Wildlife & Nature

Wildlife-Killing Feral Cats Pose Environmental Threat


The authors of a new book call feral cats an invasive species and say the only answer to solving the problem is what is euphemistically called “trap and remove,” which means capturing the animals and euthanizing them. (istock)

A new book examining the complicated issue of cats and wildlife has re-opened a difficult discussion that has long pitted animal welfare organizations against biologists, birdwatchers and the environmental community. And the position taken by authors Peter Marra and Chris Santella is doing little to make that discussion any easier.

You can tell by its title, Cat Wars: The Devastating Consequences of a Cuddly Killer, that the authors don’t pull any punches. Marra, who directs the Smithsonian Migratory Bird Center, and Santella, a journalist, argue that drastic action is necessary to curb the massacre of birds and small mammals caused by feral cats and house cats that are allowed to go outside.

After reviewing thousands of reports, pet-owner surveys, cat regurgitation studies, academic research and other data, they calculated what they say is a conservative estimate: cats kill up to 22 billion small mammals, 4 billion birds, 822 million reptiles and 299 million amphibians in the United States annually.

“More birds and mammals die at the mouths of cats than from wind turbines, automobile strikes, pesticides and poisons, collisions with skyscrapers and windows, and other so-called direct anthropogenic causes combined,” they write.

What’s more, the authors say that feral cats are also a hazard to human health. Feral cat colonies where humans provide food attract raccoons, skunks, foxes and coyotes, easing the spread of rabies. Cats also carry a variety of diseases that can be transmitted to humans, from a bacterium that causes a life-threatening infection in cat scratches and bites to a parasite that can cause birth defects when pregnant women are exposed to cat feces.

The authors call feral cats an invasive species and say the only answer to solving the problem is what is euphemistically called “trap and remove,” which means capturing the animals and euthanizing them.

“No one likes the idea of killing cats,” they write. “But sometimes, it is necessary.”

It’s unclear how many feral cats live in Rhode Island, but all the interested parties agree it’s too many. Estimates range as high as 250,000, though state veterinarian Scott Marshall said it’s probably closer to “tens of thousands.”

He established a Feral Cat Working Group in 2010 after receiving innumerable complaints about the animals. The group, which includes members from animal welfare groups, academia, environmental organizations and public-health agencies, hired a student from the Tufts University School of Veterinary Medicine to census known feral cat colonies in the state. She found 302 colonies, mostly in urban areas, with a total of about 4,000 cats.

It’s believed there are many more colonies than those she surveyed, plus thousands of uncounted cats that aren’t part of established colonies and an estimated 60,000 house cats whose owners let them go outside.

“Cats are a serious problem for wildlife,” Marshall said. “Their hunting instinct isn’t diminished by feeding them. A pet cat that is fed at home still brings birds and rodents home. We can’t deny that they’re having an impact on wild birds, rodents and to a lesser extent reptiles. They kill whatever they can get.”

According to Marshall, feral cats live very short lives. Their life expectancy is less than two years. Half don’t make it out of kittenhood, 75 percent don’t survive one year, and 85 percent die before their second birthday.

“People don’t realize that when animals are dying young in large numbers, they have a miserable life and a miserable death,” he said. “They’re struck by cars, exposed to parasitism, die of exposure, get ripped to shreds by predators. They don’t live good lives.”

He agrees with the authors of “Cat Wars” that, unfortunately, the best solution is euthanasia.

“Given the tools we have, that’s the only way to solve it,” Marshall said. “If a male contraceptive were available, that could be effective, but right now nothing else works.”

Most of the animal welfare groups in Rhode Island disagree. Vehemently. They argue instead for a method called “trap, neuter and return,” or TNR, in which feral cats are captured at colonies, brought to clinics to be spayed or neutered, and returned to their colony. Advocates say it’s the most humane alternative to euthanizing the animals, and because the cats can no longer reproduce, the colonies will eventually disappear.

Gil Fletcher, a member of the Feral Cat Working Group who runs a cat rescue organization called PawsWatch, acknowledges that not all of the animal welfare groups agree with the “return” component of TNR, and because there are numerous small grassroots groups advocating for feral cats, there is considerable tension among them. But, he wrote in a recent e-mail, “it goes without saying that any form of large scale lethal approach to reducing the free-roaming cat population (trap and euthanize, hunting, targeted poisoning, etc.) is an anathema to this group.”

Fletcher is pushing for municipal governments to adopt the TNR approach, because the feral cat problem is one he equates with other community concerns addressed with taxpayer funds, like anti-littering campaigns and roadside beautification efforts.

While he barely mentions the impact of cats on wildlife — other than to disagree with the cat predation numbers Marra and Santella claim — he said “the cat people” and “the wildlife people,” as he calls them, all seek to remove free-roaming cats from the outdoor environment. Their “interest, motivation and their presently favored means are poles apart, but the end goal is the same,” he said. “By all logic, they should be natural allies.”

Part of the reason they aren’t, according to Marshall and the scientific community, is that there is no evidence that TNR works. In practice, feral cat colonies managed with TNR don’t get smaller and disappear. Instead, the populations remain mostly the same and the animals continue to kill wildlife. To be successful, at least 80 percent of the cats in a colony must be spayed or neutered, and the colonies must be constantly monitored as new animals arrive.

“TNR seems to be the panacea that animal welfare groups endorse, but there’s virtually no evidence that it’s effective,” Marshall said. “Everybody wants it to be effective, but it’s very labor intensive, expensive, and ultimately it’s ineffective. Unless people can shut down new inputs into the colonies, it’s doomed to fail.”

The one thing Marshall and Fletcher agree on is that it will be nearly impossible to address the issue of feral cats in Rhode Island without public support for whatever strategy is chosen. And they both say the public won’t support a widespread euthanasia effort.

“The science would say that cats should be removed from the environment, but emotions run very high and there is no public support for removal,” Marshall said. “I personally don’t like the idea of tolerating their existence, because in my opinion the lives and deaths they experience are far less humane than trapping and removing them.”

The authors of “Cat Wars,” however, are less concerned with the sad lives of feral cats and more concerned for the welfare of wildlife and the environment. They say that of all the threats to birds that are directly or indirectly caused by humans, cats are the easiest problem to fix, especially when compared to complex issues such as climate change.

“To me, this should be the low-hanging fruit,” Marra is quoted in Smithsonian Magazine. “But as it turns out, it might be easier stopping climate change than stopping cats.”

Rhode Island resident and author Todd McLeish runs a wildlife blog.


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  1. It’s not just Rhode Island that has too many feral cats, it’s pretty much everywhere. But I disagree with the authors on a couple of points – that feral cats are an invasive species, and that they kill billions of birds a year. They are relying on data for that, but in my many years of experience in caring for my own cats and a feral cat colony, I have seen no evidence of this. Even if it were true, birds, lizards, rats, and other small animals are killed by the millions every year by lots of other animals for food. That is a fact of nature and life. So to single out cats to malign is unreasonable. Let’s look at how many animals raccoons kill and eat for food.

    It probably is true that feral cats don’t live long. However, it really depends on whether they are part of a colony that is being cared for. I feed and care for a colony at my home and while some have disappeared (subject to predators), the rest I have trapped, neutered, and released. I still have 5 that were born here 3 years ago, are in good health, and doing well. If a feral colony has access to food, isn’t where a lot of cars are, then the real issues are coyotes and predators that may get them, and parasites.

    I know that euthanasia is widely discussed as a solution, and in some cases it may be necessary. If so, it should only be done in a manner that is accepted as being humane. One other method that some people employ is to call a local wildlife removal business to trap and remove them. I know this first hand because there’s a <a href="http://www.phoenixpestpros.com/">Tampa animal removal company</a> near me that gets calls on a fairly regular basis for this service. Anyone who wants to hire this type of business to eliminate feral cats should find out first what the company does with the animals they remove.

  2. I have feral cats that have taken up residence under my patio and deck. I would like them removed but it doesnt seem like anyone is willing to help. This is frustrating as they will damage my fruits and vegetable garden this growing season. Where can I get help

  3. The sad truth is that you’re probably going to have to either “take the matter into your own hands” which would mean killing the cats, or hire a professional service. Like the same person who would remove a raccoon from you chimney. Nuisance animals are nuisance animals. Do everything you can to discourage them from taking up residence in the first place, and then deal with ones that do. Cats, rats, mice, ants, fleas, ticks, …….it’s not a pleasant thought or task, but it is necessary at times I’m afraid.

  4. It is amazing that people can be distressed to the extreme about birds being killed by an oil spill but millions of birds being tortured to death by feral cats doesn’t prompt them to stop feeding them.

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