In humanity’s war against rats, other animals are often collateral.
The U.S. Environmental Protection Agency released its final biological evaluation on rodenticides on Nov. 22 and found that the rat poisons are jeopardizing at least 78 endangered species such as black-footed ferrets and California condors.
The analysis adds to a growing body of research finding that the toxic ingredients in rodenticides frequently work their way up and down the ecological food chain—from iconic bald eagles and massive black bears to insects. If ingested at high doses, rat poison can cause internal bleeding, lesions, lethargy, weakened immune systems and, often, death.
Wildlife and health advocates are encouraged by the recent EPA evaluation, which could eventually inform federal decisions to limit certain rodenticides. But pushback from the pesticide industry and deregulatory fervor from the incoming Trump administration could stall this process. Delays could pose widespread risks for wildlife populations as rat poison use increases and climate change throws predator-prey interactions out of whack, experts say.
Island Rats and Cats: Kiawah Island in South Carolina is famed for its posh golf courses, pristine beaches and lush forests. It’s also gained a unique reputation as one of the country’s strongholds for bobcats, furry felines about twice the size of the average house cat.
“They are kind of like a regionally famous little population,” Meghan Keating, a researcher and doctoral candidate studying rodenticides and wildlife at Clemson University, told me. “Everybody in Charleston knows that Kiawah has bobcats.”
But in 2019 and 2020, three of these iconic wildcats met a grisly demise. Autopsies revealed that the animals had ingested second-generation anticoagulant rodenticides—the strongest and most long-lasting poisons that kill rats by inhibiting the body’s ability to clot blood. With this in their systems, two of the cats bled out while giving birth to kittens, which either died in utero or were stillborn. The male’s death was equally gruesome: “He basically was sick, wandering around in the middle of the day and just keeled over in the middle of a park, because he just had massive hemorrhaging throughout his entire body cavity,” Keating said. “His capillaries burst.”
These were the latest in a string of deaths through 2020. Though the species is not endangered nationally, the bobcat population in this area dropped from an estimated 30 to as few as 10 individuals in less than a decade. But bobcats are far from the only animals facing this toxic threat. In recent years, researchers and veterinarians have identified a wide array of species across the animal kingdom falling victim to rodenticides.
Exposure is particularly prevalent among raptors like hawks and falcons, which directly prey upon rats. The rodenticide that kills predators can then go on to kill the predators that eat them. For example, a rat that has ingested rodenticide may be devoured by a fox, which is then eaten by a cougar. Keating co-authored a recent paper detailing the far reaches of rodenticide among wild mammalian carnivores around the world.
“Animal celebrities” exposed to rodenticide have thrown a brighter spotlight on the issue, including the late California mountain lion P-22. Last year, the beloved Eurasian eagle owl Flaco flew freely above the New York City streets before dying after slamming into a window, which experts say may have been linked to the four rodenticides in his system that could have disoriented or weakened him.
Rat Poison Regulation: The EPA evaluation released in November analyzed the registered uses of 11 active ingredients in rodenticides on the market such as brodifacoum, bromadiolone, difethialone and difenacoum. The agency also recommended several strategies to reduce unintended wildlife poisonings, including product labeling updates to reflect restricted use of where, when and how the rodenticides should be administered. In the past, EPA has also recommended that second-generation anticoagulants be applied only by trained professionals.
“EPA is recognizing these products [that] are on the market right now—because we don’t have mitigations in place—are pushing species towards extinction,” Jonathan Evans, the environmental health legal director and a senior attorney at the nonprofit Center for Biological Diversity, told me. The organization works to conserve wildlife through science, law and advocacy.
The new EPA information now triggers a similar review process from the U.S. Fish and Wildlife Service, one of the agencies responsible for enforcing the Endangered Species Act—a law established to prevent at-risk species from going extinct. If the FWS finds severe enough rodenticide threats on endangered species, it could recommend nationwide limits on certain rat poisons or restrictions on application methods.
“This is kind of just a step in the process, but it’s a step in the process that’s necessary for Endangered Species Act compliance,” Evans said. “It’s really important that EPA implements the steps that it’s proposing through label changes, because it then leaves the pesticide makers more liable.”
However, this process could take several years, particularly if the Trump administration derails endangered species policies, Evans said.
Some states are moving ahead with rat poison regulation to protect wildlife. In 2014, California enacted its first restrictions on second-generation rat poisons. The state has since imposed stricter rules, only allowing this type of rodenticide in certain settings such as agricultural areas and to address public health emergencies like outbreaks of rodent-borne diseases, Science reports.
In South Carolina’s Kiawah Island, a group of residents launched a “Bobcat Guardian Program” in 2020 to educate the community on rodenticide threats, and many locals pledged to stop using the poisons, Sierra Magazine reports. However, recent testing shows that rodenticide exposure on the island is on the rise again, Keating said.
Without intervention, the issue could soon get worse. A recent market analysis report shows that anticoagulant rat poison use is expected to rise by 2030 to respond to growing rat populations. Climate change could complicate matters in several ways (including potentially triggering an explosion of rat populations deemed the “ratpocalypse,” though the jury is still out on this, Grist reports). Research shows that warming temperatures are forcing wildlife into new areas, often closer to humans and rats. And in some cases, predators may have to alter their diets in response to declining food sources, which means that rats could soon have a bigger spot on the menu for carnivores like lynx.
“That could increase their potential to [rodenticide] exposure too,” Keating said. “There’s all kinds of interactions that climate change can play on rodenticides and wildlife.”
More Top Climate News
On Wednesday, a town in North Carolina filed a lawsuit against Duke Energy, one of the country’s top utility companies, for its rampant greenhouse emissions and failing to inform the public about its climate-warming impacts, Ivan Penn and Karen Zraick report for The New York Times. The town of Carrboro argues that Duke Energy is costing residents, particularly those from marginalized communities, millions of dollars from climate-fueled extreme weather events. This is part of a growing movement from local governments and groups of impacted individuals trying to use the legal system to hold companies accountable for their climate change contributions. My colleague Kiley Bense covered one of these cases in Pennsylvania earlier this year.
With Donald Trump’s inauguration day looming, environmentalists stress that President Joe Biden is running out of time to implement the conservation measures he pledged to during his campaign, Jeva Lange reports for Heatmap News. That includes confirming designations of national monuments in California, Oregon and Maine.
“There are still several national monument campaigns that are ready to go and awaiting the president’s signature, and those are the sorts of things that could cement President Biden’s legacy as one of the great conservation presidents of all time—if he takes those steps here in the last few weeks,” Aaron Weiss, deputy director of the Center for Western Priorities, a nonpartisan conservation advocacy group, told Heatmap.
Meanwhile, a new report found that the U.S. is making and installing more solar panels than ever before and that the industry is poised to keep growing, even as Trump enters office. This widespread rollout is largely due to financial incentives distributed under the Inflation Reduction Act, Eric Wesoff reports for Canary Media. Produced by the Solar Energy Industries Association and energy analysis firm Wood Mackenzie, the report projects that the country will deploy 40.5 gigawatts of solar power this year—enough to power more than 30 million homes.
A new global analysis finds that overfishing has halved shark and ray populations since 1970. The loss of these top predators could have profound impacts on the health of marine ecosystems and coastal economies, according to the report. Sharks also face risks from climate-fueled marine heatwaves and cold snaps, which I wrote about in July.
Yesterday, a 7.0 magnitude earthquake hit Northern California, triggering a brief tsunami warning for more than 5.3 million people in the region, Olga Rodriguez and Stefanie Dazio report for The Associated Press. Alerts read: “A series of powerful waves and strong currents may impact coasts near you. You are in danger. Get away from coastal waters. Move to high ground or inland now. Keep away from the coast until local officials say it is safe to return.”
There were no immediate reports of severe injuries from the earthquake, but buildings were shaken up, with products flying off shelves and people seeking shelter under tables.
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Kiley Price is a reporter at Inside Climate News, with a particular interest in wildlife, ocean health, food systems and climate change. She writes ICN’s “Today’s Climate” newsletter, which covers the most pressing environmental news each week.
She earned her master’s degree in science journalism at New York University, and her bachelor’s degree in biology at Wake Forest University. Her work has appeared in National Geographic, Time, Scientific American and more. She is a former Pulitzer Reporting Fellow, during which she spent a month in Thailand covering the intersection between Buddhism and the country’s environmental movement.