Here is the link to the publication of lead exposure research done by Terra Kelly and Christine Johnson. http://dx.plos.org/10.1371/journal.pone.0015350
In 2008 & 2009 Terry and Christine used Big Creek Reserve as a study site to detect lead in the blood of scavenging birds. They found that lead toxicity in the blood increased during deer hunting season and was positively correlated with increasing pig hunting intensity. This work has been important in showing that the effects of lead ammunition are not isolated to California condors but involve other scavengers such as turkey vultures and golden eagles.
Here is the Abstract from their paper:
Predatory and scavenging birds are at risk of lead exposure when they feed on animals injured or killed by lead ammunition. While lead ammunition has been banned from waterfowl hunting in North America for almost two decades, lead ammunition is still widely used for hunting big game and small game animals. In this study, we evaluated the association between big game hunting and blood lead concentration in an avian scavenger species that feeds regularly on large mammals in California. We compared blood lead concentration in turkey vultures within and outside of the deer hunting season, and in areas with varying wild pig hunting intensity. Lead exposure in turkey vultures was significantly higher during the deer hunting season compared to the off-season, and blood lead concentration was positively correlated with increasing wild pig hunting intensity. Our results link lead exposure in turkey vultures to deer and wild pig hunting activity at these study sites, and we provide evidence that spent lead ammunition in carrion poses a significant risk of lead exposure to scavengers.