State officials on Sunday confirmed that a bald eagle that died in March in Middlesex County had succumbed to poisoning, after the bird ingested a toxic substance meant to kill vermin, the first time such a fatality has been reported in Massachusetts. The state MassWildlife agency provided the information in a statement.
“MassWildlife officials recently confirmed that a bald eagle that died in March was the victim of second-generation anticoagulant rodenticide (SGAR) poisoning,” the statement said. “While mortalities in bald eagles due to anticoagulant rodenticides have been documented in other states, this is the first confirmed case in Massachusetts.”
According to the statement, observers in mid-March saw the eagle acting strangely at a nest located along the Charles River. “Unfortunately, within a day, the bird had died on its nest,” the statement said. “MassWildlife officials retrieved the eagle and transported it to Tufts Wildlife Clinic at Cummings Veterinary Medical Center at Tufts University where a necropsy was performed. Toxicology testing of a liver sample was performed with the assistance of the Northeast Wildlife Disease Cooperative.”
Both the necropsy and tox screening confirmed the cause of death was “lethal levels of anticoagulant rodenticides,” the statement said.
Such rodenticides, officials said, kill vermin by preventing blood from clotting normally, which leads to a fatal hemorrhage. Wildlife can be poisoned by rodenticides either by directly eating the bait, or by consuming prey that’s ingested it, according to the statement.
“Given the hunting range of eagles, it’s impossible to determine the exact source of this rodenticide poisoning,” the statement said. “Analysis of liver tissue confirmed three different SGARs were ingested by the eagle. In the past 15 years, the US EPA has taken steps to impose restrictions on rodenticides.”
Dr. Maureen Murray, director of the Tufts Wildlife Clinic, said in the statement that birds of prey often go unrecognized in the struggle to control mice and rats.
“Many people are surprised to learn that the mouse poison they use in their basement can also kill the great horned owl hooting in the neighborhood,” Murray said.
According to the statement, second-generation anticoagulant rodenticide, or SGARs, can’t be sold through general consumer outlets for typical homeowner use.
They can, however, still be bought online in commercial use quantities, and licensed pest professionals and agricultural users are allowed to utilize them. Other rodenticides, called first-generation anticoagulant rodenticides, or FGARs, as well as non-anticoagulant rodenticides, remain approved for residential consumer use if they’re enclosed in a bait station, the statement said.