Lead (Pb) exposure occurs in birds of prey when they ingest Pb ammunition while scavenging remains left behind by hunters. In July 2019 California banned Pb ammunition for hunting purposes, which has the potential to protect raptors from exposure. We examined Pb exposure in turkey vultures (Cathartes aura) in California captured post-ban to determine (i) whether lead was present in their blood, indicating recent exposure, (ii) if Pb affected oxidative stress levels, an indicator of health and (iii) if Pb exposure and health differed between migrant and resident populations. In total 41 resident and seven migrant turkey vultures were captured, and tested for blood Pb concentrations and biomarkers indicative of oxidative stress, including glutathione (GSH), the main intracellular antioxidant, and protein carbonyls (PC), a measure of oxidative damage. Blood Pb concentrations were higher in migrants (9.37 µg/dL; SD = 2.62) than in residents (2.41 µg/dL; SD = 1.88). Among residents, PC levels were negatively correlated with GSH levels suggesting that as oxidative damage increases, antioxidants are depleted. Higher Pb concentrations in migrants indicates greater toxicological risk for turkey vultures elsewhere within the species’ range, suggesting local measures may not address the conservation needs of migrants.

Alex Eagleton is a California native and wildlife biologist with a background in field ecology and environmental toxicology. She earned her B.S. and M.S. in Biology from Cal Poly Pomona, where she researched lead exposure and oxidative stress in Turkey Vultures, investigating contaminant impacts on resident and migratory birds in Southern California. Since 2021, Alex has worked with Endemic Environmental Services, managing biology programs and leading projects in habitat conservation, species monitoring, and environmental compliance. She is passionate about connecting research with real-world conservation to better inform how California’s wildlife is protected.