Anticoagulant rodenticides influence populations of predators such as owls and threaten the stability of ecosystems. Understanding the prevalence and impact of rodenticides is crucial to inform conservation planning and policy.

In August, Owl Friendly Margaret River forwarded four frozen dead Masked Owls to Edith Cowan University for testing of their livers for rodenticides. The owls were provided by members of our community who collected them from roadsides this winter. The few Masked Owls that have been tested to date have shown high rodenticide levels, likely contributing to and in one case causing death. The cost is $140 per animal, paid for by community donations to our campaign. Nature Conservation Margaret River has added two Western Ringtails to the batch, representative of many showing symptoms of poisoning that have been brought in by community members. Our results back up national and international research on the terrible impacts of these poisons on owls and other wildlife.

Masked Owl photographed in Townview Terrace in central Margaret River in August. Sadly, rodenticide use in town may mean a cocktail of poisons in the mice and rats that have attracted this beautiful bird to live among us.
Photo Boyd Wykes.

The findings of Australian research published in a recent paper, Silent killers? The widespread exposure of predatory nocturnal birds to anticoagulant rodenticides are shocking. The researchers analysed liver samples from dead birds of four nocturnal predatory species – Powerful Owls, Tawny Frogmouths, Southern Boobooks and Barn Owls. Second Generation Anticoagulant Rodenticides (SGARs) were detected in every species and 92% of birds analysed. It’s not just birdlife at risk. Given that species that do not primarily eat rodents (Tawny Frogmouths, Powerful Owls) had comparable liver rodenticide concentrations to rodent predators (Southern Boobook, Eastern Barn Owl), it appears there is broader contamination of the food web than anticipated. They found rodenticide poisoning is ubiquitous across all landscapes sampled – forests, agricultural and urban – and concluded that this widespread human-driven contamination is a major threat to wildlife health.

The authors also highlight the need for more routine testing of animals for the presence of rodenticides. Prior to recent research, almost no public data was available on rodenticide poisoning of wildlife in Australia and the importance and potential scale of the issue were unknown. “There is a need for a national rodenticide stewardship program that includes surveillance in wildlife, similar to that instituted in the United Kingdom, and this could potentially be funded from a levy on product sales. Frameworks for ongoing testing would also allow for the evaluation of the impact of any policy changes around the regulation of SGAR use.”

Owl Friendly is working closely with Birdlife Australia and others to address control and sale of lethal SGARs. Meanwhile, please do your bit by opting for environmentally friendly rodent control and take every opportunity to raise awareness among your friends, neighbours and local businesses.