Battling feral cats: The Tiwi Islands’ conservation initiative
By Joanne Heathcote
World-wide, free-ranging cats are considered one of the most damaging invasive species, causing impacts through predation, disease transmission and competition. In Australia feral cats inhabit almost all of our continent and are an ecological catastrophe for our environment. Predation by cats is a recognised threat to more than 200 nationally threatened species. Since their arrival in this country, cats have played a role in the extinction of more than 30 of our native species, and they continue to drive many of them towards extinction. It has been estimated that collectively feral cats in Australia kill over six million mammals, reptiles, and birds every 24 hours and are the single greatest threat to Australia’s unique smaller native mammals.
One cat had a whole black-footed tree-rat (Djintamoonga) in its stomach.
Australia’s offshore islands provide important refugia for species as the threats present on the mainland are often absent or less intense on islands. Some of Australia’s islands now provide the only refuges for certain species that have been extirpated from their mainland ranges. Nestled just 20 kilometres north of Darwin, the Tiwi Islands encompass Australia’s second and fifth largest islands, Melville (5,786 km2) and Bathurst (1,639 km2). The Tiwi Islands are considered an important faunal refuge for many threatened and declining top-end species such as the brush-tailed rabbit-rat, northern phascogale, black-footed tree-rat, and the endemic Butlers dunnart. While populations of these species remain high compared to the mainland, population declines have been detected on Melville Island during the last 20 years, and predation from feral cats is implicated as the primary driver of these declines.
There has been an unbroken history of occupation and ownership of the Tiwi Islands by Tiwi people, and Tiwi Traditional Owners have identified feral cats as a key threat to their islands’ biodiversity. Fortunately, hope is on the horizon. Thanks to the backing of a two-year Australian Government Saving Native Species Grant, Tiwi Rangers and Traditional Owners, along with support from Terrain Ecology and researchers from Charles Darwin University have launched a vital conservation initiative and have taken up the challenge of undertaking cat control to protect Tiwi wildlife. The aim of this project is to understand what feral cat control methods are most effective on Tiwi. Three different cat control methods are being trialled across three priority areas on Melville Island where known populations of threatened wildlife are persisting. A combination of both traditional and innovative methods is being used. Among the tools in their arsenal are advanced Felixer Grooming Traps, which are innovative devices that deliver a poison gel to the fur of feral cats which the cat later ingests when grooming itself. Through a combination of targeted laser and built-in camera using artificial intelligence (AI) recognition, these autonomous devices are able to identify and cull feral cats while avoiding non-target species (Google The Felixer ). The team are also using .223 rifles fitted with the latest thermal scope technology as well as cage traps lured with cat urine. The team hopes to understand what methods are most effective across the wet and dry seasons as well as cost-effectiveness or ‘catch per unit effort’. This information, alongside known cat density measurements, will be used to model future cat management scenarios required to suppress cat numbers in parts of the Tiwi Islands.
From June to September 2024, the project successfully removed 38 feral cats. One particularly eye-opening dissection involved a 6.4kg male cat with an entire black-footed tree-rat in its stomach — a stark testament to the predatory prowess of these invasive felines. Alarmingly, preliminary findings indicate that savanna gliders (formerly called sugar gliders) are particularly at risk, showing up in one of every four culled cats. Other mammals found in the stomachs of cats include the delicate mouse, pale field-rat, and northern brown bandicoot, alongside various reptiles, birds, frogs, and insects.
How can hunters help protect Australia’s wildlife?
As responsible outdoor enthusiasts and hunters, we also have a role to play in native wildlife conservation. By staying vigilant for feral cats during hunting expeditions and removing them whenever possible, we can make a significant contribution. Every feral cat eliminated translates to potential survival for countless native species.
