Cats. It's a four-letter word in bird conservation. 

Domestic cats (Felis catus) can make wonderful pets, but their presence roaming the environment is a nightmare for birds and birders alike. Cute and cuddly though they may be, cats are also fierce predators that can wipe out local bird populations and disrupt ecosystem dynamics. Ornithologists have been sounding the alarm about cats and their impacts for over a century. It's time we take notice — and take action.

Magnitude of the Problem

Some cat owners claim that their cat only kills “a few birds here and there” and that such a low level of predation is trivial. The truth, however, is that even low levels of predation by cats can quickly add up. The number of pet cats in the United States has soared over the last 50 years and is now estimated at approximately 95 million (Fig. 1). The combined impact of so many introduced predators is massive: In the United States, cats kill an estimated 2.4 billion birds every year, and cats are the top source of direct, human-caused bird mortality in the United States and Canada (Fig. 2).

This level of cat-attributed mortality is unnaturally high. Research led by North Carolina State University found that pet cats that regularly hunted not only killed two- to five-times more prey than a wild predator but also existed at twice the density, resulting in four- to ten-times the impact in the local environment. And pet cats have distinct advantages over their wild counterparts, such as access to plentiful food, clean water, reliable shelter, and veterinary care. If a pet cat fails to make a kill, it doesn't go hungry; it goes home. Thus, pet cats have been removed from the typical balance between predator and prey populations, enabling cats to continue to thrive and kill wildlife even when wildlife populations are low.

Sadly, the problem of cat predation of wildlife is not unique to North America, and nationwide estimates of cat-caused bird mortality in other countries are consistent with observations in the United States and Canada. These cumulative impacts have resulted in tremendous and permanent losses of global biodiversity. Around the world, cats have contributed to the extinction of 63 species (including 40 bird species) and remain a principle threat to 367 species threatened with extinction.

How Should We Manage Cats?

Cats are instinctive hunters that will attack and kill wildlife even when not hungry. Ever play with a cat using a feather toy or see a cat chase a ball of string? That is a predatory response. Sure, it's play behavior, but the same behavior with a Wood Thrush or Eastern Bluebird can be fatal. This predatory drive, as well as incredible speed and agility, are among the attributes many of us admire in cats. But these qualities also highlight why we must manage our cats' behavior. Luckily, there is a model for how to successfully manage cats, which can be easily summed up in a single sentence:

Treat cats like we treat dogs.

In most parts of the United States, it is illegal to allow pet dogs to roam off their owner's property when not under a person's direct control. This leash law is a relatively recent and rapidly embraced requirement for dogs, and the same requirement is needed for cats. Leash laws for cats would not only protect birds and other wildlife but also keep cats safe and eliminate risks to human health or other nuisances caused by trespassing cats. Rather than open the door and hope a pet cat will return home eventually, we should keep our pet cats indoors and safe while outdoors, whether by leash, in an enclosed cat patio (“catio”), or otherwise under a person's supervision.

Change Is Possible

As a child growing up in Ohio, I believed that preventing our family's cat from roaming outdoors would have been cruel. I loved nature and thought that a cat was equivalent to a natural predator, that it belonged outdoors, and that a cat needed to express its predatory instinct through hunting. Over time, however, I came to understand a few elemental facts about cats: that they can live healthy, long lives while kept indoors; that there is an important distinction between native and invasive species; and that outdoor cats are contributing to precipitous declines in populations of our native birds and other wildlife. I also experienced the death of a beloved family pet cat that died prematurely after it was hit by a car. Today, I am not only the owner of an indoor cat but also run American Bird Conservancy's Cats Indoors program. For me, change was possible.

Be an Advocate in Your Community

“Unless someone like you cares a whole awful lot, nothing is going to get better. It's not.” – Dr. Seuss, The Lorax

Addressing these problems will require both individual behavior changes and community action. Change starts at home. If you are a cat owner, please, keep your cat indoors or safely under your supervision while outdoors. We can no longer afford to treat our cats like disposable pets that may — or may not — come home safely. Doing so is a risk to the cat, a death sentence for wildlife, and inconsiderate of any neighbors who would rather enjoy their property without your cat roaming all over it.

We also need community action by informed and persistent advocates who can help nudge everyone else along. A great place to start is with laws that protect pets and require responsible cat ownership practices, such as permanent identification (e.g., microchips), sterilization, vaccination, registration, and a leash law. You can get started today by identifying what the existing and missing laws are in your region, building a network of concerned local residents, and contacting elected officials to advocate for change. In some communities, changes to the law may be as simple as inserting “and cats” wherever similar laws exist for dogs.

This type of change is exactly what occurred several years ago in the Village of Oak Harbor, Ohio. A group of birders and community members reached out to the village's officials and successfully advocated for better cat management. Their enacted ordinance established that cats were prohibited from running at large and prohibited nuisances, including the urination and defecation on the property of others and the concentrating cats (or other critters) by feeding cats outdoors.

Advocacy need not be a full-time job, and it doesn't matter if you're not a conservation professional. Laws are made by the people who show up. Interested in getting started? Take just a moment and send an email to your local elected officials to voice your concerns; it only takes a few clicks.

In Conclusion

For too long in this country, we have looked the other way and ignored the inconvenient realities of letting our cats roam outdoors. In light of recent science regarding bird declines, however, we can no longer afford inaction. Responsible cat management should be among our top priorities, not only because it will protect birds but also because it can keep cats and communities safe. It's time to treat cats like we treat dogs.

This piece originally appeared in the Biggest Week Magazine.