Hawke's Bay predator control project
Discovery Issue 40 | Nov 2015
The Hawke's Bay is embarking on a predator control project at a scale unheard of in New Zealand - 26,000 hectares. Aside from the obvious benefits to biodiversity, it could also have huge economic benefits for farmers.
From atop Te Mata Peak, overlooking Hawke’s Bay, Rod Dickson points out the Cape to City boundary.
“I haven’t seen anything like it,” the Hawke’s Bay Regional Council (HBRC) biosecurity advisor says.
The scale of the predator control operation, which is equivalent to about 26,000 rugby fields, is the first of its kind in New Zealand.
But it isn’t just the size of the five-year project – which will target ferrets, stoats, rats, hedgehogs and feral cats – that makes it stand out.
It’s also the innovative techniques, developed by Landcare Research, to monitor predator abundance. This is critical to knowing if trapping is making a dent on predator numbers.
Following in the footsteps
Dickson said the successful Poutiri Ao ō Tāne – an 8000 hectare ecological restoration project based 50km north of Napier – “paved the way” for Cape to City.
“We’ve learnt some valuable lessons and the development of new devices and new technology, particularly wireless, and also using trail cameras to pick up predator abundance.”
Dickson believes Cape to City will build on initiatives such as the Poutiri Ao ō Tāne project and the Cape Sanctuary.
“We’ve already started to see tomtit and robin turn up at Te Mata Peak (from Cape Sanctuary). We’re quite hopeful once we start doing more targeted predator control that we’ll see more of those species become more prevalent in our landscape.”
He said lizard and weta numbers had also “gone through the roof” since pest control began.
And that’s just the start if the Poutiri Ao ō Tāne is anything to go by, says Dave Carlton, Department of Conservation Hawke’s Bay operations manager.
“We’ve seen an increase in the amount of lizards and invertebrates in the surrounding landscape (around Boundary Stream Reserve). It has given us the confidence to put some species back that we haven’t attempted before.”
This included kakariki, kaka and just recently pāteke (brown teal).
“It’s a bit of a window into what might happen with Cape to City,” Carlton said.
An added advantage with Cape to City is that the community will get to see the benefits, he said.
“Poutiri is a bit out in the styx, away from human habitation, aside from the farms. Cape to City is right in the urban fringe. It provides an opportunity to create an environment for people to see a lot more of these native species.
“If we want people to value our biodiversity they have to be able to see it.”
HBRC land services manager Campbell Leckie said the community – particularly farmers – were critical to the success of the project.
“Without the farming community involved in large scale biodiversity projects in New Zealand we don’t believe we have a 100 year solution. We have basically got small islands of biodiversity arks and a sea of pests,” Leckie said.
Former Federated Farmers president Bruce Wills’, who is on the Cape to City board, said the cost-effective and time-efficient methods, such as cellphone alerts when a trap was triggered, meant farmers were behind the project.
He viewed the project as an extension of the region’s successful possum control programme, which farmers had strongly supported.
Benefits for farmers
There were also potentially huge financial gains for farmers.
Reducing feral cat numbers could eliminate toxoplasmosis – a disease that causes abortions in sheep and is estimated to cost the industry millions of dollars.
“That’s a really exciting possibility,” Wills said.
Landcare Research managing invasives portfolio leader Dan Tompkins said it was well-known that cats carried toxoplasmosis, but nowhere in the world had attempted to use predator control to stomp out the disease. It was mostly controlled through vaccination and rodent control.
“Lots of modelling work has been done that shows control of cats should control the disease. It just hasn’t been tried yet. We’re the first to see if feral cat control is the way to eradicate toxoplasmosis.
“We’re going to monitor what happens to the levels of this disease within the Cape to City footprint and outside to see if the cat control is eradicating the disease,” Tompkins said.
One-year-old ewes, within the Cape to City footprint and outside, would be examined each year to see if there was a decrease in the number infected with the disease. Current tests found one third were exposed annually.
“We’ll look at the next flock in a year’s time and hope to see that level drop,” he said.
Point and shoot
Motion-sensitive cameras would assist in monitoring feral cat numbers.
Researcher Al Glen, of Landcare Research, said it would be the first time in New Zealand that camera traps were used on such a big scale.
“People often use these cameras to detect species but it’s another step to use them to figure out predator abundance and determine once we’ve carried out control if we’ve been effective or not.”
The cameras provided a much more accurate picture of predator abundance – particularly with wary predators such as feral cats – than previous methods, he said.
“The number caught in traps doesn’t provide any information about how many are still out there. Not catching any more could mean you’ve got rid of them all or you’ve simply only caught all the stupid ones and the smart ones won’t go in the traps.
“The cameras allow us to know how many more are out there that haven’t been caught.”
The cameras had been trialled with success on Waitere Station.
For three weeks the cameras monitored how many predators were around before pest control began, for the same period during intensive pest control and after pest control. The results found a 90 per cent reduction in cats and ferrets, Glen said.
In the Cape to City project the cameras would be set much further apart, he said.
“At Waitere Station 40 cameras were spaced 500m apart in a grid formation. That’s a lot of effort and equipment concentrated in a relatively small area. This time around, we’ll have a similar number of cameras but spread out across the entire Cape to City footprint. They’ll be anywhere from two to three kilometers apart,” he said.
This approach proved successful in Australia to measure the effectiveness of fox control, “so we’re pretty confident it will work”, Glen said.
“But it’s not enough to show you’ve reduced predator numbers unless that leads to an increase in the number of native species so we’re also monitoring native lizards, invertebrates and birds,” Glen said.
Those involved in the project view it as just another stepping stone in the bid to protect New Zealand’s biodiversity.
Leckie said the project was large but even if it was doubled “wouldn’t be transformational”.
He hopes the project can eventually be upscaled and used as a template to be rolled out across the rest of the region, and may be one day the country.
The project has been made possible due to funding by the philanthropic Aotearoa Foundation, Department of Conservation (DOC), HBRC, Landcare Research and Cape Sanctuary – the largest privately owned and funded wildlife restoration project in the country.
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