Environmental Lead and Wild Birds: A Review

Lead is a persistent inorganic environmental pollutant that affects humans and animals worldwide. Avian species are especially susceptible to lead exposure through consumption of lead ammunition, lead fishing tackle, and other contaminated food sources such as aquatic species ingesting lead contaminated sediments in mining areas. Even with government regulations on the use of lead ammunition in many countries, including the United States, terrestrial, aquatic, predatory, and scavenger avian species are still at risk of exposure to potentially lethal concentrations of lead. The toxicities seen in these avian species include increased oxidative stress and decreased anti-oxidant enzymes in hepatic and renal tissue. The avian immune system is also a target of lead and displays a number of altered functions suggestive of immune suppression; however, studies in wildlife and laboratory species remain too limited for definitive statements with regard to population risk. In contrast, lead clearly inhibits reproductive capabilities in adult birds, and alters growth and development of hatchlings. Environmental remediation for lead removal, which would lower toxic exposure in wildlife, presently is a monumental and prohibitively expensive effort. Wildlife exposure will therefore continue in contaminated areas, necessitating development of new remediation practices. These plans should aim toward limiting more widespread or heavier contamination of wildlife habitats. This chapter reviews presently available information of lead toxicity in wild bird species, and suggests continued monitoring and reduction strategies to reduce lead exposure for at-risk avian populations.