DELAY OF THE AUTUMN MIGRATORY PERIOD IN THE BLACKCAP (SYLVIA-ATRICAPILLA) 1966-1993 - A REACTION TO GLOBAL WARMING

Mistnet data and wing-lengths of Blackcaps trapped at the northern border of the Alps on their way from northern Europe southward showed a similar but shifted migration pattern in the two periods 1966-78 and 1987-93. The onset of the migration has delayed about one five-day period, the median is six days later. Simultaneously, in northern Europe mean temperatures in autumn have raised. The later onset of migration is interpreted as the prompt microevolutionary reaction to advantages caused by the warming of climate.