The anti-1080 lobby has made a martyr out of kea, but that ignores another salient fact: kea survival in large part depends on pest control. Dave Hansford explores on the challenge to balance pest control with conservation.
In April this year, Zero Invasive Predators (ZIP) announced that two kea had died after eating 1080 baits during a pest control operation in the Perth Valley, in South Westland.
The deaths were wrenching news, not least because ZIP had gone to extraordinary lengths to prevent them. But for some kea – and they are just a few – poison bait would seem irresistible. That’s a heartache for the people of Te Runanga o Makaawhio, who share their rohe – from Hokitika all the way south to Puysegur Point – with kea. The bird is held in such high regard that it’s enshrined in the Ngai Tahu Settlement as a taonga.
“We appreciate all the efforts ZIP made to avoid harming the birds,” says Makaawhio Chair Tim Rochfort, “but the loss of any native bird is really sad. They’re an iconic species, and for me, coming through Arthur’s Pass, kea have always been a sign that I was nearing home.”
The two Perth Valley birds join a toll of 24 out of 222 radio-tagged kea found dead after DOC 1080 operations since 2008.
Kea by-kill is all the more worrisome because these cheeky, inquisitive, high-living parrots are on the endangered species list. They’re damnably hard to count, but best estimates run to a total population of between 3000 and 7000 birds, which might sound OK until you learn just how common they once were – farmers and contract hunters shot around 150,000 kea – condemned as sheep killers – between 1860 and 1970, for bounties as high as £1 a beak.
Despite the protection finally granted in 1986, they continue to die in a plethora of mostly preventable ways: Massey University receives corpses every year with shotgun and blunt trauma injuries. In 2011, five young kea were shot and dumped on a picnic table at Klondyke Corner near Arthur’s Pass. In August 2016, Robert Aberson pleaded guilty to shooting at eight kea he said were “trashing” his Takaka Hill home, killing one.
Still more are killed by cars every year. Others fall foul of the very predator traps set to protect them: one bird was famously filmed setting off DOC 200 stoat traps with a stick – one of the first records, incidentally, of kea using tools – apparently for sheer entertainment. But, says the Kea Conservation Trust’s Tamsin Orr-Walker, “we’ve lost kea to those same traps, and to Timms traps, to Warrior traps, to Sentinel traps, to leg hold traps. They’ve interfered with bait stations, too.”
A still-bigger concern is lead. Kea like to trash soft, yielding fixtures with the powerful pincers of their beak. Sometimes, that’s the windscreen wipers of your car while you’re away skiing. Other times, it’s the lead-head nails and flashings on older roofs. But lead can kill kea, and even if it doesn’t, it leaves insidious effects: depressed immune function, impaired development, and decreased cognitive function. The problem is widespread: “We caught 52 birds in Arthur’s Pass village, and tested them for lead,” she says. “Twenty-seven returned levels over 20 micrograms per deciliter. That’s seriously high, and means they’re in urgent need of treatment.” Overwhelmingly, the lead victims were young males.
The research is clear: kea that mingle with humans are far more likely to die from misadventure than their backcountry brethren. Department of Conservation ecologist Josh Kemp has been studying kea since the early 1990s. He says a picture has formed in the data showing that, if kea learn to scrounge food from people, they’re much more likely to eat 1080 baits.
“Kea are adaptable omnivores,” says Kemp, “but they’ve evolved a cautious strategy of carefully investigating new, strange foods before moving them into their catalogue of safe, familiar diet. That’s the natural behaviour of a kea in the wild.” But when they hang around skifields, or cafes, or tourist spots – places Kemp calls “scrounging sites” – kea learn to abandon that natural caution, because the competition with other birds, and the reward from just tucking straight in, is so high.
Since 2008, 26 radio-tagged kea have died from 1080 poisoning, a figure heavily skewed towards scrounging front country birds, which Kemp’s work has shown are almost seven times more likely to die from 1080 poisoning than kea living in remote areas. Between 2008 and 2016, kea were monitored 222 times through 19 different 1080 operations. Overwhelmingly, deaths occurred in those operations nearest human habitation – Otira, Okarito, Franz/Fox – where 21 out of 112 radio-tagged kea died. At remote sites, such as Wangapeka, Oparara, the Copland Pass and Abbey Rocks, there were just three deaths among 110 monitored birds.
“A lot of overseas visitors go to places like Arthur’s Pass – and the Homer tunnel is another hotspot –specifically to interact with kea,” says Orr-Walker. “They all want that photo of a kea up close and personal, and the way they do that is to encourage them closer with food, and that’s a real problem. Because they’re getting fed,” she says, “those are the birds at particular risk of picking up 1080 baits, because they’re regularly rewarded for investigating novel items.”
There are documented cases of tour bus drivers feeding kea so that punters can get their selfies, and Orr-Walker is particularly worried about an Arthur’s Pass resident who continues to feed kea even though “we’re seeing birds dying on the highway right outside their place. It puts those birds in great danger, but there’s nothing legally we can do to stop it, short of changing the Wildlife Act.”
The anti-1080 lobby has made a martyr out of kea, insisting that they’re being poisoned to extinction, but that ignores another salient fact: kea do much better with pest control than without it. “Everyone focuses on 1080 as the problem with kea,” says Orr-Walker, “and we don’t deny that we’ve lost birds to 1080, but predation is still a much bigger concern. We’re not saying ‘stop doing pest control’, because that would be the fastest way to lose this bird.”
In 2011, Kemp compared the fortunes of kea nests at Okarito, which got a 1080 drop that year, and Fox, which didn’t. At Okarito, 1080 got stoat tracking down to zero for two breeding seasons, and kea there enjoyed 100% nesting success the first season, and 69% the next. Each female produced an average of 1.4 fledglings over the two years.
The Fox birds, unprotected, went backwards. They managed 38% success the first season, but just 1% the next – four times fewer than the Okarito birds – when stoat numbers mushroomed after a mast. “We had camera footage of a female kea laying an egg,” recalls Kemp, “and it was stolen that same day by a stoat. She tried again, and that egg was stolen, and so on, until she just gave up.”
“Any kea death to 1080 is one too many, and nobody thinks it’s acceptable,” says Kemp. “DOC agonises over this massively, and we ask ourselves the hard questions.” But pest control is a calculated business, guided by the greater good. “DOC’s in the population game,” says Kemp, “not the individual game. That’s our yardstick, and our modeling suggests that if you do a 1080 operation that delivers two years of high nesting success, as we saw at Okarito, then you can sustain a mortality rate of around about 22 per cent. That’s the point at which a kea population is better off with 1080 than without it. Mortality rates, even around scrounging sites, aren’t such that you’re going to drive a kea population extinct.”
Kemp’s work has shown a vanishingly small risk of back country kea succumbing to poisoning: the longer the history of 1080 use at a given site, the more likely kea are to survive it – by a factor of more than 21, compared to sites of first-time treatment, “so the mortality rates in remote country are in the range of about 5%”.
That’s a trade-off some New Zealanders, who voted the kea Bird of the Year in 2017, may find hard to accept, but Kemp points out that DOC is bound by other considerations too: “Kea aren’t the only thing in this picture. 1080 drops are usually triggered by other, more threatened species. Around the Milford Road, you’ve got endangered populations of short-tailed and long-tailed bats. Those are really rare as hen’s teeth. Around Arthur’s Pass, there are orange-fronted parakeet, and great spotted kiwi, and DOC has an obligation to protect those species, too. So it’s a complicated business that involves a lot of pros and cons for a whole lot of species – not just kea”.
ZIP’s experience in the Perth Valley shows that even the best laid plans won’t always keep kea from harm. On the strength of Kemp’s finding that kea survivorship is greater in areas with a history of 1080 use, ZIP in part selected the Perth because it’s had five previous drops (they expected to encounter around 18 kea in the block: surveys instead found between 75 and 100, which would seem to reinforce the benefits of regular pest control for kea).
The site is 28 kilometres from the nearest kea scrounging site, the Franz Josef township. ZIP leg-banded 55 kea, 30 of which also carried radio-tracking devices, and checked on them before and after each pre-feed and toxin drop.
Rangers regularly placed tahr carcasses at one-kilometre intervals along the upper boundary, to keep the birds fed and preoccupied while the 1080 drop was going on (59 birds stripped the carcasses clean in just seven days).
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For good measure, they placed non-toxic baits laced with anthraquinone – an agent that makes the birds feel sick after eating it – around the tahr carcasses, and across the wider drop zone, in a bid to train kea to avoid baits. ZIP chief executive Al Bramley says, “Our pen trials showed that captive kea learned to avoid such baits within a day of sampling them, and remote cameras confirmed similar results in the wild.” All the same, two out of 13 radio-tracked birds succumbed during the first 1080 drop in April.
A second operation, in late July, had a happier outcome – all 12 birds present during that drop were later found safe and well, and early monitoring by ZIP suggests that kea in the Perth should enjoy this breeding season free from the ravages of stoats and possums.
Meanwhile, the Kea Conservation Trust is trying to get tourists and residents alike to understand that feeding kea is to kill them with kindness. “It’s all about education,” says Orr-Walker. Tim Rochfort thinks that signs erected at kea hotspots are “rather minimalist – they just say ‘Don’t feed kea’. Our whanau would like to see a more comprehensive story told,” he says, not just about why people shouldn’t feed kea, but about the bird’s place in culture and history. “People are starting to show a new awareness of their own impacts, and we should be taking advantage of that.”
Orr-Walker agrees: “Communities are taking positive steps. I think it’ll get harder to put the birds at risk that way, because there’ll be more peer pressure on people to do the right thing.”
The Spinoff’s science content is made possible thanks to the support of The MacDiarmid Institute for Advanced Materials and Nanotechnology, a national institute devoted to scientific research.