LAUSR

Lead poisoning occurs worldwide in populations of predatory birds, but exposure rates and population impacts are known only from regional studies. We evaluated the lead exposure of 1210 bald and golden eagles from 38 US states across North America, including 620 live eagles. We detected unexpectedly high frequencies of lead poisoning of eagles, both chronic (46 to 47% of bald and golden eagles, as measured in bone) and acute (27 to 33% of bald eagles and 7 to 35% of golden eagles, as measured in liver, blood, and feathers). Frequency of lead poisoning was influenced by age and, for bald eagles, by region and season. Continent-wide demographic modeling suggests that poisoning at this level suppresses population growth rates for bald eagles by 3.8% (95% confidence interval: 2.5%, 5.4%) and for golden eagles by 0.8% (0.7%, 0.9%). Lead poisoning is an underappreciated but important constraint on continent-wide populations of these iconic protected species. Description A persistent lead problem Although it occurs naturally, lead levels increased during the industrial revolution and have posed serious problems for humans and animals. Since the mid-1900s, efforts were made to limit anthropogenic sources of lead in the environment, and these were largely considered successful. Despite this headway, anthropogenic lead remains an underappreciated threat to wildlife. Slabe et al. looked at lead levels in samples collected from bald and golden eagles across the United States. They found that almost half of all animals sampled had chronic, toxic levels of lead. Demographic modeling suggested that these levels are high enough to suppress population growth in both species. —SNV Lead poisoning is unexpectedly widespread, frequent, and demographically relevant to populations of both bald and golden eagles.