Population impact to bald eagles by ingested lead in New York State, 1990–2018

Abstract

While the recent population recovery of bald eagles (Haliaeetus leucocephalus) in New York State, USA, is a conservation success, evidence from necropsies suggest that ingested lead (Pb) from ammunition fragments is causing morbidity and mortality to wild eagles. Wildlife managers and officials at the New York State Department of Environmental Conservation would benefit from analysis of their necropsy data to understand how documented morbidities or mortalities impact dynamics of the remaining wild eagle population. We integrated necropsy data on bald eagles in New York State collected between 1990 and 2018 by the New York State Department of Environmental Conservation into a matrix population model. We compared annual survival of hatchling, non-breeding, and breeding eagles under factual (Pb) and counter factual (Pb-reduced or Pb-free) scenarios. We found no evidence that Pb altered annual survival of hatchlings. Lead was associated with a reduction in the annual survival of nonbreeders by 0-0.056 (females) and 0.052-0.057 (males), and a reduction in the annual survival of breeders by 0.051-0.057 (females) and 0-0.032 (males). Lead was associated with a reduction in the long-term growth rate (λ) by 0.009-0.036 (females) and 0.023-0.035 (males). Due to altered dynamics over the prior 3 decades, abundances of eagles in the most recent year of the study (2018) differed between Pb

Special Section on Lead Ammunition

“…Hanley et al (2023) provide an evaluation of the long-term effects of lead ingestion on a bald eagle (Haliaeetus leucocephalus) population in New York, describing how lead poisoning likely dampened the rate of increase in population size.Several papers deal with the factors influencing hunter use of non-lead ammunition Schulz et al (2023). examine many of the complexities in the debate between mandatory and voluntary non-lead use for nonwaterfowl hunting and the effectiveness of voluntary programs in reducing lead ingestion in California condors (Gymnogyps californianus).…”

“…Because AFWA members are state, provincial, and federal fish and wildlife agencies in the United States and Canada, their policies, and the science gathered to inform those policies, play a significant role in how and where lead hunting ammunition is regulated. Hanley et al (2023) provide an evaluation of the long‐term effects of lead ingestion on a bald eagle ( Haliaeetus leucocephalus ) population in New York, describing how lead poisoning likely dampened the rate of increase in population size.…”