Image: Tina Tiller

Is it time to keep our cats at home?

Cats, both feral and domestic, are killing our native fauna. We need to keep them confined, writes Anna Yeoman.

A couple of weeks ago, on the outskirts of the Central Otago town of Alexandra, a pile of 28 dead native lizards was found. They’d been regurgitated by a cat, which had caught and eaten all 28 in just several hours.

As a science communicator living in Alexandra, I took on the job of making a short video and article for Stuff about the find, and about how scientists responded. Very quickly, the issue of pet cats came up. Dr Grant Norbury, an ecologist with Manaaki Whenua Landcare Research, who has spent 38 years researching predator-prey dynamics, said while it was unclear whether the culprit in this case was a feral cat or a pet cat, he had a clear message for cat owners.

“Many people think their pet cats aren’t a problem. They think feral cats do that damage, and their pet cats don’t. But they do. They’ve got the same instincts, they’re hunters,” Norbury said.

Professor Yolanda van Heezik, an urban ecologist from the University of Otago, said it wasn’t unlikely that this cat was someone’s pet. “It’s only 400 metres from the housing,” she explained. Cat tracking studies she’s done show pet cats can roam up to 28 hectares, much to the surprise of their owners.

“We’re not saying don’t have a cat. But it’s about how you manage your cat to reduce harm to vulnerable wildlife,” said van Heezik. “Ideally people should be confining their cats 24/7.”

Dr James Reardon, a herpetologist and science advisor at the Department of Conservation, was also consulted in response to the find. “New Zealand is unusual in that we let our cats roam.” He explained that in Australia, and in large parts of America, it’s much more the norm to keep cats indoors, rather than have them out hunting.

And from van Heezik, “It’s like we’re a decade or two behind those other parts of the world in terms of our cat regulations. So we need to move in that direction.”

So is it time for New Zealand to change the way we keep our cats, and start confining them indoors? And why, if it’s the norm in North America, Japan and Australia, do we not already do it?

In 2013, Gareth Morgan brought the cat issue blazing into the spotlight. The stated goal of his campaign was to ensure cats were registered and kept indoors, yet he named his campaign ‘Cats to Go’, a move guaranteed to do more for media attention than for diplomacy. And he certainly raised attention.

Cats are beloved companions for so many people. One in three New Zealand households have at least one cat. So to talk about our moggies as problem predators, or to challenge their right to roam, is difficult. Yet maybe the solution isn’t as hard as it seems. Already in New Zealand we keep our most valuable cats confined. Pedigree cats aren’t allowed to roam freely in case they get injured, lost or impregnated by a non-pedigree Tom. They’re very well looked after and kept in peak health. Could we not make this the norm for all cats?

A major barrier to containing cats on their home property is that it would entail a hassle, and likely an expense, for cat owners. If an owner wasn’t comfortable confining their cat indoors 24/7, they’d need to build an outdoor cat enclosure. This is what’s meant by the term “catio” – a patio for cats.

In this scenario, all cats would also be micro-chipped and registered, so that they could be returned home if found straying. So to justify the effort of doing this, there would need to be a seriously good reason.

Reardon sees our native lizards as a major part of that reason. We’ve got one of the most diverse and fascinating lizard faunas on the planet. “We’ve got over 120 species of native lizards. That’s more lizard species for our land area than Australia.” Yet most are in serious conservation trouble.

Reardon explains why cat predation is such an issue for New Zealand lizards. “Our lizards evolved in a land without mammals, where birds were the major predators. Birds generally hunt by sight, not smell, so our lizards protect themselves by being hard to see.”

It was humans who brought rodents, cats and other predatory mammals to New Zealand, which all hunt by scent. So when these mammals hunt our native lizards, birds and invertebrates, it’s not a natural part of a food chain. And it explains why they decimate our native populations so quickly.

Small mammals like mice and rats, which evolved alongside cats, breed incredibly quickly, and so can easily keep up with cat predation. But our native lizards can’t, nor can most of our birds. While mice can give birth to up to ten babies every six weeks, our skinks have two-to-six young once a year. Our geckos have even less, only one or two young after a pregnancy that can last up to 14 months.

So when 21 skinks and 7 geckos were found in one regurgitated pile, that’s at least four years’ worth of breeding wiped out in a matter of hours. Schist geckos are extremely long lived, and the adults could have been 40 or 50 years old. “And that’s why we have vanishingly small numbers of our rare lizards left,” says Reardon.

Yet surely most pet cats aren’t killing 28 native lizards for breakfast?

Van Heezik agrees this will be at the higher end of predation, but explains that many cat owners are unlikely to have an accurate impression of just what their cat is killing. “Recent studies using miniature cameras, ‘kitty-cams’, show that what cats bring back is on average only a quarter or a third of what they actually catch and kill,” says van Heezik. Some cats don’t bring back any of the things they kill.

A cat (Image: Getty)

There have certainly been other records of thirty or more native lizards being found in the stomachs of feral cats. And in Ruapehu in 2010, 102 short-tailed bats were found to have been killed by one cat within a week. Norbury explains that it’s the scale of the issue that’s so alarming. “When you multiply a day’s hunting by 365, and then by all the cats in the landscape, you get an understanding of why it’s a real problem,” says Norbury.

It can certainly seem strange to consider the enormous amount of work and expense going into the Predator Free 2050 campaign when we have cats roaming freely in towns, cities and countryside. The issue is becoming especially obvious in Wellington. The city is leading the way in rat and stoat eradication, while at the same time kakariki/red-crowned parakeets, which are spreading out from Zealandia sanctuary, are being eaten by people’s pet cats.

While ideas like colourful bird-scaring collars, bells, keeping your cat well fed, or keeping it in at night might help reduce predation a little, Norbury and van Heezik both explain that these things have limited effectiveness, and are at best only partly reducing the problem. Containing cats 24/7 is the only thing that really works.

Van Heezik also raises the issue of toxoplasmosis, a disease spread by cats. “I’m surprised more people aren’t freaked out about it!” she says. “Once you’re infected by the toxoplasma parasite it essentially lodges in your brain forever, and it’s linked to an increase in impulsive, aggressive behaviours,” she explains. If our cats were contained, it would reduce the spread of toxoplasmosis.

So there are some strong conservation and human health reasons for keeping our cats at home. But is it fair on our cats to do so?

It turns out that the major animal welfare groups are also calling for cat registration and containment. In the January 2021 edition of New Zealand Geographic, Hayden Donnell observes that, “the most surprising thing about the cat management debate in New Zealand isn’t the division it inspires, but the consensus.” He goes on to quote the chief science officer at the SPCA, Arnja Dale, as saying, “It’s a very emotional issue, but it’s not a controversial issue.”

A National Cat Management Strategy Group (NCMSG) was formed in 2014 and consists of all the major animal welfare groups – the New Zealand Veterinary Association, the Royal New Zealand Society for the Protection of Animals, and Local Government New Zealand, with the Ministry for Primary Industries and the Department of Conservation involved as technical advisors.

The strategy group calls for new laws around responsible cat ownership to be legislated in a National Cat Management Act. Their long term goal is that in New Zealand there would be no feral or stray cats. That all companion cats would be micro-chipped and desexed. And that all companion cats would be contained on the owner’s property, either indoors or in an outdoor enclosure.

The New Zealand Veterinary Association website already provides guidelines for how to keep your cat healthy and happy if it spends its whole time inside, specifying that “If a cat is confined indoors, suitable enrichment should be provided to enhance the environment, such as climbing frames, scratching posts and toys.”

It sounds a long way from the current situation. But van Heezik recalls how far we’ve come with dogs. When she was a child her pet duck, rabbits and guinea pigs were all killed by wandering dogs coming onto their property. “We just accepted it as bad luck, whereas nowadays of course it’s completely unacceptable. Our attitudes have changed with regards to what dogs should be able to do, and hopefully we’ll get there with cats too,” she says.

The Dog Control Act was enacted in 1996, but so far we don’t have anything similar for cats. Which is why the NCMSG is calling for a National Cat Management Act. With such a strong consensus among conservation, public health and animal welfare groups, there is still one thing missing. There needs to be action on the issue in Parliament. And because the emotional charge of the issue is so high, it’s seen as too politically risky for a leader to touch. Despite calls to bring in tighter cat controls, so far Jacinda Ardern has remained quiet on the subject.

Finding 28 dead native lizards is just a reminder that delaying the necessary change is costing the country’s vulnerable wildlife. Containment works overseas, and it works for our pedigrees. Is it really too hard to imagine that it could work for all our cats?




The Spinoff is made possible by the generous support of the following organisations.
Please help us by supporting them.