Seasonal movements of Fennoscandian Blackbirds Turdus merula

Abstract

Recoveries provided by 15 European ringing schemes have been used to investigate the seasonal movements of Danish, Norwegian, Swedish and Finnish Blackbirds Turdus merula. All populations are partially migratory, estimated minimum migrant fractions being 16% (Denmark), 61% (Norway), 76% (Sweden) and 89% (Finland). Britain & Ireland receive an estimated 47%, 75%, 40% and 25% of the migrants from Denmark, Norway, Sweden and Finland respectively. Most movements to Britain & Ireland from Norway, and probably from Denmark also, are directly across the North Sea. Most Swedish Blackbirds migrate through Denmark; a minority travelling through Norway in autumn may return by the majority route in spring. Most Finnish Blackbirds migrate through Sweden, with a minority crossing the Gulf of Finland to more easterly parts of Europe. Swedish and Finnish Blackbirds tend to arrive later, and to winter farther south in Britain & Ireland, than do Norwegian birds. More adult than first-year Danish Blackbirds migrate, but no other age or sex differences can be confirmed. © 2002 British Trust for Ornithology.