2^nd International Bat Research Online Symposium (IBROS):
Daily and seasonal movements of bats

Dr. Ivana Budinski is a senior research associate at Department of Genetic Research, Institute for Biological Research "Siniša Stanković", University of Belgrade (Serbia). She obtained her PhD in 2019 at Faculty of Biology, University of Belgrade, and in her thesis she investigated population genetics of Mediterranean horseshoe bat in the Balkans. Apart from population genetics, her main interests are bat ecology and conservation and ecological services provided by bats. She is a member of several EUROBATS Intersessional Working Groups, and she is involved in bat rescue and rehabilitation in Serbia.

Keynote talk abstract:

Daily movements of bats evaluated by conventional VHF tracking

Bats rely on a variety of habitats and pathways for roosting, foraging, and commuting. During their active periods they move daily between these habitats, and understanding their movement ecology is essential for effective bat monitoring and conservation. Very high frequency (VHF) radio-tracking has been used for decades for wildlife tracking, revealing the myriad of factors that affect animal movements, including elusive nocturnal wildlife like bats. As part of the ‘EUROBATS Intersessional Working Group for Monitoring of daily and seasonal movements of bats’ work, the aim of this study is to compile existing information on the movements of European bats obtained by VHF telemetry, and to build a comprehensive database. Our ongoing extensive literature search has resulted in 126 publications with movement data for 32 European bat species. For each, available metadata including morphological traits, reproductive status, habitat, home-range, distance travelled, number of roosts etc. is being extracted into the database. Data collection is ongoing and we encourage researchers to join the initiative and contribute data. Once this phase is completed, we will proceed to wide-scale analyses to investigate various aspects of bat movements.

Richard Holland is a Professor of Animal Behaviour at Bangor University, UK. His work focuses on animal navigation at multiple spatial scales, from large scale movement of bats and birds during migration and homing, to small scale challenges of remembering locations in space. He looks at both the cognitive mechanisms and the sensory cues used by animals to learn about space.

Keynote talk abstract:

Navigation behaviour and sensory cue perception in homing and migratory bats

Driven by Donald R. Griffin’s research on the extraordinary ability of bats to echolocate 80 years ago, their spatial orientation ability has become a key research focus. Alongside this, however, Griffin was an intellectual pioneer in general animal navigation, providing definitions that frame our current understanding of animal navigation. One of these was to develop what became known as true navigation: an ability to navigate from places they have never previously visited. In our joint talk, we will present work on celestial, magnetic, and social cues, which play a key role for navigation in other taxonomic groups, and which may also play a key role in determining direction during long-distance movements of bats. Here we discuss research on temperate, insectivorous species, which showed early promise as a focusfor true navigation in mammals, and since the mid 2000’s we have revisited them as a model species. Our research has produced some surprising discoveries on how homing and migrating bats determine the direction to fly when navigating, and how this can be studied methodologically.

Dr. Jakobsen studied at the university of Southern Denmark (SDU), Denmark, where he obtained his Ph.D. in 2010 under the supervision of Prof. Annemarie Surlykke. He stayed on at SDU as a post-doc until 2013 after which he did a post-doc with Prof. Anders Hedenström in the animal flight lab at Lund University in Sweden. In 2015 he returned to SDU as an assistant professor obtaining tenure as an associate professor in 2018. Dr. Jakobsen leads a research group that studies echolocation in bats with a strong emphasis on sensory filtering: How bats modify and filter echo information to optimize perception. Both through adjusting the emitted echolocation call and by controlling the morphology of the outer ears.

Keynote talk abstract:

Habitat and foraging specific echolocation in European bats – the guild concept

The guild structure as put forth by Schnitzler, Denzinger and colleagues is a categorization of bats in relation to habitat and foraging mode that to a great extend explains their echolocation behaviour. In my talk I will detail the different foraging guilds and the associated echolocation behaviour and highlight where European bats fit into the concept and how recent discoveries shed further light on what drives echolocation call design.

Dr. Oliver Lindecke completed his PhD on bat navigation at the Freie Universität Berlin. He worked as a postdoc in Bangor on general aspects of animal navigation. Since 2021, he is leading a research group at the Carl von Ossietzky Universität Oldenburg, where he is continuing his scientific work on animal navigation with a special focus on bats.

Keynote talk abstract:

Navigation behaviour and sensory cue perception in homing and migratory bats

Driven by Donald R. Griffin’s research on the extraordinary ability of bats to echolocate 80 years ago, their spatial orientation ability has become a key research focus. Alongside this, however, Griffin was an intellectual pioneer in general animal navigation, providing definitions that frame our current understanding of animal navigation. One of these was to develop what became known as true navigation: an ability to navigate from places they have never previously visited. In our joint talk, we will present work on celestial, magnetic, and social cues, which play a key role for navigation in other taxonomic groups, and which may also play a key role in determining direction during long-distance movements of bats. Here we discuss research on temperate, insectivorous species, which showed early promise as a focusfor true navigation in mammals, and since the mid 2000’s we have revisited them as a model species. Our research has produced some surprising discoveries on how homing and migrating bats determine the direction to fly when navigating, and how this can be studied methodologically.

Fiona Mathews is a professor at the University of Sussex. Having conducted numerous radiotracking and banding studies of bats, she is currently overseeing a project in the UK to apply different technologies to study bat movements. Twelve static radiotracking CTT sensor stations, together with smaller nodes for monitoring activity more locally, have been installed in a network in southwest England and preliminary data are currently being collected.

Keynote talk abstract:

Following bats using static radiotracking networks

Static radiotracking networks have been established for some years as a method for studying the large scale movement of birds. However, their application to bats is much more recent. Prompted in large part by the recognition that bats migrating across Europe might be at risk from the rapid development of wind energy installations, research using static receivers has been used to investigate long-distance bat movements (for example, between the Netherlands and the UK). In addition, static networks offer potential for studying bat movements on a much finer spatial scale. In the UK, we have established a network of 12 receivers, plus 20 smaller nodes, to study foraging activity of greater horseshoe bats in a region under high development pressure.  This talk will give an overview of the alternative approaches available to establish static radiotracking networks, discuss the value of the ‘Motus’ scheme, and also consider some of the logistical, financial, and analytical constraints inherent in the systems.

Prof. Ran Nathan is Professor at the Alexander Silberman Institute of Life Science of the Hebrew University of Jerusalem. Dr. Nathan was key in launching the discipline of movement ecology. He has devoted much of his academic career to understanding why, where and when animals move.

Keynote talk abstract:

The high-throughput revolution in movement ecology and its contribution to bat research

Movement shapes how animals interact, survive and thrive in a dynamic world. Technological advances are now transforming movement ecology into a big-data discipline, enabling rapid, cost-effective generation of large amounts of data on movements of animals in the wild. High-throughput systems provide new research opportunities beyond simply enlarging datasets and sample sizes, allowing thorough investigations of fine-scale variation among individuals, the true nature of biological interactions, behavioral decisions in response to the physical and anthropogenic environment, and behavioral shifts across spatiotemporal scales. In this talk, I will overview the emerging high-throughput technologies in movement ecology research, and present examples for biological insights uniquely gained from big high-resolution datasets, focusing on studies of Egyptian fruit bats. These include the first comprehensive evidence for a cognitive map among wild animals; disclosing the role of memory and conformity in spatial partitioning of foraging range among bats from neighboring colonies; and movement-based characterization of (the notable) intraspecific variation among individual bats.

Prof. Dr. Gunārs Pētersons is professor at the Latvia University of Agriculture. In his research he is mainly working on migratory bats.

Keynote talk abstract:

Migration of European bats assessed by banding data

Individual marking of bats with wing bands (rings) is the oldest method of obtaining direct evidence on the movements of these animals. Animal migration is a term usually used for regular seasonal movements to avoid unfavorable climatic conditions. The temperate bats usually perform seasonal migrations switching between their summer roosts and hibernation sites. In Europe, bats are often classified into three groups based on the distances they travel – sedentary species, regional migrants and long-distance migrants. In this presentation, I will focus mainly on species that have been proven to be long-distance migrants by banding data. In this, I will summarise newest published knowledge, which has been obtained after the last review on bat migrations published by Hutterer et al. 2005. I will discuss the future perspectives of the banding in the study of bat migration.

Manuel Roeleke studies flexibility of hunting strategies, and the use and transfer of social information in insectivorous bats. He completed his PhD in the IZW batlab in 2019 and is now working at University of Potsdam. His focus is on the use high-throughput telemetry techniques - such as miniaturized GPS loggers or the automated radio-telemetry system 'ATLAS' - that allow the recording of finescale daily foraging movements and individual interactions of open-space foraging bats in the agricultural landscape of northern Germany.

Keynote talk abstract:

Daily movements of European bats – captured with high-resolution tracking systems

During the active season, European bats leave their roosts almost every night, mainly to forage within their home range. Traditional methods like acoustic monitoring, netting, or manual radio-telemetry have revealed habitat use of bats, but are either restricted to average space use on group level or to very few individuals at coarse spatial scale. In the first part of the talk, I will give an overview how technological developments allowed the tracking of an increasing number of European bat species at the high spatial and temporal resolution that is necessary to study the daily movement behaviour of bats. In the last twelve years, a little less than 20 studies that used either GPS or automated radio telemetry systems to investigate daily movements of European bats have been published. The diversity of topics investigated - e.g. navigation, social learning and social hunting, habitat use and human-wildlife conflicts, 3-dimensional flight behaviour, and energetics – show the great potential of high-resolution tracking methods. Indeed, despite their cryptic lifestyle that makes it seemingly hard to study bats, some species are becoming model species for mammal research. However, high resolution movement data for European bats is currently only available for very few species, although the technical prerequisites for tracking most species are already in place. Reasons for a lack of data include time and cost intensive work, limited access to study animals, complicated procedures for animal experiment approval, and practical reasons such as lack of gold standards for attachment of tracking devices for several weeks.

In the second part of the talk, I will illustrate the potential of high-resolution tracking data with examples of our work on the common noctule bat, concentrating on flexibility and sociality in different foraging contexts.

Charlotte Roemer is a post-doctoral research associate at the CESCO lab at the French museum of natural history. She previously conducted bat expertise and research & development at Biotope consulting firm, where she was notably in charge of methodological design and the exploitation of big acoustic datasets. She currently develops tools to conduct bat acoustic monitoring at large scales. She takes part in the facilitation of the citizen-science programme Vigie-Chiro, and coordinates the international programme Bat migration routes in Europe intended to build distribution and connectivity maps for three migrating bats.

Keynote talk abstract:

Movements of bats assessed by acoustic recordings

Acoustic recordings are a key method for the study of bats. They provide information on when and where bat species were active, and on population densities. Therefore, with spatio-temporal comparisons of acoustic activity, it is possible to indirectly infer bat movements. But recordings with single microphones also include other underused information related to movement. Indeed, bat pass duration is a predictor that can be used to classify foraging vs. commuting flights, and the peak frequency could be used to predict the relative flight height of individuals. In addition, the use of microphone arrays makes the tracking of bat movements possible: two microphones allow the binary location of bats in relation to the bisection line between both microphones, and can also provide flight direction, while four microphones allow the 3D reconstruction of flight trajectories. Citizen science and international collaborations bring bat acoustic monitoring to a new dimension, and make possible the national and even continental mapping of bat corridors for migration. With their use of echolocation, bats led researchers to think out of the box and develop unique methods for the study of animal movements.

Christian C. Voigt is head of Department Evolutionary Ecology at the Leibniz Institute for Zoo and Wildlife Research. He has published more than 250 papers in scientific journals about the ecology, physiology, behaviour and conservation of bats. He has co-edited and edited various e-books such as ‘Bats in the Anthropocene: Conservation of bats in a changing world’. Currently, he serves as co-convener of the UNEP/EUROBATS intersessional working groups on ‘Bats and light pollution’ and ‘Diurnal and seasonal movements of bats’.

Keynote talk abstract:

Stable isotopes for deciphering the movements of European bats

Stable isotope analyses are useful for assigning species to food webs (stable C isotope ratios), determining trophic positions of consumers (stable N isotope ratios), and identifying the summer origin of migratory bats (stable H isotope ratios). Stable isotope analysis is particularly useful for studying small and elusive species, because only tiny samples are required for stable isotope analysis. Here, I will summarize the literature on isotopic geographic assignments performed on European bats.

Such isotopic geographic assignments have been made for several bat species. Using stable isotopes, eastern populations of Miniopterus schreibersii were shown to have a larger proportion of migrating individuals than western populations. In Central and Eastern Europe, common pipistrelles and noctule bats have been identified as partial migrants, i.e., hibernating populations are composed of individuals from local and from distant populations, e.g., northeastern and eastern Europe. Common noctule bats are consistent in their migratory behavior, i.e., based on repeated stable isotope analyses of samples collected from the same individual over several years, it has been demonstrated that individuals move between the same summer and wintering areas during their lifetime.

The ratio of stable isotopes is maintained even in historical specimens. This property was used in a time series analysis of common noctule specimens from hibernating populations in Kharkiev, Ukraine. Stable isotopes indicated that local male juveniles are most important for shifting the geographic distribution of the common noctules northward in response to climate change.

Because stable isotopes in fur keratin remain unchanged in carcasses, it is also possible to determine the likely place of origin of bats that collide with wind turbines. Isotopic geographic mappings showed that bats killed at wind turbines may originate from near and far locations, highlighting that wind energy generation can have negative impacts not only on local populations, but also on populations in northeastern Europe.

In summary, stable isotopes have contributed significantly to our understanding of the long-distance movements of bats. In addition, stable isotope data has highlighted some major conservation issues that arise from the unregulated operation of wind turbines in Europe and beyond.