Moult migration of Latvian Whooper Swans Cygnus cygnus

摘要

This study is the first to demonstrate moult migration in the Whooper Swan Cygnus cygnus. Of cygnets hatched in Latvia and known to be alive about 99% left the country to moult somewhere else in their 2~(nd)-6~(th) calendar year. One-sixth of these were re-sighted in Finland during moult migration; these were solely from western Latvia. Moulting sites were recorded for nine individuals, of which seven had been marked with neck collars and two had satellite transmitters. Five of these nine swans moulted in Latvia, one in Estonia and three in the Arkhangelsk Region of Russia. Distances between sites of ringing and moulting varied between 0 and 1,455 km. All individuals were recorded moulting as two-or three-year old birds. Those moulting in Russia left Latvia/Estonia before 20 June and returned after mid September.