Lead Exposure in South African Waterfowl: Implications for Conservation and Human Health

Ingestion of lead (Pb) derived from ammunition used in the hunting of game animals is recognised as a significant potential source of Pb exposure in wild birds globally. While Pb poisoning in wild birds has been studied extensively in North America and Europe, the prevalence of Pb exposure in bird populations elsewhere, particularly in Africa, remains understudied. To address this gap in knowledge, we examined Pb concentrations in the feathers and bones of four waterfowl species (n = 37) from a region in South Africa where recreational hunting regularly occurs. Lead was detected in all feather and bone samples. While most birds had bone Pb concentrations consistent with low-level exposure (< 10 mg kg^-1), three individuals displayed concentrations (maximum = 63.5 mg kg^-1) associated with lethal Pb poisoning. Lead isotopic ratios in bone samples suggested that Pb shot was the most probable source of Pb in birds with high exposure. These findings align with recent studies on vultures, suggesting that Pb poisoning is more widespread in southern Africa than is currently recognised, affecting not only scavenging species but also waterfowl. The prevalence of elevated bone Pb concentrations compatible with lethal poisoning (8.1%) indicates that Pb exposure could have significant implications for waterfowl populations in the region. Furthermore, substantial indirect risks exist for scavenging and predatory species, as well as for humans consuming meat contaminated with Pb shot. Our findings highlight the importance of addressing the unregulated use of Pb-ammunition across southern Africa, particularly given the large hunting industry the region supports.