Predator control helps hold the line in the Dart, Routeburn and Caples

Date:  14 August 2023

Monitoring data shows rodent numbers in the area remained low until at least May when the last results came in, following the aerial 1080 predator control operation in December last year.

Department of Conservation Senior Biodiversity Ranger Rebecca Teele says this is continuing to provide much needed relief for native species in the area.

“These valleys are home to rare and vulnerable species like mohua, rock wren, kea, whio and long tailed bats. Before the operation, all indications were pointing towards a tough breeding season with rat numbers in particular forecast to increase after a mast – or seeding event last summer.

“The operation gave some of our most precious and threatened native wildlife a chance to breed and raise their young last summer without the threat of introduced predators.”

While most monitoring data for native species won’t be available until this coming summer, anecdotally, DOC has received reports from visitors, hut wardens and other staff that the bird song in the area is the best it’s been in years. Long-term monitoring of long-tailed bats is showing a gradual increase thanks to ongoing predator control efforts.

“Even more incredibly, a member of the public came across a mohua on the Routeburn Track that, based on the colour combination on its leg band, was at least ten years old. Given the predation pressure present at times this is a huge win.”

Yellowhead/mohua used to be the most common bird in South Island forests but have declined over the years with populations at sites like the Dart, Routeburn and Caples, at risk of extinction, Rebecca says.

“The timing of the operation in early summer, before beech forest seeding, along with the large size and solid shape of the predator control area, is likely the reason we have had such a good result.  It’s clear that without predator control, mohua would be lost to these valleys completely.”

With Conservation Week taking place this week, it is a great chance to reflect on the work achieved so far, and for those wanting to help protect biodiversity in their own backyard, look at contacting your nearest local trapping group and consider a installing a trap in your own backyard, Rebecca says.

DOC will continue monitoring rodent numbers over the coming months in the lead up to the spring and summer breeding season. The numbers are expected to increase over the coming months, but it’s still a huge positive that we have been able to provide respite for native species since December.

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