Drivers of European bat population change: a review reveals evidence gaps

• Published in: Mammal review 2021-07, Vol.51 (3), p.353-368
• Main Authors: Browning, Ella, Barlow, Kate E., Burns, Fiona, Hawkins, Charlotte, Boughey, Katherine
• Format: Article
• Language: English
• Subjects: abundance; Bats; Chiroptera; Climate change; Conservation; development; Environmental changes; Environmental impact; Europe; habitat fragmentation; Land pollution; Mitigation; mitigation measures; monitoring tools; Offshore operations; Pollution effects; Population; Population (statistical); Protected species; Recovery; Statistical methods; Synergistic effect; Trends; Turbines; Urbanization; Water pollution; Wildlife conservation; Wind power; Wind turbines
• ISSN: 0305-1838; 1365-2907
• DOI: 10.1111/mam.12239

Bat populations are thought to have suffered significant declines in the past century throughout Europe. Fortunately, there are some signs of recovery; for instance, of the 11 species monitored in the UK, population trends of five are increasing. The drivers of past losses and recent trends are unclear; identifying them will enable targeted conservation strategies to support further recovery. We review the evidence linking proposed drivers to impacts on bat populations in Europe, using the results of a previous cross‐taxa semi‐quantitative assessment as a framework. Broadly, the drivers reviewed relate to land‐use practices, climate change, pollution, development and infrastructure, and human disturbance. We highlight where evidence gaps or conflicts present barriers to successful conservation and review emerging opportunities to address these gaps. We find that the relative importance or impacts of the potential drivers of bat population change are not well understood or quantified, with conflicting evidence in many cases. To close key gaps in the evidence for responses of bat populations to environmental change, future studies should focus on the impacts of climate change, urbanisation, offshore wind turbines, and water pollution, as well as on mitigation measures and the synergistic effects of putative drivers. To increase available evidence of drivers of bat population change, we propose utilising advances in monitoring tools and statistical methods, together with robust quantitative assessment of conservation interventions to mitigate threats and enable the effective conservation of these protected species. European bat populations are thought to have suffered significant losses over the past century due to anthropogenic activities and environmental change. However, the reasons for these historic declines and recent bat population trends remain unclear due to gaps in evidence for the impacts of many putative drivers of change. Closing these evidence gaps is important if conservation measures targeted at species’ recoveries or to mitigate the impacts of anthropogenic activities are to be successful. We review evidence for the impacts of proposed drivers of European bat population change and group them by drivers with reasonable evidence and drivers with poor or conflicting evidence. We then identify emerging opportunities to combine biodiversity data collection tools and statistical methods to increase evidence availability for the drivers of bat popul