Wintering bird communities are tracking climate change faster than breeding communities

Global climate change is driving species' distributions towards the poles and mountain tops during both non-breeding and breeding seasons, leading to changes in the composition of natural communities. However, the degree of season differences in climate-driven community shifts has not been thoroughly investigated at large spatial scales. We compared the rates of change in the community composition during both winter (non-breeding season) and summer (breeding) and their relation to temperature changes. Based on continental-scale data from Europe and North America, we examined changes in bird community composition using the community temperature index (CTI) approach and compared the changes with observed regional temperature changes during 1980-2016. CTI increased faster in winter than in summer. This seasonal discrepancy is probably because individuals are less site-faithful in winter, and can more readily shift their wintering sites in response to weather in comparison to the breeding season. Regional long-term changes in community composition were positively associated with regional temperature changes during both seasons, but the pattern was only significant during summer due to high annual variability in winter communities. Annual changes in community composition were positively associated with the annual temperature changes during both seasons. Our results were broadly consistent across continents, suggesting some climate-driven restructuring in both European and North American avian communities. Because community composition has changed much faster during the winter than during the breeding season, it is important to increase our knowledge about climate-driven impacts during the less-studied non-breeding season.Peer reviewe

Unravelling migration connectivity reveals unsustainable hunting of the declining ortolan bunting

In France, illegal hunting of the endangered ortolan bunting Emberiza hortulana has been defended for the sake of tradition and gastronomy. Hunters argued that ortolan buntings trapped in southwest France originate from large and stable populations across the whole of Europe. Yet, the European Commission referred France to the Court of Justice of the European Union (EU) in December 2016 for infringements to legislation (IP/16/4213). To better assess the impact of hunting in France, we combined Pan-European data from archival light loggers, stable isotopes, and genetics to determine the migration strategy of the species across continents. Ortolan buntings migrating through France come from northern and western populations, which are small, fragmented and declining. Population viability modeling further revealed that harvesting in southwest France is far from sustainable and increases extinction risk. These results provide the sufficient scientific evidence for justifying the ban on ortolan harvesting in France.Peer reviewe

Declining population trends of European mountain birds

Mountain areas often hold special species communities, and they are high on the list of conservation concern. Global warming and changes in human land use, such as grazing pressure and afforestation, have been suggested to be major threats for biodiversity in the mountain areas, affecting species abundance and causing distribution shifts towards mountaintops. Population shifts towards poles and mountaintops have been documented in several areas, indicating that climate change is one of the key drivers of species' distribution changes. Despite the high conservation concern, relatively little is known about the population trends of species in mountain areas due to low accessibility and difficult working conditions. Thanks to the recent improvement of bird monitoring schemes around Europe, we can here report a first account of population trends of 44 bird species from four major European mountain regions: Fennoscandia, UK upland, south-western (Iberia) and south-central mountains (Alps), covering 12 countries. Overall, the mountain bird species declined significantly (-7%) during 2002-2014, which is similar to the declining rate in common birds in Europe during the same period. Mountain specialists showed a significant -10% decline in population numbers. The slope for mountain generalists was also negative, but not significantly so. The slopes of specialists and generalists did not differ from each other. Fennoscandian and Iberian populations were on average declining, while in United Kingdom and Alps, trends were nonsignificant. Temperature change or migratory behaviour was not significantly associated with regional population trends of species. Alpine habitats are highly vulnerable to climate change, and this is certainly one of the main drivers of mountain bird population trends. However, observed declines can also be partly linked with local land use practices. More efforts should be undertaken to identify the causes of decline and to increase conservation efforts for these populations.Peer reviewe

Effets des variations temporelles et spatiales des contraintes sur les systèmes écologiques, implications pour l'étude des scénarios de biodiversité

Les modèles de projection visant à comprendre les effets des changements globaux sur la biodiversité souffrent du manque d'un cadre théorique solide. Ce cadre devrait pouvoir apporter des réponses au sujet des modalités d'action des contraintes associées aux changements globaux sur les communautés biologiques à différentes échelles de temps et d'espace, ainsi que sur les outils (indicateurs) pertinents à utiliser pour diagnostiquer l'état des systèmes étudiés. Mon approche est basée sur l analyse de trois modèles. (1) Dans un premier modèle théorique de simulation, nous nous sommes focalisés sur l utilisation des ressources abiotiques par une communautés d espèces en compétition, et les effets de différents types de contraintes sur le système à l équilibre. Ce modèle a abouti à une réflexion sur la Théorie Neutre de la Biodiversité et a permis de proposer un nouveau cadre théorique d'étude des changements globaux selon trois axes : les contraintes directionnelles ou stochastiques, les contraintes spécifiques ou globales, les contraintes directes ou indirectes. (2) Le second modèle théorique simule le comportement d'un réseau trophique dans lequel les individus consommateurs peuvent adapter leur stratégie alimentaire en fonction de la disponibilité des ressources biotiques, que nous soumettons à une analyse de sensibilité. Cette analyse nous a permis de mettre en évidence le paramètre le plus sensible d'un réseau trophique, la diversité spécifique des producteurs primaires. (3) Le troisième modèle, empirique, est le couplage entre un module spatialisé individu-centré et un jeu de données d'inventaires floristiques standardisés. Il a permis de comprendre l'effet de la variabilité de la qualité de la matrice paysagère sur la structuration de méta-communautés en milieu urbain et de proposer de nouvelles méthodes de mesure de la connectivité des habitatsPARIS-BIUSJ-Biologie recherche (751052107) / SudocSudocFranceF

Predicting the fate of French bird communities under agriculture and climate change scenarios

The use of forward scenarios to forecast the environmental implications of potential changes in climate and land use is a useful tool for policy development. In this paper, we projected the potential responses of bird communities to both climate and agricultural changes. We created four scenarios of agricultural changes (current trends, biofuel development, livestock extensification and agricultural extensification), each developed at national or regional level of policy-making. We further considered three climatic scenarios (A1B, A2 and B1) from among the IPCC 4th Assessment Report scenarios. We assessed changes in bird communities based on the predicted changes in agricultural land use and climatic suitability using various indicators, including the European Farmland Bird Indicator (FBI) and the Community Specialisation Index (CSI). We found that trends in the different indicators differed greatly from each other depending on the agricultural scenarios and policy-making scale. Our results suggest that public policies that promote extensive agricultural practices are more appropriate for improving the fate of bird communities in agricultural landscapes, especially with the regionalisation of agricultural policy. These results provide a readily accessible visualisation of the potential impacts of land use and climate change on farmland bird communities

Forecasting the Effects of Land Use Scenarios on Farmland Birds Reveal a Potential Mitigation of Climate Change Impacts

Climate and land use changes are key drivers of current biodiversity trends, but interactions between these drivers are poorly modeled, even though they could amplify or mitigate negative impacts of climate change. Here, we attempt to predict the impacts of different agricultural change scenarios on common breeding birds within farmland included in the potential future climatic suitable areas for these species. We used the Special Report on Emissions Scenarios (SRES) to integrate likely changes in species climatic suitability, based on species distribution models, and changes in area of farmland, based on the IMAGE model, inside future climatic suitable areas. We also developed six farmland cover scenarios, based on expert opinion, which cover a wide spectrum of potential changes in livestock farming and cropping patterns by 2050. We ran generalized linear mixed models to calibrate the effects of farmland cover and climate change on bird specific abundance within 386 small agricultural regions. We used model outputs to predict potential changes in bird populations on the basis of predicted changes in regional farmland cover, in area of farmland and in species climatic suitability. We then examined the species sensitivity according to their habitat requirements. A scenario based on extensification of agricultural systems (i.e., low-intensity agriculture) showed the greatest potential to reduce reverse current declines in breeding birds. To meet ecological requirements of a larger number of species, agricultural policies accounting for regional disparities and landscape structure appear more efficient than global policies uniformly implemented at national scale. Interestingly, we also found evidence that farmland cover changes can mitigate the negative effect of climate change. Here, we confirm that there is a potential for countering negative effects of climate change by adaptive management of landscape. We argue that such studies will help inform sustainable agricultural policies for the future

Common birds during winter in the face of urbanization, foraging ecology questioned thanks to an original citizen science scheme (BirdLab)

Supplementary feeding of birds during the winter is a widespread phenomenon in temperate countries. While such practice can boost individuals' winter survival, not all species are likely to use bird feeders. We were particularly interested in examining if feeders on private gardens adjacent to areas impacted by agriculture could benefit farmland birds. Since 2014, the French Museum of Natural History started an ambitious citizen science schemes named BirdLab to observe the bird communities and the intra- and inter-specific interactions on a pair of birdfeeders by asking participants to reproduce the movements (arrival, feeder switch, and leaving) of each bird on two identical birdfeeders (platform or tube), on their smartphone or tablet by drag and drop small characters representing species, for a protocol of exactly 5 minutes. Four seasons after, this with more than 25000 five minutes' samples that observe around 500000 birds of 27 easily recognisable species among the most common species that used the birdfeeders in France.  Thus, after work to verify that the expertise level of contributors does not affect the quality of data provided by this citizen science scheme, we use this big and well-standardised dataset to study winter bird diversity at feeders at the national level of France. In particular, we examine whether the proportions of artificial and agricultural territories, forests and semi-natural environments, wetlands and water areas in the buffer zone of 500 m around the feeders affect the avian diversity multifaceted indicators (as the number of visits, species richness, trophic index, and Shannon's index). As expected, the diversity of species recruited to feeders increases with the presence of natural elements in the gardens such as trees and edges but also it diminishes with urbanisation, and this even for low gradients of urbanisation. Nevertheless, our results point to a clear synergy between agricultural territories and urban areas around the gardens, with diversity increasing in urban areas adjacent to agricultural territories. Our result supports the hypothesis that private gardens may participate in the conservation of declining farmland species, and with some precautions to limit the risks associated to the local increasing bird densities on feeders (predator attack, epidemic risk), they offer an alternative source of seeds to granivorous species, particularly in farmland intensive landscape which does not provide food for animals during the whole winter. Furthermore, this innovative application and citizen science encourages reconnection to nature and allows highly standardized data production by novice naturalists. In addition, the data provided will make it possible to question the species interactions in the bird feeder context.peerReviewe

Potential of bat pass duration measures for studies of bat activity

<p>Acoustic detectors have become increasingly used by bat workers to investigate bat ecology and assess the impacts of anthropogenic pressures. Within these studies, the metric used, ‘bat activity’, is based on the number of bat passes, without considering the bat pass duration (i.e. each event of a bat detected within the range of an ultrasonic detector). We expected that bat pass duration may contain information about site quality in terms of foraging potential. Because bats are expected to have a more sinuous trajectory and slower velocity when they exhibit foraging behaviour, as opposed to commuting behaviour, we hypothesize a longer bat pass duration in favourable habitats; during seasons with important energetic demands; or during night peak activity. We used datasets from a large-scale acoustic bat survey (<i>n</i> = 2890 sites), with a total of 24,597 bat pass measures from 6 taxa, and performed GLMM modelling. We detected a significant effect of habitat type on bat pass duration for five taxa. Shorter bat pass durations were detected at the beginning of the night. We detected longer pass durations during the lactation period or just before hibernating, while weather conditions or ageing and wear of the detector rarely influenced bat pass duration. Bat pass duration appears to be a simple and easy measure for position calls on a gradient between commuting vs. foraging behaviour. We suggest that the traditional measure of bat activity may be weighted by bat pass duration by giving more weight to events with potentially stronger links to foraging behaviour.</p

How do urban green space designs shape avian communities? Testing the area-heterogeneity trade-off

Abstract: In cities, green areas are essential for biodiversity conservation, with land cover heterogeneity being a decisive factor. Yet, as heterogeneity increases for a given green area, the patch size of land covers automatically decreases, as the area available for individual species, especially habitat specialist species. This relationship, known as the area-heterogeneity trade-off, is expected to lead to a unimodal relationship between species richness and land cover heterogeneity, and contrasted effects between species according to their level of urban avoidance. We investigated the potential consequences of this trade-off on birds in green areas selected along an urban intensity gradient in six European cities. Using a European database on bird occurrences in nesting habitats, we defined a continuous gradient of urban avian avoidance. We confirmed the marked area-heterogeneity trade-off in urban green areas but found no effect of land cover heterogeneity on total avian richness at green area level. However, both land cover heterogeneity and patch size were positively associated with richness of urban avoider species, indicating that urban avoiders fared better in green areas with large and heterogeneous patches. Total richness was also higher in green areas surrounded by an urban matrix composed of a variety of land covers. To protect urban bird avoiders, which are most at risk in cities, green area managers and urban planners should thus be aware that land cover heterogeneity is not a panacea if patch sizes are too small. To conserve avian richness, we stress the importance of maintaining large vegetated areas as well as heterogeneity in land covers within the urban matrix

Declining populations of European mountain birds

Mountain areas often hold special species communities and are thus in the high priority list of conservation. Changes in human land use, such as grazing pressure and afforestation, and especially in climate have been suggested as major threats for biodiversity in the mountain areas, because species have difficulties to find new suitable habitats in circumstances. Despite the special species communities very little is known about the population trends of species in mountain areas [1,2]. Here we studied population trends of 44 bird species in four major European mountain regions: Fennoscandia, UK upland, south-western (including Pyrenees) and south-central mountains (including Alps), covering 12 countries. We predicted that more species should show negative trends due to unfavourable environmental conditions. We also predicted the declines to be more severe in mountain specialists compared to mountain generalists, which are also found in the lowlands. We found in accordance with our predictions that mountain bird species have experienced significant declines (c. -7%) during 2002–2014. Mountain specialists showed a significant c. -10% decline in population numbers, and the slope for generalists was also negative but not significantly so. The slopes of specialists and generalists did not differ from each other. Fennoscandian and south-western populations were on average declining, but UK or south-central mountain birds showed on average stable situations. Our findings support the hypothesis that mountain species are declining. Thus more efforts should be undertaken to identify the causes of decline in order to protect these populations. [1] Lehikoinen, A., Green, M., Husby, M., Kålås, J. A. &amp; Lindström, Å. 2014: Common montane birds are declining in northern Europe. Journal of Avian Biology 45: 3–14. [2] Scridel, D., Brambilla, M., Martin, K., Lehikoinen, A., Iemma, A., Anderle, M., Jähnig, S., Caprio, E., Bogliani, G., Pedrini, P., Rolando, A., Arlettaz, R. &amp; Chamberlain, D. E.: The effect of climate change on holarctic mountain and upland birds: a review and meta-analysis. Ibis (in press).peerReviewe