Self-setting pest traps in National Park trial

22:30, Nov 04 2012

Eight-hundred self-setting gas-powered stoat traps are being tested in the Nelson Lakes National Park.

A two-year trial of the goodnature traps, which kill up to 24 pests by knocking them on the head, was launched at the Department of Conservation's St Arnaud headquarters on Friday.

Conservation Minister Kate Wilkinson, Greens conservation spokeswoman Eugenie Sage and DoC director general Al Morrison all got to hear about the traps' potential.

Scientist Craig Gillies, of Hamilton, said 815 of the $145 traps were being set out in the 6000 hectare area around Lake Rotoiti, where DoC carries out intensive possum, rat, stoat and wasp control.

The traps kept on killing without having to be reset, unlike the boxed snap-traps they replaced, Dr Gillies said. "The animal comes in, presses a leaf spring trigger, a striker flies out under CO2 compression and strikes the animal on the back of the head and kills it," he said. "This can happen up to 24 times."

Birds including grey spotted kiwi reintroduced to the area in 2004 and 2006 would benefit from reducing the number of predators, he said.


Retired Blenheim builder and Friends of Rotoiti member Warwick Ward said the group was sent a plan of a box to put the new trap in and asked to make 900.

He built a prototype "which was a bloody terrible thing" so invented a way of converting existing traps.

Not only did this save time and money, it meant traps could be easily switched between the two trapping methods, Mr Ward said. Dr Gillies said his one worry was that the lure-paste supplied was odourless and unlikely to attract pests. A rabbit meat jerkey called Erayz should be more successful and baiting traps with sex pheromones was another possibility being explored by Landcare Research.

The traps' efficiency would be tested by comparing stoat numbers in targeted and non-targeted areas, using tunnels with ink-covered floors to record their footprints, Dr Gillies said.

Otago University wildlife management graduate Jenny Long is overseeing the two-year programme at Rotoiti. Her days will be spent checking traps and analysing data.

The Marlborough Express