Feeding ecology drives lead exposure of facultative and obligate avian scavengers in the eastern United States.

Lead poisoning of scavenging birds is a global issue. However, the drivers of lead exposure of avian scavengers have been understood from the perspective of individual species, not cross-taxa assemblages. We analyzed blood (n = 285) and liver (n = 226) lead concentrations of 5 facultative (American crows (Corvus brachyrhynchos), bald eagles (Haliaeetus leucocephalus), golden eagles (Aquila chrysaetos), red-shouldered hawks (Buteo lineatus) and red-tailed hawks (Buteo jamaicensis)) and 2 obligate (black vultures (Coragyps atratus) and turkey vultures (Cathartes aura) avian scavenger species to identify lead exposure patterns. Species and age were significant (α < 0.05) predictors of blood lead exposure of facultative scavengers; species, but not age, was a significant predictor of their liver lead exposure. We detected temporal variations in lead concentrations of facultative scavengers (blood: median = 4.41 µg/dL in spring and summer vs. 13.08 µg/dL in autumn and winter; p = <0.001; liver: 0.32 ppm in spring and summer vs. median = 4.25 ppm in autumn and winter; p = <0.001). At the species level, we detected between-period differences in blood lead concentrations of bald eagles (p = 0.01) and red-shouldered hawks during the winter (p = 0.001). During summer, obligate scavengers had higher liver lead concentrations than did facultative scavengers (median = 1.76 ppm vs 0.22 ppm; p = < 0.001). These data suggest that feeding ecology of avian scavengers is a determinant of the degree to which they are lead-exposed, and they highlight the importance of dietary and behavioral variation in determining lead exposure. This article is protected by copyright. All rights reserved.