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“It’s the DDT of our generation. We shouldn’t be allowed to even buy the rat poisons we can buy in Australia – in Europe and North America, they’re banning them.”
During 2020 lockdowns, people started bringing Cooke – who specialises in Australian owls and raptors – dead owls at the rate of one a week.
The talons of a powerful owl, found dead in Victoria.Credit: Eddie Jim
In 2022, a team of scientists at Deakin University, including Cooke and White, dissected 160 possums and sent samples to the National Measurement Institute to see what was killing the animals the powerful owls predated upon.
They found rat poison in 91 per cent of brushtail possums tested and 40 per cent of ringtail possums tested.
SGAR poisons are so toxic that they survive even after an animal is killed and can kill birds or animals that eat the dead rodent or possum. The poison can also be in live possums eaten by owls.
Powerful owls eat as many as 250 possums a year, but are increasingly being killed by their diet.Credit: John White
Cooke and White are among six co-authors of an alarming new study based on that work that proves SGARs have entered the foodchain of apex predators such as powerful owls and barn owls via possums and rodents.
Further testing revealed SGARs in powerful owls and wedge-tailed eagles, neither of which primarily consume rodents.
The ratios of SGARs found in powerful owls was similar to the levels detected in possums.
Apart from the powerful owl, Cooke’s freezer holds a boobook, a barn owl and a tawny frogmouth – all of which were discovered dead in Melbourne and regional Victoria, having eaten possums or rodents that had consumed SGARs.
Clockwise from top left: a boobook, a barn owl, a powerful owl and a tawny frogmouth. All are believed to have been poisoned by rat bait.Credit: Eddie Jim
“We’re finding that poison in agricultural areas, but we’re finding it in urban areas as well,” Cooke said.
“This is not just an agricultural issue, this is increasingly becoming an urban issue.”
She said brushtail possums – which eat a more varied diet – appeared to be consuming more rat poison, probably in roof cavities and scattered around homes, than ringtail possums.
“Australia is so far behind, and we are urging the APVMA to shift all anticoagulant rodenticides onto the restricted chemical products list, which would take them off the shelves of our supermarkets and hardwares.”
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A spokesman for the Australian Pesticides and Veterinary Medicines Authority (APVMA) said the regulatory body “takes all concerns related to safety of humans or non-target species very seriously”.
“The APVMA is also aware of decisions taken by comparable regulators, such as limitation of use of second-generation anticoagulant rodenticides in North America, where they are available to commercial pest controllers and for agricultural use, including uses in bait stations, baiting in burrows and baiting in and around buildings,” he said.
“Based on concerns identified through the published literature and through a public consultation, the APVMA initiated a reconsideration of both first- and second-generation anticoagulant rodenticides.”
A scientific assessment was “well advanced”, he said, and a regulatory decision would be published before the end of the year.
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