environment

The danger with pest control figures

What do the Department of Conservation’s pest control numbers tell us and what do they mean for the goal of being predator-free by 2050? David Williams reports.

It was billed as an epic battle.

When the Battle for our Birds programme was announced in July 2014, it was estimated a million tonne of seed had dropped in the beech mast – a “megamast” of seeds dropping to the forest floor. It was estimated that would spark a five-fold explosion in the rat population, from about three million to 15 million. The plague was of “biblical proportions”, then Conservation Minister Nick Smith said. Late that year, controversial 1080 poison drops were made on 660,000 hectares of beech forest. Rats, stoats and possums would be killed to save kiwi, kaka and kea, the public was told.

What Battle for our Birds also did was reverse a sharp decline in pest control spending by the Department of Conservation (DOC), as outlined in figures released to Newsroom.

Five years after the 2008-09 financial year, DOC’s planned direct budget for predator control had almost halved from $10 million to $5.3 million. But the Battle for our Birds programme led to a huge boost to the predator control budget over the following three years, including an extra $21.3 million in 2016-17.

Department of Conservation predator control

Year Planned direct budget Battle for our Birds
2008/09 $10m --
2009/10 $9.1m --
2010/11 $8.7m --
2011/12 $9.3m --
2012/13 $6.3m --
2013/14 $5.3m --
2014/15 $13.5m $10.2m
2015/16 $12.8m $12.8m
2016/17 $12.3m $22m


The hectares treated actually rose initially, from 187,562 in 2008-09 to 285,338ha the following year. But then it dropped to 180,069ha in 2013-2014. By 2016-17, the target was to treat 875,143ha.

(DOC warns its budget data are subject to variability, as sometimes multiple pests species are targeted on single sites. Also hectares of treatment were under-reported in 2014/15 because specific performance measures didn’t come into effect until the following year.)

Battle for our Birds was a dream project. It took a catchy phrase that people could easily understand, paired with an approach underpinned by scientific research. But it was variable. The fact DOC’s pest control spending remained high late into the National Government’s last term was related to widespread beech mast, with heavy seed falls. Normally, they happen once every two-to-six years.

DOC predator control, hectares treated

Year Possum treated Rats/mustelid treatment
2008/09 (actual) 187,562 --
2009/10 285,338 --
2010/11 223,523 --
2011/12 234,636 --
2012/13 184,179 --
2013/14 180,069 --
2014/15 357,316 --
2015/16 164,459 190,385
2016/17 (target) 163,228 711,915


DOC’s numbers are still being debated in Wellington. It boils down to whether you prefer one-off increases in mast years, as happened under National, or the new Government’s approach of increasing baseline funding.

Contradicting DOC’s figures and the department’s 2008-09 annual report, National’s conservation spokeswoman Sarah Dowie claims that when it was in Government her party increased predator control seven-fold from 100,000 hectares to more than 700,000 hectares a year. “We had strong growth in endangered bird numbers during our watch,” Dowie says. “Takahē numbers grew by 52 percent, kākāpō by 64 percent and kōkako by 130 percent – a massive improvement. And our Predator Free 2050 is one of the largest and most ambitious conservation efforts in New Zealand’s history.”

She also throws a barb at the Government’s recent Budget announcement, asking why it only earmarked an underwhelming $4.4 million in the coming financial year (which starts on Sunday) despite Conservation Minister Eugenie Sage saying she would ensure funding levels were maintained at the same level as in 2017, “when National announced $21 million for Battle for our Birds”.

Sage, who announced in May an extra $81.3 million for predator control over the next four years, says there’s no beech seed mast event in the coming financial year, so DOC didn’t need a full-scale response. The $4.4 million is to get DOC what she calls “game ready”.

“The funding gives DOC all it needs to scale up, build capacity, get the plans in place, source suppliers and organise contracts to deal with the very large mast predicted for 2019/20 and then a stable stream of funding every year thereafter.”

She points out DOC will get $30.4 million for predator control the following year, for more work on an ongoing basis than it has ever done before. That’s sustained predator control over more than 1.8 million hectares by 2020/21, the largest area ever covered – about the size of Northland and Auckland combined.

“In light of that, one year for planning, which is not a mast year, is a very pragmatic and sensible approach.”

Sage says Dowie claiming credit for a one-off spend highlights the problem under National.

“Every mast year, DOC had to go cap-in-hand to stop precious species being wiped out. Under this Government it has secure funding and can do its work in a planned way to get the best results for our precious native birds, plants and insects.”

“It’s important that people understand that the crisis affecting nature before the election hasn’t changed just because the Government has changed.” – Kevin Hague

Kevin Hague, a former Green MP who now heads conservation lobby group Forest & Bird, stomped up and down the country last year complaining loudly about nature being in crisis. It’s an argument that seemed to resonate – despite then Conservation Minister Maggie Barry saying “DOC’s doing fine”.

Years of concerns about degraded waterways, the effect of agricultural intensification and climate change finally bubbled to the surface last year, making the environment and conservation crucial election issues. A Colmar Brunton research report from last December, commissioned by Fish & Game NZ, showed that pollution of lakes and rivers was a key concern for Kiwis, almost on a par with worries about the cost of living and the health system.

Hague says the Government’s increase in pest control funding is very substantial but it’ll cover only about a quarter of the public conservation estate.

“It’s important that people understand that the crisis affecting nature before the election hasn’t changed just because the Government has changed,” he says. “The depth of the crisis is easily underestimated. This is a very big problem that we’re needing to shift.

“Only a quarter of conservation estate getting regular predator control. While it’s a big step up it’s not actually where we need to be. We’re going to be looking for further increases in the future.”

Stoats caught in a DOC 150 trap. Photo: Shinji Kameyama/DOC

According to former Parliamentary Commissioner for the Environment Jan Wright, 1080 drops work. They’re essential in a mast year and, with few exceptions, rat and stoat numbers reduce significantly afterwards. They also lead to substantial improvements in nesting success for mohua, rifleman, rock wren and South Island robin.

But what’s happening is not enough. The 2014 drops covered only 16 percent of the total area of masting forest.

Wright’s report Taonga of an Island Nation, released in May last year, said of the 168 different species of native birds only one-in-five was in good shape. Birds need three things, the report said – safety from predators, suitable habitat and genetic diversity. Undoubtedly, the first was the most urgent, Wright wrote, and that would require a great deal more money.

The 2014 Battle for our Birds operation cost about $20 million. To control predators in all masting forest would have cost about six times as much. And, Wright noted, there are fertile forests in places like Northland where rate numbers are high every year. How to pay for the extra pest control? Perhaps through the ever-increasing numbers of tourists. Wright recommended bringing in what she called a “nature border levy”. The Government is now consulting on an international visitor conservation and tourism levy. (Submissions close on July 15.)

Wright also called for more work on a plan for New Zealand to reach the goal of being predator-free by 2050.

‘Everything else is doing worse’

DOC’s director of national operations Hilary Aikman says a major aim of predator-free initiatives is for a national stocktake of all predator control projects. Predator control operations have occurred at hundreds of sites up and down the country, and beyond to the sub-Antarctic islands. “The growth of predator control projects, particularly community-led projects, has been huge.”

But Forest & Bird’s Hague says New Zealand has almost 4000 species that are either at risk of or threatened with extinction. Yes, a handful of species are doing well, he says, but almost all of them have special recovery plans. “Everything else is doing worse. And that’s because of both factors, increased predation and increased habitat loss and degradation – both being exacerbated by climate change, already, we’re pretty sure.”

(Hague says the Government’s best bang for its buck, to improve the environment, is to make policy shifts, such as Resource Management Act reform to force councils to publicly notify more consents, and to stop mining on conservation land.)

Massey University’s Doug Armstrong, a professor in conservation biology, is more sanguine than Hague. Just because species are declining doesn’t mean somebody’s not doing their job, he says.

“What’s been done has made a huge difference and, certainly, I think the incentives or the sentiment to ramp up control of invasive mammals and to increase the scale of it is really good. Whether it’s being done in the right way, that’s a much more difficult question.”

He’s wary of pure pest control numbers. He says often big announcements in DOC will shift money out of one thing and put them into something else. Also, most possum control work is done by animal health boards and regional councils, which means DOC might be looking strategically at where its pest control money can most effectively be spent.

Armstrong is part of a panel discussion next week in Wellington, dubbed “Killing for Conservation”, part of the Society for Conservation Biology’s fifth Oceania congress.

He says no one can answer with confidence if New Zealand will be predator-free by 2050, but he’s not sure it matters that much. It’s just an attention-grabbing concept that can’t be mistaken for a complete management policy.

“Predator-free 2060 is presumably also pretty good, as is 90 percent predator-free by 2050. There’s room for a whole range of possibilities.” Some of the country’s approach will depend on technology, he says, while efforts may also be determined by economic factors. “A lot of it will actually just depend on public will and on public values.”

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