Felis catus

Nowadays, I'm not a cat lover. That can lose you a few friends! But back when I was a boy, we had beautiful sister cats from the same litter. Neither had a name; one was friendly, one wasn't.

The friendly one slept with me most nights, including when I was at high school. And not at the end of the bed: no, she would dig under the blankets by my head, go down to my feet, turn around, stretch out fully and look me in the eye. This was a cat that thought she was human. In the morning, I would wake to her steam breath in my face.

Her sister had a different routine. Like all the cats we know today (Latin name, Felis catus), among our cats' ancestors was the African wildcat (Felis lybica). The modern cat was domesticated about 4,000 years ago in Egypt and the Middle East, before people moved them all over the world. The first white settlers, from England, introduced them to Australia in 1788. Within 70 years, cats had spread across the entire country, all 7.7 million square kilometres of it, faster and wider than other European animals, such as foxes and rabbits.

So, especially at night, the sister would go hunting. The problem is - and this is a problem all around the world - cats are killing machines. There are almost four million pet cats in Australia, and perhaps twice that many wild (or feral) cats living mainly in the bush but also in cities and towns.

They are all the same Felis catus species and eat only meat. Every day, they kill millions of native animals; over the years, they've wiped out more than 30 mammal species. They also gobble up millions of frogs, lizards, birds and butterflies. Even pet cats that are given plenty of food by their owners still like to hunt.

The conflict for people like me is how to control cats, particularly the pets that are much loved by millions of families. Keeping cats indoors day and night is the most responsible option, environment scientists say. As a bonus, they'll have longer, safer lives.

The wild cat problem is more difficult. Suggestions include shooting and poisoning them or introducing a biological disease to kill them. Another solution would be to make safe areas for threatened native animals by building fences to stop cats from getting to them.

The ideas will be expensive and take a long time. But at least we are having the conversation. If we solve the cat problem, our attention could turn to many other dangerous non-native animals, such as the wild dogs that kill sheep and cattle. Oh, did I forget to say that I'm not a dog lover, either?