<p>Domestic Cats: Beloved Companions... </p> <p>That Can Have a Significant Impact on Biodiversity!</p>
Domestic Cats: Beloved Companions...
That Can Have a Significant Impact on Biodiversity!
They share our homes, sleep in our beds, and are part of the family.
In Quebec alone, more than two million domestic cats live alongside us, in nearly one out of every three households. But when they are allowed to roam freely outdoors, these adorable companions can have a far greater impact on wildlife than we might imagine.
The subject can be emotional. Yet the scientific data are clear: domestic cats rank among the most significant human-related causes of mortality for many small wildlife species. And contrary to what many people believe, keeping them indoors is often beneficial both for biodiversity… and for their own health.
An exceptional hunter
The domestic cat (Felis catus) is a remarkably effective predator. Even when well fed, its hunting instinct remains intact. Mice, voles, squirrels, frogs, insects, and especially birds can easily become prey.
Scientists estimate that in the United States alone, free-roaming cats kill between 1.3 and 4 billion birds, as well as between 6.3 and 22.3 billion small mammals every year. In Canada, estimates range from 20 to 200 million birds killed annually. These figures make cats one of the leading human-related causes of death among wild birds.
Unlike wild predators, cats benefit from the care of their humans: they are fed, treated, and protected from periods of scarcity. Their hunting is therefore generally not driven by hunger, but by a deeply rooted natural behaviour.
On a global scale, domestic cats are now present on every continent except Antarctica, and on most of the world’s islands.
Introduced by humans, they are considered one of the invasive alien species most harmful to biodiversity.
A threat that goes beyond the number of prey
The consequences go far beyond the simple number of animals captured. Domestic cats have contributed to the extinction of at least 63 vertebrate species around the world.
On some islands, where wildlife evolved for thousands of years without a comparable predator, they are responsible for approximately 14% of documented extinctions of birds, mammals, and reptiles, and they continue to threaten many species already at risk.
A broad scientific review published in 2023 clearly illustrates the scale of this pressure. Researchers recorded 2,084 animal species consumed by domestic cats around the world. Among them, 347 are considered of conservation concern, whether vulnerable, threatened, or endangered.
The authors also point out that this list is likely incomplete, since not all interactions between cats and wildlife are documented.
Kigumba, Western Region, Uganda. Plan rapproché d'un chat tenant un lézard dans sa bouche,
Birds that nest on or near the ground, young animals that have just left the nest, some already weakened species, and those living in urban and suburban habitats are particularly vulnerable.
And it is not only the animals that are captured. The mere presence of a cat can alter the behaviour of many species.
Birds may spend more time watching their surroundings than feeding their young, abandon certain areas, or experience reduced reproductive success. Across a neighbourhood, these effects can eventually influence local populations.
“My cat doesn’t hunt”
This is probably the argument heard most often. Yet many studies show that owners often underestimate what their cats catch. Why? Quite simply because cats bring only some of their prey back home. Many are eaten on the spot or left elsewhere.
Studies using small cameras attached to cats’ collars have shown that owners see only a small proportion of their cats’ captures. Even a cat that seems to spend its days napping can use a few outings to catch several animals over the course of a few weeks.
It is not a matter of training or “bad behaviour”: it is simply normal behaviour for a predator.
The dangers for… cats themselves
Allowing a cat to roam also involves many risks for the cat itself. Collisions with vehicles remain a significant cause of mortality. Fights between cats promote the transmission of diseases such as feline immunodeficiency virus (FIV) or feline leukemia virus (FeLV). Attacks by dogs, coyotes, or other animals, poisoning, parasites, injuries, traps, and even acts of cruelty are also very real dangers.
Added to this is the risk of contracting or transmitting certain diseases that can also affect wildlife or, more rarely, humans, such as toxoplasmosis or even rabies, as recent news has in fact reminded us.
As a result, cats that live mainly indoors generally have a life expectancy of 12 to 18 years, whereas cats allowed to roam freely are often estimated to live only 2 to 5 years.
Although these figures vary from one study to another, they all reach the same conclusion: living indoors greatly increases the chances of a long life.
Are indoor cats unhappy?
Not at all… provided their needs are met. A cat needs to climb, observe, play, explore, scratch, hide, and expend energy. These needs can be very well met indoors with an enriched environment. Cat trees, wall shelves, hiding places, scratching posts, interactive toys, daily play sessions, and stimulating food dispensers help satisfy natural instincts while ensuring safety.
Domestic cats do not need total freedom to have a good quality of life; above all, they need an environment that meets their physical and behavioural needs. In fact, many specialists in veterinary medicine and animal behaviour now recommend keeping cats indoors or offering them supervised access to the outdoors.
Yes to the outdoors… but safely
Install a catio
A secure outdoor enclosure where your cat can sunbathe, smell outdoor scents, and watch birds without reaching them.
Take your cat out with a harness and leash
Just as you would with a dog.
Further enrich the indoor environment
Indoor with games, climbing structures, and food-search activities.
If your cat still goes outside, avoid letting it out at dawn and dusk, when many wild species are most active. Bells on collars are sometimes suggested to reduce captures, but they are not a sufficient solution. Many prey animals do not hear them in time, and some cats even learn to move without making them ring. Bells may reduce some captures, but they do not prevent them.
A collective responsibility
Our cats are not “guilty.” They are simply doing what thousands of years of domestication and millions of years of evolution have prepared them to do: hunt.
However, we have a responsibility to limit the consequences of this predation on species already facing habitat loss, climate change, pollution, invasive alien species, and many other pressures. Keeping your cat safe while protecting the birds, small mammals, amphibians, and reptiles that share our living environments is one of those rare actions where everyone wins.
Loving your cat and protecting biodiversity are not incompatible goals. Quite the opposite. By offering your cat a rich, stimulating, and safe environment, you are caring for it while helping preserve the wildlife around us.
