If you’re of a certain age, you probably remember the Looney Tunes cartoon characters Tweety the canary and Sylvester the cat. Tweety always managed to avoid Sylvester’s predatory ways, much to viewers’ amusement. Unfortunately, the reality is that wild birds all too often do not manage to escape alive from a cat’s clutches.
The Problem
As you may be aware, native bird populations have declined steeply. A 2019 article in the journal Science reports that the population of birds in North America has declined by 29% since 1970. Birds face many challenges, including habitat loss, climate change, window strikes, windmills, and hunting, but the biggest of the human-related causes of bird mortality in Canada, according to an article published in Avian Conservation and Ecology, is housecat predation. Cat predation alone is estimated to be responsible for the death of 207 million birds a year in Canada.
Annual mortality of Canadian birds due to human activities, Figure 1B in A Synthesis of Human-related Avian Mortality in Canada—a scientific paper by Environment and Climate Change Canada researchers.
From an ecological standpoint, our beloved pet cats (and their feral cousins) can be viewed as a harmful invasive species, if allowed to roam free outdoors. What can be done to reduce their impact?
Possible Solutions
- Keeping pet cats inside. This one is obvious, and recommended by many organizations, including Nature Canada, who devotes an entire website to the issue. Visit Cats and Birds, or the BCSPCA website for tips and downloadable resources to keep a happy indoor cat.
- Leashing. Yes, cats can be trained to walk on a leash. (See internet articles like this one to find out how.)
- Catios. More than just a cute pun, these enclosed patios for cats have become very popular in the last few years. Like leashing, they allow cats to enjoy the outdoors while keeping both the cat and birds safe. Catios can be purchased ready-made, constructed by a contractor, or DIY if you’re handy. The BCSPCA even offers a free building plan.
- Cat fence. Installing a cat-proof fence around your yard, or topping an existing fence with a cat-proof barrier, prevents cats from wandering onto roads or hunting outside your yard. The fences don’t prevent hunting inside the yard though, so this method is more effective when combined with an anti-birding collar (see the point below).
- Anti-birding collars. These generally involve something that attaches to a cat collar: a physical barrier that hampers a cat’s ability to capture prey, a brightly coloured “clown” collar, or reflective tape that alerts birds to the cat’s presence. It’s important to note that while some anti-birding collars, like the Birdsbesafe and CatBib (both available on Amazon.ca), have been shown to significantly reduce bird deaths in scientific studies, they don’t prevent all kills, and cats wearing them can still raid nests.
- Keeping outdoor cats indoors during times of high bird activity. Birds are most active, especially in summer, during the hours around dawn and dusk. Keeping your pet cat inside until a few hours after dawn, and bringing them in for the night a few hours before sunset can help reduce bird-cat encounters.
Feral Cats
Feral cats are responsible for even more bird deaths than pet cats. In the Rithet’s Bog Ecological Reserve just north of Victoria, predation, likely by residents of a local feral cat colony, killed so many birds that a researcher was forced to stop her study of song sparrows. This is something to keep in mind when organizations are considering trap, neuter, release (TNR) programs and the location of feral cat colonies (where feral cats are fed).
Cats on Mayne
Feral cats can be particularly hard on birds and other animals living on islands, and a study of invasive cat impacts shows they have contributed to at least 14% of global bird, mammal, and reptile extinctions on islands.
On Mayne, our understory vegetation has been heavily browsed by deer, leaving less cover for birds that feed and nest lower to the ground. This makes these birds particularly vulnerable to cat predation.
More Reading and Sources
- Catios article (Stewardship Centre for BC)
- Times Colonist: Bright collars help protect birds, study finds.
- Nature Canada Cats and Birds website https://catsandbirds.ca/
- Science: Decline of the North American avifauna
- Avian Conservation and Ecology: A Synthesis of Human-related Avian Mortality in Canada
- Avian Conservation and Ecology: Estimated Number of Birds Killed by House Cats (Felis catus) in Canada
- Global Change Biology: A global review of the impacts of invasive cats on island endangered vertebrates
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