A far-reaching new review has counted the cost of feral cats on Australian ecology.

Feral cats cover over 99.8 per cent of Australia’s land area, according to research undertaken by dozens of Australian environmental scientists using evidence from nearly 100 separate studies.

“Australia’s total feral cat population fluctuates between 2.1 million when times are lean, up to 6.3 million when widespread rain results in plenty of available prey,” said University of Queensland Dr Sarah Legge.

In a worrying finding for conservation managers, cat densities were found to be the same both inside and outside conservation reserves, such as National Parks, showing that declaring protected areas alone is not enough to safeguard native wildlife.

“Our study highlights the scale and impacts of feral cats and the urgent need to develop effective control methods, and to target our efforts in areas where that control will produce the biggest gains” says Dr Legge.

“At the moment feral cats are undermining the efforts of conservation managers and threatened species recovery teams across Australia.

“It is this difficulty which is pushing conservation managers into expensive, last resort conservation options like creating predator free fenced areas and establishing populations on predator-free islands. These projects are essential for preventing extinctions, but they are not enough - they protect only a tiny fraction of Australia’s land area, leaving feral cats to wreak havoc over the remaining 99.8 per cent of the country.”

“The density of feral cats in Australia is lower than it is in North America and Europe, and yet feral cats have been devastating for our wildlife,” said Mr Gregory Andrews, Australia’s Threatened Species Commissioner.

“Australia is the only continent on Earth other than Antarctica where the animals evolved without cats, which is a reason our wildlife is so vulnerable to them. This reinforces the need to cull feral cats humanely and effectively.

“With feral cats having already driven at least 20 Australian mammals to extinction, I’m so glad the Threatened Species Strategy is investing in science like this.

“This science reaffirms the importance of the ambitious targets to cull feral cats that I am implementing with the support of Minister Frydenberg under the Threatened Species Strategy,” said Mr Andrews.

According to Dr Legge, “As well as strategically targeting areas for cat control in bushland to maximise the conservation outcomes, we also need to address the issue of feral cats living in heavily urbanised areas, where their densities can be 30 times greater than in natural environments.

“As well as preying on the threatened species that occur in and near urban areas, these urban feral cats may provide a source of feral cats to bushland areas.”

The research was funded by the Threatened Species Recovery Hub of the Australian Government’s National Environmental Science Programme.

It has been published in the journal Biological Conservation.