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Cardador L.,University of Barcelona | Sarda-Palomera F.,Catalan Ornithological Institute ICO | Carrete M.,Pablo De Olavide University | Carrete M.,CSIC - Donana Biological Station | Manosa S.,University of Barcelona
Diversity and Distributions | Year: 2014

Aim: The knowledge of both potential distribution and habitat suitability is fundamental for conservation planning and management of a variety of taxa world-wide. Species distribution models (SDMs) are increasingly applied as predictive tools for these purposes. Such models are based on the concept of ecological niche and assume that species distribute themselves based on niche spaces defined by climate and habitat features. However, this assumption can be violated due to the existence of pure spatial range constraints, a factor rarely accounted for in SDMs, particularly for highly mobile species. We analyse whether pure distance effects, niche-based environmental responses or a combination of both factors can play an important role in limiting the large-scale distribution of highly mobile species. Location: Spain, southern Europe. Methods: We modelled the spatial distribution of an expanding raptor species, the marsh harrier Circus aeruginosus, in Spain. We implemented one conventional statistical method (generalized linear model) and one nonparametric technique (maximum entropy, Maxent) using a large dataset on marsh harrier occurrence (n = 1586) in two different periods of the annual cycle, that is breeding and wintering seasons. We developed models that included environmental variables and that either ignored or incorporated spatial constraints using spatial eigenvector mapping (spatial filters). Results: By comparing model accuracy, we found evidence that the distribution of marsh harriers in Spain was spatially constrained beyond environmental variables and that the effect of spatial constraints varies depending on the period of their annual cycle. Main conclusions: Contrary to the equilibrium postulate, our results support the prediction that environmental specializations do not necessarily result in complete habitat matching due to dispersal limitations. Thus, ignoring spatial constraints in SDMs can lead to misunderstandings of the ecological mechanisms that explain species range limits. © 2013 John Wiley & Sons Ltd. Source

Sanchez-Donoso I.,EBD Group | Rodriguez-Teijeiro J.D.,University of Barcelona | Quintanilla I.,EBD Group | Jimenez-Blasco I.,University of Barcelona | And 5 more authors.
Evolutionary Ecology Research | Year: 2014

Background: The common quail, Coturnix coturnix, is a migratory bird hunted extensively across Europe. To satisfy this hunting interest, thousands of farm-reared birds are restocked every year. However, restocked individuals are not common quail but hybrids with domestic Japanese quail, C. japonica. Interbreeding between restocked and native birds in the wild allows the entry of alien alleles to the native populations, which could lead to the loss of adaptive phenotypes and behaviours, such as migratory drive. Sedentary individuals may face wintering conditions to which they are not adapted, suffering higher mortality. Some individuals have been observed to remain in northern latitudes during winter. Question: Does game restocking contribute to the sedentarization of the common quail population? Method: We sampled 42 quail during the autumn migration and 50 quail during winter in Spain. We genetically analysed them using a set of autosomal microsatellites and also sequenced a fragment of the mitochondrial DNA control region. We evaluated the proportion of admixed quail found and compared it with that previously found in a breeding population. Results: None of the migratory quail were admixed individuals, although two of them showed introgression of Japanese mitochondrial DNA. Among wintering quail, only three individuals had a genetic composition compatible with a farm origin, while the rest were common quail. Thus, the proportion of admixed quail during winter was not higher than during the breeding season. Conclusion: Restocking individuals with domestic Japanese quail ancestry is not directly associated with the presence of quail during winter in northern latitudes. The almost complete absence of individuals of farm origin among the migratory and wintering quail populations indicates that the vast majority of the restocked individuals probably die soon after release. However, the genetic composition of the breeding population has already shown that some survive until the next breeding season and introgress their genes into the wild population. © 2014 Ines Sanchez-Donoso. Source

Barriocanal C.,University of Girona | Barriocanal C.,Catalan Ornithological Institute ICO | Montserrat D.,Catalonian Forest Fire Prevention Service | Robson D.,Catalan Ornithological Institute ICO
International Journal of Biometeorology | Year: 2011

The wood warbler (Phylloscopus sibilatrix) is a migratory species in the western Mediterranean wintering in the Gulf of Guinea region, West Africa. In autumn and spring, this species, along with the populations breeding in Ireland and Britain, uses the Italian peninsula as its main axis of migration. From the data of captured birds at several ringing stations in the western Mediterranean (Balearic Islands and coastal Iberian Peninsula), we analyzed capture rates of the species during spring migration from 1993 to 2007. Based on the selection of days with a significant number of captures and those without captures, we analyzed the effect of wind direction over the western Mediterranean to determine a relationship between winds and the number of captures. From a total of 663 wood warblers captured between 1993 and 2007, a total of 31 days have been selected as significant days with a high number of captures, and 31 days have been selected as no-capture days. On days of maximum captures, winds coming from an easterly direction, i.e. Algeria and Tunisia, were dominant, indicating days with a clear eastern component. Contrary to expected results, captures were also made on days when the wind direction was predominantly from a northerly direction. Analysis of the origin of the winds in north eastern Spain (western Mediterranean) revealed that the majority of northerly winds originated from Africa and not from Europe as is usual for this region. Days or periods selected as no-capture days were characterized by winds coming from a northerly (European origin) or westerly direction. © 2011 The Author(s). Source

Robson D.,Catalan Ornithological Institute ICO | Barriocanal C.,Catalan Ornithological Institute ICO | Barriocanal C.,University of Girona
Journal of Animal Ecology | Year: 2011

+Summary: 1.Climate change has been associated with shifts in the timing of biological events, including the spring arrival of migratory birds. Early arrival at breeding sites is an important life-history trait, usually associated with higher breeding success and therefore, susceptible to selection and evolution in response to changing climatic conditions. 2.Here, we examine the effect of changes in the environmental conditions of wintering and passage areas on the mean passage time of 13 trans-Saharan passerines during their spring migration through the western Mediterranean over the 15years from 1993 to 2007. 3.We found that most of the species studied have been advancing the timing of their passage in recent years. However, annual variation in the mean date of passage was positively correlated with vegetation growth (measured as the normalized difference vegetation index [NDVI]) both in the Sahel (the region of departure) and in northern Africa (the passage area). Thus, migration dates were delayed in years with high primary productivity in passage and wintering zones. All species seem to respond similarly to NDVI in the Sahel; however, late migrants were less affected by ecological conditions in northern Africa than those migrating earlier, suggesting differences based on species ecology. 4.Mean timing of passage was not related to the North Atlantic Oscillation (NAO), El Niño-Southern Oscillation (ENSO), temperature or NDVI in the species-specific wintering areas (the overwintering region) when analysed in combination with the other covariates. 5.Our findings show that ecological conditions in the winter quarters (specifically the Sahel) and en route are relevant factors influencing trends in the passage dates of trans-Saharan migratory birds on the southern fringe of Europe. Possible long-term consequences for late arriving spring migrants are discussed. © 2010 The Authors. Journal compilation © 2010 British Ecological Society. Source

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