Flying high--assessing the use of the aerosphere by bats

Bats feature prominently among organisms that occupy the aerosphere as they extensively use this environment for foraging, but also for dispersal, migration, and behavioral interactions. Differential use of the aerosphere is an important factor structuring bat assemblages, with species exhibiting distinct morphological, physiological, and sensory adaptations to different habitat types. This necessitates comprehensive sampling methodologies such as combined ground-level and canopy-level mist netting as well as acoustic monitoring to assess the presence, diversity, and activity of different functional groups of species adequately. Recent technological advances in acoustic detection and in methods of analysis, coupled with the expansion of libraries of echolocation calls for species identification, now allow for the reliable quantification of species numbers and activity of the scarcely known group of aerial insectivorous bats, particularly in species-rich tropical assemblages. We provide a brief, exemplary overview of recent studies on bats conducted in Panamá to demonstrate the necessity of comprehensive sampling methods and application of new technologies in order to adequately depict assemblage composition and responses of bats to structural changes in habitats induced by fragmentation. In addition to acoustic methods, miniaturization of radio transmitters has provided new insights into the patterns of spatial use of the aerosphere by bats and has identified species-specific differences in mobility as one of the important traits that determines bats' reactions to anthropogenic alterations of the landscape. Following the goals of the symposium on aeroecology, we propose new avenues of research for probing the aerosphere. We discuss how integration of a diverse array of remote sensing tools with data on species distribution and species traits, such as mobility and edge-sensitivity, might provide novel opportunities for the development, and application of conservation-oriented monitoring systems.