Poisoning from lead (Pb) ammunition fragments causes death to birds of prey worldwide, but it is unclear the impact that these mortalities have on population dynamics at the ecological scale. While ingestion of Pb from spent ammunition continues to kill individual bald eagles (Haliaeetus leucocephalus) throughout the United States, eagles have been deemed a wildlife recovery success story after populations rebounded from near extirpation. We determined whether eagle deaths from Pb toxicosis altered the dynamics of the population’s recovery in the Northeast United States (NE) over the past three decades. We used a novel application of a combinatorial optimization algorithm (COA) in conjunction with a mathematically symbolic life history to synthesize regional necropsy and annual time series count data to compare population dynamics of bald eagles under current (Pb) and hypothetical (Pb-free or Pb-reduced) scenarios.
Results/Conclusions
We found that Pb-associated mortalities depressed the long-term growth rate of eagles in the NE and differentially influenced females. The application of the COA to investigate the population-scale impacts of a disease or a contaminant is not limited to Pb toxicosis in bald eagles. The methods may be used to ascertain the population impact of any disease or contaminant to any wildlife species given a detailed understanding of the species’ life history, sufficient annual time series count data, and observational necropsy data.