Inferring the migratory status of woodland birds usisng ringing data: the case of a constant-effort site located in the Iberian highlands.
Forskningsoutput: Tidskriftsbidrag › Artikel i vetenskaplig tidskrift
Understanding the spatiotemporal distribution of birds is crucial for effective management and conservation of their populations. However, we still have only limited knowledge not only of the wintering destinations of many Iberian breeding migrants but also of aspects as general as the migratory behaviour of the populations of many common avian species that breed in the Iberian highlands. We used bird-ringing data to shed light on the migratory status (migratory, partially-migratory or sedentary) of the breeding populations of 13 common species occurring year-round in a woodland located on an Iberian plateau (Garaio,Araba, Spain; 574 m.a.s.l.), where ringing activities have been carried out over the last 20 years. To assess the extent to which birds breeding on this site remain in the area during winter and/or are replaced by conspecifics coming from other areas, we analysed: (1) changes in relative abundance of birds between summer and winter, (2) the frequency of sedentary individuals (birds captured both in summer and winter period in the study area) in relation to the number of individuals captured only in summer (summer visitors) or in winter (wintering birds), and (3) variation in wing length among summer, wintering and sedentary birds. Our results revealed great variation among species in the intensity of migratory behaviour, and a general arrival of foreign conspecifics during the winter for most of the species studied. Likewise, our study represents an illustrative example of how long-term ringing can be used to shed light on the migratory status of bird populations.