“I’m very happy it’s happening,” says Peter P Marra, an ecologist at Georgetown University in the US and one of the authors of the 2016 book Cat Wars: The Devastating Consequences of a Cuddly Killer. That kind of policy is the right approach, he says, “but we shouldn’t wait until it comes down to a few individual birds.” In his opinion, no domestic cat should be out in the wild, anywhere. In the US, the free-roaming cat debate has been raging for years. Marra’s work has shown that cats – mostly feral but also domestic – kill billions of birds and mammals in the US every year. And while the motivation is primarily from the perceived dangers of coyotes and traffic, 70 percent of U.S. cat owners now keep their cats inside, up from 35 percent in the late 1990s. Cat owners in the UK feel differently: around 70% let their cats outside, a similar percentage to other European countries. Access to the great outdoors is seen as good for cats’ welfare, a position shared by charities such as Cats Protection and Battersea Dogs & Cats Home, and there are few predators to worry about. The EU has even stated that it believes in the free movement of cats. “It’s a huge social difference [from the US]says Robbie McDonald, a wildlife ecologist at the University of Exeter. But cats are prolific hunters of wildlife in both the UK and Europe. A study published in April estimated that UK cats kill 160 to 270 million animals a year, a quarter of which are birds. The actual number is likely to be even higher, as the study used the population of 9.5 million pet cats in 2011. It is now closer to 12 million, boosted by the pet craze pandemic. Given the decline in bird numbers across the EU and the UK, it is “quite worrying”, says lead author and cat ecologist Tara Pirie from the University of Reading. Lyall’s wren, Traversia lyalli. Within a year of the cats’ arrival on Stephens Island, the species’ last stronghold, it had disappeared. Illustration: John Gerrard Keulemans Such alarming numbers have now prompted charity SongBird Survival to launch the ‘Friends Not Food’ campaign, hoping to inspire cat owners to take action and curb hunting. So is it time to rethink Britain’s laissez-faire attitude towards free-roaming cats? According to the researchers, the science on the impact of cats is far from settled – but the answer is still yes. It is well established that cats can have serious effects on wildlife and even cause extinctions. The most famous example is the Lyall’s Wren, a small flightless bird that once lived on New Zealand’s Stephens Island. When Europeans arrived on the island in the late 1800s, they brought their cats and probably within a year, Lyall’s Wreath was gone. This story opens Marra’s book. In it, he argues that the domestic cat is not just an invasive species on small Pacific islands, but almost everywhere. As such, it endangers native wildlife wherever it is found. “The evidence is so clear,” says Marra. “I have analyzed it in every possible way.” In the UK and the rest of Europe, however, cat invasions happened a long time ago. Cats were brought from the Fertile Crescent to southeastern Europe several thousand years ago and then introduced to Britain by the Romans. “We’ve had a much longer history of dealing with any impacts they might have,” says Philip Baker, a mammologist at the University of Reading, adding that Britain and Europe have had indigenous wild cats for millennia. “There is at least some evolutionary history of these kinds of predators that the prey would have evolved with.” The problem, Pirie says, is “the sheer number” of domestic cats. On average, a British cat brings home about five game a year. The researchers estimate that this is about 23% of their actual deaths, or about 22 kills per year. Multiplied by the number of domestic cats, it is clearly a huge number of lives lost. If you compare that to the collective population of native wild predators such as ferrets and martens, Pirie says, cats “outnumber them by about five times.” Should the British adopt the American way and give up free-roaming? It may already be happening Although the relationship between how many cats live in an area and how many birds they take is not clear – for example, cats roam less when surrounded by neighboring cats – there is evidence that when the number of cats increases, so does the killing of cats. A large 2019 study found that the number of garden birds killed by cats in France and Belgium increased by more than 50% in 15 years, in parallel with the increase in those countries’ pet cat populations. And while many birds visit the gardens, conservationists are particularly concerned about wild areas such as woodlands and heaths, which are home to vulnerable species such as warblers and nightingales. Pirie’s study, which used GPS trackers to map how cats roamed Reading, showed that cats living next to natural habitats visit them regularly. This means that although they are mainly city birds, such as robins and blue tits that encounter cats, rural species could also be at risk. It sounds bad, but not everyone is convinced that cats are actually putting bird populations under pressure. “The knee-jerk reaction is that they have to have some kind of impact – they’re killing millions and millions,” says Baker. However, numbers can be deceiving. According to Baker, the birds most hunted by cats have so many young that they can afford to lose many of them. In the UK, he says: “I’m just saying categorically that there is no evidence of impact.” The UK’s biggest bird charity, the Royal Society for the Protection of Birds (RSPB), is not particularly concerned about the impact of cats on the British mainland. Instead, it focuses on what it says is driving the decline of birds in the UK: global warming, intensive agriculture and the expansion of towns and cities leading to loss of habitat and food. “While we know that cats kill large numbers of birds in UK gardens, there is no evidence that this is affecting the decline in the same way as these other issues,” said a spokesman. A big reason they’re less concerned is evidence that cats mostly get “the damned surplus”: weak or injured birds are likely to die anyway. In 2008, Baker led a study in Bristol that showed that birds killed by cats had, on average, less fat and muscle than birds killed by collisions with windows. While there could be other explanations — such as birds having less fat in the morning when cats tend to rush — Baker says the fat and muscle scores were so low that the birds were in dire straits before they were killed. Another 2000 study found that birds killed by cats in Denmark had smaller spleens, indicative of weaker immune systems. That said, cats take birds in good shape and Robbie McDonald says data from the US shows that large numbers of cats can have population-level effects. “But it’s hard to generalize,” he says. Cats can be a danger to some species at times. for others, not at all. Most people who have cats are animal people. They don’t want to have that impact on wildlife, Dr Tara Pirie, University of Reading Charlotte Bartleet-Cross from SongBird Survival says it’s about paying attention to birds that are already under stress. “Many of these bird species found in the [UK birds of conservation concern] The list is actually similar to the bird species commonly caught by cats,” he says. “That could have a further impact on the numbers.” Take the greenery. An outbreak of parasite-induced trichomoniasis saw the UK population decline by 65% in the mid-2000s, putting it on the conservation red list. As a ground feeder, it is easy prey for cats. The Dunnock, whose numbers have declined by more than a third since the 1960s due to disappearing food sources, is another ground feeder and frequent cat prey. It is currently on the amber list. Although Baker sees no evidence that cats are responsible for the UK’s bird decline, he agrees there is a problem worth talking about. “Cats are one of the biggest welfare problems – if not the biggest welfare problem – for wildlife in this country, in terms of the number of individual birds and animals affected and the length of time many will suffer before they die. “, says. . The number of animals involved in badger and fox culls killed for sport “pale” in comparison, he says. So should the British adopt the American way and give up free-roaming? It’s probably already happening. Although it’s early days, a growing minority keep their cats entirely indoors. And that worries Daniel Cummings from Cats Protection. “We’re not saying all cats should go outside,” he says, but if indoor-only use became the norm, some cats “would have their welfare significantly reduced.” This supports a 2019 study that suggests many indoor cats in the US may not be getting the stimulation they need. No cats allowed: a handmade sign warning cat owners in Walldorf, Baden-Württemberg, where cats must be kept indoors for three summers. Photo: dpa Picture Alliance/Alamy Instead, Cats Protection is recommending a dusk-to-dawn curfew for cats, which it hopes will be a “win-win”. SongBird Survival and the RSPB also support such a move. Cats and birds are most active at dusk and dawn. “It’s a reasonable compromise,” says Cummings. “You effectively reduce risk [the cats] in a traffic collision during the night and also reducing the risk…
