squatter pigeon
A new study says cats kill over one million birds in Australia a day. Above an image of a Squatter Pigeon, one of the species under threat of extinction from overhunting by cats. Getty

Cats, both wild and domestic, account for more than one million bird deaths in Australia every day.

A new research published in the journal Biological Conversation showed that the staggering numbers found in the study explain the decline of many species in the continent.

The study gave an in-depth estimate of the cat-assault on the bird population. A staggering 316 million birds were killed by feral cats and 61 million were killed by pet cats annually.

"Everyone knows that cats kill birds, but this study shows that, at a national level, the amount of predation is staggering," said John Woinarski, lead researcher of the study from Charles Darwin University.

The team has linked the numbers of this study to the decline in populations of many bird species. The numbers were obtained based on results from almost 100 studies conducted by environmental scientists in Australia which sampled cat population density. There was a separate set of 100 studies to assess average feline diets to get a more accurate number.

These numbers revealed some interesting insight into the issue. The number of bird deaths caused by cats was found to be higher in remote and more arid regions. In arid regions, numbers were found to be as high as 330 birds killed by cats per square kilometer. John Woinarski added in a Phys.org report that previous studies focussed on the impact of cats only on mammals and this was the first comprehensive study on birds in Australia.

Previous studies have already linked feral cats to declines in mammal populations. According to the report, feral cats have been responsible for the extinction of several species since their introduction by Europeans. Efforts to sterilize the cats have had no impact on the number of animal deaths they cause. The predatory instinct of cats is well documented, and these numbers show how too many cats could affect other animal populations in Australia.

These cats hunted over 338 species of birds. This amounts for almost half the bird species in Australia. With such a broad menu on offer, these cats seem to thrive on Australian birds. The study shows that over 71 endangered species of birds are hunted actively by cats. This included 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. He also stressed the threat these cats pose to the bird populations of Australia.

Sebastian Lang, Threatened Species Commissioner, said the study was very important to assess the situation.

The knowledge of the impact of cats on threatened mammals proved to spur important conservation efforts. More than $30 million (US$23 million) has been allocated to help reduce the impact of feral cats on mammals. He hopes that this will happen again after the alarming impact on birds is seen.

"This new research emphasizes the need to continue working to reduce the impact of cats on our native biodiversity," Lang said.