International cooperative research program (field work in 1992-1996) on Bewick's Swans, on ecological limitations in the annual cycle, mainly during periods of high energy expenditure, i.e. breeding and migration. Relates to feeding ecology (both terrestrial and aquatic (pondweed tubers) vegetation, annual variation in climatic conditions. Aims at: 1. understanding limiting factors for population size (production of young and survival) 2. understanding migratory behaviour in this large species 3. protecting crucial areas for breeding, moulting and migrating for this vulnerable swan population Research activities: - Field expeditions (2-5 months) to the Arctic, covering the entire breeding season, including moult and pre-migratory fattening - Running a ringing project with over 1,000 individually marked birds - Data analysis and publications