Activity of forest specialist bats decreases towards wind turbines at forest sites

Abstract

Worldwide, wind turbines are increasingly being built at forest sites to meet the goals of national climate strategies. Yet, the impact on biodiversity is barely understood. Bats may be heavily affected by wind turbines in forests, because many species depend on forest ecosystems for roosting and hunting and can experience high fatality rates at wind turbines. We performed acoustic surveys in 24 temperate forests in the low mountain ranges of Central Germany to monitor changes in the acoustic activity of bats in relation to wind turbine proximity, rotor size, vegetation structure and season. Call sequences were identified and assigned to one of three functional guilds: open‐space, edge‐space and narrow‐space foragers, the latter being mainly forest specialists. Based on the response behaviour of bats towards wind turbines in open landscapes, we predicted decreasing bat activity towards wind turbines at forest sites, especially for narrow‐space foragers. Vertical vegetation heterogeneity had a strong positive effect on all bats, yet responses to wind turbines in forests varied across foraging guilds. Activity of narrow‐space foragers decreased towards turbines over distances of several hundred metres, especially towards turbines with large rotors and during mid‐summer months. The activity of edge‐space foragers did not change with distance to turbines or season, whereas the activity of open‐space foragers increased close to turbines in late summer. Synthesis and applications. Forest specialist bats avoid wind turbines in forests over distances of several hundred metres. This avoidance was most apparent towards turbines with large rotors. Since forests are an important habitat for these bats, we advise to exclude forests with diverse vegetation structure as potential wind turbine sites and to consider compensation measures to account for habitat degradation associated with the operation of wind turbines in forests.

Wind energy development can lead to guild‐specific habitat loss in boreal forest bats

“…Gaultier et al (2023) and Ellerbrok et al (2022) both monitored bats at wind parks in European forested landscapes in the same period as this study and found similar avoidance effects; Myotis spp. activity was more likely to be recorded further from turbines.…”

“…Habitat fragmentation and degradation could also explain avoidance effects (Lesiński 2007, Barré et al 2018, especially if turbine development causes insect declines and subsequently reduces foraging habitat (Rydell et al 2010b, Millon et al 2015. Gaultier et al (2023) and Ellerbrok et al (2022) both monitored bats at wind parks in European forested landscapes in the same period as this study and found similar avoidance effects; Myotis spp. activity was more likely to be recorded further from turbines.…”

“…Such development can also displace species that require forest cover and/or are sensitive to the sounds and presence of turbines by degrading the habitat, resulting in broad cascading effects (Barré et al 2018, Roemer et al 2019). Ellerbrok et al (2022) and Gaultier et al (2023) both recently found that bats, especially those adapted to flying in cluttered habitat, were deterred by the presence of wind turbines in northern Europe. These studies emphasize the importance of acknowledging habitat loss from wind turbines as a risk to bats.…”

Toward solving the global green–green dilemma between wind energy production and bat conservation

“…A similar decrease was observed for open-space- and narrow-space-foraging bats at wind turbines in forests (Ellerbrok et al. 2022 , Gaultier et al. 2023 , McKay et al.…”

“…Deforestation can affect forest-dependent bat species, which may lose both foraging and roosting habitats (Ellerbrok et al. 2022 , Reusch et al. 2023 ).…”