Figure 1: Tracking rates in the Wainuiomata/Orongorongo KNE site Mainland island and Non-treatment area. Note that mast years are determined based on measured hinau (Elaeocarpus dentatus) fruit fall. Toggle through the tabs to see different animals, hover over the charts series to specific results, and click on legend entries to highlight and show/hide series. Use the month checkboxes on the top-right of charts to show/hide data from those monitoring months.
Figure 2: Wainuiomata/Orongorongo KNE site mainland island and non-treatment areas, showing the locations of the tracking tunnel lines.
Pest animal control regime: Possums are controlled over the entire Wainuiomata/Orongorongo KNE site using aerially sown 1080. Aerial 1080 operations are carried out when possum residual trap catch (RTC) results approach or exceed 5%, which occurs every five to six years.
In addition to the aerial 1080 operations, possums are kept to very low levels within a 1,200 ha Mainland Island (located in the Wainuiomata River catchment) using a network of Warrior kill-traps. Traps within a 300 m inner buffer of the Mainland Island are on a 150 m x 100 m grid and the traps in the interior of the Mainland Island are on a 300 m x 300 m grid.
Rat control is undertaken in the Mainland Island using Pelifeed bait stations on a 150 m x 100 m grid. The bait station interval is reduced to 50 m spacing around the Mainland Island boundary. Baits containing diphacinone or brodifacoum are deployed depending on rodent numbers. In mast fruit-fall years, when rat populations increase dramatically the bait station network has been supplemented with aerial 1080 operations and/or the deployment of Striker bait stations containing diphacinone and/or cholecalciferol.
Mustelids are controlled in the Mainland Island using DOC200 kill-traps spaced at 200 m intervals around the boundary and on lines through the interior that are approximately 1,000 m apart. All mustelid traps, bait stations and possum traps around the boundary are serviced at approximately five week intervals. The rest of the bait stations and possum traps are serviced at approximately ten week intervals (five times a year).
Mustelids are controlled less intensively in the southern half of the KNE site, outside of the Mainland Island. DOC200 and Good Nature A24 kill-traps are positioned at 100 m intervals on some main ridgelines and spurs. This network of traps is operated by the Remutaka Conservation Trust to help protect North Island kiwi that are spreading from a core population in the Turere Valley south of the KNE site.
Pest animal control milestones: The bait station and possum trap network was installed in 2004 and activated in 2005. Mustelid traps were installed in 2005.
In 2014 hand laid 1080 cereal pellet bait and Striker bait stations containing cholecalciferol paste were used within the Mainland Island to control the sharp increase in rat numbers that occurred in response to a mast fruit fall year.
In September/October 2017 Striker bait stations containing diphacinone paste were applied every 10 m along bait station lines in in response to consistently high rat tracking rates following the 2016 mast fruit fall event.
Aerial 1080 operations were completed across the whole KNE site in 1999, 2005, 2012 and September 2018 to control possums. An aerial 1080 operation was completed in the Mainland Island and an adjacent buffer area (which included the Non-treatment Area) in October 2019 to control the high rat numbers. The rat tracking rate was not decreased to within the 5 percent target so Striker bait stations containing diphacinone were deployed in the Mainland Island in December 2019. Both of these treatments were in addition to the continued use of brodifacoum pellets in the bait stations.
A six-month trial is being conducted in the Mainland Island to test an alternative to anti-coagulant toxins. Double Tap, a 12 gram cereal pellet bait, was used to replace the brodifacoum pellets in the bait stations. The Double Tap pellets contained a mix of diphacinone and cholecalciferol toxins, both of which have previously been applied in the Mainland Island. The trial is being conducted outside of pig hunting operations as Double Tap can pose a risk to the dogs which were used in the hunting. Baiting will be returned to brodifacoum pellets after the trial is completed in early 2021.
Surrounding pest control regimes: OSPRI’s TBfree programme undertakes intermittent possum control in the area. The Remutaka Conservation Trust undertakes mustelid control south of the KNE site.