Lead poisoning from discarded fishing weights and spent shotgun pellets is a leading cause of death in mute swans, ducks, and other waterbirds across Europe and North America.
Lead poisoning in waterfowl causes a prolonged and painful death. Affected birds show progressive neurological signs including neck weakness, loss of coordination, and inability to fly or feed normally. Death typically occurs over weeks from internal haemorrhage, organ failure, and starvation. The source of poisoning, discarded lead from human recreational activities, is entirely preventable through substitution of non-toxic alternatives. Despite the evidence for harm and the availability of effective alternatives, lead fishing weights and ammunition remain in widespread use in many countries. Bans on lead fishing tackle in freshwater fisheries have been shown to dramatically reduce waterfowl mortality.