Wide-scale predator control for biodiversity in Hawke’s Bay
Bellbird. Image – Rod Dickson
Introduced predators are implicated in the extinction of 33 terrestrial vertebrate species since European settlement in New Zealand. A further 77 native bird species are currently listed as threatened, while an unknown number of invertebrate species have been lost. To prevent further extinctions, predator control must be undertaken on a scale sufficient to allow populations of native animals to recover.
Hawke’s Bay Regional Council (HBRC) is breaking new ground in the battle to save New Zealand’s native species. Predators have been successfully controlled across 8000 ha of Hawke’s Bay farmland since 2011, resulting in the significant recovery of native lizards and invertebrates (see Jones et al.). While the land area is not in itself significant in terms of pest management, what is potentially transformational is the very-low-cost farmland maintenance control practice being developed by HBRC for predators. The proposed Cape to City Project (Fig.) aims to control predators such as stoats, ferrets and feral cats across 26,000 ha of fragmented rural and semi-urban land between Cape Kidnappers and the city of Hastings. As well as protecting remnant populations of native species in this landscape, it is hoped the project will also encourage rare native birds to disperse from the fenced Cape Sanctuary and recolonise the adjacent landscape.
A major challenge for any wide-scale pest control programme is keeping costs affordable. Encouraged by the success of their regional possum control programme and by recent trials on Rangiora and Opouahi stations (see Jones et al.), HBRC is confident that predators can be controlled across the Cape to City landscape for a few dollars per hectare. As with all conservation work, monitoring is essential to determine whether the desired results (lower numbers of predators) and outcomes (greater abundance of native species) are being achieved. Landcare Research staff will monitor predator abundance for HBRC using motion-activated cameras and use a range of monitoring techniques to determine how native species respond to predator control. Weta houses will be used to monitor invertebrates, tracking tunnels to monitor native lizards, and five-minute bird counts to monitor the abundance and diversity of bird species.
Another challenge for the Cape to City project is the large number of properties and different land uses within the project area. Much of the proposed predator control will be on private land. Predictive modelling carried out by Cecilia Latham and colleagues suggests that at least 80% of landholders will have to participate for the project to be effective, so corresponding buy-in will be critical.
From HBRC’s perspective, the Cape to City project provides the opportunity to potentially transform the benefits its community gets across economic and environmental outcomes. This is because the project is a model for how future predator control targeting possums, feral cats, mustelids and hedgehogs could be achieved over the remaining 500,000 ha of the HBRC possum control programme. Critically, the project also provides the opportunity to test operational-scale solutions relevant to wide-scale predator management. This includes trap monitoring using wireless technology, motion cameras to monitor pre- and post-control predator populations, and disease surveys to determine whether the incidence of toxoplasmosis in the area can be reduced to deliver tangible economic benefits to sheep farmers.
The Cape to City project promises not only to benefit native biodiversity in Hawke’s Bay, but also, in combination with Landcare Research, to develop knowledge and techniques valuable for the long-term aspiration of a Predator-Free New Zealand.
This work is funded by Hawke’s Bay Regional Council as well as core funding from the Ministry of Business, Innovation and Employment.