Rodenticides continue to affect Seattle’s wildlife

by Caroline Guzman

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In a recent study, 125 dead birds of prey, including owls, Cooper’s hawks, and red-tailed hawks, tested positive for rodenticides, according to the Latest Report from Urban Raptor Conservancy, an organization of ornithologists based in Seattle. However, many other species are still exposed to these substances and are not reported.

The harmful effects of anticoagulant rodenticides are well known. Although states like Massachusetts, California, and New Jersey have moved away from augmented reality to more humane pest control, Washington state is still legal.

This unresolved problem made an alliance between the Urban Raptor Conservancy (URC), PAWS Wildlife Center, Seattle Audubon, Raptors Are the Solution, Woodland Park Zoo’s Seattle Urban Carnivore Project, and others.

URC took the lead in opening a case study here in Washington State, and has been testing raptors for several years. Although the URC is still waiting for more lab results, Kersti Muul, an independent conservation scientist and urban wildlife first responder, said, “How much data do we need to make a change? Can we start doing something? Because 125 birds are like this.” Enough to get started.

Mole, who is also a science teacher at Seattle Audubon, tells the compelling story of an owl family she’s followed for more than a decade and who find that the mother died of rodenticides. Moll said, “She (my mom) passed away in 2019, and her chick from 2019 died in March 2022. So there are actually two of that family I knew very well. She didn’t have any external trauma. It looked like food had been stolen from her, because Her claws were bloody. So she was dissected and had three different types of poison. I knew she was feeding her children that poison and her partner. I was shocked about it, because she died for no reason.” It was this incident that led to Mole’s interest in the effects of rodenticides on other species, and led to her joining the coalition.

Many types of urban wild animals ingest poisoned mice, affecting their nervous system and cognitive skills, deteriorating their quality of life, and driving them to death. The toxins will also affect their offspring, either through feeding or by parents feeding poisoned mice directly to their young.

Some common signs of poisoning in wild animals include walking or flying off balance, shaking their heads frequently, an old wound not healing, and letting people close to them, which is very unusual.

One challenge with this ongoing study is that few labs can perform this type of test, and each sample costs about $100, according to URC . site. It is expensive and difficult to identify an animal affected by augmented reality before sending it to a laboratory.

Nikki Rosenhagen is a wildlife veterinarian at PAWS Wildlife Center. She has been collaborating on this project for the URC by hooking up live raptors and taking the dead to test for toxins. “There is no way that we can do an easy test on a live bird, because we have to take organ samples, and we won’t do that in live animals. So when we decide to proceed with treatment, we can only go on the basis of medical suspicions, clinical signs and history.” We have to wait until We have enough samples to ship, which can take months, and then we need to wait for the lab to run the test and send the information back.” Not only is this delaying valuable information, there isn’t enough funding to make this process more efficient or faster.

Another crucial point of discussion is the use of alternative measures to control mice. Some of the alternative solutions discussed are to overdose on vitamin D (by consuming cholecalciferol), and to bring to public attention the use of snap traps and even rodent birth control. “A cheap, easy, and effective alternative solution such as augmented reality does not currently exist,” Rosenhagen said. “We all have to believe in the idea that rodent control does not have to be inhumane, nor does it have to be fatal. Moreover, by choosing options that do not include poison, we eliminate the risk of inadvertently harming other animals.” The challenges of finding solutions to these problems are why these organizations are coming together.

Ed Deal monitors the birds of prey at URC, of ​​which he is vice president. The two toxins that act as substitutes for ARs are promethalin (a neurotoxin) and cholecalciferol (a vitamin D overdose), he says. These toxins don’t build up in the liver like AR does, Dale said, “but there’s no antidote for prothalene or cholecalciferol, so if your pet or child eats some of it, there’s no cure.”

For Rosengen, the use of vitamin D is “inhumane and extremely painful for those animals. Again, poison versus poison is not something I would ever recommend.”

Tanya Stephens is the Washington State Coordinator and Director of the Seattle Chapter of RATS. They have been working on a Experimental case study Finding positive results in rodent birth control. “Poison Free by 2023” is a pilot project in Upper Queen Anne that uses a rat birth control solution called ContraPest, and the pilot study has achieved a 91% reduction in the original rat population since its July 2021 publication.

The audience has the power to make a difference, too. The solution PAWS Wildlife Center has always provided is “exclusion”. According to Rosenhagen, “exclusion” entails removing shrubs near structures where mice feel comfortable hiding and limiting their food sources. I also mentioned other lethal options, like snap traps which are in theory instant and won’t transmit anything lethal to other animals.

On April 13, a pair of mountain lion cats died a few days after they were found with three different ARs in their livers, according to National Park Service officials. mentioned. Rodenticides affecting wildlife are not news. For years, many cases of the severity of these toxins have been recorded in our animals other than birds of prey. Fortunately, these organizations continue to work for the benefit of urban animals in Seattle, hoping that the public will shift gears to combating human pests.

Caroline Guzman He is an animal and wildlife photojournalist based in Seattle, Washington. They cover stories related to animal abuse, animal law, wildlife conservation, and more. Follow her on Instagram Tweet embed And on Twitter Tweet embedor contact her via email at

📸 Featured image is attributed to Romana Klee Under Creative Commons (CC BY-SA 2.0) license.

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