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Simple Summary: Urban areas are constantly increasing, as well as human activities related to them. This can lead to an effect in bird populations due to the alterations caused in nature. According to the latest national censuses in Spain, House Sparrow and Eurasian Tree Sparrow populations are decreasing. In this study, we used ringing station data from Spain to assess the tendency of both populations over a two-decade period of time. We also tried to determine the relation of these two populations and their breeding success with the habitat composition. The data analysis confirmed the decreasing trend in both species. However, Eurasian Tree Sparrow showed signs of increasing presence in urban areas, contrary to our predictions. Furthermore, the productivity of both populations remained stable over the study years. Urban areas are constantly increasing, which can cause an effect in bird populations since human activities lead to nature alterations. Populations of House Sparrow (Passer domesticus) and Eurasian Tree Sparrow (Passer montanus) have been decreasing in Spain according to the latest national censuses in Spain. In this study, we tried to assess the population trend over more than two decades using ringing data from Spanish constant effort sites, as well as to determine the population and breeding success proxy in relation to habitat composition at landscape level. We analysed the data and confirmed the decreasing trend in the two species. However, Eurasian Tree Sparrow showed signs of increasing presence in urban areas. Furthermore, the productivity remained stable over sampling sites and years, meaning that the causes of the decreasing populations are affecting both adult and juvenile individuals. [ABSTRACT FROM AUTHOR]

Volunteer-based (i.e., citizen science) monitoring schemes constitute a basic piece for the long-term monitoring of bird populations. This work aims to determine whether we can reduce the sampling effort, in terms of number of sampling journeys per yearly campaign, of a long-term breeding bird monitoring ringing scheme in Spain. With that goal, we test to what extent a progressive decreasing number of journeys (from the original effort of seven visits in a season to four visits) will have an impact on indices of adult abundance and/or productivity. Reducing the number of visits did not affect the estimate of abundance of adults, either if we consider a full-period population change index which takes into account the numbers of the last survey year in relation to the first one in the series, or if we consider annual trends (with a yearly index which is referred to a reference value—1—fixed for the first survey year). By contrast, the estimation of productivity was severely affected by a reduction of the sampling effort. We attribute this result to the fact that juveniles were captured late in the season and, therefore, eliminating the last sampling journeys produced biased estimates. It is proposed that the program can reduce the effort from seven to six visits (i.e., one visit per fortnight from May to July) with little impact on the estimation of abundance and productivity. Additionally, the program may admit sites with a sampling effort of four visits, from May to June, useful to estimate trends on abundance of adults and their survival rates (but not on productivity). With this dual option, we expect to increase the spatial coverage of the program and the robustness and representativeness of at least two of the indices calculated through the program, since we might both increase the number of participants (i.e., sites) and the type of habitats covered. [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]

The management of mixed municipal waste can have an impact on wildlife and ecosystems. Previous studies have investigated how opportunistic species like gulls can react very fast to new landfills; however, the impact of landfill closure on bird populations is less investigated. Yet, there is a need to understand how fast and to what extent, animal populations can be adapted to new scenarios where the waste will not be deposited in landfill sites anymore. The aim is to determine the influence of landfill closures on apparent survival of a resident Yellow‐legged Gull (Larus michahellis) population, used as a model species showing short‐distance foraging movements, and with a high dependence on local food subsidies. Complementarily, we built some basic population growth models in order to determine how potential changes in survival (before/after landfill closure) will impact on population growth rate. Using a data set of 4,437 Yellow‐legged Gull chicks ringed in four colonies over a period of 13 years, we obtained evidence supporting that the apparent survival was affected by landfill closure, especially if the landfill was located within a buffer of 10 km around the colony. Landfill closure affected the survival of first‐year gulls (with a mean decrease of ~ 0.5–0.36), but not of older birds. Consequently, we did not detect a remarkable effect of landfill closures on population growth rate, probably due to the lack of effect on adult survival rates except for one of the surveyed colonies, where we found an annual decline of 7%. [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]

Background: The dynamics and structure of many bird communities are changing due to the global warming and changes in the land use and management. The Ebro Valley constitutes one of the chief wintering areas for several passerine species in Iberia, and the reed beds spread across this Valley concentrate huge numbers of birds that use them to roost, while the surrounding agricultural areas serve as main foraging habitats. The aims of this work are (1) to quantify how variable a non-breeding passerine bird community associated to a reed bed area in the Ebro Valley is, and, (2) to test for the effect of weather on possible annual fluctuations in species' proportions at a regional/local scale. Methods: We used for that ringing data collected at Badina de Escudera lagoon (Navarra) over a 12-year period. Results: Though, overall, the assemblage did not vary strongly among years (most similarity values were > 0.8), we still found a significant linear effect of year on the proportion of captures of Reed Buntings (Emberiza schoeniclus), i.e., the dominant species detected in our passerine community. The increasing loss of weight of Reed Buntings in the community was due to a progressive decrease in its abundance. Conclusions: The structure and diversity of passerine community in Badina Escudera was not influenced by meteorological conditions at a local scale, suggesting that local weather would not have an impact on numbers of Reed Buntings in winter. [ABSTRACT FROM AUTHOR]

Transients can have a severe impact on demographic parameter estimates. For instance, the use of visual counts or number of captures at a ringing station to assess indices of abundance may result in biased over-estimates due to the presence of transients. With the aim of contributing to understand transient dynamics within the Eurasian breeding passerines, we used data collected at a ringing station (2010–2018) in a reed bed area of northern Spain designed to sample breeding reed warblers Acrocephalus scirpaceus. Specifically, we tested for the effect of season on the proportion of transients and explored for correlations of rainfall regimens at both the winter and breeding quarters on annual fluctuations of the proportion of transients. The proportion of transients was not constant across the season; it showed relatively small values until mid-June, coinciding with arrivals from Africa and the peak of the breeding period, and then increased very steeply (means > 60%) already in July, with even ca. 90% of transients captured during the second half of July, coinciding with an influx of birds that would be already passing through the area en route to winter quarters in Africa. Analyses to estimate population trends of breeding reed warblers should take this circumstance into account; otherwise, models may show odd patterns, due to a mixture of local and non-local population that might show dissimilar demographic trends. Limiting data analyses to the breeding sub-period having a lesser amount of transients is recommended. Annual fluctuations in the proportion of transients did not correlate with any of the rainfall values in Africa (winter quarters) or meteorological conditions in Europe (NAO index; rainfall values at a local level), though it might be that we did not choose the appropriate variable/period/location combination. Our data set was relatively small; hence, this may hamper us to detect weak linear trends. Future research should contribute to answer this question and deep into the factors driving transience dynamics in bird populations. [ABSTRACT FROM AUTHOR]

The article focuses on a study on the creation of the Orueta Lagoon influenced the waterbird diversity in Urdaibai, Spain. According to the author, artificial wetlands can mitigate the loss and degradation of natural wetlands. The study concludes that the lagoon was able to provide new and attractive habitat for several waterbird species as it contributed to 26.8% of total abundance in population.