Editor's choice: New research on wind farms

C.L. Devereux, M.J.H. Denny & M.J. Whittingham (2008). Minimal effects of wind turbines on the distribution of wintering farmland birds. Journal of Applied Ecology, 45, 1689–1694.

M. Lucas, G.F.E. Janss, D.P. Whitfield & M. Ferrer (2008) Collision fatality of raptors in wind farms does not depend on raptor abundance. Journal of Applied Ecology, 45, 1695–1703

Whether the reason is climate change or rising fuel costs, energy is at the forefront of societal debate worldwide. All energy production has ecological costs, be it conversion of land to solar panel arrays, damming of rivers for hydroelectric production, or release of oil into coastal waters. Perhaps the most controversial of the new technologies, however, is wind power, with raging debates between those who see wind turbines as a necessary part of the energy equation versus those who consider them ugly bird killers.

Wind farms affect biological diversity in three main ways (Langston & Pullan 2003). First, construction of towers and associated infrastructure causes habitat loss. Second, towers and their rotating blades kill aerial species that collide with them. Third, the mere presence of towers can displace species, or cause them to change their behaviour. Beyond this broad outline, however, our understanding of the ecological effects remains rudimentary (Stewart et al. 2007). Much of the research has focused on a limited set of locations (e.g. mountains in California and Spain) and species (e.g. raptors and other large birds), and few studies have systematically addressed all potential effects in a single system (Langston & Pullan 2003). Moreover, relatively little wind farm research makes it into the peer-reviewed literature where it can be fully evaluated, though this is gradually changing (e.g. Barrios & Rodriguez 2004; Garthe & Hüppop 2004).

For these reasons, this issue's Editor's Choice highlights new wind farm research. Devereux, Denny & Whittingham (2008) studied the effects of turbines on farmland bird distributions at a site in eastern England. They concluded that, other than for one non-native species, there was no evidence that farming wind on cropland was incompatible with agri-environment schemes designed to benefit birds. As the authors point out, this work is only the first step and – contrary to some headlines recently linked to the study – is far from definitive. Their study had a short duration, occurred at just one site, focused on the non-breeding season, and was restricted to birds. But, by expanding the focus of wind farm research into agro-ecosystems it is a critical first step that contributes importantly to the growing body of work on the topic.

Another new study also advances our understanding of wind farm effects. As with the Devereux et al. paper, a common limitation of wind energy studies is their short duration. To a degree this is an inevitable consequence of studying a technology that has not been around for long, but there are locations where decadal-scale assessments are possible. To this end, Lucas et al. (2008) compiled 10 years of data on raptor mortality for two Spanish sites. Like much applied research (Elphick 2008), this study had to strike a compromise between achieving a perfect study design and the need to inform policy in the short-term. For Lucas et al. a major concern was the lack of a standardized protocol for collecting mortality data. Consequently, the study was limited to large species, the carcasses of which are known to persist for long periods in the study area, thus reducing the chance of their being missed. Drawing on their large data set, the authors show that susceptibility is not simply related to abundance, and that collision risk varies substantially among species and seasons. The study also found that taller turbines, sited at higher elevations on gentle slopes, caused the most fatalities. This heterogeneity in the who, when and where of collision fatalities has clear implications for how ecologists predict the effects of planned wind farms. As understanding of these factors grows, the ability to design installations that maximize output for minimal risk should improve.

There is no doubt that wind turbines kill many birds and, as we’re rapidly learning, bats. But people readily accept that other routine aspects of our lives – cars, pet cats, even windows – also kill many animals, and in much larger numbers than do wind farms. So, the question becomes: When should we be especially concerned about the mortality level? Perhaps the largest gap in our understanding is how the documented effects on individuals translate into population-level changes. The next generation of research needs to go further in making this link. More experimental work to determine how farm design and operation can be modified to minimize effects (cf. Larsen & Guillemette 2007) is also needed. Just as important is the need to implement common standards for assessing impacts, to facilitate comparisons across locations and the pooling of data from multiple studies. Lastly, as the world works out how to address the looming transitions in energy production, we need to consider how the respective impacts of different energy sources, relative to the rate of energy production, compare. Only through this type of analysis can we fully evaluate the ecological cost of wind power.