Why Preserving Cats Inside Is Higher For Them—And The Surroundings

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Researchers estimate that cats kill between 100 and 350 million birds every year in Canada—millions of birds that would be spared if we simply kept cats indoors. (Photo: Adobe Stock)

When it comes to the question of keeping cats indoors or letting them roam, people tend to get their claws out. If you love cats, you want what is best for them—and if you love birds, you want what is best for them. As it happens, keeping cats indoors—or giving them supervised time outdoors—is the best thing for your fur baby and your feathered friends. (Not to mention the neighbours, who likely don’t appreciate cats using their yard as a litter box.)

On the question of indoor versus outdoor cats, the veterinary community is clear. In April 2020 the Canadian Veterinary Medical Association (CMVA) published its “Free-roaming Owned, Abandoned, and Feral Cats Position Statement,” which recommends that veterinarians “discourage the unsupervised roaming of owned cats due to the health and welfare risks to individual cats, their potential contribution to the stray and feral populations, impacts on wildlife populations, and increased zoonotic public health risk.”

More and more Canadian municipalities are introducing no-roam bylaws to keep people from letting cats outdoors without supervision. These “leash laws” serve to keep cats safe, decrease the number of feral cats, and protect wild birds from predation.

Whether you’re a cat lover, a bird lover, or both—here’s why experts want you to keep your cat indoors.

Indoor cats live longer

Free-roaming pet cats have an average lifespan of three years, while indoor cats live 12–18 years. These are averages—so an individual cat may live much longer—but it’s clear that indoor cats are more likely to reach a ripe old age.

“In my experience I’m not seeing very many outdoor cats past the age of 10 or 11,” says Dr. Jessica Rock, a veterinarian in Nova Scotia. “And that is sadly considered quite a long lifespan for an outdoor cat, versus indoor cats—I’m still seeing them in their late teens and sometimes even in their early twenties.”

Dr. Maggie Brown-Bury, an emergency veterinarian in St. John’s, Newfoundland, says if you want your beloved cat to be with you as long as possible, keeping it indoors is an easy way to do that.

“I have a hard time understanding why you would want to choose a life expectancy of less than 10 years when you could choose the life expectancy of close to 20 years,” she says.

A cat crossing the street in front of cars

‘“[Cats] don’t necessarily have the greatest street sense,’ one vet says. (Photo: Adobe Stock)

Outdoor cats face numerous risks

There’s a good reason outdoor cats don’t live as long—they face many risks that indoor cats are simply not exposed to.


“[Cats] don’t necessarily have the greatest street sense,” says Brown-Bury. They often dart across busy streets, thinking they can make it. Or they hide underneath cars for warmth—sometimes crawling up into the engine area.

Some of her patients have significant injuries like a broken pelvis or legs after being partially struck. But more than often or not, a cat is hit full-on and doesn’t make it. She says good samaritans bring in the victims so the owner might be able to find them and get some closure. It’s heartbreaking for a cat’s family—and for Brown-Bury, who has three cats of her own.

“For most of the people who work in veterinary medicine,” she says, “that is a big reason why they want cats to stay indoors.”

Cat fights

Outdoor cats are territorial, and Brown-Bury says cat bite wounds are a common sight in the clinic. Because cats have lots of bacteria in their mouths, these wounds can quickly start to fester, and they can be deep enough to infect bones and joints.

Rock also sees a lot of cat fight injuries in outdoor cats. “One of the most common presenting injuries in an outdoor cat is a big, infected wound or abscess,” she says.


Cats are also preyed upon by larger carnivores like coyotes, wolves, and even eagles and owls. (In some places, cats make up 42 percent of a coyote’s diet.)

All too many cat owners have decided to keep their cats indoors only after previous pets were killed.

“I have actually heard stories from people who have watched a coyote take a cat out of their yard,” says Brown-Bury.


Fleas are common with outdoor cats. While they prefer furry creatures, fleas will bite people too. Their bites can cause rashes, and fleas can also transmit infections and larvae of intestinal worms.

Ticks can hitch a ride home on kitty and will migrate from one warm-blooded creature to another. (Depending on where you live, deer ticks can transmit Lyme disease—to pets and people.)

Intestinal worms are common in outdoor cats. Hookworms, roundworms, and tapeworms can be spread to people, and roundworms can cause a disease called larva migrans.

Toxoplasma gondii is a parasite commonly found in outdoor cats. While cats themselves rarely get sick from Toxoplasma gondii, they can spread it to humans through their feces, causing a condition called toxoplasmosis. Most healthy people won’t get ill from toxoplasmosis, but some experience flu-like symptoms. Pregnant women with no previous exposure (and immunity) are the most at risk because they can spread toxoplasmosis to the fetus—with potentially dire consequences.

Diseases and infections

Feline leukemia virus (FeLV) is common in outdoor cats, and there is no cure. It affects a cat’s immune system, making it more susceptible to other diseases and illnesses. “Feline leukemia virus can cause various blood disorders and is the most common cause of cancer in cats. Cats should be vaccinated for FeLV, but the only sure protection is to keep them from being exposed to infected animals.

Feline immunodeficiency virus (FIV) is spread through bodily fluids, so cat fights are often the cause of transmission. FIV weakens the immune system, making a cat susceptible to secondary infections

a cat indoors, looking out a window

Free-roaming pet cats have an average lifespan of three years, while indoor cats live 12–18 years. These are averages—so an individual cat may live much longer—but it’s clear that indoor cats are more likely to reach a ripe old age. (Photo: Adobe Stock)

Rabies is a viral infection of the nervous system and is often fatal. Cats can get rabies from rabid animals like raccoons, skunks, foxes, and bats. If you live in an area where rabies is present, your cat should be vaccinated—or better yet, kept indoors.

Ringworm is a fungal infection that frequently affects cats and causes a red, scaly rash with a telltale “ring” appearance. Cats can be asymptomatic carriers, and they can spread the infection to people. Ringworm can be treated with antifungal cream, but it can be persistent—and the fungal spores can linger in your house for years.

A silhouette of a cat looking at a bird

Keeping your cat indoors can have a really big effect on bird populations. (Photo: Adobe Stock)

Outdoor cats kill millions of birds every year

Wild bird populations have declined by 29 percent since 1979—a loss of nearly three billion birds in North America alone. Humans have done a lot to kill birds, from destroying habitat to spraying pesticides to building glass towers—but perhaps our biggest mistake is letting house cats roam.

Cats are the leading cause of human-related bird mortality. Researchers estimate that cats kill between 100 and 350 million birds every year in Canada—millions of birds that would be spared if we simply kept cats indoors.

“We can help birds massively by doing that,” says Dr. Elizabeth Gow, an ecologist with Birds Canada. And unlike other threats facing birds, cat attacks are easy to prevent. “Keeping your cat indoors can have a really big effect on bird populations.”

Gow is tracking the movements of outdoor cats to better understand their impact on wildlife. Her volunteers—pet cats allowed to roam—wear a CatCam, a small camera that sits under the chin. She also has trail cameras where these cats are known to roam. Gow has documented cats catching American robins, black-capped chickadees, mourning doves, and a Pacific wren.

Dr. Rock volunteers at the Cobequid Wildlife Rehabilitation Centre in Hilden, Nova Scotia, where she sees firsthand the victims of cat attacks. The centre is busiest during spring migration and throughout the summer, when birds are nesting. Some birds are rescued from the jaws of a cat. Others are found with telltale signs of a cat grab, like missing feathers or a partially amputated wing. She says natural predators like hawks or foxes don’t tend to leave prey (birds or otherwise) once they’ve caught it.

“It takes a lot of energy and a lot of risk for them to catch [prey], and they don’t tend to injure the animals in the same way,” she says.

The birds most at risk are those which nest and forage on or near the ground. Birds are particularly vulnerable when they are nesting and the babies start to fledge (leave the nest). Fledgelings can’t quite fly yet, and they make easy targets. And if a parent bird is killed while it is still brooding or feeding chicks, the nest will likely fail—either because the eggs don’t hatch or the chicks starve to death.

The centre has documented about 50 wildlife species (40 avian and 10 mammalian) rescued from cats. The most common are traditional backyard birds like black-capped chickadees, blue jays, downy woodpeckers, and northern cardinals. But cats have also caught swallows, shorebirds, and even raptors like a northern saw-whet owl and a merlin.

Cats have sharp, pointy teeth that easily puncture the air sacs of small birds. Their mouths are also full of dangerous bacteria; even if a wound isn’t that bad to begin with, it can quickly start to fester and become septic.

“Having been grabbed by a cat is associated with very poor prognosis in most cases,” says Rock.

You may think your cat isn’t hunting birds because you don’t see the evidence. But just because your cat isn’t bringing home birds doesn’t mean it isn’t catching them. Brown-Bury says that if a cat catches and injures a bird—but it gets away—the bird is likely to fly away and die elsewhere.

“You can’t ask the cat, what’s your kill count today?” she says. “How many did you get today?”

Some people argue that cats should be allowed to hunt because it’s in their nature. But Gow points out that cats are not native to North America, and they are not the natural predators for our birds—yet they are often the most common.

“In cities, cats are the most abundant predator,” says Gow. “Sometimes in magnitudes of six to one. They are very, very abundant and we often don’t think about that.”

I feed my cat plenty—will it really bother to hunt?

Brown-Bury has seen a well-fed barn cat catch a songbird, let it go, and pounce on it again—making a game of it until someone intervened and rescued the half-dead bird.

“They’re not hunting for food,” she says. “They’re hunting for sport.”

Rock explains that we have made cats the avid hunters they are. Cats initially became domesticated because humans attracted rodents, which in turn attracted cats. We let them stick around because they kept the rodents under control, and the better mousers were allowed to stay and earn their keep. Over countless years, we have selected cats to hunt more than they need to for their survival.

“This behaviour does lead them to catch and play with a lot more animals than they will actually kill and eat,” says Rock. “So this is a behaviour that we have encouraged in our domestic cats and one of the reasons they are so damaging when they’re left to free-roam in the environment.”

What if I put a bell on my cat?

Rock says despite people’s good intentions, bells don’t work. When cats are stalking prey, they are very still—so still that a bell or a crinkle collar won’t make a sound. Besides, birds have no context for what the bell means.

“Oftentimes if they’re being stalked by a cat and they’ve heard the bell,” says Rock, “they’re already in the cat’s mouth. So it’s not really a learning opportunity for them.”

About 75 percent of the birds that come into the Cobequid Wildlife Rehabilitation Centre were rescued from cats wearing bells.

What about barn cats?

Many farmers rely on barn cats to control pests, especially if they want to avoid toxic rodenticides. But just because a barn cat is encouraged to hunt rodents doesn’t mean it should be allowed to kill everything in sight.

“I think there are responsible ways to have a barn cat—and irresponsible ways,” says Brown-Bury. “They should be spayed and neutered, and they shouldn’t be allowed to completely run wild and create their own little micro population.”

That’s a first step, but a fixed barn cat will still hunt birds when given the chance. So how do you protect birds from barn cats? There are no documented methods, but one farmer has devised her own strategy.

Jane Cryderman has a farm in Neebing, Ontario, where she breeds quarter horses and keeps chickens. Her cats are nocturnal, so they work the night shift contained in the barn and sleep all day in her house. They aren’t allowed to roam the property. The cats are spayed, vaccinated, and regularly de-wormed—and happy.

“With a bit of a routine I have barn workers and house pets,” she says.

How do I keep other cats from stalking my bird feeder?

A bird feeder is irresistible to a cat. Even if you keep your own cat indoors, neighbourhood cats may come around.

“If you do have local cats that have caught on to the fact that you have feeders there,” says Rock, “the feeders should go away.”

She adds that feeders should be taken inside during the summer anyway, because they are known to spread communicable diseases in warm weather. A safer way to attract birds to your property is by planting native plants.

No, indoor cats don’t have FOMO

According to Rock, the fact that domestic cats don’t eat or even kill everything they hunt demonstrates that they are already getting enough to eat—and killing isn’t the rewarding part.

“This is actually really good news,” says Rock, “because we can simulate these rewarding activities for cats! Playing games that get cats to prowl, pounce, hide, and sprint in turn are all very rewarding activities.”

As for claims that indoor cats get bored and out of shape, Brown-Bury says cats can get all the exercise and stimulation they need indoors. Puzzle feeders, scratching posts, and interactive toys give cats the opportunity to play and express their natural instincts.

“Cats are not a passive pet,” says Brown-Bury. “You cannot just have a cat in your house, put out some food for it, scoop out its litter box and be done with it. You’ve got to interact with them, spend some time with them.”

And that time spent together can be outside! Cats don’t need to roam unsupervised in order to enjoy some fresh air and sunshine. You can build a catio, take your fur baby for a walk in a pet stroller, or train your cat to walk on a leash.

For more tips, check out our article on how to keep indoor cats healthy and happy.