麻豆传媒

ONE of my cats has died, and I am bereft. It wasn鈥檛 the one we expected to lose first, the saggy old ginger tom, but the much younger one who we thought had many years left in him. Turns out he had a weak heart. Mine is now broken.

I tell you this not to wallow in grief but to raise an issue that rarely gets an airing when we talk about making personal sacrifices to help the environment. I loved my cat and I miss him, but I take comfort from the fact that my loss is the planet鈥檚 gain.

I have long suspected that my cats are a major contributor to my household鈥檚 environmental footprint. Unlike the humans who live there, they eat meat every day. They also slaughter wildlife. Though the one we lost was a gentle soul, he was also a ruthless killer. I have cleaned up my fair share of decapitated mice and shredded spiders, and once watched, helpless and aghast, as he killed a wren in the back garden.

A few cans of cat food and the odd mauled bird hardly constitute ecocide, but summed across the world, domestic cats are a serious environmental menace. If you doubt this 鈥� and I know I have already raised some hackles 鈥� I recommend a devastatingly brilliant article called 鈥淭he ecological cost of pets鈥� by biologist Peter Marra of Georgetown University and the Smithsonian Conservation Biology Institute in Washington DC.

Marra is a well-known critic of cats. In 2016, he co-authored a book called Cat Wars, which argued that domestic moggies have a devastating impact on wildlife.

His new article, published in the journal Current Biology, demolished my lingering hope that the ecological impact of my cats is negligible. In the UK, for example, pet cats kill more than 275 million small animals a year. In the US, the toll is probably in the billions. This is just pet cats; feral cats kill even more (both my cats were strays before we took them in).

This predation is ecologically significant, says Marra. It has already contributed to the extinction of 63 species worldwide and continues to threaten hundreds more. In certain circumstances even a lone cat can do irreversible damage. In the late 19th century, for example, the Stephens Island wren was single-pawedly wiped out by a lighthouse keeper鈥檚 cat called Tibbles.

鈥淚n the late 19th century, the Stephens Island wren was wiped out by a cat called Tibbles鈥�

In my defence, most of these actual and threatened extinctions are in faraway places, not gardens in London, and the British species of wren isn鈥檛 remotely endangered. But that doesn鈥檛 absolve me. The mere presence of a free-roaming cat can instil fear and stress in birds, causing nesting adults to reduce their parenting and even abandon nests.

Some of the birds I see in my garden, including house sparrows and starlings, are already in serious decline due to human-induced habitat loss. Cats are an extra pressure they could do without.

If any dog lovers are feeling smug at this point, don鈥檛. Dogs also stress wildlife. One study found that areas of woodland frequented by dog walkers experience a 35 to 40 per cent reduction in bird diversity and abundance.

Pet ownership also imposes wider environmental costs. Added together, all the cats and dogs in the US consume the same amount of energy as 60 million people, effectively increasing the population by a fifth.

Ingredients in pet food are often leftovers from the human food chain, but this isn鈥檛 always the case. Even if they are, they still have to be processed, packaged and transported. What comes out the other end is an even stinkier problem, equivalent to the faeces of 90 million people, generating 64 million tonnes of greenhouse gases.

Being an animal lover and caring about the environment often go hand in hand. But they aren鈥檛 compatible. I hate to say it, but pet ownership is another unsustainable aspect of modern consumer lifestyles that we are going to have to confront. It isn鈥檛 the biggest, but it isn鈥檛 negligible. Like almost every other environmental vice, the problem is getting worse as pet ownership rises around the world.

That isn鈥檛 to say that pet ownership is totally indefensible. Marra accepts that it can have major psychological and physical benefits, and so supports 鈥渞esponsible ownership鈥�. In the case of cats, that means keeping them indoors at all times, which I don鈥檛 think is compatible with their own physical and psychological health.

I went meat free for environmental reasons. I鈥檓 working on going cheese free and car free. Going cat free will be 10 times harder than any of these, but when the saggy old ginger tom succumbs to the inevitable, I will try to make that the end of it.