Whooper swans migrate from Iceland to winter in the UK, with welfare dependent on clean shallow wetlands, supplementary feeding sites, and protection from disturbance and power line collision.
Whooper swan welfare during UK wintering reveals how supplementary feeding at wildlife reserves can significantly benefit wild animal welfare at population scale. WWT reserves that provide grain and agricultural grass in protected, undisturbed wetland environments attract thousands of whooper swans that would otherwise need to forage across agricultural landscapes where they face disturbance and food insecurity. The family groups that characterise whooper swan social structure - parents with cygnets of the year maintaining close contact through the entire winter - provide a welfare benefit through social cohesion that supplementary feeding sites protect by reducing the need for dispersal. Power line collision is the most significant human-caused welfare harm for whooper swans: large birds flying at speed in poor visibility conditions encounter power lines with fatal consequences. Line marking with flight diverters significantly reduces collision rates, and the Whooper Swan flyway in Scotland has been a focus for line marking initiatives. Unusually severe winters that freeze wetlands can cause welfare emergencies for swans unable to access food under ice, occasionally requiring supplementary feeding or water provision by wildlife managers to prevent starvation.