Tuesday 7 January 2020
In late July 2019, Zero Invasive Predators (ZIP) completed a predator removal operation in the Perth River valley, South Westland. This operation is part of a research and development project that aims to test and refine the ‘Remove and Protect’ approach for the complete removal of possums, rats and stoats from large mainland areas, and subsequent protection of these areas against predator re-establishment. The research area covers 12,000 hectares.
Since the operation, we have been using our network of 147 trail cameras paired with MotoLure automated lure dispensers and approximately 3,000 chew cards lured with peanut butter to detect any remaining possums, rats or stoats.
By mid-November, just 3 possums and 5 rats had been detected within the area – and no stoats. We established a small network of traps and extra cameras at the site of each rat detection, and caught 4 rats.
In mid-December 2019 we discovered evidence that localised rat breeding had occurred after the predator removal operation, across a small ‘footprint’ of approximately 50 hectares. We’ve always anticipated that the Remove and Protect approach will require a range of techniques to respond to animals that survive a predator removal operation or reinvade an otherwise predator-free area. Given the nature of the terrain, the only feasible response to remove this emerging population and prevent rats from re-establishing in the valley is to carry out a small-scale aerial ‘spot treatment’.
Consequently, today we applied non-toxic cereal prefeed bait (at a rate of 1kg/ha) across the 50 hectare footprint and a surrounding buffer zone. When the weather conditions next allow, we propose to apply a single application of 1080 bait (at a rate of 2kg/ha) over the emerging rat population footprint.
The location where bait is applied will be displayed on the DOC Pesticide Summaries website, and on a map accompanying the signage within the project area itself.
Image credit: Ngā Manu Nature Images, 2007