Pesticides deadly to prairie dogs also threaten imperiled animals

Defenders of Wildlife and Audubon of Kansas sue to prevent secondary poisoning of wildlife like the endangered black-footed ferrets, bald and golden eagles, and ferruginous hawks

(09/23/2009) -


  • Defenders of Wildlife and Audubon of Kansas filed a lawsuit in US District Court against the EPA for approving pesticides Rozol and Kaput-D for use on prairie dogs, the main food source for endangered black-footed ferrets, in violation of numerous federal laws without consulting with the U.S. Fish and Wildlife Service.
  • The blood-thinning chemicals can last for weeks in prairie dogs -- also poisoning endangered black-footed ferrets and protected birds, such as bald eagles and the ferruginous hawk.

WASHINGTON (Sept. 23, 2009) — Pesticides used to kill prairie dogs are the target of a lawsuit against the Environmental Protection Agency, which has approved two deadly chemicals, chlorophacinone (Rozol) and diphacinone (Kaput-D), for use in as many as 10 states.

Defenders of Wildlife and Audubon of Kansas are seeking stronger protections today for federally protected animals that feed on poisoned prairie dogs. In addition to black-footed ferrets, many birds and raptors, including burrowing owls, bald and golden eagles, Swainson’s hawks, ferruginous hawks and turkey vultures, are at risk from use of these chemicals.  

Rozol and Kaput-D contain blood-thinning drugs that cause poisoned prairie dogs to slowly bleed to death through “various orifices, including eventually the skin membranes,” the Fish and Wildlife Service stated in a letter to the EPA earlier this month.  

The poisons can take weeks to finish off an infected prairie dog, during which time the hamster-like mammal languishes, becoming disoriented and slowly loses bodily function – making it easy prey. Because the chemicals can linger in a prairie dog’s carcass for weeks, animals and birds that feed on dead or infected rodents or live in contaminated burrows can also inadvertently become poisoned.  

“These chemicals are nasty stuff,” said Jason Rylander, an attorney with the Defenders of Wildlife. “The best available science shows that they’re inappropriate for widespread use on prairie dogs because of the impacts on threatened and endangered animals. It’s unacceptable that the EPA is expanding their use, violating federal wildlife laws, and ignoring all reasonable requests from the U.S. Fish and Wildlife Service and state wildlife agencies to limit the use of these poisons. The bottom line is that Rozol and Kaput-D need tighter regulation.”  

For years, the Fish and Wildlife Service has sought consultation with EPA under the Endangered Species Act on how to regulate use of the poisons to avoid inadvertently harming black-footed ferrets and other protected mammals and birds. On Sept. 9, 2009, FWS formally requested that EPA revoke the pesticides’ registrations. The Western Association of Fish and Wildlife Agencies, representing 23 western states, has also asked EPA not to approve these pesticides without further environmental review.

“Tons of Rozol have been used in recent years in a misguided attempt to eradicate prairie dogs in some Kansas counties where County Commissioners, urged by the Kansas Farm Bureau, are using century-old statutes to force landowners to kill these native mammals on private land,” said Ron Klataske, executive director of Audubon of Kansas. “Secondary poisoning with Rozol is a threat to swift foxes, American badgers, ferruginous hawks, golden and bald eagles that frequently feed on prairie dogs in the Great Plains. Black-footed ferrets rely almost exclusively on prairie dogs for food.”

Rozol is approved for use to poison prairie dogs in Colorado, Kansas, Montana, Nebraska, New Mexico, North Dakota, Oklahoma, South Dakota, Texas and Wyoming. The EPA allows Kaput-D to be used on prairie dogs in Colorado, Kansas, Nebraska, Texas and Wyoming.  

Learn more about black-footed ferret conservation.


Defenders of Wildlife is dedicated to the protection of all native animals and plants in their natural communities.  With more than 1 million members and activists, Defenders of Wildlife is a leading advocate for innovative solutions to safeguard our wildlife heritage for generations to come.  For more information, visit





James Navarro, Defenders of Wildlife, (202) 772-0247
Ron Klataske, Audubon of Kansas, (785) 537-4385