You are probably familiar with Flaco, the Eurasian Eagle-Owl that escaped Central Park Zoo. Flaco survived for the past year in New York City’s upper west side until it recently succumbed to acute trauma and is being tested for secondary rodenticide toxicity. We write to you today to draw attention to the same threat owls face in our own backyards: secondary rodenticide exposure, which is where a predator consumes prey that has ingested rodenticide, is leading to the deaths of our native Great Horned Owls.

You might be surprised that these apex predators commonly breed in small woodlots in residential and industrial-zoned land throughout Durham Region. Residents like us monitor these owls to track their behaviour and breeding success each year.

We’ve documented many of these Great Horned Owls succumbing to deaths we suspect are related to rodenticide toxicity. This January, we submitted a deceased female to the Canadian Wildlife Health Cooperative (CWHC) for analysis. It tested positive for multiple rodenticides, and the cause of death was anticoagulant rodenticide poisoning. Anticoagulant rodenticides are readily found in the tissues of Ontario raptors tested by CWHC, with the highest proportion of positive samples detected in Great Horned Owls. The odds of Great Horned Owls testing positive for anticoagulant rodenticides are 10 times greater compared to other raptor species tested.   

Why are Great Horned Owls susceptible?  Likely, it is because of their size; if they are hunting predominantly mice and rats, they will eat up to 3-4 daily to meet their caloric needs. Owl species may also have greater sensitivity to these rodenticides through pharmacokinetic mechanisms.

Pest management companies claim that rodenticides used in bait stations are effective, necessary and responsible.  However, if rodents are still a prevalent problem today, how can we reasonably say these rodenticides are the solution?  And how many non-target species deaths are acceptable as the cost of using them?

The City of Pickering passed an Animal Poisoning Prevention Policy in June 2023. This policy includes a ban on the use of rodenticides on Municipal properties and a communications strategy for educating residents and businesses on the harmful impacts of rodenticides and the availability of humane, ecologically sustainable alternatives.

Our goals with this petition are twofold. First, to raise awareness of the damaging effect these toxic compounds have when introduced into the environment, particularly on our Great Horned Owls. Second, to ask the Region of Durham to enact a region-wide policy similar to Pickering’s Animal Poisoning Policy.

This is a great opportunity for Durham Region to be leaders in sustainability and responsible pest management practices. Taking a stand for our local biodiversity at a time when it is so relevant could encourage other Regions and Counties to follow suit. Please help us protect our resident Great Horned Owls.