Turkey vultures were caught in a baited walk-in trap and a ladder trap. Here, Yvette Hernandez holds a bird while Terra Kelly prepares to draw a blood sample that will be used to determine lead exposure.
WHC Research Explores Influence of Hunting on Lead Exposure in Scavenging Birds
Two journal articles released in PLoS ONE this week link lead exposure in turkey vultures to deer and wild pig hunting and show that a recent ban on lead ammunition in California was effective in reducing lead exposure in turkey vultures and golden eagles. Lead ammunition has been widely used for big and small game hunting in North America, and these two scavenging bird species are at risk of lead exposure when they feed on animals injured or killed by lead ammunition. Lead bullets can produce hundreds of small fragments upon impact which contaminates animal carcasses and discarded viscera that serve as important food sources for scavenging wildlife.
The first study showed that blood lead concentration in turkey vultures was significantly higher during the deer hunting season compared to the off-season, and blood lead concentration also increased with increasing intensity of wild pig hunting at study sites. In July 2008, lead ammunition was banned for most hunting activities in the historical range of the condor in California.
The second study found that lead exposure in both golden eagles and turkey vultures declined significantly after the ban was implemented. While spent lead ammunition in carrion poses a significant risk of lead exposure to scavenging wildlife, our results indicate that hunter compliance with the new regulations was sufficient to reduce lead exposure in scavenging birds at our study sites.
Dr. Terra Kelly, a doctoral student in epidemiology at UC Davis, is primary lead author on both studies and she conducted her research under the direction of Dr. Christine Kreuder Johnson.