Dispersal of the Central European population of the Eurasián spoonbill Platalea leucorodia
Published: Volume 62.2, December 2015. Pages 219-236.
Using the Hungarian spoonbill colour-ringing scheme database, which spans 12 years of 11 cohorts (2003-2013), we clarify dispersal patterns of spoonbills in the Carpathian Basin, a part of the Pannonian biogeographical region. We found that during the course of one year, approximately 25% of adult spoonbills disperse and are seen 100 km beyond their natal area. However,this rate is roughly 20% if we analyse only the core of the breeding season (May and June). The extent of dispersal in the Hungarian population is greater than that in the Atlantic population, where the proportion of birds showing natal site fidelity is higher. This finding could be explained by increased unpredictability in the Carpathian Basin in the temporal and spatial distribution of food resources and in the water-supply of wetlands, as well as in conditions at breeding locations there. These factors may also explain the high dispersal rate of adults in continental wetland habitats compared to coastal ones. Furthermore, the minimum distance to natal colony decreased with increasing age of age groups when age group was included as a categorical variable,indicating that immature birds in the Pannonian spoonbill population tend to disperse further than adults. This also implies a higher degree of fidelity to natal areas among adult individuals. Our data showthat post-fledging dispersal of juveniles starts from late May and isnon-directional, and at least 12% of all ringed individuals were seen 100 km from their natal colonies before their autumn migration.The occurrence of a large number of long-distance dispersers of all age groups in the Carpathian Basin suggests the need for ongoing wetland restoration at landscape scales.