Sex and age dependent migration phenology of the Pied Flycatcher in a stopover site in the Carpathian Basin

Abstract Very little is known about Pied Flycatchers crossing the Carpathian Basin. We give a comprehensive picture about its migration based on the data collected during the past 26 years (1989–2014) at a stopover site in Hungary: (1) sex and age related phenological changes over the years, (2) sex, age and size dependent migration patterns during and (3) between migration periods, (4) sex and age composition in spring and in autumn and their change over years. The timing of spring migration shifted to earlier dates in the case of males, while that of females did not change implying an increasing rate of protandry. In autumn the timing did not change, but juveniles leave the area earlier than adults. The average wing length increased during the past decades in spring in the case of both sexes. In autumn, wing length did not change significantly during the years, but it increased during the seasons in all age and gender groups. The proportion of males is about 60% in spring and among juveniles in autumn, and it is around 39% in the adult group in autumn. The male ratio diminishes during spring, but it does not change during the autumn season. The average wing of adults is shorter in spring than in autumn. Based on this fact and the different sex ratios in the two seasons we may hypothesize that Pied Flycatchers are loop migrants on this area, and even the sexes of the same population take different routes.</jats:p