Whooper Swan Cygnus c. cygnus population dynamics in Finland

Abstract

Population parameters are described, based mainly on earlier studies or their primary data. Thirty percent of the spring population are breeding birds. No big flocks of non-breeders are found in Finland. Population density has been low. The density was highest in the 1970s in the northern boreal zone and declined to north and south. In northern Finland the habitat may become a limiting factor in the near future. Population growth has been 14.2% +/-0.7 per year in southern Finland and 7.5% in northern Finland. The constant rate of increase (11.0% +/-0.2 per year) throughout the whole country has continued since 1950. The recent population is about 5,000 birds. The summer distribution now covers the whole country. The dispersal has been 25 km per year. Local populations have dispersed 2 km per year. Gross annual mortality rate is 15%. Probable mean annual mortality rates of first year, secondyear and older birds 30, 25 and 12% respectively.