Birds in Australia face an onslaught from both feral and domestic cats, which kill more than one million of them every day.
The figure is revealed by a new study, published in Biological Conversation, that found that wild cats killed 316 million birds every year, while pets killed 61 million.
"Everyone knows that cats kill birds, but this study shows that, at a national level, the amount of predation is staggering," said lead researcher John Woinarski from Charles Darwin University in a statement reported by Phys.org. "It is likely to be driving the ongoing decline of many species."
This is the first such study on the impact of predatory cats on Australia's bird population. Previous research had looked at the effect on mammals. The researchers looked at almost 200 studies, almost 100 on cat population density, and another near-100 studies on feline diets.
Australia's islands and its remote or very dry areas tended to have the highest rates of bird predation, with as many as 330 killed per square kilometer per year in some areas.
There was evidence of cats killing 338 types of bird, nearly half of all the native species in Australia. Among them were 71 threatened species including the spotted quail thrush, the squatter pigeon, and the night parrot.
"We found that the birds most likely to be killed by cats are medium sized birds, birds that nest and feed on the ground, and birds that occur on islands or in woodlands, grasslands and shrublands," said Woinarski.
"For Australian birds, cats are a long-standing, broad-scale and deeply entrenched problem that needs to be tackled more effectively."
Australia began construction in June on a 69,000 hectare cat-free zone in the desert where animals whose populations have been decimated by felines can be safely reintroduced.
