The greater scaup is a diving duck that visits UK coasts and estuaries in winter from Arctic breeding grounds. Its welfare has improved since pollution reduction but remains tied to mollusc availability.
Scaup welfare illustrates the complexity of environmental improvements and wildlife welfare interactions. Historical scaup concentrations at Scottish distillery outfalls — where yeast and grain provided food enrichment — were a welfare-positive consequence of industrial pollution. As wastewater treatment improved under EU directives, scaup lost these winter food sources and populations declined. The welfare trade-off between clean water (good for most species and ecosystems) and loss of a specific anthropogenic food subsidy is unusual. Modern scaup welfare depends on natural mollusc beds on clean sandbanks — demonstrating that natural habitat provides long-term welfare stability compared to anthropogenic food subsidies.