Beneath a tree in the middle of Arlington’s Menotomy Rocks Park sits a potted plant sprouting red flowers, a solar-powered light, and a sign reading “IN LOVING MEMORY” and “YOU ARE MISSED.”
It’s a small memorial to the recent deaths of some beloved park figures: three great horned owls.
Two owls, an adult and child, were found dead May 31, Arlington Police Captain Richard Flynn said. Another owlet’s body was found shortly after.
“Everybody’s been out looking at the baby owls, wondering what they’ll look like, waiting to see if they take off from the nest,” said Chris Mooney, 72, a lifelong Arlington resident. “It’s brought a lot of enthusiasm and watchers, so I was really sad.”
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Flynn said the department did not test the owls’ bodies for toxins and cannot confirm what killed them. That, however, hasn’t stopped speculation among residents. Several passionate nature observers have identified a culprit on their own: rodenticide.
Rodenticide, more commonly known as rat poison, can cause second-generation anticoagulant rodenticide, or SGAR, poisoning. That occurs when animals ingest rats that have poison in their systems and are affected by the poison themselves.

Visitors have left flyers around the park depicting photos of the owls, and messages on chalkboards reading: “Rodenticide (rat poison) is killing. Wildlife can adapt as long as we don’t poison it.”
The messages come amid increasing awareness of rodenticides as a problem for wildlife. In 2020, Tufts Wildlife Clinic Director Maureen Murray found that 100 percent of red-tailed hawks tested at the clinic for rodenticide exposure from 2017 to 2019 were positive for some level of anticoagulant rodenticides.
Heidi Ricci, director of policy and advocacy at Mass Audubon, said the nonprofit has worked to educate the public on the dangers of rodenticide and promoted better sanitation, exclusion, and trapping as alternative methods to keep unwanted rodents away.
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A bill sponsored by State Representative Jim Hawkins, a Democrat from Attleboro, would require pesticide companies to disclose information about their products’ negative environmental effects and mandate that customers acknowledge the dangers of possessing such toxins, among other restrictions.
Arlington community members have also sought to reduce toxins in their area via local bylaws. The issue was discussed in a town meeting last month.
Jodi Sylvester, a Central Massachusetts resident who created the memorial, became invested in wildlife preservation after helping a baby eagle that died of poisoning last year in Arlington. That bird, which Sylvester described as “the most horrific, sad thing I have ever witnessed in my life,” was the second eagle to die from SGAR poisoning in 2021.
“The owls brought so much joy in our lives — with COVID and all these mass shootings, it brought together that community,” Sylvester said.
“I set up a memorial so the community would have a place to congregate, to talk about it, and there’s a note that says, ‘Please help fight our poison situation. Please save our wildlife.’ It’s not just a memorial, it’s a message.”
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Correction: A previous version of this story incorrectly described a 2020 study by Tufts Wildlife Clinic Director Maureen Murray. Murray found that 100 percent of red-tailed hawks tested at the clinic for rodenticide exposure from 2017 to 2019 were positive for some level of anticoagulant rodenticides.
Anjali Huynh was a Globe intern in 2022.Follow her on Twitter @anjalihuynh.