A device that kills feral cats by spraying them with a lethal gel that they lick off while cleaning themselves is being trialled as a way to save endangered Australian wildlife.
Since their introduction to Australia in the 18th century, cats have severely harmed the local ecosystem by preying on native birds and small mammals. They have contributed to the extinction of more than 20 Australian animals 鈥� including the paradise parrot, broad-faced potoroo, rusty numbat and desert bandicoot 鈥� and continue to threaten many more.
In 2015, the Australian government set a target of culling 2 million of the estimated 6 million cats living in the wild by 2020. But this has been challenging because the cats prefer hunting live prey to eating poison baits and are too numerous to be controlled by shooting.
Advertisement
To address these problems, John Read at the University of Adelaide and his colleagues have invented an automated device for culling cats that takes advantage of their compulsive self-grooming rituals.
The solar-powered device, called a 鈥淔elixer grooming trap鈥�, has laser sensors that detect when a cat walks past based on its size, shape and gait. When activated, the sensors trigger the release of a toxic gel that squirts onto the cat鈥檚 fur. The cat later licks the gel off while routinely cleaning its coat.
The gel contains a commonly used poison called sodium fluoroacetate or 鈥�1080鈥� that halts the production of energy in cells. The poison is thought to euthanise cats painlessly because it causes unconsciousness before shutting down brain activity, says Read. 鈥淚n most cases, they get wobbly and sleepy, then lie down and die,鈥� he says. An initial trial with two cats in a pen found they passed out within 6 hours of being squirted and died within 10 hours.
Another benefit of sodium fluoroacetate is that Australian animals have evolved some resistance to its toxic effects because it naturally occurs in several native plants, says Read.
As a test, the researchers recently installed 20 Felixer devices in a 2600-hectare fenced paddock in South Australia that is inhabited by feral cats and native wildlife.
Cameras showed that the traps correctly identified, sprayed and killed feral cats, causing their population to decline by about two-thirds over six weeks. No native animals activated the traps and none died. The effectiveness of the traps was confirmed by the observation that cat numbers didn鈥檛 decline in an adjacent paddock where no devices were installed.
In a separate experiment on Kangaroo Island, the researchers showed they could prevent pet cats from activating the traps by fitting them with special wireless tags. Read will present the results at the annual meeting of the Ecological Society of Australia later this month.
The traps currently cost A$15,000 each, but they should become cheaper once they are commercialised, says Read. He is seeking approval from the Australian Pesticides and Veterinary Medicines Authority to sell them to accredited land managers across the country.
Some cat protection groups say the most humane way of controlling Australia鈥檚 feral cats would be to trap them, surgically sterilise them, then return them to the wild. But Di Evans at animal charity RSPCA Australia says this is impractical because feral cats often live in remote, hard-to-access areas.
Felixer traps are preferable to poison baits because they specifically target cats and are therefore less likely to harm other animals, says Evans. However, the RSPCA would like to see more research on the feasibility of reducing feral cat numbers with contraception 鈥� possibly administered as single injections or slow-release implants 鈥� instead of lethal methods, she says.
