Lead toxicity in the bald eagle population of the Great Lakes region

ABSTRACT Ingestion of lead-based ammunition is one of the leading causes of the mortality of bald eagles. Their primary source is unretrieved carrion contaminated with lead from hunters’ ammunition. Lead toxicity can have serious clinical consequences, including reduced fertility and consumption. A model with ordinary differential equations describes the dynamics of available contaminated carrion and the progression of eagles through stages of lead poisoning. Nonnegative solutions exist and equilibrium points are stable for certain parameter ranges. Sensitivity analysis shows that the bald eagle population in the Great Lakes region is primarily dependent on the rate of entry of contaminated carrion in the environment, more so than on retrieval or on the rate of treatment of eagles. Estimates of financial costs of each of these three measures show that the most effective measure is to find a substitute for lead cartridges.