A new book has appeared whose thesis is, apparently, that outdoor cats are vicious predators who destroy over a billion animals a year, and are endangering wildlife—mostly birds. Stringent measures are required to extirpate the killer cats.

Here’s the new book; the screenshot goes to the Amazon site where you can buy it.

The Amazon reviews are pretty bad, but that’s what you’d expect when a bunch of incensed cat lovers encounter such a thesis as well as remedies for it, which include widespread killing of cats, sometimes by poison:

Now several readers have called this book to my attention by email, and I sometimes get rather nasty personal emails from people who think that I’m in favor of letting cats kill whatever they want—all because I like cats. By and large, though, I agree with the data and with the idea that pet cats should be kept indoors. If I got a cat now, I’d keep it indoors. My last cat, Teddy, was a rescue animal who had lived outdoors in Chicago for about three years, and wandered in through the cat door I had then. He never wandered out again: he’d had enough of outdoor living. (His coat was full of motor oil from huddling under cars, and it took many baths to reveal his lovely white coat.) My cat before that, another rescue, had been an outdoor cat in California and wanted badly to go outdoors, and so I let him. As far as I know, he never caught a bird or mouse—or at least never brought one to my attention.

Cats allowed to live outdoors, at least in urban areas, live short lives and often die violently: from cars or hawks or dogs. My philosophy is that, in urban areas, you should bring up your cats to be indoor cats. But if you adopt a cat that has lived in the outdoors and likes it, like Hili, it’s hard to then make them permanent indoor cats. If kept indoors, Hili would simply go insane, and it would be heartbreaking.

As for the problem of cats destroying other wildlife, I don’t like that happening, and am in favor of trap/neuter/release programs, though those seem to be most efficacious in urban areas where the impact is on other invasive wildlife, like sparrows and pigeons. But I have to say that I don’t like the idea of poisoning feral cats, and I’m not going to tolerate viciousness toward cats in the comments.

The problem, as discussed below, is how to weigh the “morality” of destroying feral cats versus allowing wildlife to be killed by them and keeping the cats indoors where they can be miserable. If you have the view that all birds and mice deserve to live, then it’s easy, but if you look at the issue from a “well being” point of view, then it becomes a bit harder (see below). In some cases, though, I think there’s a good case for rounding up or humanely killing cats as in the famous case of the Stephens Island wren, a flightless songbird that was driven to extinction by cats on a small island.

I haven’t read the new book, but have read two reviews of it, one by noted science writer Natalie Angier. Her piece, in the New York Review of Books, is called “The killer cats are winning!” By and large, Angier agrees with the authors’ thesis, though she sees some circumstances in which allowing pet cats to roam free isn’t so bad. The problem, as she notes accurately, is that we love our cats more than our birds or rodents, and it’s simply hard for cat people to come to grips with the problem of the slaughter produced by those cute moggies. First, some facts from Angier’s piece:

For island-bound species, cats of all colors are a sign of bad luck. In a 2011 review in the journal Global Change Biology examining wildlife crises on 120 islands, Felix Medina and his colleagues concluded that cats helped cause the decline or extinction of 123 species of songbirds, parrots, seabirds, and penguins; twenty-five species of iguanas, lizards, turtles, and snakes; and twenty-seven species of small mammals, including a lemur and a bat.

. . . In 2013, Marra and his colleagues decided to calculate a grand, nationwide estimate of just how much havoc free-ranging cats wreak on wildlife each year. They reviewed thousands of smaller reports: academic research, field counts, animal welfare data, pet owner surveys, kitty cam studies, cat regurgitation studies. They multiplied together variables like the number of owned and unowned cats in the US, the percentage of owned cats allowed to spend time outdoors, the percentage of those cats known to have hunted. They tried to be conservative, to lowball their numbers at every stage. Still, the final tallies were shocking: up to 4 billion birds, 22 billion small mammals, 822 million reptiles, and 299 million amphibians are killed by free-ranging cats each year—and that’s just in this country. Not surprisingly, the publication of their estimates in the journal Nature Communications went viral. (As Marra and Santella point out, the piece I wrote about the study for The New York Times in 2013 “was the most e-mailed and most commented-upon piece” of the week.)

Finally, Angier’s conclusion is a bit ambivalent, but only because people are ambivalent.

But does wildlife protection require mass feline extermination? In sensitive environments, yes, as the Fish and Wildlife Service decided when free-roaming cats were found to be a major threat to endangered piping plovers on Long Island beaches. It’s harder to defend a zero-tolerance policy toward stray cats in urban areas, where the local wildlife population is likely to include a profusion of house sparrows (another invasive species) and house mice (ditto).

The cat wars have all too often been portrayed as a cartoon, Tweety vs. Sylvester. Are you a cat person or a bird person? You don’t think pet cats should be allowed to ramble at will? Oh. You’re one of those bird-watching loons. You’re ambivalent about shuttering the neighborhood TNR colony and shipping its members straight to the sleepytime chamber? So you’re a crazy cat lady. Or maybe you’re a cat lover and a bird person, and you’re searching in all directions for that fugitive middle ground.

Colin Dickey also has a thoughtful review, “The case against cats“, this time in the Los Angeles Review of Books. While agreeing with Angier in the main, it also faults the book on several grounds:

Cat Wars is one of those strange books, reading which one can feel generally comfortable with the authors’ conclusions while growing increasingly frustrated with their bad faith arguments, rhetorical sleights-of-hand, and other abuses of the reader’s trust. A chapter that focuses on cats as disease vectors is the worst offender. They point out, correctly, that housecats can be carriers of bubonic plague (an Arizona man died in 1992 after catching plague from a cat) as well as rabies, and that Toxoplasma gondii, a parasite found in cat feces, has been linked to behavioral changes in humans. It’s true, of course, that cats can transmit plague and other diseases, but this trait is not unique to them, nor are toxoplasma cysts restricted to outdoor cats. The haphazardness of these arguments makes the book seem indiscriminate in its anti-cat bias. Repeatedly, Marra and Santella offer rhetorically strong arguments that fall apart under scrutiny. They claim, for example, that “[w]ild birds and mammals […] have rights that do not seem to receive as much attention as the claimed rights of cats to wander freely outdoors.” It’s true that threatened and endangered species are protected under law, as are pets (mostly in the form of animal cruelty laws). But what can it mean to say that other, non-protected birds and mammals have “rights”? What kind of rights? Moral rights? Rights under some unstated but presumed “natural law”? Is this a call to extend legal protection to all American animals? Are all animals created equal? Does the equally invasive black rat lack rights that more charismatic native songbirds have?

Cat Wars also bends over backward to paint cat-owners, particularly those who advocate for outdoor lifestyles, as unstable and poorly educated. As Marra and Santella become increasingly polemical, they resort to refuting a straw-man “leading outdoor-cat advocate’s website” bullet-point-style. . .

. . . The authors also tend to overstate the unique role cats play in species destruction. The Hawaiian crow, for example, is among those whose “extinctions are attributed to cats,” according to the authors, but the list of dangers to the Hawaiian crow are long: coffee and fruit farmers (who began shooting the crows in the 1890s), mongooses and rats, deforestation, and the Hawaiian hawk (itself a threatened species). It is one thing to say that free-range cats are part of a complicated, interconnected set of ecological problems; it’s another altogether to afford them an outsized, murderous agency. By repeatedly overstating the case against cats, Marra and Santella turn what should have been a thoughtful and necessary discussion into rabid anti-feline propaganda.

The ethical issues are ones I hadn’t thought about deeply, but Dickey does highlight a provocative ethical question:

Cat Wars raises an interesting ethical question: is it justifiable to kill one animal because that animal kills other animals in disproportionate numbers? The authors cite Bill Lynn, an ethicist who has supported the culling of one species as a means to protect another, calling such work a “sad good.” But Marc Bekoff, an evolutionary biologist at University of Colorado, Boulder, contends the opposite: that the life of each individual animal must be weighed separate from a concern for species and for diversity. This kind of dilemma — is it morally acceptable to sacrifice the one to save the many, or the many for the one? — has long vexed philosophers of human ethics, and it is fascinating to see it here played out with regards to interspecies warfare.

In other words, if we consider only “well being” here, how do we weigh the well being of cats who are not killed against the loss of birds who are killed by cats? And what about the well being of humans deprived of species like the Stephens Island wren? As a biologist I want all species to survive, for I’m fascinated with diversity, and every species lost is an evolutionary book burned before it could be read.  Many biologists prize diversity like I do, and will often couch their desire to retain diversity in economic terms, for the public understands dollars and cents—or the possible health benefits of preserving tropical plants that could have curative properties.

But does this give species “rights” to exist? I don’t know. Nor do I know how to weigh “well being” in a fraught situation like this. All I know is that if you can keep your cat inside without driving it insane, you should do so.