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Fuentes de Nava, Spain

Andueza M.,Institute of Biodiversity and Evolutionary Biology | Barba E.,Institute of Biodiversity and Evolutionary Biology | Arroyo J.L.,CSIC - Donana Biological Station | Feliu J.,Institute Investigacion en Recursos Cinegeticos IREC | And 13 more authors.
Ardea | Year: 2014

We determined the degree of connectivity in the Eurasian Reed Warbler Acrocephalus scirpaceus between breeding regions in central and northern Europe and stopover sites in Iberia, during the autumn migration. We used both recovery data and wing length analyses to achieve this. Biometric data were obtained during 2009 at 11 sampling localities in Iberia, which we amalgamated into four major migratory areas within the region (Central, Western, Eastern and Southwestern Iberia, hereafter CI, WI, EI, SW). From the EURING database, we selected birds captured at their breeding sites in Europe and recaptured in Iberia during the autumn migration. Reed Warblers passing through WI had shorter wings than those in CI, EI and SW, suggesting that birds in WI migrated shorter distances, a fact also supported by recovery data. Although Reed Warblers showed some population overlap when passing through Iberia, we found that birds passing through EI and CI came from areas further to the east (continental Europe) than those passing through WI (mainly British Isles), thus supporting parallel migration. Reed Warblers tended to converge in southwestern Iberia, suggesting an effect of nearby geographical barriers.

Andueza M.,Cavanilles Institute of Biodiversity and Evolutionary Biology | Barba E.,Cavanilles Institute of Biodiversity and Evolutionary Biology | Arroyo J.L.,CSIC - Donana Biological Station | Feliu J.,Institute Investigacion en Recursos Cinegeticos IREC | And 10 more authors.
Ornis Fennica | Year: 2014

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.

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