Conservation biologist testifies SGAR rodenticides are killing local wildlife, urges wider restrictions

Laura Kiesel, a conservation biologist and environmental writer, testified to state representatives that second‑generation anticoagulant rodenticides (SGARs) are causing widespread wildlife harm in the Boston Metro region and urged broader restrictions beyond municipal public‑lands bans.

Kiesel said SGARs "killed the first bald eagle to hatch in my town" in 2021 and recounted the loss of additional raptors and other species. She told lawmakers her nonprofit, Save Mass Wildlife, funded liver testing of 40 dead animals collected in 2024–2025; she said "virtually all" showed anticoagulant exposure and that most tested in a lethal range.

The testimony summarized local and scientific evidence on how anticoagulant rodenticides act in ecosystems. Kiesel described how these compounds bioaccumulate and biomagnify up food chains, causing predators to ingest poisoned rodents and suffer internal hemorrhage. She cited Tufts Wildlife Clinic research, saying a 2017 necropsy series found a 96% exposure rate among dead raptors tested and later work in red‑tailed hawks showed a 100% exposure rate among sampled dead birds.

Kiesel described species in her dataset that were affected, including red‑tailed hawks, barred owls, Cooper's hawks, great horned owls, eastern screech owls, a rare gray fox, coyotes and coyotes pups, a great blue heron and a snapping turtle; she noted that the heron and snapping turtle were the first fatalities of their kinds correlated to these poisons in her sample. She also described impacts to pets and the costs of veterinary care, citing an example of a dog that survived after about $6,000 in treatment.

On policy responses, Kiesel said Arlington, Massachusetts adopted a public‑lands ban on anticoagulant rodenticides and that roughly 40 other Massachusetts municipalities have enacted similar public‑lands restrictions. She said about 15 municipalities, including Arlington, have pending state legislation seeking permission to ban these products on private property, which municipal authorities cannot do without state authorization.

Kiesel described a legal petition in Massachusetts supported by pro bono counsel from Harvard seeking suspension of SGAR registrations. She also quoted a rodent‑control expert she interviewed, saying Bobby Corrigan called SGARs "the DDT of our generation."

During questions from state representatives, Kiesel explained exposure pathways for songbirds (direct ingestion of bait, insects that consumed bait, and scavenging of poisoned carrion), and outlined alternatives and mitigation strategies used in California where moratoria have been implemented in many sectors. She said exemptions (notably agriculture) exist in some moratoria, and listed non‑chemical approaches being piloted or expanded: sanitation and exclusion improvements, smart boxes (high‑capacity electronic traps), fertility‑control baits, and nest boxes/perches to encourage avian predators.

Kiesel cautioned that fertility control generally reduces reproduction rates over time and has a short metabolic half‑life, while anticoagulant rodenticides store in liver and fatty tissue for months, making them persistent risks for predators. She urged lawmakers to consider the food‑web consequences of continued SGAR use and pointed to local monitoring and necropsy data as evidence of harm.

The session ended with no formal vote recorded in the transcript; the moderator said slides and supplemental materials would be posted on committee websites. Kiesel said she was available for follow‑up questions and provided supporting data and sources to the panel.