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Arizaga J.,Aranzadi Society of science | Alonso D.,Aranzadi Society of science | Cortes J.A.,SEO Malaga Ringing Group | Eggenhuizen T.,Vogelringgroep de Grauwe Gans | And 9 more authors.
Ardeola | Year: 2015

Understanding the migratory connectivity of migrant species is fundamental to their effective conservation. Analysis of individual traits that can vary geographically, such as biometrics and stable isotopic values of tissues, can help establish migratory connections. The bluethroat Luscinia svecica is a species of conservation concern in Europe (Annex I Birds Directive). Our aim was to identify the possible migratory connectivity of bluethroats Luscinia svecica breeding in central and western Europe (subspecies L. s. namnetum, L. s. azuricollis and L. s. cyanecula in part) with their wintering areas in southern Europe and Africa using biometric and stable isotopic (δ2H) analyses. Overall, the morphological and stable isotopes analyses provided two clusters of localities, one for the Atlantic French, Portuguese and Moroccan localities, corresponding to the breeding and winter quarters of L. s. namnetum, and another for the remaining localities (Spain, The Netherlands, Germany and Senegal), corresponding to the ranges of L. s. azuricollis and L. s. cyanecula. Migratory connectivity of L. s. namnetum is strong but it is much weaker for the other two subspecies. Biometric data were positively correlated to the stable isotope values, suggesting that the results derived from both methodological approaches lead to similar conclusions. Source


Wojczulanis-Jakubas K.,University of Gdansk | Jakubas D.,University of Gdansk | Foucher J.,Association pour la Connaissance et la Recherche Ornithologique Loire et Atlantique ACROLA | Dziarska-Palac J.,Association pour la Connaissance et la Recherche Ornithologique Loire et Atlantique ACROLA | And 2 more authors.
Naturwissenschaften | Year: 2013

Relatively little attention has been paid to sex differences in the migration of birds in autumn. We studied the autumn migration strategy of molecularly sexed males and females in the globally threatened aquatic warbler Acrocephalus paludicola. We captured 176 birds at a stopover site in the Loire estuary at Donges, France. The median date for the passage of adults was 8 days earlier in males than females, although the timing of migration in first-year males and females was similar. This indicates that males, who are without parental duties, can start their migration earlier than females and first-year birds. Adults were significantly heavier than immature birds but did not have higher fat scores. In both age categories, more males (two to three times more) were captured. However, various factors (including tape-luring) can affect observed sex ratio. © 2013 The Author(s). Source


Arizaga J.,Aranzadl Science Society | Andueza M.,Aranzadl Science Society | Azkona A.,Aranzadl Science Society | Dugue H.,Association pour la Connaissance et la Recherche Ornithologique Loire et Atlantique ACROLA | And 8 more authors.
Alauda | Year: 2014

The Aquatic Warbler Acrocephalus paludicola is one of the most threatened passerines in the world and the only under risk of extinction in mainland Europe. The goal of this work is to determine the relevance of wetlands of the Bay of Biscay for the Aquatic Warbler, during the autumn migration period. To test this we used ringing data on migrants caught at reedbeds Phragmites spp. in six sites using a common sampling protocol, during the autumn passage of 2011. The standardized number of captures tended to decrease from North to South in France (from 1.8 to 0.3 captures/100 m of mist nets/d), and it was very low in northern Iberia (< 0.2 captures/1 00 m of mist nets/d). The percentage of captures of Aquatic Warbler in relation to all Acrocephalus was 1.5% but it differed between stations, with higher-than-expected values at two wetlands from southwestern France (4.2% and 3.7%). The proportion of first-year birds and the mean fuel load tended to decrease from North to South in France (analyses not done for Iberia due to the small sample sizes). All this is discussed under the point of view of the identification of target stopover places for the Aquatic Warbler and its strategy of migration in the Bay of Biscay, considering that a single sampling year was here used. Source


Jakubas D.,University of Gdafisk | Wojczulanis-Jakubas K.,University of Gdafisk | Foucher J.,Association pour la Connaissance et la Recherche Ornithologique Loire et Atlantique ACROLA | Dziarska-Palac J.,Association pour la Connaissance et la Recherche Ornithologique Loire et Atlantique ACROLA | Dugue H.,Association pour la Connaissance et la Recherche Ornithologique Loire et Atlantique ACROLA
Ardeola | Year: 2014

The aquatic warbler Acrocephalus paludicola is the only globally threatened passerine breeding in Europe. We studied morphometric traits of 176 individuals captured at one of the key European autumn stopover sites, the Loire estuary on the Atlantic coast of France, in relation to age (first-year and older) and sex (based on molecular determination). We found significant sex differences in wing length, third primary feather length and body mass, with males being longer-winged and heavier than females; adult females also had deeper bills. However, high overlap in all measurements between the sexes meant the best discriminant functions based on wing length and bill depth (adults) and wing length (inmatures) correctly classified only 87% and 75% of individuals, respectively. The mean potential non-stop flight range of autumn staging birds at the Loire estuary with high fuel load was estimated at 1,178 km for adults and 926 km for immatures. We conclude that in autumn migrant aquatic warblers probably do not fly directly to wintering grounds in west Africa. Instead they gain significant body mass for onward migration at a few key stopover sites in western Europe and the southern Mediterranean region. Conservation of a series of important refuelling stopover sites, especially wet grassland habitats, along the migration route is therefore essential for effective protection of the aquatic warbler. Source

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