A Ban on Cats in New Zealand?

I swear, I really didn’t want to put any energy in to the Gareth Morgan story—didn’t want to give the thing any more oxygen. As a former co-worker used to say, “Never wrestle with a pig. You both get dirty, and the pig likes it.”

But, as if often the case with such PR stunts, the media is having a field day with Morgan’s just-launched campaign to rid New Zealand of cats. All of them. “The fact is,” he explains on his Cats to Go website, “that cats have to go if we really care about our environment.” For Morgan, “a New Zealand businessman, economist, investment manager, motor cycle adventurer, public commentator and philanthropist,” according to Wikipedia, “that little ball of fluff you own is a natural born killer.”

Which, I suppose, would have been easy enough to ignore. Not so easily ignored, however, if the way Morgan and others have co-opted various scientific studies in an effort to justify his proposal.

An Arms Race of Misinformation

Among the numerous news outlets to cover the story are NBC, ABC, USA Today (where, thankfully, they ran the AP story rather than turning it over to science reporter and 2012 Trap Liner Award winner Elizabeth Weise), and The Telegraph. One reason for all the media attention: Morgan is—however misguided—very quotable. He told New Zealand’s 3 News, for example, “cats just love killing things—and that’s your cat we’re talking about.”

Of the coverage I’ve seen thus far, the one that stood was Laura Helmuth’s piece on Slate, a publication for which I generally have a great deal of respect (an assessment in need to reconsideration, it seems). In “Cats Are Evil”—which reads almost like something out of The Onion—Helmuth (Slate’s science and health editor) attempts to draw on some relevant science, but fails miserably, offering us little more than the infamous Wisconsin Study and Peter Marra’s (only slightly more rigorous) catbird research.

TVNZ took a slightly different approach, proclaiming on its website: Scientist backs Gareth Morgan’s cat claims. A closer look, though, and we find the opinions of two scientists—one of whom does not back Morgan’s claims.

The one in Morgan’s camp is Yolanda van Heezik, senior lecturer in Zoology at the University of Otago, who supports him “in his campaign to raise awareness about the impacts that pet, stray, and feral cats have on our native wildlife.” In fact, van Heezik herself has acknowledged that these impacts are poorly understood. “It’s unclear,” she wrote in “The Impact of Free Ranging Cats,” a special section of the Spring 2011 issue of The Wildlife Professional, “to what extent declines in wildlife can be attributed to cats versus other human-related modifications to urban landscapes.” [1]

Landcare Research scientist John Innes, also quoted in TVNZ story, actually agrees with van Heezik on this point:

“The impact of cats—whether feral or pet—on valued wildlife remains controversial because it is site-dependent and ecologically complex, and because key impact questions are frequently unresearched. In New Zealand native forests, ship rats are the major prey, and this little-seen predator eats many more birds than cats do.”

But Innes also emphasizes the important of context: “The Gareth Morgan website refers to kaka, kokako, weka, mohua, pateke, and robins as endangered, perhaps implying that cat control might help them, but cats are not significant predators of any of these species, except possibly weka.”

Eradication “Successes”

On his website, Morgan refers to a 2011 paper by Medina et al. in which the authors “review[ed] the literature on the impacts of feral cats on island animals and use[d] meta-analysis techniques to help predict which types of threatened native island species are most impacted by feral cats and under what conditions are they most impacted.” [2] Interestingly, although Medina et al. refer to the often-cited 2000 paper by Courchamp et al., their interest in its contents seems remarkably selective. Indeed, they fail to acknowledge one of its authors’ key findings:

“In some ecosystems [eradication of alien predators] can generate a greater threat for endemic prey through what is called the ‘mesopredator release.’ This process predicts that, once superpredators are suppressed, a burst of mesopredators may follow which leads their shared prey to extinction… This work emphasizes that, although counter-intuitive, eradication of introduced superpredators, such as feral domestic cats, is not always the best solution to protect endemic prey when introduced mesopredators, such as rats, are also present.” [3]

Medina et al. argue that “more studies are needed that quantify changes in the survival, reproductive success, or population size of native vertebrates following cat eradication.” [2] But again, the authors fail to acknowledge what’s already been done.

A 15-year cat eradication effort on Macquarie Island, a United Nations Educational, Scientific and Cultural Organization World Heritage Site located less than 1,200 miles from New Zealand’s capital, Wellignton, concluded in 2000 with “unintended consequences [that] have been dire.” In the absence of cats, the population of rabbits and rodents skyrocketed, prompting the Australian government to commit $AU24 million to further eradication efforts. [4]

Morgan’s response to such concerns (noted on the Cats to Go site): “The fact is that we don’t need cats to control rats any more—we have traps. In cities cats alone are killing native birds faster than they can breed—never mind the rats. We need to control cats and rats together.”

Those Other Invasive Mammals

Like Morgan, van Heezik is asking her fellow Kiwis to “consider not replacing your cat when it eventually dies.” But neither one is talking about controlling the country’s population of humans—thus mitigating their enormous impact.

Between 1971 and 2006 (the last year for which data are available), the NZ population grew 44.7 percent, from 2.9 to 4.1 million. [5] Today, it’s an estimated 4.5 million. (According to Wikipedia, “69 percent identify as ‘New Zealand European,’ another uncomfortable “detail” that I’ve yet to see brought up.)

•     •     •

Morgan’s call to action includes getting a bell for your cat, having it sterilized, and keeping it indoors. Oh, and this:

“Overcome your denial, domestic cats are an environmental threat, don’t replace your cat. Sign this petition now lobbying local governments to require registration and micro-chipping of cats, to provide eradication facilities for unregistered cats, and encourage people to trap and turn in unwanted cats on their property.”

Morgan’s gotten plenty of press over the past couple days. But, if his online survey is any indication, he’s not been very persuasive with cat owners. Responding to the question, Will you make your current cat the last one you own?, only 25 percent have indicated they would, compared to 75 percent indicating that they’re not buying into Morgan’s scheme.

And judging by some of the online comments (see, for example, Slate, with 376 and counting, or The Telegraph, with 173 at the time of this writing), it’s a wonder the URL garethmorgantogo.com is still available.

Literature Cited

1. van Heezik, Y., “A New Zealand Perspective.” The Wildlife Professional. 2011. 5(1): p. 70.

2. Medina, F.M., et al., “A global review of the impacts of invasive cats on island endangered vertebrates.” Global Change Biology. 2011. 17(11): p. 3503–3510. http://dx.doi.org/10.1111/j.1365-2486.2011.02464.x

3. Courchamp, F., Langlais, M., and Sugihara, G., “Cats protecting birds: modelling the mesopredator release effect.” Journal of Animal Ecology. 1999. 68(2): p. 282–292. http://dx.doi.org/10.1046/j.1365-2656.1999.00285.x


4. Bergstrom, D.M., et al., “Indirect effects of invasive species removal devastate World Heritage Island.” Journal of Applied Ecology. 2009. 46(1): p. 73–81. http://onlinelibrary.wiley.com/doi/10.1111/j.1365-2664.2008.01601.x/abstract


5. n.a., Demographic Trends 2006. 2007, Statistics New Zealand: Wellington, New Zealand. http://www.stats.govt.nz/browse_for_stats/population/estimates_and_projections/demographic-trends-2006.aspx