Abstract
On March 18, 2024, a workshop convened in Utrecht to address the presence of the Nathusius’ pipistrelle (Pipistrellus nathusii) in the North Sea and the associated collision risks with wind farms. The primary objective was to refine the estimation of bat fatalities on the North Sea. Relevant for this estimation is the number of bats that collide with turbines annually. Key discussions centered around data availability, knowledge gaps, and avenues for future research.
Participants engaged in fruitful discussions regarding existing data and uncertainties. This note aims to capture these diverse viewpoints while gathering comprehensive information. The participants of the workshop, as well as international reviewers, reviewed this document and added their additional thoughts and feedback.
- The first goal of this project was to refine the assumptions for bat fatalities. The current reasoning lacks scientific substantiation, necessitating further research on population estimates, migration patterns, and behaviour. Alternative approaches discussed include using ratios and proportions or a conversion factor based on density.
- The second goal was to gain spatio-temporal insights. Translating current knowledge into a relative number of bat fatalities per OWF-area (relative impact factor) proved challenging. Some key insights include gaps in the MOTUS monitoring system hinder land-based migration understanding. Besides this, data is lacking in the northern North Sea but warrants investigation due to observed species presence.
- The final goal was to capture the required next steps that will lead to an improved quantification of bat fatalities from OWFs. The proposed steps include an enhancement of bat detection methods. It was noted that it is important to gain more knowledge about bat behaviour around wind turbines.
It was suggested to better utilize existing data and improve land-based estimates for offshore scenarios. It is evident that much remains unknown, but there is sufficient information to conceptualize possibilities for a new line of reasoning. The information in this note can guide further research and address existing gaps in knowledge. Large-scale research projects were proposed, as well as low-hanging fruit such as analysing existing data. Throughout the session, two potential new lines of reasoning were identified - a promising starting point for further exploration and development.