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Killer cat stats

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Dr Karl Kruszelnicki

Contributor

Dr Karl Kruszelnicki

Dr Karl is a prolific broadcaster, author and Julius Sumner Miller fellow in the School of Physics at the University of Sydney. His latest book, Vital Science is published by Pan MacMillan. Follow him on Twitter at @DoctorKarl
By Dr Karl Kruszelnicki • 8 January 2025
Feral cat
Image credit: shutterstock
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A crunching of the numbers reveals some extremely sobering facts about the carnage caused by feral cats in Australia.

Every day, cats kill more than one million birds in Australia. This means that three to four per cent of our birds are killed by cats each year. About 99 per cent of these birds are native. In fact, cats impact 71 of the 117 threatened bird species here in Australia.

There are an estimated seven to eight million cats in Australia. About half of these are pets, while the other half are feral. These cats fit into three categories. 

Firstly, there are about 2–5.5 million feral cats living in natural environments spread across some 7.7 million sq.km of Australia. Their numbers can vary with the season. For example, the number of feral cats living in dry areas increases markedly after a period of high rainfall and drops during droughts. In these largely natural landscapes, there’s about one cat in each 2sq.km. Nobody is giving them food, so they can eat only what they hunt or forage. These cats kill about 272 million birds each year – about 72 per cent of all bird deaths. Each cat kills about 73 birds a year.

A feral cat with a dead phascogale in its mouth
A remote camera captures a feral cat hunting a phascogale – one of two billion native Aussie animals killed each year by these introduced predators. The Federal Government is preparing a national action plan against feral cats to protect native wildlife. Image credit: DBCA Western Australia

Secondly, there are an estimated 720,000 feral cats living across Australia’s ‘highly modified’ urban areas (about 57,000sq.km), including places such as rubbish dumps. This works out to about 12–13 feral cats in each square kilometre of highly modified landscape. In these areas, feral cats often scavenge food scraps from bins and rubbish tips, so their average kill rate of birds a cat (61 a year) is slightly lower than that of feral cats living in the wild. These cats kill another 44 million birds each year – about 12 per cent of all Australian bird deaths.

The third case is that of the 3.88 million pet cats that also live in Australia’s highly modified landscapes. That’s nearly 70 cats in each square kilometre. But the bird kill rate a cat (15 a year) is much lower than for feral cats, because their food is overwhelmingly given to them by their owners. These pet cats – living with their owners – kill about 61 million birds each year, about 16 per cent of the total.

For most of us, the typical bird-mammal interaction is a cat with a dead bird.

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