The day before National Pig Day, which is on March 1st, those visiting Hirsch Fruit Farm could meet small and large pigs from Flo Acre Farms.
Monterey County, California – Wild pigs in Monterey County have been found with muscle and fat tinted an unnatural blue, a disturbing sign that the animals may have ingested toxic rodenticide bait, according to the California Department of Fish and Wildlife (CDFW).
Laboratory testing confirmed the presence of diphacinone—an anticoagulant rodenticide—in the stomach and liver of one pig with the blue-tinted tissue. The chemical prevents blood from clotting, ultimately killing rodents through internal bleeding, but it can also sicken or kill non-target wildlife.
The investigation began in March when a wildlife trapper reported the unusual coloring. “I’m not talking about a little blue… I’m talking about neon blue, blueberry blue,” Dan Burton, owner of Urban Trapping Wildlife Control, told The Los Angeles Times. Samples were sent to CDFW’s Wildlife Health Lab and the California Animal Health and Food Safety Laboratory in Davis, where tests confirmed the poison’s presence.
Rodenticides are designed to target rats and mice, but their use has a much wider environmental footprint. Non-target animals can be poisoned by eating bait directly or by consuming prey that has already ingested it. Many rodenticides are dyed—blue or green—to signal their toxicity. But CDFW cautions that a lack of visible discoloration does not mean the meat is safe.
“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,” said Dr. Ryan Bourbour, CDFW’s pesticide investigations coordinator. “Rodenticide exposure can be a concern for non-target wildlife in areas where applications occur near wildlife habitat.”
The department advises hunters not to consume any meat from game animals that show blue muscle or fat, or any other abnormal signs. Suspected cases should be reported to the Wildlife Health Lab.
This is not the first time California has seen the phenomenon. In 2015, images of a “blue pig” circulated online, later confirmed to be the result of rodenticide poisoning. A 2018 statewide study found anticoagulant rodenticide residue in more than 8 percent of wild pig tissue samples, with the highest rates in animals from agricultural or residential areas. The same study found an alarming 83 percent contamination rate in black bears tested.
State officials are urging pesticide applicators to reduce the risk to wildlife by using secure bait stations, checking for non-target species in treatment areas, and considering alternative pest control methods. As the neon-blue flesh of Monterey County’s pigs makes clear, the reach of rodenticides extends far beyond their intended targets.
