Search

Artificial food subsidies like landfills generate very strong impacts on animal ecology and spatial behavior. Landfills indeed have been considered to be one of the most influential factors explaining the very fast recovery of many colonial waterbird populations worldwide, as documented for the white stork Ciconia ciconia. More recently, the increase of rice fields in some regions have also been argued to be part of an influencial process underlying the spatio-temporal distribution patterns of this species over many areas in southern Europe. It remains unknown whether these two habitat factors play an important role at explaining the spatial distribution pattern of the white stork and, more particularly, whether colony funding or colony size is dependent on them. Using data from a census conducted in 2018, we aimed to assess the effect of distance to a landfill or to rice fields, among other habitat factors, on the breeding colony size of a white stork population in northern Spain. Larger colonies were more likely to appear in trees or cliff, but less likely in buildings or other artificial substrates. They were also significantly more likely with decreasing distance to landfill, and when the habitat was dominated by dry cropland and meadows close to water bodies. Rice fields did not seem to have any significant effect. Our findings fit with those from other regions in Europe, and highlight the effect landfills have on population dynamics and spatial ecology for those species which are able to feed on this type of food subsidy. Our results also show that the main habitat cover over large geographic scales still plays a role independently of landfills. The European agricultural policies associated with the type and management of crops, and the Common Agricultural Policy in particular, will still have a decisive role for the species. [ABSTRACT FROM AUTHOR]

Aim: In temperate mountain ranges, sharp spatial variations in habitat heterogeneity and climate provide a perfect study setup to assess genetic and phenotypic differentiation in bird populations. In this paper, we analysed morphological divergence patterns across geographical and environmental gradients, in correlation with genetic differentiation and geographical isolation, in the breeding grounds of a long‐distance migratory passerine. Location: Northwestern Iberian mountains. Taxon: The Iberian bluethroat, Luscina svecica azuricollis. Methods: We collected a sample of 625 Iberian bluethroats across their whole breeding range to measure body weight and tarsus length, as well as wing length and pointedness. Morphological differentiation across geographical (latitude and elevation) and environmental (climate and vegetation) gradients was assessed using generalized linear mixed models. Additionally, the role of genetic distance and geographical isolation as drivers of morphological differentiation was evaluated with Mantel tests. Results: Bird morphology varied significantly with latitude and elevation, but not with climate or vegetation. In the case of latitude, morphological differences in body size were contrary to Bergmann's rule statements. All biometric and morphometric variables diverged among localities. A similar trend was found for genetic clusters, except for wing shape. Body weight and wing length were both correlated with geographic distance, while only the former varied with genetic differentiation. The greatest genetic and phenotypic differentiation was detected in the southernmost mountain range, that holds the most geographically isolated genetic group. Main conclusion: Evidence suggests that the strong morphological differentiation observed in the Iberian breeding bluethroat across geographical gradients results from the combination of unambiguous deterministic forces, such as ecological selection mechanisms, and other factors, such as geographical isolation, that can be either deterministic, stochastic or both, all acting at different scales. [ABSTRACT FROM AUTHOR]

Wildlife conservation policies directed at common and widespread, but declining, species are difficult to design and implement effectively, as multiple environmental changes are likely to contribute to population declines. Conservation actions ultimately aim to influence demographic rates, but targeting actions towards feasible improvements in these is challenging in widespread species with ranges that encompass a wide range of environmental conditions. Across Europe, sharp declines in the abundance of migratory landbirds have driven international calls for action, but actions that could feasibly contribute to population recovery have yet to be identified. Targeted actions to improve conditions on poor-quality sites could be an effective approach, but only if local conditions consistently influence local demography and hence population trends. Using long-term measures of abundance and demography of breeding birds at survey sites across Europe, we show that co-occurring species with differing migration behaviours have similar directions of local population trends and magnitudes of productivity, but not survival rates. Targeted actions to boost local productivity within Europe, alongside large-scale (non-targeted) environmental protection across non-breeding ranges, could therefore help address the urgent need to halt migrant landbird declines. Such demographic routes to recovery are likely to be increasingly needed to address global wildlife declines. [ABSTRACT FROM AUTHOR]

During the winter, Bramblings Fringilla montifringilla are known for concentrating in huge communal roosts, normally situated along a NE–SW axis from west Russia to France in southern Europe. Irruptions of Bramblings in Iberia are rare and normally only in an attenuated form. Exceptionally, in November of 2010 a large roost of c 900,000 Bramblings formed in the Basque mountains of northern Iberia. We caught and ringed Bramblings from this roost from November 2010 to February 2011, and compared age and sex ratios, wing length and body mass to data reported in the literature. Overall, first-year birds comprised more than half the roost and the sex ratio in first-year birds was biased to females. This is in agreement with the prediction that first-year birds and females migrate to regions further south than males and adult birds. Wing length was constant across the season, but not body mass. Body mass was also negatively correlated with temperature and positively correlated with snowfall. [ABSTRACT FROM AUTHOR]

Compared to other animal movements, prospecting by adult individuals for a future breeding site is commonly overlooked. Prospecting influences the decision of where to breed and has consequences on fitness and lifetime reproductive success. By analysing movements of 31 satellite- and GPS-tracked gull and tern populations belonging to 14 species in Europe and North America, we examined the occurrence and factors explaining prospecting by actively breeding birds. Prospecting in active breeders occurred in 85.7% of studied species, across 61.3% of sampled populations. Prospecting was more common in populations with frequent inter-annual changes of breeding sites and among females. These results contradict theoretical models which predict that prospecting is expected to evolve in relatively predictable and stable environments. More long-term tracking studies are needed to identify factors affecting patterns of prospecting in different environments and understand the consequences of prospecting on fitness at the individual and population level., (© 2023. The Author(s), under exclusive licence to Springer-Verlag GmbH Germany, part of Springer Nature.)

Wildlife conservation policies directed at common and widespread, but declining, species are difficult to design and implement effectively, as multiple environmental changes are likely to contribute to population declines. Conservation actions ultimately aim to influence demographic rates, but targeting actions towards feasible improvements in these is challenging in widespread species with ranges that encompass a wide range of environmental conditions. Across Europe, sharp declines in the abundance of migratory landbirds have driven international calls for action, but actions that could feasibly contribute to population recovery have yet to be identified. Targeted actions to improve conditions on poor-quality sites could be an effective approach, but only if local conditions consistently influence local demography and hence population trends. Using long-term measures of abundance and demography of breeding birds at survey sites across Europe, we show that co-occurring species with differing migration behaviours have similar directions of local population trends and magnitudes of productivity, but not survival rates. Targeted actions to boost local productivity within Europe, alongside large-scale (non-targeted) environmental protection across non-breeding ranges, could therefore help address the urgent need to halt migrant landbird declines. Such demographic routes to recovery are likely to be increasingly needed to address global wildlife declines.