Information about SGARs
Town of Groton Massachusetts Conservation Commission
Last updated 24 Sep 2025
This document explains what SGARs are, what problems they cause, and what you as a homeowner in Groton can do about it.
What are SGARs?
SGARs are Second Generation Anticoagulant Rodenticides. Rodenticide means a poison intended to kill rodents. As “second generation” implies, these are relatively new. Anticoagulant refers to how this particular type of poison works. Without going into medical details, these poisons cause the rodent to bleed to death internally.
To put it in really basic terms SGARs are a “new” type of rat-poison. These poisons first became available around 1980. The original first generation anti-coagulant rodenticides (ARs) became available in the early 1950s.
These newer second generation ARs distinguish themselves from the original first generation ARs (FGARs) in predominantly two ways:
- More potent. It takes less poison to eventually kill the same rodent.
- Longer lasting. SGARs are concentrated in the liver, but are not broken down as readily. This does not help kill the rodent, but it does make the dead rodent more toxic to predators and scavengers.
What’s the problem?
Anticoagulent rodenticides kill the rodent slowly. It can take 3-5 days. During that time, the rodent may eat more of the bait, gathering more of the poison in its body even though it has already ingested a lethal dose.
Despite the poison being ingested in your house, the rodent has time to wander outside. Since the poison is making them sick, they aren’t so good at hiding and evading predators anymore. A rat dosed with SGAR is more likely to be spotted by a predator, and the predator is more likely to catch the affected rat than a healthy one.
Unfortuately, SGARs aren’t just poisonous to rodents. They are equally poisonous to the predators and scavengers that eat the rodents. While the original intent may have been to kill mice or rats, the result can be dead owls, eagles, hawks, foxes, coyotes, bobcats, and neighborhood cats and dogs.
What can I do?
Don’t use SGARs. There are other ways to handle mouse or rat problems, such as mechanical traps. These usually kill the rodent instantly, and cause no cascading effect on the ecosystem and the neighborhood pets and wildlife.
SGARs are not allowed to be sold in stores to the general public anymore, but pest control companies can still use them. If you hire a pest control company, please make sure that they are not using SGARs.
More information
How to Spoil an Owl’s Dinner
Article in Nov 2014 issue of Massachusetts Wildlife with great background on rodenticides, FGARs versus SGARs, how they work, history of rodenticide use and its regulation, and the slow realization since the early 2000s that rodenticides are killing wildlife.
Mass Wildlife web page
This page discusses problems with rodenticides, their alternatives, and provides technical and regulatory information on SGARs.
US EPA web page
Links to a variety of information including about rodents, how to deal with them, and how rodenticides are regulated.
Rodenticide effects on immune systems of bobcats
October 2017 article by the US National Park Service about attempts to understand why bobcats in the Santa Monica mountain of California were dying from mange, when this disease rarely killed cats in the past. A strong link to SGARs was found.
“Overall, the implication is that bobcats exposed to rodenticides have dysfunctional immune systems that may not be able to muster a targeted response to a disease like mange.”
Rodenticides and red-tailed hawks
September 2020 study by Tufts University Wildlife Clinic that measured levels of rodenticide in dead red-tailed hawks.
“One hundred percent of the red-tailed hawks in the present study tested positive for exposure to anticoagulant rodenticides”
Anticoagulant rodenticide in Eagles
This paper from April 2021 examined dead bald and golden eagles. 83% of the bald eagles, and 77% of the golden eagles had AR in their systems, and 4% of the eagles were found to have died from AR poisoning.
