Stray cats harm wildlife. Should we kill them?

On a warm day last spring, dozens of protesters gathered outside a shopping center on the west side of Hawaii’s Big Island. They weren’t there to boycott a store or a pipeline or to deride a politician. They came to revolt against a new ban on feeding cats in the parking lot. “Stop starving the cats,” the protesters chanted, according to a local newspaper.

The lot outside Queens Marketplace, the shopping center, is home to one of the island’s many colonies of stray, or free-ranging, cats. While there are no formal estimates, experts guess that there are hundreds, if not thousands, of these colonies across Hawaii, each comprising anywhere from a few to more than a hundred felines. Hawaii is, to put it simply, teeming with cats.

These furry strays are descended from, or are themselves, abandoned pet cats, though they’re not really abandoned. Most of them have at least one “colony manager,” a term you’ll hear in Hawaii and elsewhere for locals who provide groups of free-ranging cats with food, water, and even medical care. Sometimes colony managers (or their friends) will also build feeding stations, like the one pictured below. These are self-described do-gooders, common across the Hawaiian islands, who feed cats that don’t live with them.

Hawaii Department of Land and Natural Resources

Caring for stray cats sounds pretty harmless — sweet, even. What makes it so contentious in Hawaii and in many other parts of the world is that outdoor cats, which are not native to Hawaii, kill local birds and can sicken humans and other animals. And kibble sustains them. Researchers estimate that free-ranging cats kill between 1.3 and 4 billion birds each year in the continental US. This number doesn’t even include Hawaii, where there are, according to various estimates, at least tens of thousands of cats — and more endangered species than any other state. In Hawaii, many bird species are on the edge of extinction.

That’s why Hawaii’s wildlife agency decided to ban cat feeding outside the shopping center last year (the state still allows feeding stray cats in most other areas on the islands, except at boat harbors). During the protest, two women were cited by state officers for putting bowls of cat food on the ground. The food was not only drawing in cats but attracting a federally threatened goose, known as the nēnē. The geese — which are the state bird of Hawaii and protected by federal law — were eating the cat food, exposing them to disease, predation by cats, and potential car collisions, the state said.

Hawaii Department of Land and Natural Resources

“We are lovers of all animals but have a responsibility to protect our native species first and foremost,” Raymond McGuire, a state wildlife biologist, said in a statement.

The protest at Queens Marketplace inflamed a longstanding tension in Hawaii between cat advocates and ecologists. The advocates want to keep feeding the islands’ colonies, and they blame ecologists for putting the lives of one animal over another. Ecologists, meanwhile, say that is exactly what cat lovers are doing by propagating colonies: When you protect cats, more native species die by their hands (or rather, fangs).

Ultimately, cats are not the problem. It’s the humans who dump them on the street.

How deadly is a cat?

Hawaii, like many islands, is a paradise for non-native species. The weather is warm and, at least historically, the state had a large number of native animals that evolved without predators, leaving them largely defenseless and easy to eat.

When cats arrived in the 1700s — on European ships, where they were likely used to kill mice and rats — they had plenty to eat. Their numbers ballooned. When Mark Twain visited Honolulu in 1866, stray cats were already abundant. As he wrote in the Sacramento Union at the time, he saw “tame cats, wild cats, singed cats, individual cats, groups of cats, platoons of cats, companies of cats, regiments of cats, armies of cats, multitudes of cats, millions of cats.”

Not long after, it became clear that cats are good at killing things. Although they often seem lazy at home, luxuriating on the couch and only occasionally springing for a shoelace or Ping-Pong ball, house cats are highly skilled predators outdoors. One cat can kill a hundred or more animals in a single year.

State officials in Hawaii warn that these animals are “devastating” to native wildlife, preying on everything from small native forest birds to waterfowl. Cats have almost certainly also contributed to the extinction of birds in the state, helping turn Hawaii into the “extinction capital of the world.”

Courtesy of André Raine

Courtesy of André Raine

André Raine, a seabird expert, has seen the damage that free-ranging cats can do. Much of his work is in remote seabird colonies in Kauai, which are home to the federally endangered ua’u (Hawaiian petrel) and federally threatened a’o (Newell’s shearwater). The birds nest in the ground, making them highly vulnerable to prowling strays. And while a number of other invasive species like rats will eat bird eggs and chicks, cats kill the adults, too, Raine said. That’s much more damaging to the colonies since only a portion of seabirds survive to adulthood even without feline predation.

“[Cats] are an apex predator,” said Raine, who lives on Kauai, where he’s the science director at the ecological consulting firm Archipelago Research and Conservation. “In areas where you’ve got lots of birds, it’s like ringing a dinner bell. They’re cuing in on scent and sound. The cats are like, ‘Oh, here is a hole in the ground with a meal inside.’”

A video he shared with Vox, below, shows a free-ranging cat killing an a’o chick and then returning to the burrow to kill its parent, according to Raine. (Warning: This video is somewhat gruesome.)

Jordan Lerma, a conservation researcher and native Hawaiian, has also come across nēnē with “obvious signs” that they’ve been attacked by a cat, he told Vox. Strays likely kill nēnē chicks more than adults, he said, though these kills are hard to document because cats typically don’t leave a carcass behind.

Beyond directly killing things, many stray cats in Hawaii (and elsewhere) carry a parasite called Toxoplasma gondii, which can cause the disease toxoplasmosis. The parasite only reproduces in cats, but it can infect warm-blooded animals, sometimes proving fatal in wildlife. Toxo has killed at least a dozen federally endangered Hawaiian monk seals, according to the National Oceanic and Atmospheric Administration. The parasite has also been linked to the death of several bird species and even spinner dolphins, according to the state.

Then there’s this whole question of how toxoplasmosis affects human behavior — an area of research that, at times, sounds like science fiction. Some scientists suspect, based on their read of animal and some human studies, that the parasite may alter human minds to make us less fearful of cats. One study found that chimpanzees, our closest living relatives, lost their aversion to the urine of leopards, the apes’ main non-human predator, if they were infected by the parasite. Other research has linked toxoplasmosis to cognitive decline, schizophrenia, and other behavioral disorders in humans.

Benji Jones/Vox

Leaning on this evidence, some ecologists in Hawaii suggest that people who manage cat colonies — who refuse to stop feeding cats — are infected by toxo, which makes them irrationally invested in caring for these animals. This claim remains untested. Colony managers say they just love cats.

The great cat divide

Free-ranging cats can do serious damage to native wildlife. That’s not controversial. The debate heats up when you start asking what to do about them.

Many animal welfare advocates want to keep feeding them. They claim that, by giving these cats kibble, they’ll have full bellies and be less likely to wander around, hunting down native species, entering buildings, and digging through trash. “They’re less likely to be a problem if you feed them,” said Debbie Cravatta, who runs the KARES pet adoption agency on the Big Island. “Starvation is not the answer.”

In an effort to rein in cat populations — which people like Cravatta very much want to do; she doesn’t want a world full of outdoor cats — these groups also tend to support a management approach called trap, neuter, return, or TNR. This practice essentially involves fixing stray cats and then putting them back outside, where they’ll no longer be able to breed. Feeding stations make it much easier to trap cats. And with enough TNR, the outdoor cat populations should eventually dwindle, these groups say.

The only reason this hasn’t worked yet, they say, is that there aren’t enough affordable spay and neuter services. “We could be fixing more cats if we had more resources,” said Malia Wisch, a designer in Oahu who works with Pōpoki Place, a nonprofit cat advocacy organization. “Supply [of spay and neuter services] does not meet current demand.”

Benji Jones/Vox

Conservation scientists say that many of these claims are bogus. Fed cats still hunt, said Raine, who has a pet cat himself. While some research suggests that feeding cats food that is higher in meat may reduce the number of wild animals they kill, these animals are instinctive hunters. What’s more is that even if the cat colonies are in urban or suburban areas, they can still do damage to threatened species. That’s the thing about Hawaii: Endangered species are everywhere, not only in reserves but in parking lots and golf courses. What feeding does, ecologists told me, is help sustain these colonies.

TNR, meanwhile, is largely ineffective, according to Christopher Lepczyk, an ecologist at Auburn University who’s one of the world’s top experts on free-ranging cats. Unless the cat population is fenced in, restricting migration, TNR typically fails to shrink colonies over the long term, research by him and others shows. Plus, outdoor cats tend to have a poor quality of life and live far shorter lives than indoor felines, according to additional studies.

For these and other reasons, some animal welfare groups, including PETA, don’t support TNR. “Having witnessed firsthand the gruesome things that can happen to feral cats, we cannot in good conscience advocate trapping and releasing as a humane way to deal with overpopulation,” PETA states. “Then there’s the inconvenient truth that TNR doesn’t even work. On the contrary, it actually encourages more people to abandon their cats because they think the animals will be cared for.”

Lepczyk and other scientists say that effective control requires a mix of approaches: more adoption, enclosed sanctuaries, and, yes, euthanasia. “If you remove euthanasia from your toolbox, you’re not really going to solve anything,” he said.

What’s frustrating, Lepczyk said, is that this reality often doesn’t reach colony managers. Understandably, they don’t want to kill cats. Understandably, it’s harder to choose to kill animals — especially pet-like animals — than to let them live, even if they’re unwell.

No one actually wants to kill cats, Raine said. Yet, he added, choosing not to kill cats is akin to choosing to kill native species.

The human problem behind the cat problem

In the weeks after the feeding ban at Queens Marketplace, cat advocates still found ways to feed the animals, Cravatta said. They’d go shopping, she said, and quietly dump kibble from their cars as they pulled out of the parking lot. Many of the resident cats have since been trapped, fixed, and relocated, according to the Tribune-Herald, but a number of them remain.

The state’s cat crisis is a tough problem with equally tough solutions. It mirrors similar tensions between animal welfare advocates and conservationists the world over. In the West, for example, these two camps have been sparring for decades over what to do with free-ranging horses, which are technically nonnative. It seems impossible to make both groups happy.

In Hawaii, cat advocates are still pissed at ecologists, accusing them of vilifying cats and fueling violence toward them. Ecologists are annoyed with colony managers for carelessly pushing native species closer to extinction. Meanwhile, both cats and wildlife continue to suffer.

Bonnie Jo Mount/Washington Post via Getty Images

There is, however, a solution that everyone seems to agree on: Get people to stop dumping their pet cats on the street. It’s these actions that created the problem in the first place, and they continue to undermine control efforts today, be they TNR or euthanasia. Even if vets spay or euthanize free-ranging cats, more will still get dropped off outdoors.

In some cases, people can’t afford to spay or neuter their pets. Free services are hard to come by in Hawaii. And if you pay out of pocket, you could be charged as much as $300 per cat, Cravatta said, due in part to a vet shortage.

One simple solution, she said, is for the state government to make it easier for licensed vets from other states to practice in Hawaii; vets from the mainland could, for example, come to Hawaii for a few months on vacation and help out pet owners. (As it stands today, vets from other states have to take a licensing exam or work under the supervision of a vet licensed to practice in Hawaii.)

More fundamentally, Lepczyk said, is that many people — in Hawaii but really everywhere — simply don’t understand the responsibility of owning a pet, whether it’s a cat, a dog, or an iguana. Fixing cats may be especially costly in Hawaii, but pet ownership is always expensive and full of unexpected costs. “It’s not your right to have a pet,” Lepczyk said. “It’s a privilege.”

This post was shared from Vox.