The National Digital Atlas for the Analysis of Bat Population Data (BATLAS) focuses on compiling and analysing data collected from all over Germany. The tool, which was developed at the University of Greifswald, is currently being enhanced through close collaboration between the academic community, local authorities, volunteers and the Competence Centre for Bat Conservation Sachsen-Anhalt. The platform currently contains around 150,000 data sets from winter roost counts from all over Germany and, for the first time, provides nationwide population trends for 16 native bat species. BATLAS thus provides a basis for monitoring the development of native bat populations across Germany and for reliably assessing changes in the populations of individual species.
The evaluations present a mixed picture: whilst some species – such as the lesser horseshoe bat – are showing positive trends, others, such as the grey long-eared bat, continue to see their populations decline. The findings therefore provide important insights for nature conservation and help to plan protective measures in a more targeted manner and assess their effectiveness. “BATLAS demonstrates what can be achieved when people share their data and work together towards a common goal,” says Dr. Marcus Fritze, who developed the platform together with Dr. Saskia Schirmer, Stefan Mayr and other researchers at the University of Greifswald. “Large amounts of bat data have been collected by volunteers over the decades, but the data was scattered across various databases, spreadsheets and archives. BATLAS now combines this data in a novel approach to create a joint system that can be used for analysis,” adds Schirmer.
Three published studies – one shared goal
The three studies examine the project from different perspectives. An article published in the journal Ecological Indicators presents new statistical methods that can be used to derive reliable population trends even from incomplete monitoring data. A second study in Ecological Informatics describes BATLAS as a digital platform for compiling, standardising, and analysing nationwide bat data. The third publication in Nature and Landscape focuses on the people behind the data and highlights just how vital the long-standing commitment of volunteers is for bat conservation. Together, these three studies lay an important foundation for planning nature conservation, assessing protection measures, and reporting on the status of protected species.
BATLAS is currently based on winter census data, which has been collected in many places for decades through a considerable amount of personal dedication – mostly by volunteers, working groups, nature conservation associations, or local groups of experts. “Without this commitment, BATLAS would not exist,” emphasises Prof. Dr. Gerald Kerth, Professor of Applied Zoology and Nature Conservation Research Group at the University of Greifswald. “The platform thrives on trust, personal interaction, and a shared interest in bat preservation.”
Volunteering as the cornerstone of bat protection
The three studies show that effective nature conservation counts on long-term data and long-term commitment. The results provide a vital basis for nature conservation planning, Germany’s reporting on the status of protected species under the EEC Directive on the Conservation of Natural Habitats and of Wild Fauna and Flora (Habitats Directive), and for Red List assessments. At the same time, they demonstrate just how valuable long-term citizen science is for the protection of biodiversity. BATLAS demonstrates how data collected by volunteers can be transformed into a reliable basis for research, conservation, and political decision-making through modern analytical methods and digital tools.
The researchers also see BATLAS as a model for how biodiversity data should be handled in the future. The project serves as an example of how citizen science, modern research, and digital infrastructure can work together to lay a secure foundation for the protection of biodiversity.
Further information
BATLAS: Portal for bat population trends
Zoology at the University of Greifswald
Publications
Schirmer, S., Fritze, M. & Scheuerlein, A., (2026): How to estimate overall population trends when sites show varying population counts over time? Ecological indicators 183, 114588. https://doi.org/10.1016/j.ecolind.2025.114588
Fritze, M., Mayr, S., Scheuerlein, A., Kerth, G., Schirmer, S. (2026): BATLAS: A scalable citizen science platform for integrating biodiversity monitoring data with automatic population trend analysis. Ecological Informatics, 103817. https://doi.org/10.1016/j.ecoinf.2026.103817
Fritze, M., Mayr, S., Scheuerlein, A., Kerth, G., Balzer, S., Neukirchen, M., Petermann, R., Bauer, J., Berg, J., Giese, G., Harbusch, C., Harder, J., Hoffmeister, U., Horn, J., Koch, R., Maetz, G., Meschede, A., Petzold, A., Pfalzer, G., Prüger, J., Rackow, W., Ripperger, S., Röse, N., Roßner, M., Roßner, S., Sauerbier, W., Schorcht, W., Schritt, K., Teubner, Ja., Teubner, Je., Thiele, K., Vollmer, A., Wielert, S., Zaenker, S., Zöphel, U., Schirmer, S. (2026): BATLAS: A nationwide digital atlas for analysing bat population data. Nature and Landscape 101 (1), pp. 2–13. https://doi.org/10.19217/NuL2026-01-01
Contacts
Dr. Marcus Fritze
Competence Centre for Bat Conservation Sachsen-Anhalt
c/o Biosphärenreservat Karstlandschaft Südharz
Hallesche Straße 68A, 06536 Roßla
Tel.: +49 1511 8838514
marcus.fritzebiores.mwu.sachsen-anhaltde
Dr. Saskia Schirmer
Zoological Institute and Museum
University of Greifswald
Loitzer Straße 26, 17489 Greifswald
Tel.: +49 3834 420 4222
Saskia.schirmeruni-greifswaldde