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Arteaga, Spain

Arizaga J.,Aranzadi science Society | Musseau R.,BioSphere Environnement | Musseau R.,British Petroleum | Laso M.,Aranzadi science Society | And 4 more authors.
Bird Study | Year: 2015

Capsule: The effects of playback use on number of captures, recaptures, fuel load, and age and sex ratios, and so potential bias in stopover studies in migrant Bluethroats was investigated. Playback promoted biases in the number of captures (although this was site-dependent) and fuel load. We strongly advise against the systematic use of playback to sample Bluethroats at constant effort sites or other type of ringing station, especially if studying fuel loads. © 2015 British Trust for Ornithology. 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


Arizaga J.,Aranzadi science Society | Unamuno E.,Urdaibai Bird Center | Azkona A.,Aranzadi science Society | Laso M.,Aranzadi science Society | Peon P.,GIA Asturias Torquilla. Alonso de Ojeda 2
Revista Catalana d'Ornitologia | Year: 2014

It is generally accepted that bird species/populations that migrate longer distances undertake less extensive moults than those that migrate shorter distances. First-year Bluethroats of two subspecies with different migratory distances (Luscinia svecica namnetum and L. s. cyanecula; the latter migrating the further of the two) were captured during the autumn migration period in 2012 in northern Iberia to test whether birds with longer migratory distances display less extensive post-juvenile moults than those that migrate less far. As predicted, the L. s. namnetum captured displayed more extensive moult in their greater coverts than the L. s. cyanecula but not in their tertials. However, due to the large degree of overlap between the two subspecies, moult extent does not seem to be a useful marker for separating these two subspecies. Source


The spread of exotic tree plantations on the North Atlantic coast of the Iberian peninsula raises concern regarding the conservation of avian biodiversity as current trends suggest this region might become a monoculture of Australian Eucalyptus species. To shed more light on the factors promoting differences in avian communities between and within exotic tree (Monterey Pine Pinus radiata and Eucalyptus spp.) plantations and native forests in the Urdaibai area (northern Spain), this study aimed to explore (1) how the type of habitat and vegetation characteristics affect bird species richness and the settlement of some particular species during the breeding period, (2) if some reproductive parameters (i.e. egg-laying date and clutch size) vary among habitats in a generalist bird species (the Great Tit Parus major), and (3) the existence of differences among habitats in the abundance of a key food resource on which some insectivorous birds are expected to rely upon for breeding (i.e. caterpillars). Our results confirmed that Eucalyptus stands house the poorest bird communities, and identified understory development as an important determinant for the establishment of titmice species. Furthermore, we found that exotic trees showed lower caterpillar abundance than native Oak trees (Quercus robur), which might contribute to explain observed differences among habitats in bird abundance and richness in this region. However, we did not find differences among habitats in egg-laying date and clutch size for the Great Tit, suggesting that the potential costs of breeding in exotic tree plantations would occur in later stages of the reproductive period (e.g. number of nestlings fledged), a circumstance that will require further research. © 2013 Museu de Ciències Naturals de Barcelona. Source


Arizaga J.,Urdaibai Bird Center | Unamuno E.,Urdaibai Bird Center | Clarabuch O.,Catalan Institute of Nanoscience and Nanotechnology | Azkona A.,Urdaibai Bird Center
Animal Biodiversity and Conservation | Year: 2013

Migration is highly energy-demanding and birds often need to accumulate large fuel loads during this period. However, original habitat at stopover sites could be affected by invasive exotic plants outcompeting native vegetation. The impact of exotic plants on the stopover behavior of migrant bird species is poorly understood. As a general hypothesis, it can be supposed that habitat change due to the presence of exotic plants will affect migrants, having a negative impact on bird abundance, on avian community assemblage, and/or on fuel deposition rate. To test these predictions, we used data obtained in August 2011 at a ringing station in a coastal wetland in northern Iberia which contained both unaltered reedbeds (Phragmites spp.) and areas where the reedbeds had been largely replaced by the invasive saltbush (Baccharis halimifolia). Passerines associated with reedbeds during the migration period were used as model species, with a particular focus on sedge warblers (Acrocephalus schoenobaenus). The saltbush promoted a noticeable change on bird assemblage, which became enriched by species typical of woodland habitats. Sedge warblers departed with a higher fuel load, showed a higher fuel deposition rate, and stayed for longer in the control zone than in the invaded zone. Invasive plants, such as saltbush, can impose radical changes on habitat, having a direct effect on the stopover strategies of migrants. The substitution of reedbeds by saltbushes in several coastal marshes in Atlantic Europe should be regarded as a problem with potential negative consequences for the conservation of migrant bird species associated with this habitat. © 2013 Museu de Ciències Naturals de Barcelona. Source

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