Knowledge of species distributions is essential for informing policies on nature conservation and restoration. However, updating them on a regular basis and doing so in a harmonized manner at the international level is difficult. The European Bird Census Council integrated national monitoring data covering 5 years to update farmland bird distributions and assessed how they changed. We used these data on 50 farmland bird species to generate 10×10 km maps showing their probability of occurrence from 2018 to 2022. We produced these maps with weighted ensemble species distribution models. We also developed models for the previous 5 years and plotted the differences in probabilities of occurrence per 10 × 10-km area between the two periods as calibrated change maps. We evaluated model performance at continental and regional levels and interpreted changes in probability of occurrence in relation to known abundance trends. Models showed good predictive performance (mean AUC ≈ 0.84; mean squared error ≈ 0.13). Change estimates were reliable for 43 species (high accuracy, low bias), and distribution changes were positively correlated with independent abundance trends (Pearson's r ≈ 0.50). Thus, the distribution maps for the two periods accurately captured species' distribution patterns and their temporal changes for all species at the European scale and for the majority of species in all regions except southeastern Europe. Among the 43 species with reliable estimates, predicted occurrences declined for 33 species, increased for nine, and were the same for one species. For most species, the direction of change in distribution was consistent with changes in species overall abundance in the same period, except for four species. Overall, our results indicated a recent contraction of farmland bird distributions in Europe, highlighting the strong capacity of existing bird monitoring networks to provide continent-wide species maps that can be updated regularly.

The United Nations and European Union have set ambitious conservation goals to halt and reverse declines in biodiversity by protecting 30% of land and sea areas by 2030. Effective conservation planning requires evidence-based spatial prioritization to maximize the coverage of species within designated protected areas. Based on a pan-European database for occurrence and abundance of breeding birds collected in the 2010s, we applied the Zonation algorithm to identify key areas that would maximize the protection of ranges and populations for 435 species of breeding birds across Europe using either continental or national prioritization targets. When 30% of Europe's highest priority terrestrial areas were selected by the algorithm, 49% of species' ranges and 63% of species' populations were protected. When 10% and 30% of the highest priority lands were selected, compared with prioritization using occurrence data, prioritization using abundance data resulted in a higher percentage of species' populations, especially rare and range-restricted species, being represented for protected area coverage. Stratifying prioritization by habitat criteria greatly enhanced habitat-specific conservation efficiency, enabling coverage of over 80% of breeding bird species' populations in tundra, Mediterranean, and coastal habitats with a selection of 10% of the highest priority areas for each. Our prioritization supports international targets adopted under the Kunming-Montreal Global Biodiversity Framework by identifying key areas and providing a roadmap to guide optimal site protection and conservation planning in Europe.

Deposition of atmospheric N (nitrogen) is assumed to be a major cause of biodiversity decline in Europe. To date, few studies on the direct or indirect effects of N on bird species have been conducted. Using Swiss bird count data and habitat data, we analyzed the correlation of N deposition with numbers of territories of 112 breeding bird species. Fifty-five species had a negative correlation with N, and 21 had a positive correlation. Thirty-six species showed no clear linear relationship. Insectivorous and herbivorous species were more negatively associated with N deposition (insectivores: 23 species with well-supported negative correlation vs. 9 species with well-supported positive correlation; herbivores: 6 vs. 1) than omnivorous birds or birds feeding on vertebrates (2 with negative correlation vs. 2 with positive correlation and 1 with negative correlation vs. 1 with positive correlation, respectively). Species associated with forest (23 negative vs. 3 positive), human settlement and wetland (each 3 negative vs. 0 positive), and birds that could not be attributed to a single guild (3 negative vs. 1 positive) showed mainly a negative relationship with N deposition, whereas more positive than negative correlations were found for alpine (0 negative vs. 2 positive) and common farmland species (0 negative vs. 7 positive). Ground-nesting species were more negatively associated with N deposition (8 negative vs. 2 positive) than species that nest high aboveground (24 negative vs. 11 positive). The negative correlation of N deposition with territory numbers was slightly more pronounced in long-distance migrant species (9 negative vs. 3 positive) than in resident or short-distance migrants (23 negative vs. 10 positive). Rare species were excluded, likely biasing farmland bird results positively. We assumed that differences in the vegetation due to higher N inputs were the main cause for our results. Reduced plant diversity, altered vegetation structure, and more frequent mowing affect breeding habitat and availability of food (invertebrates and seeds) for birds. In Switzerland, airborne N deposition exceeds by far the critical loads for most ecosystems. Our results highlight the urgent need to reduce N deposition to protect a wide range of Swiss bird species.

Climate change has been associated with both latitudinal and elevational shifts in species’ ranges. The extent, however, to which climate change has driven recent range shifts alongside other putative drivers remains uncertain. Here, we use the changing distributions of 378 European breeding bird species over 30 years to explore the putative drivers of recent range dynamics, considering the effects of climate, land cover, other environmental variables, and species’ traits on the probability of local colonisation and extinction. On average, species shifted their ranges by 2.4 km/year. These shifts, however, were significantly different from expectations due to changing climate and land cover. We found that local colonisation and extinction events were influenced primarily by initial climate conditions and by species’ range traits. By contrast, changes in climate suitability over the period were less important. This highlights the limitations of using only climate and land cover when projecting future changes in species’ ranges and emphasises the need for integrative, multi-predictor approaches for more robust forecasting.

Species' range shifts and local extinctions caused by climate change lead to community composition changes. At large spatial scales, ecological barriers, such as biome boundaries, coastlines, and elevation, can influence a community's ability to shift in response to climate change. Yet, ecological barriers are rarely considered in climate change studies, potentially hindering predictions of biodiversity shifts. We used data from two consecutive European breeding bird atlases to calculate the geographic distance and direction between communities in the 1980s and their compositional best match in the 2010s and modeled their response to barriers. The ecological barriers affected both the distance and direction of bird community composition shifts, with coastlines and elevation having the strongest influence. Our results underscore the relevance of combining ecological barriers and community shift projections for identifying the forces hindering community adjustments under global change. Notably, due to (macro)ecological barriers, communities are not able to track their climatic niches, which may lead to drastic changes, and potential losses, in community compositions in the future.

Countries' agricultural systems have an important impact on biodiversity, for example bird populations. Here, we estimate such impacts by exploiting a natural experiment in the middle of Europe, where there is a naturally homogenous area that is divided into three countries: Switzerland, Germany, and France. These countries have markedly different agricultural systems and policies. Using a methodologically unified and unusually rich bird dataset available across these borders, both for the 2010s and 1990s, we analyze (a) whether there is a clear pattern that bird diversity systematically changes when crossing these borders and (b) whether this has changed over time. To assess bird populations, we focus on Shannon diversity, species richness and number of territories, as well as the individual effect on 29 common bird species. We find that Switzerland has systematically smaller and less diverse bird populations compared to Germany and France, driven entirely by agricultural differences. At the same time, we find that the difference between the countries was considerably more pronounced in the 1990s than in the 2010s. Yet, to reach the bird friendliness of Switzerland's neighboring countries, additional policy effort seems required, for example in the form of targeted agri-environmental payments.

Wetland bird species have been declining in population size worldwide as climate warming and land-use change affect their suitable habitats. We used species distribution models (SDMs) to predict changes in range dynamics for 64 non-passerine wetland birds breeding in Europe, including range size, position of centroid, and margins. We fitted the SDMs with data collected for the first European Breeding Bird Atlas and climate and land-use data to predict distributional changes over a century (the 1970s–2070s). The predicted annual changes were then compared to observed annual changes in range size and range centroid over a time period of 30 years using data from the second European Breeding Bird Atlas. Our models successfully predicted ca. 75% of the 64 bird species to contract their breeding range in the future, while the remaining species (mostly southerly breeding species) were predicted to expand their breeding ranges northward. The northern margins of southerly species and southern margins of northerly species, both, predicted to shift northward. Predicted changes in range size and shifts in range centroids were broadly positively associated with the observed changes, although some species deviated markedly from the predictions. The predicted average shift in core distributions was ca. 5 km yr−1 towards the north (5% northeast, 45% north, and 40% northwest), compared to a slower observed average shift of ca. 3.9 km yr−1. Predicted changes in range centroids were generally larger than observed changes, which suggests that bird distribution changes may lag behind environmental changes leading to ‘climate debt’. We suggest that predictions of SDMs should be viewed as qualitative rather than quantitative outcomes, indicating that care should be taken concerning single species. Still, our results highlight the urgent need for management actions such as wetland creation and restoration to improve wetland birds’ resilience to the expected environmental changes in the future.

Die Entwicklung der Verbreitung der Schweizer Brutvögel ist ein Spiegelbild unseres Umgangs mit Natur und Umwelt. Mit dem Brutvogelatlas 2013-2016 wurden die aktuellen Vorkommen, die Häufigkeit und die Höhenverbreitung aller Brutvögel der Schweiz und des Fürstentums Liechtenstein dokumentiert. Zusammen mit den drei früheren Brutvogelatlanten lassen sich damit die Veränderungen in der Schweizer Vogelwelt in den letzten 20 bis 60 Jahren aufzeigen. So weist, im Vergleich zu anderen Lebensraumgilden, der Bestandsindex der Waldvögel den positivsten Verlauf auf. Trotzdem gibt es auch im Wald gefährdete Vogelarten mit sehr kleinen und/oder abnehmenden Beständen. Es handelt sich primär um Arten, die auf hohe Alt- und Totholzmengen, lichte Wälder oder Waldränder mit breiten Übergangszonen zum Kulturland angewiesen sind.

Spatiotemporal patterns in biological communities are typically driven by environmental factors and species interactions. Spatial data from communities are naturally described by stacking models for all species in the community. Two important considerations in such multispecies or joint species distribution models (JSDMs) are measurement errors and correlations between species. Up to now, virtually all JSDMs have included either one or the other, but not both features simultaneously, even though both measurement errors and species correlations may be essential for achieving unbiased inferences about the distribution of communities and species co-occurrence patterns. We developed two presence-absence JSDMs for modeling pairwise species correlations while accommodating imperfect detection: one using a latent variable and the other using a multivariate probit approach. We conducted three simulation studies to assess the performance of our new models and to compare them to earlier latent variable JSDMs that did not consider imperfect detection. We illustrate our models with a large Atlas data set of 62 passerine bird species in Switzerland. Under a wide range of conditions, our new latent variable JSDM with imperfect detection and species correlations yielded estimates with little or no bias for occupancy, occupancy regression coefficients, and the species correlation matrix. In contrast, with the multivariate probit model we saw convergence issues with large data sets (many species and sites) resulting in very long run times and larger errors. A latent variable model that ignores imperfect detection produced correlation estimates that were consistently negatively biased, that is, underestimated. We found that the number of latent variables required to represent the species correlation matrix adequately may be much greater than previously suggested, namely around n/2, where n is community size. The analysis of the Swiss passerine data set exemplifies how not accounting for imperfect detection will lead to negative bias in occupancy estimates and to attenuation in the estimated covariate coefficients in a JSDM. Furthermore, spatial heterogeneity in detection may cause spurious patterns in the estimated species correlation matrix if not accounted for. Our new JSDMs represent an important extension of current approaches to community modeling to the common case where species presence-absence cannot be detected with certainty.

Capsule: We used data from different sources, developed and applied several estimation methods, and confronted the resulting estimates with species experts to achieve breeding size population estimates for all bird species currently breeding in Switzerland. Aims: Population size estimates of birds have a wide range of practical conservation uses. As part of the Swiss Breeding Bird Atlas 2013–2016, we aimed to update the national breeding population size estimates for all species. Methods: For very rare species and for rare colonial breeders, the estimates are complete enumerations based on annual compilations of all breeding records. For the other species, we applied extrapolation methods of varying complexity, either based on the data from the 2318 one-kilometre squares where territory mapping for the breeding bird atlas was conducted, or based on all breeding period records from 2013 to 2016. In some cases, these data were combined with regional population estimates. For most species, we considered the results of several different approaches to determine the final estimate. Here, we give an overview of the applied procedures, along with some examples. We provide access to code that allows the reproduction of our analyses. Results: We present population size estimates for all 210 species and 4 subspecies of birds breeding in Switzerland. The total population size of all Swiss breeding birds amounts to just over ten million breeding pairs. The largest share consists of species with forest as their main habitat. Conclusions: A main challenge was to decide species by species which approaches lead to the most reliable results. The application of a rule-based selection approach alone is dangerous. Comparing the outcome of different approaches and involvement of species experts are crucial steps to getting sound population size estimates.

Site attachment and displacement of adult Somatochlora alpestris were studied by means of mark-release-resighting during two years at two clusters of ponds (A, B) ca 8 km distant from each other on opposite slopes of Prattigau Valley in the Swiss Alps. Data on 127 marked tenerals in 1998 and 92 in 2000 at (A) were obtained. Additionally, in 1998, 187 and in 2000, 23 matures were marked at (A) and 162 at (B). No marked individuals were detected during the prereproductive period in the surroundings of the breeding sites. 14.0% of the males and 7.1% of the females marked as tenerals in 1998 were resighted at water subsequently. In 2000 the corresponding resighting rate was significantly lower due to a cold spell (4.0% and 2.4%, respectively). Only one male was resighted for the first time at its emergence pond. The resighting rates of marked adults at (A) were 59.2% (males) and 28.6% (females) in 1998, but only 5.6% and 0% in 2000, respectively. The corresponding resighting rates at (B) in 2000 amou...

Male-biased operational sex ratios are very common in sexually mature dragonflies. These may be due to differential survival or differences in time spent at the breeding site by the sexes. Because most studies are carried out at the breeding site, these two processes can be measured as survival rates or recapture rates using modern capture–mark–recapture methods. We marked 66 female and 233 male Coenagrion puella, and 137 female and 347 male Ischnura elegans during three capture periods spread over 18 days. Each time an animal was recaptured it was re-marked so that the capture history of any captured animal could be readily identified. We recaptured 131 C. puella and 55 I. elegans at least once. We used the Cormack–Jolly–Seber model to estimate the daily probability of survival and recapture. The probability of recapture was, on average, more than three times higher for male C. puella (0.489) than females (0.133) with significant day to day variation. The daily probability of survival did not differ significantly between the sexes (0.860), with no significant variation among days. In contrast, in I. elegans the probability of recapture did not differ between the sexes (0.139 for the first 5 days; between 0.032 and 0.287 for the final 3 days), but the daily probability of surviving was much higher for males (0.812) than for females (0.579). Assuming that the sex ratio was unity at sexual maturity, the recapture and survival rates predicted well the sex ratio of the sample of C. puella but predicted more males than were observed in the sample of I. elegans. This suggests that male I. elegans may suffer higher mortality than females in the immature stage.

Hunting pratices which have been recorded in wetlands of the Dinaric Karst in the Federation of Bosnia and Herzegovina during bird surveys, 2006 - 2009, are documented. Data on hunting methods are presented and their possible impacts on waterbird behaviour, population numbers, and on the conservation significance of wetland habitats in Livanjsko polje, Neretva Delta (Hutovo blato Nature Park and wetlands near Gabela) and Mostarsko blato are discussed. Recommendations for the installation of hunting ban areas as well as considerations on the implementation of national law and international standards in nature protection are given.