Relationship between blood lead levels and clinical and physiological factors in Bonelli's eagle

Abstract

Lead is a toxic metal that produces effects on the overall health of animals, resulting in mortality at high exposures, adverse physiological and behavioral effects at lower concentrations, and population declines in many species. Scavengers and predators are more susceptible to lead toxicity because of behavioral and physiologic factors, and long lifespans increase the risk of exposure cumulatively. Bonelli's eagle (Aquila fasciata) is a long‐living predator that may have reduced breeding success because of lead exposure. We analyzed the blood lead levels of 54 wild and captive Bonelli's eagles admitted to a recovery center in Spain from May 2014 to July 2015 and the lead relationship among physiological, clinical, and environmental variables. We detected blood lead using anodic stripping voltammetry. Lead levels were below the limit of quantification (3.3 μg/dL) in 100% of captive animals (n = 22); in contrast, 21.9% of wild birds (n = 32) had higher lead levels than captive birds (P = 0.020). Among wild animals, the 2 adults tested had detectable lead, the only eagle sampled in autumn had the highest lead levels of the study (14.7 μg/dL), and 16.7% of nestlings had detectable lead levels. There is no evidence that the lead levels differ between sexes. There were no symptoms associated with lead intoxication or any correlation between lead levels and hematological or biochemical values; however, subclinical lead exposure at early ages can be harmful and could influence neurological and body development. Researchers should determine if lead could be causing damage to wildlife from early ages to determine if lead exposure affects the conservation of the threatened population of Bonelli's eagles in Spain and elsewhere.