IMAGINE THERE’S NO CAT. Imagine there’s no mouser, no pet, no fuzzy thing rubbing against your leg, meowing for dinner. Imagine there’s no word for jazz hipsters, nothing to always land on its feet, nothing for animal hoarders to hoard, nothing to dangle from a tree limb telling you to “Hang in there!” Imagine there’re no cat memes, no Grumpy or Nyan Cat, no cat playing keyboard or framed by a misspelled catchphrase. Imagine a world without cats.

It’s not that easy to do. The cat has become ubiquitous in our lives, whether serving as pest repellent, loyal friend and companion, inexhaustible reservoir of metaphor and cultural association, or internet content. This last is the latest, but not the least, of the cat’s accomplishments. Of all the things that get shared, retweeted, liked, favorited, loved, or memed on any given day of our networked lives, up at the top of the list is always cats: cats with their heads between slices of bread, cats trying to fit into a cardboard box, cats riding around on Roombas in shark costumes. Because we love them, we put them anywhere and everywhere, spreading their images far and wide.

Cats are colonizers: this is what they do. They have colonized the internet just as they have colonized so many other habitats, always with the help of humans. This is the lesson of Cat Wars: The Devastating Consequences of a Cuddly Killer, a new book by conservation scientist Peter P. Marra and travel writer Chris Santella. From remote islands in the Pacific to the marshes of Galveston Bay, Cat Wars traces the various ways in which felines have infiltrated new landscapes, inevitably sowing death and devastation wherever they go.

Perhaps the most famous case of genocide-by-cat is that of the remote Stephens Island in New Zealand. Before the end of the 19th century, it was home to a unique species: the Stephens Island wren. One of only a few species of flightless songbirds, the wren ran low to the ground, looking more like a mouse than a bird. After a lighthouse was built on the island in 1894, a small human settlement was established; and with humans, invariably, come pets. At some point a pregnant cat, brought over from the mainland, escaped and roamed wild. The island’s wrens, unused to facing such a skillful predator, were no match for the feral cats that spread throughout the island. Within a year, the Stephens Island wren was extinct. It would take another 30 years to eradicate the feral cats.

This is not an isolated incident. Cats have contributed to species decline and habitat reduction in dozens of other cases. Because they’re so cute and beloved, we have little conception of — and little incentive to find out — how much damage cats are doing to our environment. When researcher Scott Loss tallied up the number of animals killed by North American housecats in a single year, the results were absolutely staggering: between 6.3 and 22.3 billion mammals, between 1.3 and 4 billion birds, between 95 and 299 million amphibians, and between 258 and 822 million reptiles.

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It is undeniable, then, that cats are a menace to animal society, particularly those cats that are allowed to roam free outdoors. We have known this for almost a century. In 1929, the ornithologist Edward Howe Forbush commented that “the widespread dissemination of cats in the woods and in the open or farming country, and the destruction of birds by them, is a much more important matter than most people suspect, and is not to be lightly put aside, as it has an important bearing on the welfare of the human race.” Forbush, having tallied up an impressive anecdotal record of death and destruction, concluded that the cat “has disturbed the biological balance and has become a destructive force among native birds and mammals.” The cat doesn’t much care if its prey is threatened with extinction. Any small mammal, bird, or reptile is fair game, regardless of its rarity.

In one of Cat Wars’s more enlightening analogies, Marra and Santella compare housecats to the pesticide DDT. The cat, they argue, is one of the earliest known invasive species, and invasive species, they argue, are “simply another form of an environmental contaminant; like DDT, they can cause great harm and, once introduced, can be exceptionally difficult to remove from the environment.” Both started out as human technologies used to rid the landscape of unwanted pests, and both came with unintended side effects and unwanted additional destruction in the wild. Given the amount of energy we have devoted to banning DDT and ridding the environment of its consequences, it’s noteworthy that we seem so uninterested in a similar remedy for the scourge of cats, which, by most metrics, are far more destructive. The authors note that, while cats have been implicated in the decline and extinction of some 175 different species, “there are no confirmed bird extinctions from the pesticide DDT.”

The news that housecats are laying waste to wide swaths of biodiversity has not, like revelations about climate change or other ecological evils, led to some kind of scientific consensus about what was to be done. It’s led, instead, to the establishment of two warring camps: the cat people and the bird people. The bird people think that the wholesale slaughter of the world’s bird population is a problem requiring human intervention, namely the banning of feral and outdoor cats, forced sterilization, and euthanization. The cat people are aghast at these solutions, and argue instead that cats, being innate predators, should be allowed to fulfill their natural directive. When University of Wisconsin professor Stanley Temple published a report noting the high number of birds being killed by cats, he was besieged with death threats. “Many Wisconsites (at least those who wrote letters to the editor and hate mail to Temple),” Marra and Santella write, “were much more concerned that cats were being blamed for songbird deaths than with the fact that millions of songbirds were being killed. And some were more troubled about the possibility of cats being killed than they were about the life of a researcher.”

In the ensuing stalemate, legislation has been halfheartedly introduced, allowed to languish in committee, and finally scuttled altogether. Half-measures have been introduced that do no good. Invective has been hurled from both sides with increasing ferocity. And, meanwhile, cats continue to kill all manner of creature of field and stream.

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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.

Rather than explore this difficulty further, though, Cat Wars remains mostly about the war between cat people and bird people. Marra and Santella are clearly bird people. (Marra, after all, is the head of the Smithsonian’s migratory bird center.) The pro-bird, anti-cat thrust of their book is not subtle. “Allowing owned cats to roam freely outside,” they write, is an example of “irresponsible pet ownership,” a message they drive home with increasing emphasis. (Full disclosure: I don’t have a dog in this fight. I’m a dog person.)

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:

CAT ADVOCATE CLAIMS: Cats have lived outdoors for more than 10,000 years — they are a natural part of the landscape

SCIENCE SAYS: Domestic cats are an invasive species throughout their current range, including North America

This point-counterpoint continues for much of a page, never getting any more thoughtful than this. Such language — including the gallingly general “science says” — enlightens no one, and serves only to quell dissension and shut down meaningful debate.

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.

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Cats, Marra and Santella want us to know, are an invasive species, no different from lion fish in the Caribbean or the eucalyptus in California. They are foreign-born (from an American perspective, anyway; their likely ancestor is the Near Eastern wildcat, native to North Africa and the Middle East). Once they move in, they quickly begin overtaking the local citizenry, upsetting the equilibrium of well-established biomes, sucking up resources that don’t belong to them, overstaying their visas and their welcomes. These sinister immigrants, once they put down roots, can be incredibly difficult to evict. They bring their foreign-born culture to their new homes, changing the landscape beyond recognition, diluting its purity and making it harder for native-born species to compete.

“How should we deal,” they ask, “with the animals that people have domesticated and enjoyed as beloved companions for thousands of years, but that when allowed to become feral or to freely range are capable of tearing away at the tapestry of life that has evolved since time immemorial?” It’s unclear to me why anyone with a background in biology and evolution would use a phrase like “time immemorial,” as though life evolved perfectly to a static equilibrium at some moment just before the arrival of humans. Language such as this, along with the very term “invasive species,” presumes a pristine, Edenic landscape that existed in some cloud-shrouded past. The invasive species itself has no agency here: it’s only further proof of humanity’s reckless, ecology-destroying hubris. We are the villains; cats are only our henchmen.

But we should remember that, while the Stephens Island wren died off due to human/feline interaction, almost all the other flightless songbirds went extinct thousands of years earlier, with no help from us or our pets. Nature, it seems, is no more precious with its creations than cats are. The problem here, as so often in these kinds of polemics, lies in the authors’ overreliance on the concept of the “natural.” Marra and Santella would have you believe that songbirds are natural, whereas invasive species like cats, imported from other ecosystems, are not. Cat lovers, on the other hand, would have you believe that the cat’s predatory instincts are equally “natural” and must also be respected. Each side appeals to this transcendental, undefined concept, arguing that it makes their position a priori correct. But what does it mean to be natural? (Everyone agrees that humans are most definitely unnatural, but that’s about it.)

A better question, and one for which there is no easy answer, is: Where, exactly, do cats belong? Are they animals, at home in the wild, where they must hash it out against other species, killing birds and being killed by coyotes and raccoons, dying of starvation or disease? Or are they social parasites, bred and evolved to light up the endorphins in our brain, providing comfort and emotional care in exchange for food and shelter? Currently, they are both, and we have no easy language for such a creature. The problem with the housecat is that it calls into question the very notion of a clean divide between human and nature. Every time they exit our houses or apartments through a pet flap or an open window they show us how easy it is to slip past the boundaries between our artificial world and the wilderness all around. If we want to make headway with this seemingly intractable debate, we’ll have to think harder about what “nature” really means — for the cats, for the birds, and for us.

Until then, the cat, along with all of its delicate prey, will just have to hang in there.

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Colin Dickey is the author, most recently, of Ghostland: An American History in Haunted Places.