Landscapes’ use for pest control investigated

University of Otago Department of Zoology researcher Nick Foster installs a motion-activated...
University of Otago Department of Zoology researcher Nick Foster installs a motion-activated camera in the upper Mackenzie Basin. PHOTO: SUPPLIED
Alpine ecosystems are under intense pressure from pest species, but University of Otago research has highlighted how the mountains themselves can be used to help eradicate them.

The study demonstrates how mountain ranges can act as barriers to species such as stoats, hedgehogs and mice, highlighting opportunities to create sanctuaries for threatened wildlife.

Lead author Nick Foster, a PhD candidate in the zoology department, said the research showed the "enormous potential" in using landscape features to naturally limit the rate of reinvasion from areas which have undergone pest eradication.

"Any landforms which influence the movement of pests are incredibly valuable in pest-removal programmes which take a ‘remove and protect’ approach," Mr Foster said.

"It has long been presumed that big mountains are barriers to New Zealand’s pest species, but this is the first study to analyse and really validate this strategy."

Published in Landscape Ecology, the study analysed the movements of 10 invasive species in a 310,000 ha area in the upper Mackenzie Basin, proving the effectiveness landforms had in segregating the animals.

Mr Foster said he hoped the findings would lead pest removal groups to better understand how natural landscape barriers function in their areas, as well as highlight opportunities to protect upland areas in areas like the Southern Alps/Ka Tiritiri o te Moana.

"Aotearoa New Zealand is plagued by a suite of invasive small mammals, each of which play a part in the ongoing degradation of native biodiversity and native species populations," he said.

"As regional predator-free initiatives grow larger in size and ambition, larger tracts of increasingly complex and inaccessible terrain will need to be cleared of predators — natural barriers will help in reducing costs and such work and ensure success."

In practice, that would work by removing a pest population from an area that was defended from reinvasion by surrounding high-elevation landforms.

Incursions from the area down-valley would be managed by maintaining a buffer zone of lethal devices until the reinvading population could be removed.

Mr Foster said he was pleased the research provided some hope for those working hard to protect New Zealand’s native species.

"Removing pest species is a daunting task and it’s nice to know that there are things out there working in our favour."

"High-elevation landforms limit the movement of invasive small mammal species", by Nicholas J. Foster, Richard F. Maloney, Philip J. Seddon, Mariano Rodriguez-Recio, Yolanda van Heezik, published in Landscape Ecology.

Staff Reporter