Poisons taking deadly toll on owls

VINCENT bird advocates are calling for a city-wide ban on rodent poisons that also kill other animals, with native owls at great risk if they consume a poisoned rat.

At the Vincent council electors’ AGM on February 2, Birdlife Australia member Betty Bryant said the group is sounding the warning “about the dangers of rodenticides… we’re killing our owls”.

Rats are a recurring problem around Vincent, and in ratty hotspots like West Perth it’s common to hear scuffling in the undergrowth from rats feasting on ubiquitous palm tree fruit. 

“We all hate rats, I get that, but the second generation rodenticides which are freely available through Bunnings are anticoagulants,” Ms Bryant said.

“If there’s a delay between when the mouse or rat eats the bait to when it dies, and if an owl or a cat or a dog eats those rats or mice, they are affected.

“My brother actually had his dog in the vet for a very expensive three days, having eaten one of these rats.

“The problem is the [anti] coagulants stay in the body where they don’t disseminate.

“Our pets, our owls, our raptors, tawny frogmouths, any of those are likely to be killed.”

The second generation poisons contains fast-acting super-anticoagulants which last longer and are up to 100 times stronger than the old warfarin-style anticoagulant poisons.

“Second generation rodenticides are actually banned or restricted in America, Europe, and the UK already,” Ms Bryant said.

Her motion to ban them in Vincent and “strongly discourage” other rodenticides was passed by a majority of electors present at the AGM, and councillors will now consider whether to make it policy at an upcoming meeting.

In 2018 a study by ECU researcher Michael Lohr found 72.6 per cent of dead southern boobook owls collected around Perth and south-west WA had some rodenticide in their system. 

Just over 50 per cent of the birds had dangerous levels of rat poison residue in their livers and would likely be experiencing blood problems (though a lot of them had been hit by cars before collection, so it was hard to tell how many would have died from rat poison).

Birdlife Australia recommends if people must use poisons as a last resort, they avoid anything containing the ingredients brodifacoum, bromadiolone, difethialone, difenacoum or flocoumafen, all indicating second generation status.

The group petitioned Bunnings to remove second generation poisons from sale; its website advises they are “the most humane option for eliminating rodents; however, they pose a greater risk of harm to non-target species… so it’s important to remove any dead rodents that you find”.

by DAVID BELL