Introduction

Cats: cuddly kittens on lethal killers? In the past decades, a huge debate has sprung up over the role cats play in animal ecosystems and is cats effect on wildlife is really so bad. Are they blood-thirsty killers of birds and small mammals? Undoubtedly, cats are born hunters – and pretty good ones at that! They have superb hearing and can jump, creep, climb and pounce at lightning speeds. But if so, what’s their actual impact on biodiversity and should we be doing anything about it? Needless to say, it’s a debate that’s seen tensions rise on both sides of the argument.

Cats on islands – a problematic combination

The case against cats often begins with the role non-native cats have played on islands around the world, and it doesn’t look good on their record. Books such Cat Wars paints a compelling history of the cat on remote islands, where, following their introduction by sailors, colonising nations, or simply cat-loving visitors, cats have successfully wiped out entire species found only in these locations.

As this BBC article states, islands have seen 75% of known bird, mammal, amphibian and reptile extinctions over the past 500 years. Unfortunately, many of these losses are directly linked to animals such as cats that were not naturally present there until introduced by new settlers. When introduced, they had a field day, preying on animals that have evolved over millennia without the cat as a local predator.

What about the UK? 

According to The Mammal Society, a leading UK charity advocating for science-led mammal conservation, it is estimated that in just Spring and Summer, UK cats catch up to 100 million animals, of which 27 million are birds. This is the number of known catches and the real figure (i.e. including those catches which are never brought home) is likely much higher. Of the birds that are caught, the most common species include starlings, house sparrows, blackbirds and blue tits.

The good news, however, is that according to the same charity, there is no evidence that this high number of caught prey has contributed to a decline in bird populations. Millions of small mammals and birds die naturally from disease, starvation, predators and other causes. It’s worth bearing in mind that cats usually hunt on sick or weak creatures which are easier to target – as such, it’s quite likely that they might have died anyway.

Does that mean there’s no real issue with cats effect on wildlife?

Unfortunately, it’s not quite that simple. What we don’t really have an answer to is whether cats are mopping up surplus wildlife according to the natural order of things or are in fact having a significant impact on wildlife populations.

There are simple things you can do: for example, making sure your cat is equipped with a colourful collar or bell. The results from a Swiss study on the issue found that a coloured collar is enough to reduce cats effect on wildlife and the number of birds a cat kills. In fact, these colourful collars reduced the prey count by almost 40%. Combined with a bell, this figure drops to 60%.

Studies of a similar nature conducted in the UK, Australia and United States have re-produced these findings, concluding that there is a great value in having some form of highly visual or acoustic collar to reduce the hunting success of domestic cats.

For a much fuller discussion on the subject of cats effect on wildlife, we highly recommend Marra and Santella’s Cat Wars, a book we’ve enjoyed reading for a romp through the history of this highly divisive social topic!