Natal dispersal and migratory behaviour of juvenile kingfishers (Alcedo atthis) from Central Europe

Abstract

The costs and benefits of post-fledging dispersal give rise to diverse dispersal strategies in birds; however, the underlying patterns and mechanisms remain poorly understood in many species. We investigated natal dispersal and migration in juvenile Common Kingfishers (Alcedo atthis) originating from Czech and Slovak populations. Natal dispersal was examined by monitoring two breeding populations between 2014 and 2018. Of the 1,911 nestlings ringed during this period, 19 juveniles were subsequently recaptured, yielding a recovery rate of 0.36%. Most individuals (74%) settled within 20 km of their natal sites (median dispersal distance = 10.5 km), with no significant differences observed between populations or sexes. To assess large-scale migratory patterns, we supplemented our field data with ringing recoveries obtained from the Czech and Slovak Bird Ringing Centres (n = 264). In the last 50 years, migratory individuals (62%) slightly outnumbered resident birds (38%). The proportion of migrants and residents differed significantly among decades, with migrants increasingly predominating over time. Migration distance was significantly associated with fledging date: individuals fledging earlier in the breeding season (May–July) tended to migrate longer distances than those fledging later (August–September). Clear geographical variation in migratory direction was also detected. Juveniles from Bohemian and Slovak populations predominantly migrated southwest, whereas birds from Moravia generally migrated southward. Most kingfishers originating from Bohemia wintered in Western Europe, while individuals from Moravia and Slovakia were more likely to overwinter in southern Italy, the Balkans, and North Africa. It appears that juvenile Common Kingfishers exhibit a flexible migratory strategy shaped by both breeding phenology, which affects migration distance, and location of breeding sites determining migratory direction.