• Energy Research

Many countries are investing heavily in wind power generation,1 triggering a high demand for suitable land. As a result, wind energy facilities are increasingly being installed in forests,2,3 despite the fact that forests are crucial for the protection of terrestrial biodiversity.4 This green-green dilemma is particularly evident for bats, as most species at risk of colliding with wind turbines roost in trees.2 With some of these species reported to be declining,5,6,7,8 we see an urgent need to understand how bats respond to wind turbines in forested areas, especially in Europe where all bat species are legally protected. We used miniaturized global positioning system (GPS) units to study how European common noctule bats (Nyctalus noctula), a species that is highly vulnerable at turbines,9 respond to wind turbines in forests. Data from 60 tagged common noctules yielded a total of 8,129 positions, of which 2.3% were recorded at distances <100 m from the nearest turbine. Bats were particularly active at turbines <500 m near roosts, which may require such turbines to be shut down more frequently at times of high bat activity to reduce collision risk. Beyond roosts, bats avoided turbines over several kilometers, supporting earlier findings on habitat loss for forest-associated bats.10 This habitat loss should be compensated by developing parts of the forest as refugia for bats. Our study highlights that it can be particularly challenging to generate wind energy in forested areas in an ecologically sustainable manner with minimal impact on forests and the wildlife that inhabit them.

Many countries are investing heavily in wind power generation,1 triggering a high demand for suitable land. As a result, wind energy facilities are increasingly being installed in forests,2,3 despite the fact that forests are crucial for the protection of terrestrial biodiversity.4 This green-green dilemma is particularly evident for bats, as most species at risk of colliding with wind turbines roost in trees.2 With some of these species reported to be declining,5,6,7,8 we see an urgent need to understand how bats respond to wind turbines in forested areas, especially in Europe where all bat species are legally protected. We used miniaturized global positioning system (GPS) units to study how European common noctule bats (Nyctalus noctula), a species that is highly vulnerable at turbines,9 respond to wind turbines in forests. Data from 60 tagged common noctules yielded a total of 8,129 positions, of which 2.3% were recorded at distances <100 m from the nearest turbine. Bats were particularly active at turbines <500 m near roosts, which may require such turbines to be shut down more frequently at times of high bat activity to reduce collision risk. Beyond roosts, bats avoided turbines over several kilometers, supporting earlier findings on habitat loss for forest-associated bats.10 This habitat loss should be compensated by developing parts of the forest as refugia for bats. Our study highlights that it can be particularly challenging to generate wind energy in forested areas in an ecologically sustainable manner with minimal impact on forests and the wildlife that inhabit them.

AbstractUrbanization has significant impacts on wildlife and ecosystems and acts as an environmental filter excluding certain species from local ecological communities. Specifically, it may be challenging for some animals to find enough food in urban environments to achieve a positive energy balance. Because urban environments favor small‐sized bats with low energy requirements, we hypothesized that common noctules (Nyctalus noctula) acquire food at a slower rate and rely less on conspecifics to find prey in urban than in rural environments due to a low food abundance and predictable distribution of insects in urban environments. To address this, we estimated prey sizes and measured prey capture rates, foraging efforts, and the presence of conspecifics during hunting of 22 common noctule bats equipped with sensor loggers in an urban and rural environment. Even though common noctule bats hunted similar‐sized prey in both environments, urban bats captured prey at a lower rate (mean: 2.4 vs. 6.3 prey attacks/min), and a lower total amount of prey (mean: 179 vs. 377 prey attacks/foraging bout) than conspecifics from rural environments. Consequently, the energy expended to capture prey was higher for common noctules in urban than in rural environments. In line with our prediction, urban bats relied less on group hunting, likely because group hunting was unnecessary in an environment where the spatial distribution of prey insects is predictable, for example, in parks or around floodlights. While acknowledging the limitations of a small sample size and low number of spatial replicates, our study suggests that scarce food resources may make urban habitats unfavorable for large bat species with higher energy requirements compared to smaller bat species. In conclusion, a lower food intake may displace larger species from urban areas making habitats with high insect biomass production key for protecting large bat species in urban environments.

AbstractUrbanization has significant impacts on wildlife and ecosystems and acts as an environmental filter excluding certain species from local ecological communities. Specifically, it may be challenging for some animals to find enough food in urban environments to achieve a positive energy balance. Because urban environments favor small‐sized bats with low energy requirements, we hypothesized that common noctules (Nyctalus noctula) acquire food at a slower rate and rely less on conspecifics to find prey in urban than in rural environments due to a low food abundance and predictable distribution of insects in urban environments. To address this, we estimated prey sizes and measured prey capture rates, foraging efforts, and the presence of conspecifics during hunting of 22 common noctule bats equipped with sensor loggers in an urban and rural environment. Even though common noctule bats hunted similar‐sized prey in both environments, urban bats captured prey at a lower rate (mean: 2.4 vs. 6.3 prey attacks/min), and a lower total amount of prey (mean: 179 vs. 377 prey attacks/foraging bout) than conspecifics from rural environments. Consequently, the energy expended to capture prey was higher for common noctules in urban than in rural environments. In line with our prediction, urban bats relied less on group hunting, likely because group hunting was unnecessary in an environment where the spatial distribution of prey insects is predictable, for example, in parks or around floodlights. While acknowledging the limitations of a small sample size and low number of spatial replicates, our study suggests that scarce food resources may make urban habitats unfavorable for large bat species with higher energy requirements compared to smaller bat species. In conclusion, a lower food intake may displace larger species from urban areas making habitats with high insect biomass production key for protecting large bat species in urban environments.

{"references": ["1 GWEC (Global Wind Energy Council) (2021). https://gwec.net/wp-content/uploads/2021/03/GWEC-Global-Wind-Report-2021.pdf ; Viewed 25th November 2021.", "2 Arnett, E.B., Baerwald, E.F., Mathews, F., Rodrigues, L., Rodr\u00edguez-Dur\u00e1n, A., Rydell, J., Villegas-Patraca, R., and Voigt, C.C. (2016). Impacts of wind energy development on bats: a global perspective. In Bats in the Anthropocene: conservation of bats in a changing world (pp. 295-323). Springer, Cham.", "3 Bunzel, K., Bovet, J., Thr\u00e4n, D., and Eichhorn, M. (2019). Hidden outlaws in the forest? A legal and spatial analysis of onshore wind energy in Germany. Energy Research & Social Science 55, 14-25.", "4 FAO, \"Global Forest Resources Assessment 2015\u2014How are the world's forests changing?\" (Food and Agriculture Organization of the United Nations, 2015)", "5 Frick, W. F., Baerwald, E. F., Pollock, J. F., Barclay, R. M. R., Szymanski, J. A., Weller, T. J., Russell, A. L., Loeb, S. C., Medellin, R. A., and McGuire, L. P. (2017). Fatalities at wind turbines may threaten population viability of a migratory bat. Biological Conservation 209, 172-177.", "6 Friedenberg, N. A., and Frick, W. F. (2021). Assessing fatality minimization for hoary bats amid continued wind energy development. Biological Conservation 262, 109309.", "7 BfN (Bundesamt f\u00fcr Naturschutz). 2018. National Implementation Report to EUROBATS; accessed on 28.12.2021 at https://www.eurobats.org/sites/default/files/documents/pdf/Meeting_of_Parties/Inf.MoP8_.21_NIR_Germany.pdf", "8 Printz, L., Tschapka, M., and Vogeler, A. (2021). The common noctule bat (Nyctalus noctula): population trends from artificial roosts and the effect of biotic and abiotic parameters on the probability of occupation. Journal of Urban Ecology 7 (1), juab033.", "9 Rydell, J., Bach, L., Dubourg-Savage, M.J., Green, M., Rodrigues, L., and Hedenstr\u00f6m, A. (2010). Bat mortality at wind turbines in northwestern Europe. Acta Chiropterologica 12(2): 261-274.", "10 Ellerbrok, J.S., Delius, A., Peter, F., Farwig, N., and Voigt, C.C. (2022). Activity of forest specialist bats decreases towards wind turbines at forest sites. Journal of Applied Ecology 00: 1\u2013 10. https://doi.org/10.1111/1365-2664.14249"]} Many countries are investing heavily in wind power generation,1 triggering a high demand for suitable land. As a result, wind energy facilities are increasingly being installed in forests,2,3 despite the fact that forests are crucial for the protection of terrestrial biodiversity.4 This green-green dilemma is particularly evident for bats, as most species at risk of colliding with wind turbines roost in trees.2 With some of these species reported to be declining,5-8 we see an urgent need to understand how bats respond to wind turbines in forested areas, especially in Europe where all bat species are legally protected. We used miniaturized global positioning system (GPS) units to study how European common noctule bats (Nyctalus noctula), a species that is highly vulnerable at turbines,9 respond to wind turbines in forests. Data from 60 tagged common noctules yielded a total of 8129 positions, of which 2.3% were recorded at distances <100 m from the nearest turbine. Bats were particularly active at turbines <500 m near roosts, which may require such turbines to be shut down more frequently at times of high bat activity to reduce collision risk. Beyond roosts, bats avoided turbines over several kilometers, supporting earlier findings on habitat loss for forest-associated bats.10 This habitat loss should be compensated by developing parts of the forest as refugia for bats. Our study highlights that it can be particularly challenging to generate wind energy in forested areas in an ecologically sustainable manner with minimal impact on forests and the wildlife that inhabit them. This project was funded by the Deutsche Bundesstiftung Umwelt DBU (34411/01-43/0).

{"references": ["1 GWEC (Global Wind Energy Council) (2021). https://gwec.net/wp-content/uploads/2021/03/GWEC-Global-Wind-Report-2021.pdf ; Viewed 25th November 2021.", "2 Arnett, E.B., Baerwald, E.F., Mathews, F., Rodrigues, L., Rodr\u00edguez-Dur\u00e1n, A., Rydell, J., Villegas-Patraca, R., and Voigt, C.C. (2016). Impacts of wind energy development on bats: a global perspective. In Bats in the Anthropocene: conservation of bats in a changing world (pp. 295-323). Springer, Cham.", "3 Bunzel, K., Bovet, J., Thr\u00e4n, D., and Eichhorn, M. (2019). Hidden outlaws in the forest? A legal and spatial analysis of onshore wind energy in Germany. Energy Research & Social Science 55, 14-25.", "4 FAO, \"Global Forest Resources Assessment 2015\u2014How are the world's forests changing?\" (Food and Agriculture Organization of the United Nations, 2015)", "5 Frick, W. F., Baerwald, E. F., Pollock, J. F., Barclay, R. M. R., Szymanski, J. A., Weller, T. J., Russell, A. L., Loeb, S. C., Medellin, R. A., and McGuire, L. P. (2017). Fatalities at wind turbines may threaten population viability of a migratory bat. Biological Conservation 209, 172-177.", "6 Friedenberg, N. A., and Frick, W. F. (2021). Assessing fatality minimization for hoary bats amid continued wind energy development. Biological Conservation 262, 109309.", "7 BfN (Bundesamt f\u00fcr Naturschutz). 2018. National Implementation Report to EUROBATS; accessed on 28.12.2021 at https://www.eurobats.org/sites/default/files/documents/pdf/Meeting_of_Parties/Inf.MoP8_.21_NIR_Germany.pdf", "8 Printz, L., Tschapka, M., and Vogeler, A. (2021). The common noctule bat (Nyctalus noctula): population trends from artificial roosts and the effect of biotic and abiotic parameters on the probability of occupation. Journal of Urban Ecology 7 (1), juab033.", "9 Rydell, J., Bach, L., Dubourg-Savage, M.J., Green, M., Rodrigues, L., and Hedenstr\u00f6m, A. (2010). Bat mortality at wind turbines in northwestern Europe. Acta Chiropterologica 12(2): 261-274.", "10 Ellerbrok, J.S., Delius, A., Peter, F., Farwig, N., and Voigt, C.C. (2022). Activity of forest specialist bats decreases towards wind turbines at forest sites. Journal of Applied Ecology 00: 1\u2013 10. https://doi.org/10.1111/1365-2664.14249"]} Many countries are investing heavily in wind power generation,1 triggering a high demand for suitable land. As a result, wind energy facilities are increasingly being installed in forests,2,3 despite the fact that forests are crucial for the protection of terrestrial biodiversity.4 This green-green dilemma is particularly evident for bats, as most species at risk of colliding with wind turbines roost in trees.2 With some of these species reported to be declining,5-8 we see an urgent need to understand how bats respond to wind turbines in forested areas, especially in Europe where all bat species are legally protected. We used miniaturized global positioning system (GPS) units to study how European common noctule bats (Nyctalus noctula), a species that is highly vulnerable at turbines,9 respond to wind turbines in forests. Data from 60 tagged common noctules yielded a total of 8129 positions, of which 2.3% were recorded at distances <100 m from the nearest turbine. Bats were particularly active at turbines <500 m near roosts, which may require such turbines to be shut down more frequently at times of high bat activity to reduce collision risk. Beyond roosts, bats avoided turbines over several kilometers, supporting earlier findings on habitat loss for forest-associated bats.10 This habitat loss should be compensated by developing parts of the forest as refugia for bats. Our study highlights that it can be particularly challenging to generate wind energy in forested areas in an ecologically sustainable manner with minimal impact on forests and the wildlife that inhabit them. This project was funded by the Deutsche Bundesstiftung Umwelt DBU (34411/01-43/0).