To Save Birds, Keep Your Cat Indoors

By Lane Scher

When a Chicago animal shelter deliberately released 1,000 feral cats earlier this year to control a rodent problem in the city, they may have unintentionally put a more desirable group of animals in harm’s way: songbirds. Domestic cats kill more than 2 billion birds each year, making them one of the largest human-caused threats to birds.

As birds face the challenges of a changing climate, habitat loss, and transcontinental migrations, we should protect them by keeping our cats indoors.

A shocking study published in 2019 showed that there are almost 3 billion fewer birds in North America now than there were 50 years ago. That means 3 billion fewer birds to eat bothersome insects, pollinate flowers, and disperse seeds. The authors cite a variety of causes for this decline, ranging from habitat loss and increased insecticide use to urbanization and window collisions. The team also offers seven actions to help. The second item on its list is to keep cats indoors.

What’s the big deal about cats? Why are they so bad for birds — and other wildlife, for that matter? Researchers tracked almost 1,000 outdoor house cats and found that each cat killed fewer prey than a wild predator, and that the cats generally stayed close to home. But the damage adds up when you consider the high density of house cats, which is much higher than that of wild predators: overall, the authors estimate that house cats have two to ten times the impact of wild predators.

On the cats’ side, a life indoors might seem boring, unfulfilling, or unjust to some. In fact, keeping cats indoors is recommended by the ASPCA, the Humane Society, and the American Association of Feline Practitioners, as it protects them from injury and disease and leads to a longer life. To promote a fulfilling life inside, the Humane Society suggests 10 tips to keep indoor cats happy. These tips include providing a cat tree to climb on and cat grass to graze on, and even leash-training your cat for outdoor adventures. They recommend starting cats indoors when they’re young, but they believe that even an old cat can learn new tricks when it comes to staying indoors. Their tips for moving an older cat indoors include introducing them to life indoors gradually and making the indoors fun.

Feral, community, and “working” cats require different accommodations. These “un-owned” cats are found in urban areas, often originating as escaped pets, and rural areas, where their rodent removal services make them desirable neighbors. However, these cats are huge dangers to birds. Trap-Neuter-Release (TNR) programs are often used to manage feral cat populations, however these programs are unsuccessful in reducing cat population size. Instead, feral cats should be relocated to permanent indoor homes when possible. Barn cats can be replaced by attracting birds of prey to control rodent populations without the negative side effects.

In a time of unprecedented global change, wildlife face extraordinary challenges. While we may feel helpless to deal with some of these issues, there are some things we can control. If your cat has ever delivered a mangled bird to your doorstep, you’ve seen this problem firsthand. But a lack of evidence of your cat’s hunting prowess doesn’t mean it isn’t happening. By keeping our cats indoors and supporting policies that reduce feral cat populations, we can have a huge impact conserving birds. Birds already face too many threats. Domestic cats shouldn’t be one.

Lane Scher is a PhD student in the Nicholas School of the Environment. She studies birds to understand how they respond to environmental conditions.