Hunters and trappers in California have been shocked to discover neon blue flesh beneath the skin of feral pigs, National Geographic reported. The alien-like coloration has come from the animals ingesting rat poison used by ranchers and farmers.
Dan Burton, an animal-control expert in Monterey County, told National Geographic the coloration was not subtle or muted but a bright, “7/11 slushie” shade of blue, per National Geographic.
In a news release, the California Department of Fish and Wildlife said it “urges hunters to always use caution when harvesting game animals and be aware of potential risks.”
What’s happening?
The blue color came from the dye used in the rodent-control poison diphacinone, an anticoagulant.
While working for a ranch that was experiencing issues with wild pigs, Burton observed the animals breaking into poison-containing traps that had been left for rodents and eating the poison-laced oats inside, according to National Geographic.
Despite much recent publicity involving the blue-fleshed swine, the issue is not new, nor has it been limited to feral pigs.
In the fall of 2020, Canadian geese shot by hunters in the Bay Area’s Contra Costa County were found to have blue-colored fat, according to a California Department of Fish and Wildlife alert from the time.
Diphacinone was detected in at least one of the birds’ livers.
“Rodenticide baits like diphacinone often contain a dye which identifies the bait as a poison,” said Krysta Rogers, an avian disease specialist for the CDFW. “We suspect the blue-colored fat was caused by ingestion of diphacinone bait containing blue dye.”
Scientists also have detected diphacinone in a number of the state’s iconic species, including California condors, bobcats, black bears, San Joaquin kit foxes, red-tailed hawks, and northern spotted owls, according to National Geographic.
Not all of these animals ingested the poison directly. Some of the contamination comes from predators eating animals that themselves have consumed diphacinone. This means that the poison can bioaccumulate in species further up the food chain.
“It’s really widespread poisoning,” Jonathan Evans, an attorney for the Center for Biological Diversity, told National Geographic. “The ability of anticoagulants to bioaccumulate through the food web is dramatic.”
Why are blue-fleshed pigs important?
The situation highlights the incredible interconnectedness of ecosystems and the ways in which a solution for one issue — for example, rodent control — can create a host of other problems.
Experts have warned that the situation is not as simple as merely banning diphacinone outright and switching to other poisons, or simply not engaging in rodent control at all.
Groups ranging from farmers to public-health officials require an effective means of controlling rodent populations, and other poisons or means of population control also could have devastating consequences, often unforeseen.
What’s being done about the poisoning of wildlife?
Despite the complicated, interconnected nature of the problem, advocates say that alternatives to poisons do exist.
For example, both Chicago and New York City have experimented with fertility-control methods, using substances that are not toxic but do hinder the ability of rats to reproduce, according to National Geographic.
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