The problem with cats

Feral cats kill an estimated 2 billion animals in Australia every year, but nuanced solutions on Bush Heritage reserves and partnership properties across Australia are helping to turn the tide.

There’s absolutely no silver bullet when it comes to cat control,” says University of Queensland ornithologist Dr Steve Murphy. “So that means we’ve got to work out ways to make the tools we have more efficient.”

Steve is one of Australia’s foremost experts on Night Parrots, a critically endangered bird found on Bush Heritage’s Pullen Pullen Reserve, Maiawali country in Queensland, where a live Night Parrot was sighted eight years ago for the first time in almost a century.

Dr Steve Murphy sets up a motion sensor camera next to a Night Parrot roost in Spinifex grass on Pullen Pullen Reserve, Maiawali country, Qld. Photo by Lyndon Mechielsen.

At 56,000 hectares, the outback reserve is a vast expanse of rich red plains broken by dramatic table-topped mesas and spinifex mounds, where, if you’re very lucky, you might just find a Night Parrot nest tucked away on the ground.

These spiky mounds provide Night Parrots with an almost impenetrable fortress, but the moment the birds step outside them they're exposed to their biggest threat: feral cats.

“Night Parrots nest on the ground, which makes them highly vulnerable to predation,” says Steve.

“They’re nocturnal, which is when cats are mostly hunting. And when the young birds are in the nest, they become incredibly vocal just before they fledge – which of course draws cats in from all over the place."

It’s for this reason that cat control is the major focus of Bush Heritage’s work on Pullen Pullen. About 35 cats have been removed from the reserve over the past 18 months alone using a combination of shooting and trapping.

But finding those cats has been time consuming and costly and there are many more still out there, which is where Steve’s research comes in. He has been tracking feral cats on Pullen Pullen by capturing them and fitting them with GPS collars to see whether he can identify landscape features such as dune tops or creek lines that they frequent in order to improve the effectiveness of Bush Heritage’s cat control there.

“We’ve now got really good information about where these cats went over the past six months,” says Steve. “So let’s imagine we’re a reserve manager and we’ve got 50 cat traps to put out across the 20,000 hectares of core Night Parrot habitat. Where should we put those traps to get that optimal encounter rate?”

Vast spaces, few roads and endless mounds of spinifex make it hard to find cats on arid reserves like Pullen Pullen and Ethabuka. Photo by Lachlan Gardiner.

Steve’s research is contributing to a rapidly growing pool of knowledge about feral cat behaviour that is changing the way cat control is carried out on Bush Heritage reserves across Australia.

Nowhere is this more important than in arid landscapes.

About one third of arid zone mammal species have disappeared since European settlement, and feral cats are considered to be the main culprit, posing a greater threat to native animals than climate change or wildfire.

On Ethabuka Reserve, Wangkamadla country, in far western Queensland, the decline has been chronicled in almost three decades of data collected by researchers at the University of Sydney’s Desert Ecology Research Group (DERG), led by Professors Chris Dickman and Glenda Wardle.

“We’ve seen some species drop out of our records altogether, while with others their numbers are gradually declining,” says Chris. “The pattern of loss just can’t continue.”

For Ethabuka Reserve Manager Dr Helene Aubault, it’s a trend she’s determined to turn around.

“Ethabuka has the richest diversity of reptiles in Australia. It’s also home to many small mammals like Mulgaras, Hopping Mice and Planigales – all the perfect-size for feral cats.”

Just like on Pullen Pullen, cat control is particularly difficult at Ethabuka. The reserve’s size (215,000 hectares, roughly the area of greater Sydney), lack of roads, and terrain spinifex plains - perfect for hiding behind), make it very difficult to hunt cats there.

Helene realised a more targeted approach was also needed, and she found it in the one driving factor that all desert-dwellers have in common: the search for water.

Although cats get most of their water from their prey, Helene discovered that they congregate at Ethabuka’s waterholes to drink and hunt during extreme heatwaves (not uncommon during the Summer months). For her study, she placed motion-sensor cameras at springs, sand dunes and roads across the reserve. Far greater cat activity was recorded at the springs during heatwave events than at any other site.

This knowledge will allow Helene to target cats at Ethabuka more efficiently – focusing it around the springs during hot summer months, when cat populations are typically lowest, to limit any potential population boom in response to wet season rains later in the year.

Her strategy might not be a silver bullet, but complex issues require complex solutions, and she is not alone in her battle.

On Olkola country in Cape York, Aboriginal rangers are using motion-activated Felixer cat traps to help reduce predation on Alwal, the Golden-shouldered Parrot. When the traps were first trialled, they misidentified Dingoes, a culturally significant species for Olkola people, as cats. So the rangers worked with the traps’ creators until that risk was mitigated.

In south-west Western Australia, a highly fragmented landscape in which properties are smaller and land ownership more diverse, a new project is bringing together farmers, Traditional Custodians, Bush Heritage ecologists and WA Parks and Wildlife staff to collaboratively tackle cats, foxes and rabbits across 37,000 hectares.

Dozens more projects with equally nuanced approaches are being rolled out across Australia.

So, while the scale of the problem might be daunting and the work not very pleasant, as Helene says: “it’s worth it knowing we’re giving native species the chance to survive and reproduce.”

Dr Murphy’s research at Pullen Pullen was funded by the Threatened Species Recovery Hub (National Environmental Science Program) and the University of Queensland. The Britton Family (Brighton Downs Station) and Alistair McDonald (Mt Windsor Station) provided important logistical support.