Abnormal lead exposure in globally threatened Cinereous vultures (Aegypius monachus) wintering in South Korea

Abstract

Globally threatened Cinereous vultures (Aegypius monachus) regularly over-winter in South Korea, and they have frequently been found dead in their natural habitats. As one possible factor for their mortality, we investigated tissues for heavy metal contaminants along with necropsies on 20 dead Cinereous vultures. Severe emaciation was found in the survey, being associated with 19 of the deaths. Two of the 19 showed lesions suggestive of lead poisoning in the tissues; there was no indication of trauma, embedded shot, lead bullets in the stomach, or signs of electrocution in the specimens. Of 20 vultures, two showed lesions compatible with death from lead poisoning with 19.7 ppm dry weight (6.9 ppm wet weight) and 34.1 ppm dry weight (11.1 ppm wet weight), and 14 individuals had a potentially toxic level of lead with >6 ppm dry weight (about 2 ppm wet weight) in liver or kidney. The ingestion of lead-contaminated carcasses probably occurs along their migratory route. The possibility of lead exposure from the breeding site (Mongolia) or stopover area (China) should also be considered because some individuals are likely to die at or upon arrival. Our results suggest that most of the dead Cinereous vultures may be suffering from abnormally high lead exposure, indicating a potentially important cause of mortality in this endangered species.