Knowledge of species' functional traits is essential for understanding biodiversity patterns, predicting the impacts of global environmental changes, and assessing the efficiency of conservation measures. Bats are major components of mammalian diversity and occupy a variety of ecological niches and geographic distributions. However, an extensive compilation of their functional traits and ecological attributes is still missing. Here we present EuroBaTrait 1.0, the most comprehensive and up-to-date trait dataset covering 47 European bat species. The dataset includes data on 118 traits including genetic composition, physiology, morphology, acoustic signature, climatic associations, foraging habitat, roost type, diet, spatial behaviour, life history, pathogens, phenology, and distribution. We compiled the bat trait data obtained from three main sources: (i) a systematic literature and dataset search, (ii) unpublished data from European bat experts, and (iii) observations from large-scale monitoring programs. EuroBaTrait is designed to provide an important data source for comparative and trait-based analyses at the species or community level. The dataset also exposes knowledge gaps in species, geographic and trait coverage, highlighting priorities for future data collection.

Isolated trees are increasingly recognised as playing a vital role in supporting biodiversity in agricultural landscapes, yet their occurrence has declined substantially in recent decades. Most bats in Europe are tree-dependent species that rely on woody elements in order to persist in farmlands. However, isolated trees are rarely considered in conservation programs and landscape planning. Further investigations are therefore urgently required to identify which trees – based on both their intrinsic characteristics and their location in the landscape – are particularly important for bats. We acoustically surveyed 57 isolated trees for bats to determine the relative and interactive effects of size, tree-related microhabitat (TreM) diversity and surrounding landscape context on bat activity. Tall trees with large diameter at breast height and crown area positively influenced the activity of Pipistrellus pipistrellus and small Myotis bats (Myotis spp.) while smaller and thinner trees favoured M. myotis activity. The diversity of TreMs that can be used as roosts had a positive effect on (i) Barbastella barbastellus activity only when trees were relatively close (<50 m) to woody patches, (ii) Pipistrellus nathusii/kuhlii activity only in the most heterogeneous landscapes, and (iii) Myotis spp. activity only in the most forested environment (>10% within 100 radius scale). The potential benefits of isolated trees for bats result from ecological mechanisms operating at both tree and landscape scales, underlining the crucial need for implementing a multi-scale approach in conservation programs. Maintaining the largest and most TreM-diversified trees located in the most heterogeneous agricultural landscapes will provide the greatest benefits.

Road construction is expanding worldwide, exacerbating both direct mortality by road-kills and habitat fragmentation, especially for mobile vertebrates such as bats. Understanding how road density affects bat communities in mosaic landscapes of various compositions and configurations is therefore critical. We acoustically sampled bat communities in 172 landscapes of southern France to: (i) disentangle the relative and interacting effects of road density and forest fragmentation by farmland on the activity of bat communities; (ii) investigate how road density affects different aspects of bat diversity (taxonomic, functional and phylogenetic) and species activity according to their life-history traits; and (iii) assess whether road density effects on bats change with the level of forest fragmentation. Forest amount and patchiness were more important than road density for all components of bat diversity, except for functional evenness. Bat diversity peaked in landscapes with intermediate levels of forest fragmentation, while road density had negative effects on functional and phylogenetic diversity. The effect of road density on the activity of R. ferrumequinum, R. hipposideros, N. leisleri and P. pipistrellus was only negative in landscapes with either a low forest amount or a low number of forest patches. By better understanding interactions between forest fragmentation and road density, our study will contribute to a more adequate landscape planning that will improve the resilience of bat communities to both road expansion and forest fragmentation. Moreover, the complex landscape-level interactions between habitat fragmentation and matrix quality on bats advocate for the use of a more holistic view in future fragmentation studies.

Artificial light at night (ALAN) is nowadays recognized as a major anthropogenic pressure on the environment on a global scale and as such is called light pollution. Through its attractive or deterrent effects, and its disruption of the biological clock for many animal and plant taxa, ALAN is increasingly recognized as a major threat to global biodiversity, which ultimately alters the amount, the quality, and the connectivity of available habitats for taxa. Biodiversity conservation tools should, therefore, include ALAN spatial and temporal effects. The ecological network, i.e., the physical and functional combination of natural elements that promote habitat connectivity, provides a valuable framework for that purpose. Understood as a social-ecological framework, it offers the opportunity to take into account the multiple uses of nocturnal spaces and times, by humans and nonhumans alike. Here we present the concept of "dark ecological network." We show this concept is able to grasp the effects of ALAN in terms of habitat disturbances and integrates temporal dimensions of ecological processes into biodiversity conservation planning. Moreover, it is also intended to trivialize the practices of darkness protection by turning them into the ordinary practices of land use planning. From an operational point of view, the challenge is to translate the levers for reducing ALAN-induced effects into a political method for its "territorialization." To achieve this objective, we propose a course of action that consists of building an interdisciplinary repertoire of contextualized knowledge (e.g., impacts on wildlife, human/lightscape relationship, existing legal tools, etc.), in order to deduce from it a number of practical supports for the governance of the dark ecological network in response to societal and ecological issues.

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.

Landscape anthropization through habitat loss and fragmentation is one of the main threats to biodiversity. This PhD (CIFRE funding) was carried out in at INRAE Toulouse (Dynafor lab) in collaboration with the Conservatoire des Espaces Naturels de Midi-Pyrenees (CENMP). It aimed at a better understanding of the impacts of light pollution and road expansion on bats, two major and inevitable elements of anthropization, using a landscape ecology framework applied to bat conservation. This work is structured in 4 sections: (i) by means of an exhaustive review of bat telemetry studies in Europe and North America, I explored how landscape anthropization influenced bat mobility through mean home range sizes and commuting distances; (ii) using simultaneous acoustic sampling of bat communities at both edge and interior forest patches in 172 landscapes varying in terms of forest amount and road density, I analyzed how forest fragmentation and road network shaped the taxonomic, functional and phylogenetic diversity of bat communities at multiple spatial scales; (iii) by developing models of species distribution and connectivity (least-cost path) at the scale of a large urban area, I assessed the effect of different street lighting extinction scenarios on landscape connectivity for three bat species; and(iv) using a field experiment, I tested the influence of landscape context around road underpasses on their use by bats and the efficiency of these structures in maintaining landscape connectivity while reducing the risk of collision with vehicles. While the first two sections of the PhD seek to better understand the mechanisms underlying the effects of landscape anthropization on bats, the last two axes are applied to their direct conservation by demonstrating how landscape ecology can contribute to improve existing measures.

Light pollution can alter animal movements and landscape connectivity. This is particularly true in urban landscapes where a need to incorporate conservation issues in urban planning is urgent.

The worldwide expansion of road networks is a major concern in biological conservation because of its predominantly negative effects on terrestrial fauna. Roads also affect bats, acting as barriers to movements and causing direct mortality by collisions with vehicles. Among wildlife crossing structures existing to maintain landscape connectivity, road underpasses are considered as one of the most effective conservation measure for bats. While a few studies assessed the effects of underpass attributes on bat use, none to date has assessed the impact of landscape context on underpass use and attractiveness. To address this knowledge gap, we monitored bat activity during three consecutive nights around 24 underpasses selected along a gradient of forest cover. We compared bat activity below and above underpasses (i.e., underpass use), at road sections with and without underpasses and at habitats adjacent to roads (i.e., underpass attractiveness). We found a significant positive effect of forest cover on both underpass use and attractiveness for Myotis spp. and Barbastella barbastellus, and significant negative effects of distance to the nearest forest patch for Rhinolophus spp. and hedgerow length for Myotis spp. Our study highlights the key influence of landscape context on road underpass efficiency to maintain landscape connectivity for bats. We advocate for incorporating a landscape-scale approach in the decision-making process of underpass location during road project planning to enhance efficiency of such costly crossing structures.