On Tuesday 23rd July, Zero Invasive Predators (ZIP) completed the second phase of a predator removal operation in the Perth River valley, South Westland.

We are pleased to report that all 12 radio-tagged kea[1] and all 15 radio-tagged tahr that were present during the second phase of the operation are alive.

Since the operation, sufficient rain has fallen in the area to remove any remaining toxicity from baits on the ground. Visual surveys of whio (blue duck) and pīwauwau (rock wren) will be carried out during the coming months, as weather and snow conditions allow.

The first phase of the operation was completed in April, and resulted in a significant knock-down of possums, rats and stoats. Our team has now begun to carry out intensive detection in the area, to determine whether the second phase of the operation succeeded in removing the small number of individual possums and rats that survived the first phase, and to confirm the impact of the operation on stoats. This work will continue for several months.

This operation was carried out with the support of the Department of Conservation, NEXT Foundation and Predator Free 2050 Limited, and is part of a wider programme of research and development led by ZIP in a 12,000 ha area within the Perth River valley. The work aims to develop an approach to completely remove possums, and potentially rats, and to then enable long-term protection of the area, without the ongoing use of aerial toxins at landscape scales.

The Perth River valley is bounded by the Perth, Bettison and Barlow Rivers, and capped by Kā Tiritiri o te Moana – the Southern Alps. We have reinforced these natural boundaries to invasion by possums and rats with a network of traps and devices that automatically alert our team (via satellite) when predators are detected. We may further reinforce the barriers through the targeted use of toxins.

We anticipate that the permanent removal of possums and, potentially, rats, along with the work to control stoats to very low numbers, will help restore the mauri of the Perth River valley and safeguard its many natural treasures. Most importantly, if we successfully develop an approach to completely remove introduced predators and prevent them from re-establishing, then this approach could be applied to protect native species elsewhere in South Westland.

For more information about this programme of work, please contact us at info@zip.org.nz.


[1] This figure includes the 11 radio-tagged kea that were present during the first phase of the operation, along with another kea from the radio-tagged population that returned to the research area prior to the second phase.