Snowy owls are among the most iconic birds visiting Massachusetts during winter. Known for their striking white feathers and piercing yellow eyes, these majestic creatures can travel thousands of miles in a season in search of habitats with enough food to sustain them before returning to their breeding sites in the high Arctic. However, an often-overlooked danger threatens their survival: rat poisons.
A team of wildlife veterinarians affiliated with Project SNOWstorm has been collecting data on the health of these Arctic wanderers to provide scientific insights that will inform future conservation efforts. The importance of this data became especially critical in 2021 when the US Fish & Wildlife Service listed the snowy owl among several species representing significant conservation priorities beyond those already listed under the federal Endangered Species Act.
The Project SNOWstorm team is finalizing its data and preparing it for publication in a peer-reviewed journal. However, it released preliminary findings in a blog post on the organization’s website earlier this year. The excerpt below summarizes those findings:
In our analyses, 44 birds (22 percent) were over that 0.03 ppm threshold. Ninety-three percent of them had signs of internal hemorrhaging and bleeding. While there are other common causes of hemorrhage in snowy owls, such as vehicle strikes, many of these birds showed no other signs of injuries, such as wounds or fractures. And even for the birds that suffered obvious trauma, it is possible that anticoagulant poisoning, which reduces the blood’s ability to clot, made them more vulnerable to injuries in the first place.
Perhaps most alarming, our preliminary results seem to indicate an upward trend in snowy owls’ level of exposure. While the number of tested birds over the threshold was near zero about 10 years ago, by 2022, 56 percent of those tested were over the suggested threshold of toxicity — far above the 22 percent average for the entire 10-year period.
Ironically, our necropsy data also show that many snowy owls had rodents in their stomachs when they died, including the invasive Norway rat. Therefore, they might have been killed just as they were offering us an invaluable ecosystem service by getting rid of the very rodents the poisoned baits were set for.
Although these are preliminary findings, the takeaway is clear: more rat poisons are appearing in our environment and jeopardizing the health of our wildlife and natural systems, with implications for ecosystems far beyond our town’s borders. Folks on the South Shore eagerly await the potential return of Snowy owls every November and make some pretty sizable journeys themselves in the hope of catching even a glimpse of these charismatic birds. Accordingly, we must do everything we reasonably can to remove potential threats to the health of our Arctic visitors.
As I wrote in April, no data or peer-reviewed study supports the claim that these chemicals protect public health better than non-toxic alternatives outlined in the state’s Integrated Pest Management toolkit and other resources compiled by conservation organizations like Mass Audubon. Continuing to deploy a chemical agent that adversely affects our wildlife and natural systems with no verifiable public health benefit is not the right choice for Plymouth.
One of the action items with the town’s Climate Action and Adaptation Plan recognizes this issue and urges town leaders to “[i]mplement an Integrated pest management program that restricts the use of pesticides and fertilizers on municipal land.” Adopting this action item would further protect those species, like snowy owls, threatened by rodenticides and avian flu. Since prolonged exposure to rodenticides has been shown to compromise animal immune function, they are more susceptible to communicable diseases. The Project SNOWstorm reported several cases of snowies suffering from and succumbing to avian flu in upstate New York.
We should encourage town employees and elected officials to proactively execute this action item to preserve the health of our local ecosystems and enhance the town’s resilience for future generations.
– Will Fitzgerald
Fitzgerald is a member of Plymouth’s Climate Action/Net Zero Committee and founded Rescue Plymouth Wildlife, a project of Mission.EARTH.