Common rat poison continues to disrupt wildlife health

Snowy Owl Rodenticide Poisoning
Posted at 9:36 AM, Feb 25, 2022

GLEN ELLYN, IL — Rats are undoubtedly a nuisance. During the pandemic, rat populations and infestations exploded in some areas. But killing them with poison has an unintended consequence on wildlife.

Captivating and majestic snowy owls migrate south from the Arctic each winter.

But on a recent voyage, this mesmerizing raptor became deathly ill by consuming a poisoned rodent.

“Eventually, with a high enough dose of whatever rodenticide they ingested, they would also bleed out internally,” said Darcy Stephenson, a staff veterinarian with the Willowbrook Wildlife Center, a high-capacity animal hospital and rehab facility that treats some 10,000 animals each year.

She says the more potent second-generation anticoagulant rodenticides, or SGARs, kill targeted animals by inhibiting blood clotting—something that gets passed on up the food chain.

“The point of those anticoagulants is to cause internal bleeding to the point that animal dies. So, it is the exact same set of clinical signs for any animal that then ingests those rodents that have previously ingested the rodenticides,” explained Stephenson.

The center is treating a red-tailed hawk for rodenticide toxicity and recently rehabilitated a poisoned bald eagle before releasing it back into the wild.

“It can affect everything from our raptor species that we're talking about today to creatures like coyotes and other mammals that tend to scavenge on small rodent species,” said Stephenson.

These second-generation anticoagulant rodenticides that were developed in the 1970s as one-shot killers are so dangerous to humans and wildlife that they’re no longer EPA-registered for sale to consumers and only registered for commercial pest control market. Yet, they remain widely available.

“Second-generation anticoagulant rodenticides are really the worst of the worst on the market,” said Jonathan Evans, senior attorney and environmental health legal director at the Center for Biological Diversity.

Evans says in 2020, more than 2,600 children in the U.S. were also poisoned by anticoagulant rodenticides.

“Most people don't realize that when they have a rodent problem and go to the store to buy rat poison or call an exterminator that it can have a devastating effect on wildlife and even their own family,” said Evans.

Amid the COVID-19 crisis, demand for anticoagulant rodenticides is on the rise. Its global market is projected to grow from $5 billion in 2020 to $7.1 billion by 2026, with the United States accounting for more than 34% of sales.

“The Environmental Protection Agency found super-toxic rat poison in 44 different non-target species throughout the United States,” said Evans.

Evans says the unintended consequence of rat poisons are that they disrupt the natural order.

“Barn owls can eat up to five mice per day,” he said. “So, when you're feeding these mice that are your problem, these poisons end up killing the solution, killing a lot of the wildlife that actually can help control rodent populations.”

Over the course of several weeks, veterinarians here will treat these poisoned animals with vitamin K, which helps restore their blood’s ability to clot.

Periodic blood draws will help them determine when this snowy owl is healthy enough to be released back into the wild.

“We've got a lot of domestic pets coming in with rodenticide toxicity that they're going to die off just as quickly as are our wild friends that we see here are,” said Stephenson.

Wildlife experts say more must be done to protect animals, especially endangered species from these chemicals.

“If you absolutely can't find a natural product that works, try to find something more humane, like quick kill traps as opposed to baiting stations.”