Active and passive monitoring of lead poisoning in birds of prey in Spain

Abstract

Máster en Investigación Básica y Aplicada en Recursos Cinegéticos.The ingestion of lead ammunition is the most important source of exposure to this metal in birds of prey, and consequences on their health are well-know. In the present study we have performed a passive monitoring of lead poisoning by measuring blood (n=27) and liver (n=685) lead levels in birds of prey of 16 species found dead or sick in Spain between 2004 and 2017, but also an active monitoring by measuring blood lead levels in birds (n=196) of 9 species trapped alive in the field. Adverse effects of lead exposure on heme biosynthesis, P/Ca metabolism, oxidative stress and immune function were also evaluated in the active monitoring. Passive monitoring revealed that the species with lead levels in liver associated with clinical poisoning (18-30 μg/g d.w.) were Cinereous vulture (1/39), Eurasian griffon (2/228) and Western marsh-harrier (1/32); and the species with clinical severe poisoning (>30 μg/g d.w. of Pb in liver) were Eurasian griffon (19/228), Red kite (1/129) and Golden eagle (3/36). The active monitoring showed that some individuals of Bearded vulture (1/3), Eurasian griffon (87/118), Spanish imperial Eagle (1/6) and Red kite (1/18) presented abnormal blood Pb exposure levels (>200 ng/ml). The study of biomarkers reveals a negative relationship between δ-ALAD activity in blood and blood Pb concentration. Ca/P homeostasis was also affected by Pb exposure, because elevated blood Pb levels were associated with lower Pb levels and higher Ca:P ratio in plasma of birds. Carotenoids levels in plasma were also increased in birds with higher blood Pb levels, indicating a possible allocation of antioxidants in plasma to cope with adverse effects of Pb. Our result reveal a significant mortality rate by lead poisoning in Eurasian griffon and Golden eagle and elevated blood Pb levels in several threatened species.Peer Reviewe