When wild pigs turn blue, it’s best to avoid them. That’s what the California Department of Fish and Wildlife (CDFW) has advised, anyway, now that the wild pigs in Monterey County have started becoming bright blue, thanks to their ingestion of the restricted rodenticide diphacinone.
“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 Ryan Bourbour, the CDFW Pesticide Investigations Coordinator, according to a press release. “Rodenticide exposure can be a concern for non-target wildlife in areas where applications occur in close proximity to wildlife habitat.”
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Bright Blue Pigs
The domesticated pig (Sus domesticus) has roamed through the state of California since its introduction in the 1700s, and the wild boar (Sus scrofa) has done the same since the 1920s. Breeding in the wilderness, these two populations have blended together, producing the domestic-pig-and-wild-boar hybrid that today damages environments throughout California.
Humans have targeted these wild pigs for decades, helping manage their populations and mitigate their destruction to California’s ecosystems. But when hunters and trappers take these animals, they aren’t supposed to be blue on the inside.
In March 2025, however, several reports of blue muscle and fat in the wild pigs from Monterey County were made to the CDFW. Investigating these reports, the authorities have now identified the traces of rodenticide in the stomach and liver of one of the reported wild pigs, concluding that it became blue after ingesting diphacinone — an anticoagulant poison that’s used to control rats and mice.
Colorful Contamination
Wild pigs are voracious omnivores, consuming plants and animals in a variety of habitats, from the woodlands to the grasslands of California. As such, the CDFW warns that they can become contaminated in various ways, ingesting rodenticides themselves, or ingesting rodenticide-contaminated animals.
While the blue-colored flesh may signal that a wild pig has consumed these poisons — which are typically treated with dyes and applied to rat- and mouse-friendly-foods such as nuts and seeds to serve as “bait” — the bright coloration may not always appear in the meat of affected individuals.
The CDFW therefore advises hunters and trappers to “always use caution when harvesting game animals,” and to always pay attention to the possible risks of consuming hunted and trapped game, whether the meat is blue or not, according to the press release.
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Consuming Contaminated Meat
California’s bright blue pigs may seem strange, but the state has had trouble with this sort of contamination before. In fact, a study from the U.S. Department of Agriculture from 2018 found that 10 out of 120 of wild pigs and 10 out of 12 bears from agricultural or residential areas in California are contaminated with rodenticides. Not only that; the discoloration of these animals is well documented, though it isn’t the most reliable indicator of whether an individual has consumed rodenticides.
According to the press release, hunters and trappers in California should “report unusual findings in harvested wildlife” and should not “consume any part of an animal with blue fat or muscle or other abnormalities.”
Meanwhile, those applying rodenticides should make sure that their poisons are not applied to non-target animals, selecting appropriate application systems and locations that restrict access to the toxin to rats and mice alone.
While wild pigs aren’t that beneficial for California’s wildlife, the results of the CDFW’s investigation suggest that blue pigs aren’t any better, posing an additional threat to hunters, trappers, and to anyone who could consume their contaminated meat.
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