Invasive wild pigs are on the rise in California, and so is wild pig hunting, especially in the central flock’s range. But because they’re a generally considered to be a nuisance species rather than big game, which typically has stricter regulations, people hunting them might not be aware that they can’t use lead shot to do so, says Chris West, a senior wildlife biologist with the Yurok Tribe who was not involved with the study.
“Some of these people may be in violation of the law, but not because they don’t want to follow the law. It’s because they don’t know,” West says. Big game hunters generally pay attention to year-to-year regulation changes, but land managers or ranchers who use firearms to control pest wildlife populations might not check as often, he says.
So Bakker added the numbers of pig hunting tags claimed each year to the model. Suddenly, the numbers made sense.
“Lo and behold, that was such a clear predictor of the increased lead exposure for the central flock,” Bakker says. When more pig hunting happened, more condors died from lead poisoning. For the researchers, that suggests lead is still being used to control wild pig populations, despite the ban. But future research should keep exploring this potential relationship, including better data collection on wild pig populations and hunting and using environmental DNA swabs to home in on condors’ diets, Bakker says.