Species attributes are commonly used to infer impacts of environmental change on multiyear species trends, e.g. decadal changes in population size. However, by themselves attributes are of limited value in global change attribution since they do not measure the changing environment. A broader foundation for attributing species responses to global change may be achieved by complementing an attributes-based approach by one estimating the relationship between repeated measures of organismal and environmental changes over short time scales. To assess the benefit of this multiscale perspective, we investigate the recent impact of multiple environmental changes on European farmland birds, here focusing on climate change and land use change. We analyze more than 800 time series from 18 countries spanning the past two decades. Analysis of long-term population growth rates documents simultaneous responses that can be attributed to both climate change and land-use change, including long-term increases in populations of hot-dwelling species and declines in long-distance migrants and farmland specialists. In contrast, analysis of annual growth rates yield novel insights into the potential mechanisms driving long-term climate induced change. In particular, we find that birds are affected by winter, spring, and summer conditions depending on the distinct breeding phenology that corresponds to their migratory strategy. Birds in general benefit from higher temperatures or higher primary productivity early on or in the peak of the breeding season with the largest effect sizes observed in cooler parts of species' climatic ranges. Our results document the potential of combining time scales and integrating both species attributes and environmental variables for global change attribution. We suggest such an approach will be of general use when high-resolution time series are available in large-scale biodiversity surveys.
Abstract Each species generally has a close relationship with one or more habitats and can therefore be classified as either specialist or generalist. We studied whether specialist and generalist species are spatially distributed independently of each other. Repeating the analysis for 100 of the most frequent terrestrial bird species recorded over the 10 000 sampled sites of the French Breeding Bird survey, we found that specialists were more abundant if the rest of the community was specialized, and that the inverse was also true. This pattern was far subtler than just a simple dichotomy: most species actually presented a maximum abundance at a value of community specialization similar to their own level of specialization. Bird communities appear very well defined along a specialist–generalist gradient. We believe this pattern becomes more apparent with habitat degradation. The consequences on both ecological services and community resilience may well be considerable.
Abstract Species assemblages and natural communities are increasingly impacted by changes in the frequency and severity of extreme climatic events. Here we propose a brief overview of expected and demonstrated direct and indirect impacts of extreme events on animal communities. We show that differential impacts on basic biological parameters of individual species can lead to strong changes in community composition and structure with the potential to considerably modify the functional traits of the community. Sudden disequilibria have even been shown to induce irreversible shifts in marine ecosystems, while cascade effects on various taxonomic groups have been highlighted in Mediterranean forests. Indirect effects of extreme climatic events are expected when event-induced habitat changes (e.g. soil stability, vegetation composition, water flows altered by droughts, floods or hurricanes) have differential consequences on species assembled within the communities. Moreover, in increasing the amplitude of trophic mismatches, extreme events are likely to turn many systems into ecological traps under climate change. Finally, we propose a focus on the potential impacts of an extreme heat wave on local assemblages as an empirical case study, analysing monitoring data on breeding birds collected in France. In this example, we show that despite specific populations were differently affected by local temperature anomalies, communities seem to be unaffected by a sudden heat wave. These results suggest that communities are tracking climate change at the highest possible rate.
Le lek est l'un systemes d'appariement polygynes des plus originaux et des plus spectaculaires. Les males paradent de maniere agregee, et les femelles visitent les arenes principalement dans un but de fertilisation. Le premier travail a ete de verifier si les agregats formes par les males d'outarde canepetiere tetrax tetrax, pouvaient reellement etre assimiles a des leks, notamment dans le milieu fragmente et changeant que constitue la plaine cerealiere. L'agregation des males a ete prouvee, et les males ne defendent pas de ressources critiques pour monopoliser l'acces aux femelles. Le lek des outardes est eclate : les territoires des males couvrent quelques dizaines d'hectares. Dans un deuxieme temps, les criteres de choix du partenaire par la femelle sont envisages. Les leks semblent etre d'excellents modeles pour l'etude de la selection sexuelle, car les femelles choisissent les males sur la base de caracteristiques intrinseques, avec le plus souvent un choix consensuel. Il s'est d'abord agi de determiner les traits des males montrant une forte variabilite inter-individuelle mais une faible variabilite intra-individuelle, de potentielles cles utilisees par les femelles. Les correlats de ces traits avec l'attractivite des males vis-a-vis des femelles sont ensuite etudies, alors que la preference des femelles pour le caractere symetrique d'un trait de plumage est verifiee experimentalement. Il semble bien que le choix du partenaire soit base sur un faisceau de criteres comme la symetrie du collier blanc ou le taux de parade. Enfin, l'utilisation de leurres a permis d'etudier les mecanismes de formation des leks chez cette espece, en testant les predictions des quatre principaux modeles avances pour expliquer l'evolution des leks : les modeles du point chaud, du virtuose, de la preference des femelles et du trou noir. Dans le cas des leks eclates chez l'outarde, aucun de ces modeles n'est exclu, plusieurs memes sont verifies. Ces modeles non exclusifs agissent probablement a differents niveaux (evolution initiale, localisation, fonctionnement des leks). Les connaissances acquises au cours de ces travaux ont ete d'une grande utilite dans un programme europeen de conservation de l'espece.
The highabundance and impact on honeybees of the Asian hornet Vespa velutina var. nigrithorax have caused great concern among European public authorities and beekeepers. The species was reported for the first time in France in 2005 and spread out across 66 European districts (ca. 360 000 km 2 ) within 7 years (INPN, 2012; Rome et al., 2013). Its arrival was reported in 2010 in Northern Spain, in 2011 in Portugal and Belgium and in 2013 in Italy. Its wider expansion in Europe is soon to be expected.We discuss here the advances of the collaborative research project initiated in 2008 in France.1. The potential invasion risk of the species was assessed using modeling tools of climatic suitability (Villemant et al., 2011, Barbet-Massin et al., 2013). Interestingly, the potential distribution of V. v. nigrithorax matches the current distribution of another invasive social wasp, the German yellow jacket, Vespula germanica (Beggs et al., 2011).2. Apartfrom reported damages on hives, little is known on the biology of V. velutina throughout its native Asian range. In the invaded range, the impact of V. v. nigrithorax on the diversity and biomass of the invertebrate fauna is under study. Preliminary results reported a diversified diet varying among seasons and habitat types.3. The genetic variability between individuals of V. v. nigrithorax from France and Asia was assessed in order to describe the history of its invasion. The analysis has evidenced a low variability among the invasive population, which indicates a single introduction of one or more queens. The sampling of specimens in France and in the area of origin has been extended to confirm this hypothesis and the most probable area of origin (Arca, 2012).Given the potential economic and biological impact of V. v. nigrithorax, a better understanding of its invasion dynamics is necessary to predict regions at risk, hence to help with planning dedicated control measures, a prerequisite for replacing the reactive nature of current solutions with a proactive, predictive approach.
