On March 3, upwards of 300 Arlington, Massachusetts residents took to the streets to mourn the death of a beloved member of the local ecosystem: a bald eagle named MK, who died after ingesting rat poison. MK, who was born in Waltham and is the protagonist of a children’s book, is only the latest fatality in a slew of rat-poison-related predator deaths. And as Waltham’s rat population continues to grow alongside the 65,000 person community, debate has ensued on how to control growing rodent numbers while also prioritizing the health of local ecosystems. 

In 2018, the Waltham Board of Health declared the rat population in the area to be a public health emergency. And on Feb. 6 of this year, Ward 8 Councilor Cathyann Harris brought a resolution before the city’s Economic and Community Development Committee on the issue. “I’ve been receiving … an influx of pictures of dead rats on snowbanks, on playgrounds, near the [Charles] River in Ward 8,” she said. 

Waltham’s 8th Ward is located in the city’s South Side. The South Side is home to many Brandeis students and is where the rat problem is the greatest, according to Assistant Director of Public Health for the Waltham Health Department Thomas Creonte, who spoke at the Feb. 6 meeting. Creonte suggested that the large number of food establishments on Moody Street caused the higher concentration of rats in the area. However, he explained, there are rats all over the city. The Health Department gets about 20 calls a week reporting rats, dispersed throughout different neighborhoods. 

At the same meeting, Councilor Harris posed ContraPest as a method for controlling the city’s rat population. One male and one female rat produce 15,000 offspring per year. ContraPest renders them sterile after ingestion. Creonte said that as of Feb. 6, the Health Department had not been allocated the necessary budget to use ContraPest. Harris requested that Creonte look into ContraPest as part of a “multi-pronged approach” that includes rodenticides.

Currently, according to Creonte, the city primarily uses two methods to control the rat population: rodenticide, also known as rat poison, and snap traps. The traps are more expensive because they only kill two rats at a time, and the traps have to be cleared of the rats every week. Rodenticide can kill up to 20 rats per dose, and dead rats are picked up by the Health Department when a report is made. The city places snap traps in parks, playgrounds, and school areas, where they don’t want dead rats on the premises, according to Creonte, but uses rodenticide elsewhere. Creonte explained in the Feb. 6 meeting that the Health Department plans to continue using rodenticide.

“It’s the trash,” Creonte said to the Committee on Feb. 6. He explained that if people placed their trash in bins rather than left them out in bags, the rats wouldn’t have food to eat. The city does have an ordinance requiring people to place their trash in airtight bins with lids. Residents aren’t held to this, though, as their trash is picked up regardless of whether it’s in a bin or not, Creonte said. 

Rodenticides are anticoagulants, which means they prevent blood from clotting and leads to internal bleeding until the rodent dies. It’s a slow death; it can take up to 10 days for a rodent to die after ingesting the poison. The method is considered inhumane according to the Royal Society for the Prevention of Cruelty to Animals. Conversely, snap traps deliver a rapid, heavy blow to the rodents’ heads and kill them instantly. 

But it’s not only rats that have been killed. The poison also kills the local ecosystem’s natural predators, such as hawks, owls, and foxes, who prey on and ingest the poisoned and dying rats. In June 2022, a great horned owl and her owletsfederally protected under the U.S. Migratory Bird Treaty Act — died in Arlington after consuming a poisoned rat.

During the Feb. 6 meeting, City Councilor Jonathan Paz, who recently announced his campaign to run for mayor of Waltham, raised a concern about this method’s impact on the local food chain. “I witnessed a dead owl on the path by the Charles River and have gotten pictures of dead cats,” he said. 

According to the Boston Herald, March 2021 was the first time in Massachusetts’ recorded wildlife history that a bald eagle died from ingesting rat poison. In July 2021, another eagle, named C25, died. 

On the night of Feb. 28, C25’s mom, known as MK, died the same way, according to the New England Wildlife Center. MK was born to parents “Ozzie” and “Harriet,” who used to reside in the trees of Waltham’s Mt. Feake Cemetery, according to Diane Gaskill, a Waltham resident who monitors eagles for MassWildlife. 

MK flew the nest in 2016, and nested with her mate, “KZ,” on the Mystic Lakes — the first occurrence of a bald eagle nest there since the population was decimated by the use of DDT, an insecticide that caused eggshell thinning and other reproductive issues in birds. DDT was banned in the 1970s, and the bald eagle was designated an endangered species from 1978 to 2007 by the federal government. MK and KZ were cited as a sign of hope — a living example of the bald eagle population’s rebound. 

MK was beloved by the local community. “She was funny. At Mt. Feake she used to take the flowers off headstones,” Gaskill told the Justice during a March 10 phone interview. Gaskill and her husband Bob have monitored eagles for MassWildlife for over seven years. 


MK THE EAGLE: MK was a beloved community figure, born in Waltham.

On Feb. 27, MK was found by passerby lying on the ground in Arlington’s Mt. Pleasant Cemetery. She was then brought to the New England Wildlife Center hospital in Barnstable. The Wildlife Center posted on Feb. 27 that they strongly suspected MK had been poisoned due to her “delayed blood clotting time.” The Wildlife Center began treatment to counteract the blood thinning, and MK made it through the night with staff monitoring her. 

On March 1, she began “spontaneously hemorrhag[ing] and began bleeding internally,” a March 1 Facebook post by the Wildlife Center said. “With the poison in her system she did not have the ability to clot and the bleeding … began to occlude her airway … she was gone in a matter of minutes,” they wrote. “Her presence inspired [people] to connect with our natural environments and the wildlife in them,” the Wildlife Center said in the announcement. The Wildlife Center also called for the restricting of anticoagulant rodent poisons: “Rodent control does not need to come at the expense of our natural heritage and ecosystem.” 

Phil Moser, the head of the Waltham Conservation Commission, described in a March 19 correspondence with the Justice that he shared a statement addressing concerns about rodenticide that was expressed at their March 2 Commission meeting: “Anticoagulant rat poison is a well-documented, frequent cause of death for hawks, owls, foxes, and other predators … The predator mortality caused by ingestion of poisoned rats reduces the ability of ecosystems to naturally control rodent populations.” 

Bald eagles mitigate rat populations by eating them and using rodenticides eliminates a natural source of rat control. 

 Beyond Waltham, there have been some legislative pushes to limit the use of rodenticides in Massachusetts. In February of this year, Representative James K. Hawkins and State Sen. Paul R. Feeney put forth HD. 577 and SD. 1144 in the Massachusetts Legislature, bills that would mandate reporting of public use of anticoagulant rodenticides and encourage non-toxic alternatives. 

The bill would be welcome to mourning community members, such as Gaskill. “We watched them [the eagles] for seven years,” she said to the Justice as she stood in Mt. Feake cemetery and wiped away tears. “They were like our family.”