Across the world, a killing machine is running a rampage through our wildlife and shows no signs of slowing down. Inhabiting nearly every corner of the globe, these highly adapted creatures can hunt all manner of animals during all times of the day, collectively consume around the same amount of meat as a developed country, and annually claim the lives of more than 300 million native prey in Australia alone. It's a serious pest and is arguably second only to humans in its ability to hamper biodiversity levels.

I am, of course, talking about roaming domestic cats.

Cats have long ruled the world. Wherever we've gone, they've ultimately followed and been suitably worshipped by all who've come across them. In ancient times, we built statues of them, wrote literature in their honor, ingrained them into our mythologies, and even took them along on war campaigns. Today, we use what is arguably our greatest invention — the internet — mostly to share pictures and videos of them online.

Speaking as a cat owner, I think cats are great. So, it's not with any glee that I bring up the fact that there are some uncomfortable truths we need to face up to concerning our feline friends, especially when it comes to the environment. The world's second most popular pet isn't just a threat to our wildlife, they also come with a sizeable carbon footprint.

So what are the issues, and what can we do about them?

The feline destroyers down under

A black cat
Photo by Ruby Cevallos on Unsplash

Trevor Bauer is a cat owner. He also works for the Australian Wildlife Conservancy (AWC), where he uses bait, traps, and firearms to eradicate feral cats. But talking to The Guardian, Trevor mentions that he doesn't feel conflicted about these two facts:

"Cats are beautiful animals; they've got a good design. And that design [means] they're really good at killing animals. Unfortunately, for the cat, they've been introduced to an area where they don't really belong — the Australian ecosystem."

In Australia, cats aren't just a nuisance. Instead, they're a serious pest and one of the leading causes of biodiversity loss. Australia's native animals might have fearsome reputations to foreigners, but against the invasive cats (first introduced during the British invasion) most lack the natural defenses needed to repel them. Small mammals such as the numbat, bilby, and bettong are especially vulnerable and often wiped out in cat-infested areas. So, while the responses of the AWC might seem cruel, they're increasingly required.

But it's not just feral cats that are the issue here. Pet owners who let their cats roam free are also unwittingly or apathetically causing significant problems, with each roaming feline killing an average of 186 reptiles, birds, and mammals annually. It's enough of an issue that territory governments are now intervening. For instance, a new law in the Australian Capital Territory means that all cats born on or after July 2022 must be contained at all times.

But while Australia's cat problem is undoubtedly a severe case, it's not as exceptional as you might think. And even in places where cats are "native," our feline friends are still causing a nuisance. Thanks, of course, to us.

A cat’s paws
Photo by Erda Estremera on Unsplash

'Free-ranging domestic cats are an environmental disaster' — that's essentially the conclusion of one paper co-authored by scientists at the Smithsonian Conservation Biology Institute and the U.S. Fish and Wildlife Service.

The study estimates that "free-ranging domestic cats kill 1.4–3.7 billion birds and 6.9–20.7 billion mammals annually" and "are likely the single greatest source of anthropogenic mortality for U.S. birds and mammals." The study also notes that domestic cats pose a serious risk to the future of wild cats due to cross-breeding leading to hybridization and the loss of unique species. A more recent study by the British Ecological Society identified similar issues.

The problem is in part simply due to the sheer number of cats. Take, for instance, a 2019 survey that found that in the U.K. alone, 10.9 million people own at least one cat, resulting in the eradication of around 200 million wild animals annually. Numbers have only shot up since then, not only in the U.K. but worldwide, thanks, in part, to the pandemic, which led more people to seek comfort in animal companions.

Unfortunately, direct attacks from wondering cats on local wildlife are only the tip of the environmental troubles they cause. Another issue is how much we feed (and overfeed) them. According to one 2017 study paper, cats and dogs are responsible for a whopping 25 to 30 percent of the environmental impact of meat consumption in the U.S. Such is an issue not helped by the fact that around 60 percent of cats in the U.S. are overweight.

And once cats are done eating? We all know what happens next. And yes, cat feces is another environmental headache due to the prevalence of non-biodegradable litters such as clay that require extensive mining to procure.

To be clear, there are far more carbon-intesive lifestyle choices than owning a cat. Compared to say, packing your wardrobes with fast fashion, flying around the world on private jets, or going on yearly cruises, bringing up a kitten is barely a factor. Instead, most of the problems surrounding them come when we let them run riot on the local wildlife or make poor choices surrounding their care. Thankfully, there are several ways to mitigate these issues.

How to reduce the environmental impact of your cats

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Photo by Roberto Huczek on Unsplash

So, apart from opting for different pets, how can we realistically reduce the environmental impact caused of domestic cats?

As far as protecting the local wildlife is concerned, keeping cats inside or contained with the use of 'cat runs' is one of the best things you can do. Unfortunately, there's a persistent misconception that cats need to free-roam, with some suggesting it's even cruel to keep them indoors. In reality, a lot of evidence points to the contrary. In fact, as long as they are provided with enrichment and a safe environment, indoor cats tend to live longer, healthier (and arguably happier) lives.

Of course, context is everything. If your cat is used to being outside, forcing them to live inside can cause stress. The website for the Australian 'Safe Cats, Safe Wildlife' program suggests that "whatever stage of life your cat is at, with the proper care and attention they can thrive when kept safe at home." However, at the end of the day, there are always variables to consider, including what impact your cat may or may not have on your local environment and their temperament. Again, always consult a vet.

If you choose to let your cat loose on the world, be careful about the time of year and day you let them out. Again, it all depends on where you live, but early mornings in the summer can be particularly troublesome due to the presence of young, defenseless chicks. In any case, since feral cats cause the most wildlife damage, neutering your cat is almost always a must. Neutered cats are also more likely to stick closer to home, which is a bonus for the wildlife and your cat's safety.

Reducing your cat's carbon pawprint is more of a challenge, especially since going vegetarian is not an option for these furry hunters. One obvious way to reduce their footprint (and really, I mean our footprint) is to avoid overfeeding your cat since that ultimately means buying less food and theoretically reducing the number of slaughtered animals. There are also pet food that actively source wasted food from slaughterhouses that would otherwise be thrown away. The U.K. brand Planet Pet Society, for example, states that it sources "second chance" ingredients: " Take chicken, for example. Most manufacturers take the breasts and legs off to the supermarket, leaving the tasty, protein-rich organ meats, offcuts and trims to go to waste. We give these nutritious ingredients another chance, because they're the healthiest and most sustainable way to make pet food." An independent environmental impact assessment found that its meals produce 95.7% less CO2 than chicken breast meals, and 95% less than insect-based meals.

When possible, you should also opt for organic, locally produced brands and ones that use environmentally-friendly packaging. Avoiding cheap toys made of plastic can certainly help as well. And opt for compostable cat litter, such as those made from recycled paper, wood shavings, or sawdust. And please dispose of the stuff responsibly (and not down the toilet).

Paws for thought

Facing up to the environmental impact of our actions is never easy or fun, especially when it concerns our beloved pets. But being more climate-conscious doesn't necessarily equate to going without our four-legged companions. All it means is thinking carefully about how we go about caring for their needs while considering the needs of our local wildlife.

Cats aren't to blame for their carbon footprint or their habit of killing wildlife — we are. So it's up to us to make adjustments to help them and nature thrive in harmony.

Further sources & reading

Quick disclaimer: it's worth iterating that I am not a vet. You'll find links to studies from experts here, but always consult a professional if you are considering making any changes that can affect your pet's lifestyle. Thanks for reading. If this story brought you value and you'd like to support my efforts as independent writer, consider buying me a coffee.