Wildlife officials in California are urging hunters and pesticide applicators to exercise greater caution after wild pigs in Monterey County were found to have ingested poison that is used to kill rodents, raising new concerns about contamination in game meat and risks to non-target animals.
The California Department of Fish and Wildlife’s Wildlife Health Laboratory, along with the California Animal Health and Food Safety Laboratory in Davis, confirmed in an advisory released Wednesday that wild pigs had been exposed to the anticoagulant rodenticide diphacinone, which kills rodents by causing internal bleeding. The discovery came after a wildlife trapper reported observing blue-colored muscle or fat in multiple pigs, which the CDFW says is an indicator that the animals may have consumed rodenticide bait.
Wildlife investigators said they examined a recovered wild pig and detected diphacinone in the animal’s stomach and liver contents. Wildlife can be unintentionally exposed to rodenticides either by eating the bait directly or by consuming prey that has ingested the poison. Many rodenticide baits reportedly include a brightly colored dye, often blue, to signify toxicity.
“Hunters should be aware that the meat of game animals, such as wild pig, deer, bear and geese, might be contaminated if that game animal has been exposed to rodenticides,” Ryan Bourbour, CDFW’s pesticide investigations coordinator, said in a statement. “Rodenticide exposure can be a concern for non-target wildlife in areas where applications occur in close proximity to wildlife habitat.”
CDFW officials warned that while blue fat or muscle may serve as a visible warning of contamination, the discoloration may not always be present. Hunters are encouraged not to consume any part of an animal that shows blue tissue or other abnormalities and to report such findings to the Wildlife Health Lab.
CDFW cited a 2018 statewide study on rodenticide exposure in game animals that revealed anticoagulant rodenticide residue in 10 of 120 wild pig samples and in 10 of 12 bear samples, particularly in animals found near agricultural or residential zones where rodenticides are commonly used.
Pesticide applicators were urged to prevent exposure to non-target wildlife by avoiding bait placement in areas frequented by wild animals and by using secure bait stations and approved methods.
To report suspected pesticide misuse, Monterey County residents are encouraged to dial (831) 759-7355. Unusual wildlife findings, including blue tissue in game, can be reported to CDFW’s Wildlife Health Lab at WHLab@wildlife.ca.gov or by calling (916) 358-2790.