Growing up, my family always had indoor/outdoor cats and for some odd reason, those two cats loved to bring any animal they caught to my (carpeted) room, often hiding the dead animal under my bed. It was a particularly gross habit they had but it meant that after a while, I stopped being absolutely horrified and disgusted (although I still find it pretty gross!). I’m sure I’m not the only one with stories like this. Many cats that spend any amount of time outside can and sometimes will hunt a wild animal and bring it home. And unfortunately, this isn’t the only way that domesticated animals living with humans interact with local wildlife.


Studies have shown that domesticated cats around the world have had an immensely negative impact on native wildlife. Cat litter/poop that’s not properly thrown out (or cats that poop outside) can cause illness and death in some sea otters, as a parasite called Toxoplasma is found in cat poop can result in confusion, seizures, and more in sea otters. And it’s not just sea otters that can be affected by the Toxoplasma gondii parasite, as it can cause toxoplasmosis in humans. Toxoplasmosis causes muscle pains and flu-like symptoms in people that can last for more than a month.

Cats that spend any amount of time outside are significantly more likely to be infected with and be carriers of toxoplasma, as they can pick it up and deposit it just about anywhere. If you have a sandbox or similar outdoor play areas for your kids, it’ll be important to securely cover those areas when not in use, as cats will often mistake them as a litter box. Washing your hands (and having your kids do the same) after playing outside and/or cleaning the litter box can also incredibly important.

Cats also impact wildlife other than sea otters, as many outdoor cats will hunt and kill native wildlife like birds and small snakes. Nature, a scientific journal, published an article back in 2013 that looks at the impact of free-range domestic cats on wildlife in the US. Outdoor and free-ranging cats kill an estimated 1.3 – 4 billion birds and 6.3 – 22.3 billion mammals each year, a significantly greater impact than previously estimated. And this isn’t the only scientific study on the issue. Another study from the Journal of Wildlife Management and the Wildlife Center of Virginia found that a significant amount of wild animals that were attacked by cats either died or had to be euthanized.

While all of this is pretty scary and depressing, it doesn’t mean you have to immediately go and get rid of your cat! Feral, unowned, and abandoned cats have a bigger impact on wildlife than cats that spend little to no time outside. If you do have cats, it might be time to consider having them be strictly indoor or restrict the amount of time outside. And programs that neuter/spay feral or stray cats can help decrease the number of cats on the streets.


Domestic cats aren’t the only pets that have an impact on local wildlife. One study looked at how dogs disturb wildlife while out on walks in parks and found that the impact was relatively minor. Wildlife did have a stronger reaction to people with dogs than without by avoiding areas where dogs and people were seen for longer periods and by being more vigilant. But eventually, prey species like squirrels and deer would still return to those areas.

However, this doesn’t mean that dogs have no impact on wildlife around the world. Some dogs, especially feral and street dogs, have become predators and will kill wild animals, spread disease, compete for resources, and interbreed with closely related species. In other countries, like Chile, Brazil, and India, native wildlife species have been attacked or negatively affected by domestic dogs. One of the world’s smallest deer is the pudu, an animal that’s considered vulnerable, faces attacks from domestic dogs. The mortality rate for pudus attacked by dogs is an astounding 68%.

But attacks of any kind aren’t the only way dogs can affect wildlife. Even just chasing wild animals can have a negative impact, as the chase/harassment can result in stress, dangerously low energy, or injury. And the spread of diseases like rabies and canine distemper from dogs can cause all sorts of issues for wildlife and people. Hookworms and roundworms are just two parasites that dog poop can spread.

It can be easy to read all of this and get discouraged. But there are ways for people, pets, and wildlife to coexist. We may never completely eliminate the impact that household pets have but we can decrease the ways our pets might negatively interact with wild animals. Properly disposing of pet waste can help reduce the likelihood that they spread diseases and parasites like Toxoplasma gondii, hookworms, giardia, and more.

Keeping your dog on a leash in places that require leashed pets can mean they are less likely to scare or hurt wild animals. That doesn’t mean you have to completely give up on off-leash time, as many cities and counties around the US have designated off-leash areas for you and your dog! Additionally, keeping cats inside can really help the nearby wildlife populations (as your cat can’t hunt birds or other animals if they’re inside!). If you’re worried that your cat will get bored, there are ways to keep your cat engaged and happy with toys, play structures, and treats.

Ultimately, there’s a certain responsibility that pet owners have to help decrease the impact they have on wild animals and ecosystems. Scooping up poop and disposing of it correctly isn’t the most pleasant activity but doing so decreases the spread of diseases and parasites, in addition to being the polite thing to do. Keeping pets inside or on a leash in the right areas can also limit the negative interactions they might have with wild animals. All of this is a lot of work and responsibility but is a part of having pets!

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