island."
Introducing pests such as stoats constitutes an offence in New Zealand, and penalties include imprisonment of up to five years and significant fines.