Wind turbines kill bats, but they don’t have to

Global expansion of renewable energy is critical as we transition away from fossil fuels; however, wind turbines pose a serious threat to bat populations, with hundreds of thousands of fatal collisions per year in the USA and Canada alone (Arnett and Baerwald, 2013; Arnett et al., 2016; Hayes, 2013; Smallwood, 2013; Thompson et al., 2017 ). This is unsustainable given:

• Many bats are long-lived and slow to reproduce, making recovery from population declines difficult (Barclay et al. 2004);
• Bats appear attracted to turbines (Cryan et al., 2014, Richardson et al., 2021), and;
• The paucity of studies on bat and wind turbine interactions in Australia limits our understanding of population-level impacts (Arnett & Baerwald 2013; Bennett et al., 2022).

Curtailment (restricting blade rotation at low wind speeds, e.g., <7 ms^-1, when bats are active; Arnett et al., 2008; Behr et al., 2017) is the most successful method of reducing collisions globally, with typical fatality reductions ranging from 44 to 93% (Adams et al., 2021; Arnett et al., 2009, 2011; Hayes et al., 2019; Martin et al., 2017; Whitby et al., 2021). As such, mandatory curtailment during high-risk periods is standard practice in some parts of Europe (Rodrigues et al., 2015;Voigt et al., 2022). Meanwhile, only one study has investigated curtailment in Australia, with a 54% fatality reduction (turbine cut-in speed 4.5 ms^-1; Bennett et al., 2022).

Economically, losses from curtailment in the northern hemisphere range from 1 to 4% of annual revenue (Arnett et al., 2011; Hayes et al., 2019; Martin et al., 2017; Thurber et al., 2023), whilst in Australia, a reduction of <0.1% was reported (Bennett et al., 2022). By incorporating site-specific weather and bat activity data, both economic and ecological losses can be further minimised (Hayes et al., 2019; Martin et al., 2017; Rnjak et al., 2023; Salguero et al., 2023; Squires et al., 2021). Additionally, international good practice guidelines recommend a project’s energy yield assessment should account for curtailment-related energy loss (Hulka and Conzo, 2021; IFC, 2023).

Installed wind energy in Australia has grown on average 15.4% per annum over the past decade, and this is expected to continue (Australian Energy Update 2023). However, current fatality rates are sufficiently high to cause population declines of even common species (Arnett and Baerwald, 2013; Frick et al., 2017; Friedenberg and Frick, 2021; O’Shea et al., 2016; Rodhouse et al., 2019), with increased risk for those frequently killed, such as the Australian Austronomus australis (Bennett et al., 2022). But solutions exist for the continued growth of wind energy whilst minimising biodiversity impacts. Incorporating impacts into the planning stages of wind farm development and implementing curtailment in Australia will encourage critical research into bat-turbine interactions, assist in developing smart curtailment strategies, and prevent potentially irreversible population declines.

More on this Hot Topic:

– Plain-English factsheet (PDF) –

– Evidence from the scientific literature to support this Hot Topic (references) –

– Link to peer-reviewed article via Austral Ecology –

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