Mute swans recovered from near-extinction from lead fishing weights but face ongoing welfare challenges from lead poisoning, habitat loss, and disturbance.
Mute swan welfare is affected by lead poisoning that causes neurological symptoms, weakness, and progressive deterioration before death. Individual swans ingesting lead shots or weights show characteristic drooping neck posture indicating toxicity. Recovery from sub-lethal poisoning is possible with chelation therapy but is expensive and not always successful. Habitat loss from bank erosion and disturbance at nesting sites causes breeding failure. Human-caused disturbance to nesting pairs remains common on popular waterways. Conservation of lead-free waterways and undisturbed nesting banks directly improves individual swan welfare.