Bats rely on clear water sources, like small ponds and lakes, for their feeding and hydration needs. Access to these water sources plays a crucial role for their survival, especially during the hotter, drier summers exacerbated by climate change. This period also coincides with the time when female bats are pregnant and caring for their young. A research team has found that wind turbines disrupt access to drinking locations in agricultural areas; many bat species tend to steer clear of both the turbines and nearby water sources for several kilometers.
Bats rely heavily on open bodies of water, such as ponds and lakes, for feeding and drinking. This access is vital for their survival during the increasingly hot and dry summers intensified by climate change, which coincides with the period when female bats give birth and care for their young. A research team from the Leibniz Institute for Zoo and Wildlife Research (Leibniz-IZW) has demonstrated that the presence of wind turbines in agricultural landscapes limits access to drinking locations. Numerous bat species avoid these turbines and the water bodies near them for several kilometers. These findings appeared in the scientific journal Biological Conservation.
In an effort to combat climate change, many nations are boosting their wind energy production to decrease greenhouse gas emissions like CO2. Nonetheless, the expansion of wind energy can adversely affect wildlife and their habitats, thereby making it harder for some species to adapt to global warming. According to Prof. Dr. Christian Voigt and Dr. Carolin Scholz from the Leibniz-IZW, alongside Hannah Klein from the University of Potsdam, their study on the acoustic activity of bats in agricultural regions revealed that numerous bat species are displaced from areas near wind turbines close to smaller water bodies. They analyzed the behaviors of bats from three functional groups: open space foragers (which hunt above fields or top of forests), narrow space foragers (which hunt in dense vegetation, like under tree canopies), and edge space foragers (which typically forage near transitions like forest edges). “Our findings made it clear that bats specialized in open and dense areas tend to avoid water bodies when wind turbines are nearby,” Voigt explains. “Only the edge space foraging bats seem to remain unaffected by the presence of wind turbines at water sites.”
The researchers set up acoustic sensors at 59 small ponds that have water year-round, positioned between 50 and 5,000 meters from wind turbines in northern Brandenburg, a state in Eastern Germany. Due to its glacial past, this area has over a thousand small ponds, known as kettle holes or kettle lakes, which play essential ecological roles even amidst intensive agriculture. “In July, during the reproductive period, we recorded the acoustic activities of bats at water bodies at varying distances from wind turbines. We ensured we compared data under similar conditions, like minimal rain and moderate wind,” Scholz describes. “As July is when female bats finish lactation and wean their young, it becomes energetically challenging for them. Furthermore, many waterholes are likely to dry up in summer, making those remaining perennial water bodies even more crucial for the bats.”
The team detected almost 8,400 calls from various bat species across the three groups: open space hunters, narrow space hunters, and edge space foragers. “As the distance from wind turbines decreased, the activity of open space foraging bats at water bodies dropped by 53%, while that of narrow space foragers decreased by 63%,” the authors report. A similar trend was seen in the foraging behaviors indicated by the sensors, which dropped by 87% and 76% as the turbines drew closer, from 5 kilometers to nearly zero.
“These findings carry a significant irony, as an effort meant to address climate change adversely affects certain bat species’ ability to endure hot and dry summers due to their displacement by wind turbines,” comments Voigt. “This highlights the necessity of carefully considering wind turbine locations to avoid conflicting objectives. Habitats vital for conservation should be prioritized as low or entirely inappropriate sites for wind energy production.”
The bat species under study included the common pipistrelle (Pipistrellus pipistrellus), the soprano pipistrelle (Pipistrellus pygmaeus), and the western barbastelle (Barbastella barbastellus) representing edge space foragers, along with species from the noctule (Nyctalus), house (Eptesicus), and vesper bats (Vespertilio) as examples of open space foragers. Additionally, the narrow space foragers included species from the mouse-eared bats (Myotis) and long-eared bats (Plecotus).
Under German and EU laws, bats are protected species and should receive special consideration as migratory animals. However, this protection conflicts with the growth of wind energy, which poses numerous direct threats to bat populations and disrupts their habitats. Voigt’s team at the IZW has focused on studying this ongoing “green-green conflict” between enhancing wind energy and conserving bat populations for many years.
