Predator Free South Westland has now completed the second phase of a predator elimination operation in South Ōkārito Forest. This is a major milestone for the project, which seeks to protect and restore nature by eliminating possums, rats and stoats from 100,000 hectares across South Westland. Now, the work to protect the forest against predator re-establishment begins.
Predator Free South Westland Board Chair Katie Milne says, “The elimination of invasive predators from the forest of South Ōkārito will have significant benefits for the last remaining population of New Zealand’s rarest kiwi, the rowi, along with the many other native taonga that call this area home.”
The first phase of the operation was completed in November 2021, and achieved a substantial reduction of possums, rats and stoats. However, a small number of rats survived, and went on to breed in the site. To remove this emerging population, the second phase was initiated on 23 March.
Due to the nature of the South Ōkārito site, this predator elimination operation was particularly complex, and required a combination of aerial broadcast, ‘trickle sowing’, hand- and drone-laying techniques to complete. This complexity was further compounded by a highly unusual turn of events for the West Coast: low rainfall! To ensure that target predators interact with the toxic baits, it is important that no non-toxic prefeed baits remain in the environment when toxin is applied. In South Westland, this would typically occur within 1-2 weeks. In this instance, the prefeed application was followed by 23 fine nights before sufficient rainfall occurred to degrade the bait. Toxic bait was applied between 10-13 April.
The operation appears to have been a success. Pleasingly, no rats have been detected since the operation. If any rats are detected in the coming weeks, they will be removed using targeted ground-based techniques.
A small number of stoats, and an estimated two possums, have been detected in the site since the operation was completed. The team is now working to remove these using targeted ground-based techniques before they are able to re-establish a population.
The measures taken to minimise the risk of karoro (black-backed gulls) eating bait appear to have also been largely successful, and substantially reduced the impact on the karoro population. Pleasingly, there have been no reports of affected dogs or livestock.
The field team has been pleased to report many kea sightings since the operation, and surveys of popular kea sites are also encouraging. A group of kea (including this season’s fledglings) were recently seen at the Pakihi Walk carpark, and local helicopter pilot Gus Gordon reported seeing a flock of kea over the Waiho Loop.
ZIP Operations Director Duncan Kay, who oversees the predator elimination work on the ground, says, “The Predator Free South Westland team has greatly appreciated the ongoing support and patience of the local community during our work to eliminate invasive predators from South Ōkārito. We are now looking forward to protecting the site and watching the native taonga respond!”