Researchers have sounded the alarm over what is believed to be the first case of a black cockatoo dying from rodent bait poisoning in Western Australia.
The Carnaby’s cockatoo in question was taken to a veterinary hospital in 2019 after falling from a tree in Kalamunda.
Carnaby’s black cockatoos near a pine plantation in Perth.Credit: Miles Tweedie Photography
While the bird did not at first show signs of poisoning by anticoagulant rodenticide toxicosis, after four days it stopped eating and had lost weight.
Further investigations by vets found a haemorrhaging blood clot and the cockatoo had to be euthanized after its condition rapidly declined.
Its liver was then sent for analysis with researchers finding substantial quantities of two different AR poisons.
While second-generation ARs – sold in big-brand hardware stores – have been widely reported to kill predatory birds that eat rodents, a recently published paper in the Journal of Avian Medicine and Surgery reported it was the first time AR intoxication was detected in a wild Australian parrot or cockatoo species, which eat nuts and seeds.
Even more startling is the report’s suggestion that the bird most likely ate the poison directly, possibly learning to open bait boxes or from unboxed baits.
Murdoch School of Veterinary Medicine lead researcher and Perth Zoo veterinarian Dr Anna Le Souef said while it was hard to definitively say why the bird ate the poison, there were links between declining habitat, dwindling food sources and increasing numbers of black cockatoos in human habited areas.
“Carnaby’s in particular will try a lot of different food sources and I think that’s both to their benefit and their potential detriment,” she said.
“The Baudin’s, they have a different beak shape, so they’re more specialised feeders, whereas Carnaby’s will try a lot of different food sources, both native and introduced … they’ll eat grain and seed and feed from gardens … so it does expose them to different risks.”
Le Souef, the great-great-grandaughter of Perth Zoo founder Ernest Le Souef, has spent much of the past 18 years dedicated to the zoo’s cockatoo rehabilitation program.
“Their natural habitat was always the Perth area, and now they’re sharing that with a lot of human activity and these threats are continuing to show themselves,” she said.
“Over the years [human impact] is becoming significant, our research now and into the future will hopefully continue to build on our understanding of how toxins in the environment, such as pesticides and rodenticides and things like that are affecting these birds.
“[Finding ARs in black cockatoos] really just speaks to the number of wildlife species that we know could be affected and therefore help bolster the awareness of [AR] use.”
The public sale of ARs is currently under review by the Australian Pesticide Veterinary Medicine Association.
Bird conservation group Birdlife Australia has been advocating for the removal of these products from Australian shelves for more than four years.
“These are the products in Australia and internationally to impact a huge number of species,” Birdlife Australia priority sites manager Holly Parsons said.
“At the moment we’re relying on people using ARs correctly, but even when they do, we still find them in the native population.
“The US has withdrawn these products and we want to see Australia follow suit.”
In the recent Carnaby’s case, the finding of two different poisons not sold together in one formula, suggests the bird ate more than one bait from different sources.
The move against the use of the toxic baits has recently gained traction at the grassroots level with local governments in Augusta-Margaret River, Denmark, Nannup, Mundaring, Bayswater, Cockburn, Fremantle, East Fremantle and Melville joining the Owl Friendly movement.
Owl Friendly shires and cities will no longer use second generation rodenticide treatments in the community, instead using first-generation ARs and other forms of pest control like traps.
In a grievance to Parliament on October 17, WA opposition leader Shane Love alleged Labor’s lack of intervention had exacerbated cockatoo habitat loss and led to a decline in their food source.
He asked Environment Minister Reece Whitby to allow volunteers to give supplementary feeding to Carnaby’s while food stock was low.
“I call on the minister to immediately intervene to ensure that starving Carnaby’s are fed to get them through this season – time is of the essence,” he said.
But Whitby hit back at Love and his “party of historical climate denialists”, saying low autumn rainfall and drought conditions had affected flowering and fruiting of plants fed on black cockatoos.
Whitby said the Department of Biodiversity, Conservation and Attractions was examining the issues but that it was not feasible to set up supplementary feeding stations due to the widely dispersed habitat.
“The immediate priority is to support sick and injured Carnaby’s cockatoos that may be impacted by reduced food resources,” he said.
“Our government is providing specific additional support to the Perth Zoo veterinary department to ensure it can provide treatment for sick birds and to specialised black-cockatoo rehabilitation centres to enable them to rehabilitate birds and release them back to the wild.”
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