The person responsible for vandalising traps on Brow Peak near Arrowtown last week does not understand New Zealand's pest problem, Predator Free Arrowtown co-ordinator Ben Teele says.
A volunteer checking the trapline along the hill's ridge on Saturday found more than 20 of the traps either blocked with stones or kicked over.
Mr Teele said the traps were among 35 laid in a circle between Brow Peak and Sawpit Gully, near Arrowtown, in January.
They had already proven their worth, catching ferrets at the highest altitude recorded in New Zealand.
He could only speculate on the vandal's ''thought process''.
''It could have just been someone unfamiliar with New Zealand's issues with introduced pests.
''It's unfortunate for us because it was a big community effort to get those traps funded, and a lot of work went into it.''
He had learned from other trapping groups in the Wakatipu that vandalism did happen, but it was ''infrequent''.
A donation box at the Bobs Cove car park was broken into recently, and another by the Bush Creek track was broken into twice earlier this year, he said.
Wakatipu Wildlife Trust director Ting Zhang said the traps were there to save endangered native birds and wildlife.
They were tested to ensure predators were trapped humanely, were pet and child-safe, and traps placed by public tracks were clearly marked.
''These predator-control programmes are maintained purely by volunteers, and any tampering with it means the traps are useless until someone comes and fixes it.''
She encouraged anyone who saw vandalism to contact their local trapping group or the trust.