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Waingake Ungulate Control Programme

Monday 19 December, 2022

Gisborne District Council carried out ungulate (goats, deer and pigs) control across 5650 hectares of water collection areas, adjoining pastoral, and production forest land at Waingake this year. The work was carried out as part of the Waingake Transformation Programme, a partnership between Council and mana whenua Maraetaha Incorporation to restore the whenua of Waingake and Pamoa.

Trap and Trigger Ltd were the contractors engaged to carry out the operation and they worked in collaboration with Ngai Tāmanuhiri Kaitieki Roopu.

The operation consisted of a priority 1950-hectare core area consisting of remnant and regenerating native forest. The core area is also the water collection area for Gisborne city. A 3700-hectare buffer has been established around the core area to prevent invasion by transient goats from adjoining areas.

Annual goat control work within the waterworks QEII block was undertaken by DoC until 2019. The new landscape-scale ungulate management delivered its first major knockdown of goats in 2020 and has been repeated in 2021 and 2022. It was known there were high populations of browsing ungulates in the wider Waingake area.

Browsing of palatable indigenous plant species causes significant changes to native forest ecosystems. It was recognised that ungulate populations needed to be controlled at a large scale at Waingake in order to protect the remnant native bush reserve, restore the understorey and protect the areas of ex-production forest which are undergoing native regeneration and planting.

Ungulates also pose a direct threat to water quality through contamination from faecal matter and the parasites Giardia and Cryptosporidium present in the guts of all feral ungulates. The plan to maintain low populations of feral ungulates is critical for minimising the threat they pose to water quality in the city’s water supply catchment.

The operation was delivered across four coordinated pulses, approximately 3 months apart. The objective of the operation was to reduce ungulate populations within the operational area to the lowest practical density, within a budget-limited campaign without compromising public safety.

During the four operations, a total of 513 ungulates were removed from within the core project area and the buffer areas. This figure consisted of 18 deer, 73 pigs and 422 goats. The key to this success was the application of multiple control techniques across the project area. Techniques ranged from traditional detection dogs through to utilising technologies such as aerial thermal systems.

Goat populations were originally found at high densities throughout the core Waterworks Bush QEII and dams area. As the year progressed, population densities within the QEII trended downward. Goat populations are now considered low to moderate within these areas.

The buffer areas produced a variation of population densities from hyper-abundant in places to moderate densities where previous control had occurred. During the first operation, contractors established where populations were highest, and during the second operation targeted their effort in these areas.

Deer were observed at low densities within the QEII and dams area and low to moderate densities on the fringe areas. Deer are very sensitive to habitat type, and their density and distribution is a closely related to the habitat type. The low numbers of deer shot over the four culling runs indicate the population is relatively low.

Carcass recovery for the local iwi was attempted at the beginning of the program, however the location of many of the kills and the nature of the terrain means opportunities for carcass recovery are limited.

Significant progress has been made with population reductions across the board and the relationship-building side of the operation is healthy and very prospective. There are areas within the core zone that are already showing signs of benefitting from the control of ungulates, however there are still areas that require further work.

It is important that we ensure the continuing declining trend in ungulate populations. With ongoing efforts, the balance will begin to shift from a degrading forest to a recovering forest. Once population trends plateau (measured when the same “animal per effort rate” repeats), efforts will shift focus towards sustaining populations at a certain level. The vegetation recovery status or population density can be measured/monitored in order to see if the desired outcomes are being achieved.