Back from a Predicted Climatic Extinction of an Island Endemic: A Future for the Corsican Nuthatch

The Corsican Nuthatch (Sitta whiteheadi) is red-listed as vulnerable to extinction by the IUCN because of its endemism, reduced population size, and recent decline. A further cause is the fragmentation and loss of its spatially-restricted favourite habitat, the Corsican pine (Pinus nigra laricio) forest. In this study, we aimed at estimating the potential impact of climate change on the distribution of the Corsican Nuthatch using species distribution models. Because this species has a strong trophic association with the Corsican and Maritime pines (P. nigra laricio and P. pinaster), we first modelled the current and future potential distribution of both pine species in order to use them as habitat variables when modelling the nuthatch distribution. However, the Corsican pine has suffered large distribution losses in the past centuries due to the development of anthropogenic activities, and is now restricted to mountainous woodland. As a consequence, its realized niche is likely significantly smaller than its fundamental niche, so that a projection of the current distribution under future climatic conditions would produce misleading results. To obtain a predicted pine distribution at closest to the geographic projection of the fundamental niche, we used available information on the current pine distribution associated to information on the persistence of isolated natural pine coppices. While common thresholds (maximizing the sum of sensitivity and specificity) predicted a potential large loss of the Corsican Nuthatch distribution by 2100, the use of more appropriate thresholds aiming at getting closer to the fundamental distribution of the Corsican pine predicted that 98% of the current presence points should remain potentially suitable for the nuthatch and its range could be 10% larger in the future. The habitat of the endemic Corsican Nuthatch is therefore more likely threatened by an increasing frequency and intensity of wildfires or anthropogenic activities than by climate change

Relating Habitat and Climatic Niches in Birds

Predicting species' responses to the combined effects of habitat and climate changes has become a major challenge in ecology and conservation biology. However, the effects of climatic and habitat gradients on species distributions have generally been considered separately. Here, we explore the relationships between the habitat and thermal dimensions of the ecological niche in European common birds. Using data from the French Breeding Bird Survey, a large-scale bird monitoring program, we correlated the habitat and thermal positions and breadths of 74 bird species, controlling for life history traits and phylogeny. We found that cold climate species tend to have niche positions in closed habitats, as expected by the conjunction of the biogeographic history of birds' habitats, and their current continent-scale gradients. We also report a positive correlation between thermal and habitat niche breadths, a pattern consistent with macroecological predictions concerning the processes shaping species' distributions. Our results suggest that the relationships between the climatic and habitat components of the niche have to be taken into account to understand and predict changes in species' distributions

Prédire l'impact potentiel des changements climatiques sur la distribution et la diversité des oiseaux européens

Les conséquences du changement climatique actuel sur la biodiversité font l objet de nombreuses études depuis la fin des années 1990. Certaines d entre elles ont mis en évidence un déplacement de l aire de distribution des espèces. Or, les changements climatiques prédits pour la fin du siècle devraient s accélérer. L objectif de la thèse était de prédire l impact potentiel de ces changements climatiques futurs sur la distribution et la diversité des oiseaux européens. Une première partie de mes travaux a porté sur des aspects méthodologiques ayant pour objectif l amélioration des prédictions d aires de distribution actuelles. Je me suis ensuite intéressée aux problèmes pouvant résulter de la projection sous scénario futur, lorsque la niche actuelle est biaisée, mais également à l importance de considérer les capacités de dispersion des espèces. Dans un deuxième temps, l application de ces différentes méthodes au niveau monospécifique m a permis de mettre en évidence que la Sittelle corse devrait plus souffrir de la destruction de son habitat que des changements climatiques. Au niveau multispécifique, l impact des changements globaux devrait être très important sur les aires de reproduction de l ensemble des oiseaux terrestres nicheurs européens ainsi que sur les aires d hivernage sub-sahariennes des passereaux européens. A partir de ces prédictions pour l ensemble d un groupe sur toute l Europe, l étude des assemblages d espèces révèle que les assemblages futurs sur tout le bassin méditerranéen ne seront analogues à aucun assemblage actuel. Enfin, l étude portant sur l évolution prédite de diversité fonctionnelle s avère complémentaire de celle sur la richesse spécifiquePARIS-BIUSJ-Biologie recherche (751052107) / SudocSudocFranceF

Localisation of the study area.

<p>Localisation of the study area.</p

Distribution of forests in Corsica.

<p>Light green stands for mixed forests, dark green for coniferous forests and medium green for broad-leaved forests.</p

Characteristics of the current and future distributions of the Corsican Nuthatch according to the threshold used to transform the pines distributions into binary distributions used as variables for the modelling.

<p>(TSS: True Skill Statistic, LPT: Lowest Probability Threshold).</p

Current and future distributions modelled for the Corsican pine and the Maritime pine.

<p>Current (a) and future (b) distributions predicted for the Corsican pine according to the considered threshold. Current (c) and future (d) distributions predicted for the Maritime pine according to the considered threshold.</p

The economic cost of control of the invasive yellow-legged Asian hornet

Since its accidental introduction in 2003 in France, the yellow-legged Asian hornet Vespa velutina nigrithorax is rapidly spreading through France and Europe. Economic assessments regarding the costs of invasive species often reveal important costs from required control measures or damages. Despite the rapid invasion of the Asian yellow-legged hornet in Europe and potential damage to apiculture and pollination services, the costs of its invasion have not been evaluated yet. Here we aimed at studying the costs arising from the Asian yellow-legged hornet invasion by providing the first estimate of the control cost. Today, the invasion of the Asian yellow-legged hornet is mostly controlled by nest destruction. We estimated that nest destruction cost €23 million between 2006 and 2015 in France. The yearly cost is increasing as the species keeps spreading and could reach €11.9 million in France, €9.0 million in Italy and €8.6 million in the United Kingdom if the species fills its current climatically suitable distribution. Although more work will be needed to estimate the cost of the Asian yellow-legged hornet on apiculture and pollination services, they likely exceed the current costs of control with nest destruction. It could thus be worth increasing control efforts by aiming at destroying a higher percentage of nests

Representation of the data used in the study.

<p>(a) Corsican Nuthatch data, (b) Corsican pine data, (c) Maritime pine data. For the Corsican pine red circles represents data from coppices (not used in the niche modelling but to determine further LPT).</p