Getting the lead out of scavenger birds

UC DAVIS (US) — In a somewhat skewed version of the circle of life, scavenger birds are getting lead poisoning from eating the remains of animals that are killed by hunters using ammunition pellets or bullet fragments.

Eagles and turkey vultures take advantage of animal remains left behind when a hunter cleans a kill or when a shot deer or wild pig escapes the hunter but later dies.

Lead poisoning in birds causes an inability to fly, anemia, blindness, seizures, and death.

“Hunting is an irreplaceable tool for wildlife management,” says Christine Johnson, associate professor of veterinary medicine at University of California, Davis, and an expert on wildlife health, “especially now that we have fewer large predators but more invasive species like wild pigs.

“Yet we know that accidental consumption of lead can make animals and people sick.

“It just makes good sense to use non-toxic ammunition, wherever it is available, to protect wildlife as well as eliminate any potential risk to hunters and their families.”

To protect bald eagles, lead ammunition was banned in 1991 in the U.S. for hunting waterfowl. In 2008, to protect California condors, lead ammunition was similarly banned in California condor range for most hunting activities.

Johnson and her doctoral student Terra Kelly, a wildlife veterinarian earning a PhD in epidemiology, conducted two studies on the effects of lead on the scavenger birds.

The first study to investigate blood lead levels in free-flying turkey vultures found direct evidence that lead levels rose in turkey vultures during deer hunts and in areas with wild pig hunts.

Another study, the first to examine the effects of the 2008 law on any wild animals, found that the lead-ammunition ban in California condor range reduced lead exposure in golden eagles and turkey vultures in 2009.

The studies are published online in the journal PLoS ONE.

Researchers from the University of Idaho and the California Department of Fish and Game contributed to the studies, both of which were funded by the California Department of Fish and Game.

Johnson and Kelly, now a UC Davis Wildlife Health Center veterinarian will next study the impacts of ongoing lead exposure o the California Condor population, collaborating with researchers at UC Santa Cruz; Ventana Wildlife Society; California Department of Fish and Game; and the United States National Park Service, Fish and Wildlife Service, and Geological Survey.

Hunting is an irreplaceable tool for wildlife management, but lead consumption makes animals sick. (Credit: Terra Kelly)

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