Suchergebnisse

et al. ; On their route to tropical Africa, European trans-Saharan migrants must cross two major geographical barriers, the Mediterranean Sea and the Sahara Desert, which necessitates the accumulation of large fuel loads.While northernAfrica is the chief region wheremost migrants gain fuel for the Sahara crossing, Iberia is a target area to gain fuel before the sea crossing existing between Europe andAfrica. Despite the large body of studies approaching the question of fuel accumulation before geographic barriers, it is still poorly known which factors apart from distance to a certain barrier shape the geographical pattern of fuel reserves. To investigate this question in detail we used data of first-year Reed Warblers from 12 localitieswithin Iberia during the autumnmigration period of 2009.We run linearmodels to analyze the effects of location in Iberia, date, and body size on bodymass variation at each migratory flyway (eastern, central and western Iberia). Flight ranges from each site were also calculated. Our results showed that ReedWarblers in Iberia had the necessary fuel needed to arrive in northernAfrica but not to tropical Africa. However, bodymass patterns varied depending on the geographical region (eastern, central or western Iberia).Date did not affect bodymass in central andwestern Iberia, but in eastern Iberia heavier birds tended to pass later. Thus, the factors shaping body mass of Reed Warblers in Iberia before the sea crossing to Africa seemed to be more complex than just the distance to this geographical barrier, with underlying stopover quality-associated factors possibly playing a relevant role. ; This research was funded by the Spanish Ministry of Education (pre-doctoral fellowship to MA), Basque Government (Txingudi Ringing Station), Gipuzkoa Administration (Txingudi Ringing Station), Caja de Ahorros del Mediterraneo (Pego-Oliva Park), Universidad Autónoma de Madrid, Consejería de Medio Ambiente of Autonomous Andalusian Government (Doñana Biological Station) Portuguese Foundation for Science and Technology (grant SFRH/BPD/40667/2007 awarded to JMN), Spanish Ministry of Science and Innovation (project CGL2010-21933-C02-02; EB and JSM) and also by the LIFE Nature project "Restoration and management of wetlands: SPA Canal de Castilla". ; Peer Reviewed