Assessment of bird exposure to lead at Tyndall and Beale Air Force Bases

Soil contamination by lead (Pb) from past small munitions training on Beale Air Force Base, California and Tyndall Air Force Base, Florida may result in adverse effects for passerine birds that utilize the locations. A study was conducted during 2016–17 at both Air Force Bases (AFB) to assess the risk of bird exposure to Pb. Two different methods were used to estimate exposure. The first was by analysis of blood and feather samples collected from birds captured on both AFBs, while the second was by food chain modeling using data on Pb concentrations in dietary items (invertebrates and seeds) collected from both AFB. Lead concentrations in blood and feathers for birds captured at Beale AFB indicate low exposure and risk, while potential toxicity is possible based on blood and feather data for birds from Tyndall AFB. Food chain modeling utilizing dietary contamination indicates a risk likelihood of up to 35 percent at Beale AFB and up to 34 percent at Tyndall AFB. Lead exposure from incidental soil ingestion increased risk likelihood at both AFB and is a significant uncertainty in this risk assessment.