ARLINGTON — Wildlife biologists for the Stillaguamish Tribes are ringing alarm bells over commonly used rat poisons killing bald eagles across Snohomish County.
Since March 2024, the tribe and Washington Department of Fish and Wildlife have sent six eagle carcusses to Washington State University’s animal diagnostic lab. Of the six, five had signs of being poisoned by rodenticides, or rat poison.
Stillaguamish Tribe Wildlife Biologist Amanda Summers believes the poisonous chemicals found in the eagles trace back to rat bait boxes — ubiquitous black plastic containers often found outside malls, houses and apartment complexes.
These containers typically contain one of two types of rodenticides: anticoagulants or neurotoxin.
Anticoagulants destroys an organism’s blood clotting ability, meaning animals that ingest the chemicals either internally or externally bleed to death. Bromethalin is a commonly used rodenticide neurotoxin that disrupts the central nervous system, leading the organism that consumed it to become paralyzed and die.
Some cities have banned the use of most poisons to deal with rodents in all properties owned by the city. (File photo)
A majority of the poisoned eagles suffered from anticoagulants, Summers said, because the chemicals are often marketed as the safer option of pesticide.
“The animal is going to go into a bait box and then crawl away and die somewhere on the landscape. They’ll even continue to come back to the food source,” Summers said. “It can really build up a high concentration in the rodent, and then at that point, anything that would scavenge a rodent would be susceptible.”
Sometimes rodents don’t even need to be in the picture for the chemicals to disrupt a food chain. Earlier this month, a hunter in Monterey, California found a dead wild pig with electric-blue flesh. Investigations concluded pigs had gotten into rat bait boxes and consumed the poisonous pellets inside, ingesting an anticoagulant called diphacinone that sometimes dyes the insides of the animals that eat it.
While there has been no reports of blue-fleshed animals in Snohomish County, Summers said she is concerned about anticoagulants weaving their way through the local food web all the way up to apex predators like eagles.
“For the tribe, the eagles are important for ceremony and they’re also indicators of a healthy, functioning ecosystem,” she said. “When you have these instances back to back, it’s a little alarming.”
The Stillaguamish Tribe planned to bolster its efforts of collecting and identifying the cause of deaths of eagles found in Snohomish County and surrounding areas, but the funding was pulled back under the new federal administration, Summers said.
For now, when a dead eagle is found in the area, the tribe is figuring out what do on a case-to-case basis, deciding if circumstances warrant the funds to send the animal for testing. The tribe is also working on outreach to communities about the effects of using rodenticides for pest control.
“Sometimes this type of pest control is being sold as the latest and greatest and safe, and it doesn’t have a lot of non-target impacts. What we’re finding is that might not be true,” said Stillaguamish Tribe Wildlife Program Manager Jen Sevigny. “If the public were to understand the potential impacts to wildlife, they might make a better choice about how they’re going to be managing their rodent populations.”
Eliza Aronson: 425-339-3434; eliza.aronson@heraldnet.com; X: @ElizaAronson.
Eliza’s stories are supported by the Herald’s Environmental and Climate Reporting Fund.
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