Tahr cull vital to saving alpine ecosystem - DoC

The Department of Conservation and hunters have culled more than 12,000 tahr since July. Photo: File

A conservation plan is being developed to protect the Ben Ohau Ranges in the Southern Alps from Himalayan tahr.

The Department of Conservation (DoC) said tahr were wrecking native alpine tussocks in their search for food and destroying the ecosystems.

It hoped that a renewed focus on tahr would help reduce the population.

Tahr control programme manager James Holborow said the only way to kill them was by shooting, either from a helicopter or on the ground.

"So high numbers of tahr have quite strong localised impacts, we won't necessarily see those impacts everywhere in the environment. But what we see is tahr tend to herd together and where they herd together, they'll tend to have quite strong effects."

He said DoC was in the early stages of developing a new plan to cull the pest.

"Probably likely to be two phases of planning. We will need to do some more tahr control next winter. So we'll be working with our treaty partner Ngāi Tahu to develop that plan with their tahr stakeholders. And then we're also trying to make sure we can have a longer term plan that will run for, say, the next five or so years."

It was hoped the plan would reduce tahr numbers to about 10,000; doing so would hugely benefit native tussocks.

DoC ecologist Brian Rance said tussocks played a vital role in the alpine ecosystem.

"These snow tussocks, they are really like the trees in the forest. You know, they're the canopy species. So they're dominant in the vegetation here and also like a forest, they're old, they're very long lived. These species will grow and live for several hundred years."

DoC biodiversity monitoring ranger Ingrid Gruner said despite the tahr control plan, it would take many years for the tussocks to recover, as the area was "a very cold environment that is covered in snow for much of the year".