Ospreys recolonised Scotland naturally in 1954 and have expanded across the UK, with nest protection and prey availability being the primary welfare determinants for breeding birds.
Osprey welfare through the UK recolonisation story illustrates how targeted human protection can enable natural population recovery. The early Loch Garten nest, discovered by RSPB in 1958, was protected by a 24-hour guard against egg thieves for many years - a direct welfare and conservation intervention that prevented repeated nest failure. Individual osprey welfare during the breeding season depends primarily on fish availability in nearby water bodies: drought, pollution, and turbidity that reduces fishing success cause energetic stress in breeding adults and nutritional deficits in chicks. Migration welfare involves the multiple hazards of a long-distance journey: legal and illegal hunting in some Mediterranean and West African countries, collision with power lines and other infrastructure, and depletion of fish prey along migration routes. Satellite tagging has revealed that individual ospreys often show remarkable fidelity to specific wintering sites in West Africa - sites where habitat loss or disturbance can critically affect the bird's condition before the energy-demanding northward migration.