Levels of blood lead in Griffon vultures from a Wildlife Rehabilitation Center in Spain (González et al., 2017).

Lead is a highly toxic contaminant that significantly impacts bird wildlife, with Griffon vultures (Gyps fulvus) serving as sensitive indicators of environmental contamination due to their position at the top of the food chain and dependence on human-related activities. This study aimed to assess lead intoxication susceptibility in Griffon vultures admitted to Wildlife Rehabilitation Centers (WRC) by measuring blood lead levels and examining correlations with clinical signs, hematological, biochemical, or radiographic findings. Factors such as age, gender, body condition, season, and primary cause of admission were also considered. Blood lead levels were measured using anodic stripping voltammetry in vultures admitted over one year to the GREFA Rehabilitation Center. Results showed that 26% of the birds had lead levels above 20 µg/dL, while 74% had levels below 20 µg/dL (mean [Pb]<20 = 9.34±5.60 µg/dL). Statistically significant differences in lead levels were found based on sex, season of admission, and body condition. A negative correlation was observed between lead levels and hematocrit. However, no direct association was found between clinical signs and blood lead levels, except for digestive issues like stasis and weight loss. While lead poisoning in vultures is often linked to ingestion of lead ammunition, no radiographic evidence of lead was found in this study. Compared to other studies, the blood lead levels detected in this population were relatively low, though all birds had detectable lead concentrations. The vultures appeared to have a higher sensitivity to the toxic effects of lead than previously reported, and there is evidence that subclinical lead exposure may predispose them to injury or disease, even if admitted for other reasons.