A plague on both our islands

The 1964 guide to pest control in Aotearoa.

The American at the dinner table is telling us about coming across a woman, who from the sounds of it was a West Coaster, in the act of dispatching a possum. I won’t get into it, but a rock was involved.

He goes a bit pale as he describes the scene. To be fair, possums are objectively cute (saucer eyes! bushy tails!), and he probably only knows them from that scene in Bambi where the possum family shows up to greet the newborn fawn in his mother’s thicket. “Best we don’t tell him about the cat hunt,” I say under my breath.

It’s hard to explain to a foreigner how much some New Zealanders hate introduced predators. We’ve all heard of the avian Eden this place used to be: birdsong so prolific you had to shout to be heard, eagles the size of hang gliders, tame flightless birds that practically waddled straight into the pot. After 85 million years of geological isolation, we have a range of endemic species unlike any other, from carnivorous albino snails to earthbound birds to lizards that give birth to live young. But because of a previous lack of predators, it’s also a range of species that is uniquely vulnerable. When people arrived, we unleashed wave after wave after wave of new animals that decimated the creatures who lived here.

We know better now, but it almost feels too late. Nevertheless, we persist, sometimes through official channels, like the government’s Predator Free 2050 mission, which aims to eradicate rats, stoats, ferrets, weasels and possums, by 2050. Then there are the more freestyle approaches, like the West Coaster’s. We took a close look at some of our noxious pests, and the ways we dispatch them. Results have varied.

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A DOC 200 humane kill trap on Pigeon Island in Dusky Sound. PHOTO: Kimberley Collins, Wikimedia Commons

Possums

As previously mentioned, very cute, but quite awful. Our possums were first introduced from Australia in the 1830s, with the brilliant idea of establishing a commercial trade in their fur, which, to be fair, is lovely. By 1922, more than 30 batches of possums had been imported; by the early 2000s, up to 70 million of them had spread to almost every corner of the country. This is bad. Possums are omnivores, and they’ll munch on pretty much anything, including the eggs of native birds, as well as their chicks. They also eat weta and land snails, and, even worse, a possum will pick a tree and keep grazing on it until it’s been stripped of everything edible. They have wiped out entire forests this way. Not awesome, possum.

As well as whacking them with rocks, we come at controlling possums from multiple angles. There’s trapping and aerial poisoning, and the big eyes are ideal for reflecting hunters’ spotlights at night. There’s even a resident possum scat detection dog on the Otago Peninsula that flushes them out. And I heard about one unnamed individual who used to cut off their feet and ship them off to France branded as “New Zealand mountain hares”.

Rabbits

The rabbit problem in Aotearoa is what you might call Biblical, if you were that way inclined. European rabbits were brought in during the late 1800s for hunting and meat and before you could say, “what’s up, Doc?” they were decimating vegetation and digging bloody holes everywhere, contributing to soil erosion and broken ankles.

They also breed like, well, rabbits. Bunnies can give birth to up to 50 baby bunnies per year, and they start doing it from the age of five months. You do the maths. In fact, they spread so fast, a Rabbit Nuisance Act had already been passed in 1867, and by 1895, rabbit control represented a quarter of the Department of Agriculture’s budget.

More recently, biological warfare has taken centre stage, which involves infecting the animals with rabbit haemorrhagic disease (RHD). This sounds mean, but is very efficient – RHD has been known to reduce rabbit densities by 75% in some places, at least temporarily. It was first deployed in the late nineties when some fed-up Central Otago farmers smuggled the virus into the country before it had been signed off.

Speaking of Central Otago, there’s also the region’s Great Easter Bunny Hunt, an annual celebration of rabbit murder held every year in the vicinity of Alexandra – over Easter weekend, nearly 12,000 of the animals are shot. Also, New Zealanders love to run rabbits with their cars, to the point that I’ve seen drivers swerve to purposely hit them. Don’t do this, it’s dangerous. But should one stray into the middle of your lane, don’t necessarily avoid the thing. That’s all I’m saying.

In Aotearoa, the only good stoat is a dead stoat. PHOTO: Auckland Museum, Wikimedia Commons

Mustelids (stoats, ferrets and weasels) 

Oh, human folly. In the late 1870s, someone had the bright idea to bring in mustelids, in the form of stoats, weasels and ferrets, to control the rabbits. Except it turns out that while rabbits are yummy, flightless native birds are yummier, and they are a lot easier to catch.

They’re all nasty, but of the three, stoats are the worst. The Department of Conservation has called them “public enemy number one” for our native birds. “Stoats are implicated in the extinction of South Island subspecies of bush wren, laughing owl and New Zealand thrush. Even a three-kilogram takahē or two-kilogram kākāpō can be killed by a stoat.” Every year, stoats slaughter an estimated 60% of North Island brown kiwi chicks hatched.

As for reproducing, like the troublesome Tribbles the original Star Trek series, these merchants of death are practically born pregnant. As soon as a female gives birth, a male will show up for a spot of copulation with both her and her female kits. A fertilised egg will remain in a kit’s uterus until the time is right, about 10 months later, then implant. It’s called “delayed implantation”. I know, nature is messed up.

Clever as they are, stoats won’t take poisoned bait. The best way to deal to these malicious mustelids is through trapping, and you can help – get yourself an animal welfare approved stoat trap like the DOC 200 and the DOC 250, and get involved with a local backyard trapping group. They can give you advice about trap setting (places like fallen trees, hedges and fencelines are good) and bait. Think eggs and salted rabbit meat. And the car thing? Do that for these guys too.

Goats

They don’t eat native birds, but goats are problematic. This hit our shores in 1773, when Captain James Cook released a bunch in the Marlborough Sounds. Later, like the stoats, goats were introduced as a form of pest control, although in this case the pests were weeds like briar and gorse, which goats like to eat.

The bad news is they also like to eat native plants. The good news is we all (or all of us with a current firearms license) can get involved in the cull. The National Wild Goat Hunting Competition runs nationwide from August through November every year. There are some excellent categories, including Got Your Goat (enter one wild goat tail and go in the draw ), Great Goat Round Up (the more wild goat tails entered, the more chances to win ) and New Zealand Deerstalker Association’s G.O.A.T (for the head with the largest Douglas Score, which measures the horns and tusks of big game animals). The prizes are incredibly cool, and include a fully-catered wild game banquet, thermal night vision monoculars, and something called a Meater Plus Bluetooth meat probe. Get your goats!

Rattus rattus on the prowl. PHOTO: Wikimedia Commons

Rats

There are three species of rat in New Zealand, all of them introduced: the delightfully named Rattus rattus, or ship rat, the Norway rat (Rattus norvegicus) and the kiore, or the Pacific / Polynesian rat (Rattus exulans). They are all omnivorous, eating everything from eggs, to fruit, to larvae, to lizards, to birds. Recently, to the dismay of conservationists, trail cameras captured rats eating the eggs of the shortjaw kōkopu, a threatened fish, in Northland’s Waipoua Forest. Turns out they have a taste for caviar. Also, I once found a family of them living inside my very expensive full-face mountain bike helmet and I am not OK about that.

It’s all about trapping and poisoning with rats, including using anticoagulants, which, again, are mean, but here we are. Through these methods, rats have been eradicated from multiple offshore islands, which can now serve as lifeboat-style havens for rare and threatened species.  

Canadian geese gather at Huxley Gorge Station, near Lake Ohau, Waitaki District, Canterbury Region, with the homestead and mountains in the background. About 1953. Whites Aviation Ltd: Photographs. Ref: WA-32732-F. Alexander Turnbull Library, Wellington, New Zealand

Canada geese

The Guardian UK called them “the rabbit of the sky”, and the Guardian UK is not wrong. Canada geese came to Aotearoa in 1905 as a game bird. Fifty were set free at the time, and their descendants have been making a mess ever since. Apparently, a single goose can produce up to a kilogram of poop per day and not only are their faeces smelly, they contain harmful bacteria. The birds are so numerous they can even pose a danger to aviation (the engines of US Airways Flight 1549, the one that ended up in the Hudson River in 2009 and was the subject of the film Sully, were taken out by a flock of Canadian geese). Plus, they are super bad-tempered. Even Canadians think so, and I should know, I am one.

Canada geese are not officially designated as pests, so do not fall under a national management plan. Instead, control is managed regionally and privately by landowners. Some farmers even pepper their paddocks with cut-out coyote silhouettes to deter the geese. But with numbers on the rise, there’s a call for a nation-wide coordinated effort to keep the birds at bay, eh.

All dressed up for the cat hunt. PHOTO: Tatsiana Chypsanava

Cats

There’s no way to sugar coat this: cats are a disaster in Aotearoa. Here, Sylvesters catch and ingest Tweety Birds so often there have been calls to ban the animals, even domestic ones, from the country entirely. According to DOC, for example, feral cats killed 20% of monitored kea in Arthur’s Pass from 2019 to 2021, and one cat devoured 102 bats roosting in the Rangataua Forest over the course of a week.

Cat control in the wild includes poisoning, trapping and shooting, and there’s a push for cat owners to keep their domesticated moggies indoors, especially at night. The North Canterbury Hunting Competition, however, takes a more direct approach.  An annual fundraiser for the Rotherham Community Pool and Rotherham School, the comp has, alongside deer, rabbits, mustelids, rats, ducks, possums and pigs, a feral cat category. This has seen organisers targeted by animal rights advocates, including protesters from Animal Save Movement Aotearoa (in turn, some contestants wore their own “Animal Slay Movement” outfits). The whole stoush made the international news, with comedian Ricky Gervais joking that it was a PR stunt to make New Zealand seem more “loveable”.

For the record, the cats must be caught first using box traps, identified as feral, then humanely killed using a .22 rifle, minimum, and all hunting must occur at least 10 kilometres from the nearest residential area. The 2024 event saw 370 cats bagged, with one man taking out a $500 prize for dispatching 65 of them single-handedly.  

Am I comfortable with cat murder? Not entirely. But I get that this is a me problem. That we are happy knocking possums over the head but uncomfortable with culling apex predators responsible for more than a million bird deaths per year says a lot about the mental gymnastics we humans perform when it comes to morality. Still, I don’t think I could purposely run a cat over. Would you?

LAURA WILLIAMSON

Top image: Rabbit hunters at camp, 1909. New Zealand Railways: Assorted photographs. Ref: 1/2-023747-G. Alexander Turnbull Library, Wellington, New Zealand