11/08/2026
(This is long but important.) There are a new series of rodenticides on the market that are wrecking havoc in wild predators, cats and dogs. In an article in Birdwatchers Digest July/August issue, Dr Robert Giddings called these new rodenticides “the new DDT”. We are talking here about Second Generation Anticoagulant Rodenticides, commonly called “SGARs” for short. The First Generation Anticoagulant Rodenticides (“FGARs” usually associated with D-Con) used the slow acting ingredient Warfarin. Warfarin took several doses to become lethally toxic to either the rodent or to it’s predator, but it worked by thinning out the blood so the ingestor basically blead to death internally. It worked by shutting down the body’s ability to process vitamin K, so the antidote was to treat the patient with injectable vitamin K. The first generation rodenticides were developed in the 1940s and became widely used. Wildlife rehabilitators and veterinarians learned to keep a stock of injectable vitamin K on the shelf. If there was a low level of repeated exposure to poisoned bait, rodents and/or the predators that preyed on them developed resistance to it. This made the poison not reliable and became less popular.
The new SGARs are able to kill with 1 ingestion, but it can take up to 2 - 5 days to take effect. The rodent or other grain eating animal (birds! and more) wanders away from the bait source (allowing others to think the bait is safe) but is more and more dehabilitated as the internal bleeding begins, thus making them easy prey for other predators and scavengers. I mention scavengers here because the SGARs do not break down in the body as it decays, and thus are transmitted in full dose into whatever animal or bird is consuming the poisoned rodent, etc. There is no antidote. The only thing that can be done is to medically induce vomiting if the issue has been discovered quickly enough. Often with wildlife there is too long a delay. Non-target species that come in contact with the poison include (but not limited to) birds of all kinds including bald eagles and other raptors, possums, skunks, bear, raccoons, bobcats, skinks, deer, carrion beetles, snakes, some lizards, frogs, dogs, cats and pigs. The SGARs we are talking about are bridifacoum, bromdiolone, difenacoum, and difethialone. They are exclusively only used by licenced pest control companies and are usually seen in a black, tamper-proof boxes. Please note: the placement of poisoned bait outdoors is federally illegal. If you see these boxes outdoors, contact the property owner or the company immediately. The symptoms of SGARs poisoning include lethargy, bleeding gums and cuts that take too long to heal.
What can you do instead of using poisoned bait? We strongly advocate for not using poisons ANYWHERE, including on your home, lawn or those purple insect-killing bug zappers (they primarily kill pollinators). If you have a rodent problem, use baited snap traps, or electric traps. NEVER use glue traps - they are inhumane in the extreme. Eliminate the source of supply if you can: use metal trash cans to enclose grain or seeds or suet, for example. Close their access! See if you can find a hole (or many) where they can squeeze in. If they can get their head through, the rest of the body can follow. We advocate for using rough steel wool stuffed into the hole with spray insulation foam to lock it into place. They hate to get the steel wool into their teeth!
Poisons are non-specific in their ability to kill. Please help us spread the word. New Hampshire Audubon Society has an excellent, easy to print brochure on the issue and lots of information on their website: https://nhaudubon.org/policy/rodenticides/
New Hampshire Audubon
