Are cats actually that bad?

House Sparrows are quite unlucky in life, as almost everything wants to eat them. Crows, Falcons, Seagulls, Owls and Hawks all regularly hunt them, while Rats, Badgers, Weasels, Stoats and even Squirrels plunder their nests. But by far their top nemesis is the domestic cat…

The RSPB and Mammal Society estimates that out of the 100,000,000 animals killed by our cats over a British Spring and Summer (this figure was recorded in the 1980s, when there were far fewer cats) 27,000,000 are birds, House Sparrows being the commonest victims, Blackbird and Starling following suite. Typically, they make up at least 17% of all prey items taken by cats.

To some people, these figures in themselves might not seem that worrying. It’s more the fact that, while we do have our native “Highland Tiger”, domestic cats aren’t native, and in their current numbers (estimated at 12.2 million) aren’t remotely natural and are killing numbers of birds. If we’re going on what’s natural, no birds would be killed.

The argument against this, backed by several studies, is that the vast majority of House Sparrows taken are either very young, old or sick, and unable to struggle through life for much longer anyway. And of course, in a more natural environment, instead of our human-moulded version of the world, these birds would be picked off anyway by predators. So, surely this softens the blow from cats, and that this is actually ‘natural’?

Well, it’s not. Using whether or not something’s ‘natural’ in today’s world, changed beyond recognition by humans, is a weak argument, because as is being proved increasingly often, we haven’t a clue what natural is. Until recently, we thought that before humans came along and cleared the woodlands, the whole of Britain was closed-canopy Forest, but we now know it was a giant wooded grassland mosaic. Species as charismatic as the Turtle Dove, previously thought of as a granivore, we now know eats invertebrates. So, we shouldn’t claim that domestic cats killing birds is a natural proxy for the predators that would regulate bird populations.

What we do know is that is that their current densities and populations are not natural, so it’s safe to assume they’re killing unnaturally large numbers of sparrows. Not only that but unlike natural predators, whereby hunting is a matter of life and death, the birds our pets kill are just dumped there. Some occasionally decompose but most end up in the bin, also robbing the ecosystem of its nutrients and energy.

Cats preying on birds in urban areas also burgles natural predators of their food, and in the case of some species (e.g., Hobbies and Kestrels) urban birds like sparrows is the only thing enabling them to spread inwards and colonize our concrete jungle (I’ll talk about this in the next post!) so, cats should be treated as negative, alien impacts to the environment.

So, if you are a cat owner, please put a collar on them/keep them inside (especially at night!). A quick-release collar with a small bell on has been shown to reduce predation rates by up to 50% and keeping them in overnight when birds are roosting and more vulnerable further shrinks this figure. They might not ‘like’ having a collar, but I doubt baby sparrows like starving to death in their nest because their parents were killed by an animal that doesn’t even need to hunt to survive.


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Thanks for reading!