Landscape composition and life-history traits influence bat movement and space use: Analysis of 30 years of published telemetry data

Aim Animal movement determines home range patterns, which in turn affect individual fitness, population dynamics and ecosystem functioning. Using temperate bats, a group of particular conservation concern, we investigated how morphological traits, habitat specialization and environmental variables affect home range sizes and daily foraging movements, using a compilation of 30 years of published bat telemetry data. Location Northern America and Europe. Time period 1988–2016. Major taxa studied Bats. Methods We compiled data on home range size and mean daily distance between roosts and foraging areas at both colony and individual levels from 166 studies of 3,129 radiotracked individuals of 49 bat species. We calculated multi-scale habitat composition and configuration in the surrounding landscapes of the 165 studied roosts. Using mixed models, we examined the effects of habitat availability and spatial arrangement on bat movements, while accounting for body mass, aspect ratio, wing loading and habitat specialization. Results We found a significant effect of landscape composition on home range size and mean daily distance at both colony and individual levels. On average, home ranges were up to 42% smaller in the most habitat-diversified landscapes while mean daily distances were up to 30% shorter in the most forested landscapes. Bat home range size significantly increased with body mass, wing aspect ratio and wing loading, and decreased with habitat specialization. Main conclusions Promoting bat movements through the landscape surrounding roosts at large spatial scales is crucial for bat conservation. Forest loss and overall landscape homogenization lead temperate bats to fly further to meet their ecological requirements, by increasing home range sizes and daily foraging distances. Both processes might be more detrimental for smaller, habitat-specialized bats, less able to travel increasingly longer distances to meet their diverse needs

Assessment of the impacts of motorway fragmentation on bats at different spatiel-temporal scales

Les infrastructures linéaires de transports (ILT), dont les routes, sont une des principales causes du déclin de la biodiversité. Bien que les évaluations environnementales permettent de limiter ce déclin, la séquence "Eviter, Réduire et Compenser" les impacts peine à s'appliquer pleinement. En effet, la séquence ERC fait bien souvent appel à des données qualitatives en oubliant les processus biologiques et/ou écologiques et leur échelle spatio-temporelle. L'impact des routes est globalement bien documenté pour plusieurs groupes biologiques, hormis pour les chauves-souris, pourtant susceptibles d'être très fortement affectées. Par ailleurs, leur protection stricte nécessite leur prise en compte dans la séquence ERC. Pour étudier l’impact des routes, et notamment des autoroutes, je me suis concentré sur l’étude des chauves-souris afin de mesurer et quantifier leur magnitude. Pour cela, différentes méthodes développées et réutilisables par les différents acteurs de terrain seront présentées. Ainsi, dans un premier temps, je me suis intéressé à une méthode de traitement des données issues d'écoutes acoustiques et à une méthode de valorisation. Dans un second temps, nous avons appliqué ces méthodes afin (i) de connaitre quels étaient les impacts des routes sur les populations de chauves-souris et (ii) afin d'évaluer l'efficience des mesures de réductions engagées pour réduire ces impacts. Nos principaux résultats montrent que les autoroutes ont un impact négatif significatif sur l'activité de chasse et de transit pour plusieurs espèces de chauves-souris jusqu'à au moins cinq kilomètres de distance à une autoroute. De plus, l'effet des autoroutes semblerait également avoir des conséquences sur la génétique des populations. Enfin, nous avons étudié les chiroptéroducs, ouvrages dédiés aux chauves-souris visant à réduire ces impacts par l'amélioration des connectivités écologiques. Ce type d'ouvrage dédié semble être approprié lorsqu'il est situé dans des corridors écologiques fins tels que les haies.Biodiversity is being lost at an increased rate as a result of human activities. One of the major threats to biodiversity is infrastructural development. Although the measures taken in environmental impact assessments can limit this loss, the mitigation hierarchy to "Avoid, Reduce and Offset" impacts on biodiversity is not fully functional. Indeed, the mitigation hierarchy often uses qualitative data and does not account for the biological and/or ecological processes and their different spatial and temporal scales. The impact of roads is well documented for several biological groups but not for bats whereas they are likely to be very strongly affected. Moreover, as they are strictly protected, they should be considered in the mitigation hierarchy. Therefore, through the study of bats, I investigated the effects of roads, especially major roads, and intended to measure and quantify the magnitude of their impacts. This thesis presents different methods developed to reach this objective and which may be used by stakeholders in the field. First, I intended to determine how to process data collected through passive acoustic monitoring and how to exploit these data. Then I determined what the impacts of roads on bat populations are and I proposed a method in order to assess the mitigation measures which presume to restore bat habitat connectivity. Our main results show a significant negative effect of roads on bats foraging and commuting behaviour for several species and up to at least five kilometres away from a major road. In addition, the effect of major roads also seems to have consequences on populations’ genetics. Finally, we studied bat overpasses which are structures specifically dedicated to bats and aiming at reducing the impacts of roads by improving bats’ habitat connectivity. These structures seem to be appropriate when located in narrow ecological corridors such as hedgerows

Evaluation des impacts de la fragmentation du paysage par une autoroute sur les chauves-souris à différentes échelles spatio-temporelles

Biodiversity is being lost at an increased rate as a result of human activities. One of the major threats to biodiversity is infrastructural development. Although the measures taken in environmental impact assessments can limit this loss, the mitigation hierarchy to "Avoid, Reduce and Offset" impacts on biodiversity is not fully functional. Indeed, the mitigation hierarchy often uses qualitative data and does not account for the biological and/or ecological processes and their different spatial and temporal scales. The impact of roads is well documented for several biological groups but not for bats whereas they are likely to be very strongly affected. Moreover, as they are strictly protected, they should be considered in the mitigation hierarchy. Therefore, through the study of bats, I investigated the effects of roads, especially major roads, and intended to measure and quantify the magnitude of their impacts. This thesis presents different methods developed to reach this objective and which may be used by stakeholders in the field. First, I intended to determine how to process data collected through passive acoustic monitoring and how to exploit these data. Then I determined what the impacts of roads on bat populations are and I proposed a method in order to assess the mitigation measures which presume to restore bat habitat connectivity. Our main results show a significant negative effect of roads on bats foraging and commuting behaviour for several species and up to at least five kilometres away from a major road. In addition, the effect of major roads also seems to have consequences on populations’ genetics. Finally, we studied bat overpasses which are structures specifically dedicated to bats and aiming at reducing the impacts of roads by improving bats’ habitat connectivity. These structures seem to be appropriate when located in narrow ecological corridors such as hedgerows.Les infrastructures linéaires de transports (ILT), dont les routes, sont une des principales causes du déclin de la biodiversité. Bien que les évaluations environnementales permettent de limiter ce déclin, la séquence "Eviter, Réduire et Compenser" les impacts peine à s'appliquer pleinement. En effet, la séquence ERC fait bien souvent appel à des données qualitatives en oubliant les processus biologiques et/ou écologiques et leur échelle spatio-temporelle. L'impact des routes est globalement bien documenté pour plusieurs groupes biologiques, hormis pour les chauves-souris, pourtant susceptibles d'être très fortement affectées. Par ailleurs, leur protection stricte nécessite leur prise en compte dans la séquence ERC. Pour étudier l’impact des routes, et notamment des autoroutes, je me suis concentré sur l’étude des chauves-souris afin de mesurer et quantifier leur magnitude. Pour cela, différentes méthodes développées et réutilisables par les différents acteurs de terrain seront présentées. Ainsi, dans un premier temps, je me suis intéressé à une méthode de traitement des données issues d'écoutes acoustiques et à une méthode de valorisation. Dans un second temps, nous avons appliqué ces méthodes afin (i) de connaitre quels étaient les impacts des routes sur les populations de chauves-souris et (ii) afin d'évaluer l'efficience des mesures de réductions engagées pour réduire ces impacts. Nos principaux résultats montrent que les autoroutes ont un impact négatif significatif sur l'activité de chasse et de transit pour plusieurs espèces de chauves-souris jusqu'à au moins cinq kilomètres de distance à une autoroute. De plus, l'effet des autoroutes semblerait également avoir des conséquences sur la génétique des populations. Enfin, nous avons étudié les chiroptéroducs, ouvrages dédiés aux chauves-souris visant à réduire ces impacts par l'amélioration des connectivités écologiques. Ce type d'ouvrage dédié semble être approprié lorsqu'il est situé dans des corridors écologiques fins tels que les haies

Modelling landscape connectivity for greater horseshoe bat using an empirical quantification of resistance

International audience1.Habitat fragmentation and isolation as a result of human activities have been rec-ognized as great threats to population viability. Evaluating landscape connectivity in order to identify and protect linkages has therefore become a key challenge in applied ecology and conservation.2.One useful approach to evaluate connectivity is least- cost path (LCP) analysis. However, several studies have highlighted importance of parameterization with empirical, biologically relevant proxies of factors affecting movements as well as the need to validate the LCP model with an independent dataset.3.We used LCP analysis incorporating quantitative, empirical data about behaviour of the greater horseshoe bat Rhinolophus ferrumequinum to build up a model of functional connectivity in relation to landscape connecting features. We then vali-dated the accumulated costs surface from the LCP model with two independent datasets; one at an individual level with radiotracking data and one at a population level with acoustic data.4.When defining resistance, we found that the probability of bat presence in a hedgerow is higher when the distance between hedgerows is below 38 m, and decrease rapidly when gaps are larger than 50 m. The LCP model was validated by both datasets: the independent acoustic data showed that the probability of bat presence was significantly higher in areas with lower accumulated costs, and the radiotracking data showed that foraging was more likely in areas where accumu-lated costs were significantly lower.5.Synthesis and applications. Through our modelling approach, we recommend a maximum of 38 m (and no more than 50 m) between connecting features around colonies of greater horseshoe bats. Our quantitative study highlights the value of this framework for conservation: results are directly applicable in the field and the framework can be applied to other species sensitive to habitat loss, including other bats. Provided that it is parameterized with empirical, biologically relevant data, this modelling approach can be used for restoring and evaluating green net-works in agri- environmental schemes and management plans

Data from: Modelling landscape connectivity for greater horseshoe bat using an empirical quantification of resistance

1. Habitat fragmentation and isolation as a result of human activities have been recognized as great threats to population viability. Evaluating landscape connectivity in order to identify and protect linkages has therefore become a key challenge in applied ecology and conservation. 2. One useful approach to evaluate connectivity is Least-Cost Path (LCP) analysis. However, several studies have highlighted importance of parameterization with empirical, biologically-relevant proxies of factors affecting movements, as well as the need to validate the LCP model with an independent dataset. 3. We used LCP analysis incorporating quantitative, empirical data about behaviour of the greater horseshoe bat Rhinolophus ferrumequinum to build up a model of functional connectivity in relation to landscape connecting features. We then validated the accumulated costs surface from the LCP model with two independent datasets; one at an individual level with radio tracking data and one at a population level with acoustic data. 4. When defining resistance, we found that the probability of bat presence in a hedgerow is higher when the distance between hedgerows is below 38 m, and decrease rapidly when gaps are larger than 50 m. The LCP model was validated by both datasets: the independent acoustic data showed that the probability of bat presence was significantly higher in areas with lower accumulated costs, and the radio tracking data showed that foraging was more likely in areas where accumulated costs were significantly lower. Synthesis and applications. Through our modelling approach, we recommend a maximum of 38m (and no more than 50m) between connecting features around colonies of greater horseshoe bats. Our quantitative study highlights the value of this framework for conservation: results are directly applicable in the field and the framework can be applied to other species sensitive to habitat loss, including other bats. Provided that it is parameterized with empirical, biologically-relevant data, this modelling approach can be used for restoring and evaluating green networks in agri-environmental schemes and management plans.20-Jun-201

Comment modéliser les connectivités écologiques pour les chauves-souris ? Une étude à application directe sur le terrain, pour identifier, protéger ou restaurer les corridors autour des colonies

International audience1. La fragmentation des habitats etl’isolation résultant des activités humainesont été reconnues comme une grandemenace pour les populations. Évaluer laconnectivité paysagère pour identifier etprotéger les corridors devient alors undéfi crucial en écologie appliquée et enconservation.2. La modélisation par les Cheminsde Moindre Coût (LCP) est une approchetrès utilisée pour évaluer la connectivité.Cependant, plusieurs études ont pointél’importance du choix des paramètresaffectant les mouvements (qui doiventcorrespondre à une réalité biologiquemesurée sur le terrain), ainsi que le besoinde valider le modèle de connectivité avecun jeu de données indépendant.3. Nous proposons ici un modèle deconnectivité fonctionnelle pour le GrandRhinolophe Rhinolophus ferrumequinum.Une analyse par LCP est paramétrée avecdes données empiriques et quantitativesen lien avec le déplacement desrhinolophes près des éléments fixes du paysage. Ce modèle a été ensuite validéavec deux jeux de données indépendants,un au niveau individuel avec du radiopistageet l’autre au niveau populationnelavec des données acoustiques.4. En définissant la résistance sur leterrain, nous trouvons que la probabilitéde franchir une discontinuité dansune haie est plus importante quand latrouée est inférieure à 38m, et diminuefortement quand cette distance dépasse50m. Le modèle LCP est validé par lesdeux jeux de données : les probabilitésde présence des rhinolophes mesuréespar l’acoustique et par le radio-pistagesont plus importantes dans les zones oùle coût accumulé de déplacement estsignificativement plus faible

Claireau_et_al_bat_crossings

Number of bat crossings per site, per pair and per date within the context of the habitat (A, agricultural land; F, forest; H, hedgerow; O, bat overpass and S, stream)

Major roads have important negative effects on insectivorous bat activity

International audienceThe development of transportation infrastructure has been identified as one of the main pressures on biodiversity. The effects of transport infrastructure are more documented for terrestrial mammals, birds and amphibians than for bats. To assess the impacts of roads on bat activity, we carried out full-night acoustic recordings of bat calls at 306 sampling points at different distances from a major road at three study sites in France. To assess the relationship between bat activity and the distance to the major road, we performed generalized linear mixed model analyses for thirteen different species or groups and additionally explored the non-linear effect with generalized additive mixed models. Our results showed that low-flying species are more affected than high-flying species. Indeed, we found a significant negative effect of major roads on bat activity for the 'clutter-adapted' species, Eptesicus serotinus, Myotis spp., Pipistrellus pipistrellus and Rhinolophus hipposideros. These results demonstrate that the road-effect zone of major roads extends up to five kilometres. Extrapolating those road-effects zones to the major roads in the European Union, we estimated that 35% of the European Union is potentially negatively impacted. Finally, it seems urgent to consider these road effects with the cumulative effects of other roads by improving habitat connectivity and foraging areas in land use policies. Additionally, to implement drastic conservation practices for species of conservation concern in environmental impact assessment studies, efficient mitigation and offset measures implemented should be sized proportionally to the disturbance caused

Bat overpasses as an alternative solution to restore habitat connectivity in the context of road requalification

International audienceRoads have a multitude of negative effects on wildlife, including their prominent role in habitat fragmentation. Habitat fragmentation particularly affects bats during their nightly movements between roosts and foraging areas. Bat overpasses are among the proposed improvements intended to reduce the fragmentation impact of roads, but they have rarely been tested. In this study, we performed a Before-After Control-Impact analysis (BACI) to assess the efficiency of one bat overpass on the number of bat crossings, by using an acoustic flight path reconstruction (AFPR) approach. We obtained 888 bat crossings of five taxa. Our results showed that the number of bat crossings increased significantly after the installation of the bat overpass. Finally, we demonstrated that an overpass correctly placed with respect to a narrow commuting route (a twenty-meter-wide hedgerow) could efficiently restore bat habitat connectivity