A new study published earlier this month has found that wind turbines and wind farms have the potential of acting as a new apex predator in a given ecosystem, but the authors of the study are quick to point out that this is not an argument against wind energy, but rather an argument for more informed decision-making.
The findings are the result of several years’ worth of observations on the richly biodiverse Western Ghats in India, conducted by Maria Thaker from the Centre for Ecological Sciences at the Indian Institute of Science in Bangalore, and her project students, Amod Zambre and Harshal Bhosale, and presented in the journal Nature Ecology & Evolution earlier this month. The region was chosen because, as Maria Thaker explained to me, “The Western Ghats in India have a large number of endemic species and so it is wonderfully unique.”
Specifically, Thaker and her students identified not only the new-normal reduction in the number of birds in the area but also found that this has a trickle-on impact on lizards that, previously, were the birds’ prey. According to the research, with the reduction in predation, the density of fan-throated lizards increased in the presence of wind turbines. Conversely, however, even though their numbers increased, the lizards suffered changes in their hormonal stress levels, anti-predator behavior, body condition, and even colors.
The overlying conclusion is that wind farms have a cascading indirect effect on lizards, “driven by a combination of predator release and density-dependent competition” which are “akin to a trophic cascade with wind farms at the top of the food chain.” But this does not stop the authors from also making clear that “Wind farms are a cleaner alternative to fossil fuels for mitigating the effects of climate change,” only that “they also have complex ecological consequences.”
Two terms are worth clarifying, therefore, to better understand the results of this research. The first, “trophic cascade,” is the result of the introduction or removal of a top predator from an ecosystem which has repercussions down the chain. For example, removing wolves from a North American region might result in an increase in certain types of deer, which in turn results in a decrease of certain plants which are eaten by the deer.
Less complex is the term “apex predator” which, in the preceding illustration, would be the wolf — the animal at the top of the food chain which impacts the rest of the food chain with their behavior.
These two terms help us understand the idea of how a wind farm can act akin to an apex predator, given the impact it has on the immediately surrounding food chain. What’s also important to take into consideration is that the introduction of wind turbines as a potential apex predator does not mean that wind turbines are killing off the previous apex predators — such as raptors — but simply causing those predators to avoid the region. “There is some mortality from collisions,” Thaker explained, “but most of the reduction in abundance is from the predatory birds avoiding the areas with wind-turbines.” Writing in their study, the authors further explain, ” By reducing the activity of predatory birds in the area, wind turbines effectively create a predation-free environment that causes a cascade of effects on a lower trophic level.”
Another thing that is worth being aware of is the impact that wind farms actually have on birds. For many of us who are not read up on our avian fauna history, a giant wind turbine stuck in the middle of a bird’s traditional migratory flight path leaves us with one question: Why don’t they just fly around it?
Turns out, that’s exactly what the birds do!
“Birds can fly around wind-turbines so a single or a few turbines are not a big ecological problem,” said Maria Thaker. “Wind farms with many turbines in close proximity make it difficult for some birds to fly under or between the turbines, so they fly around the entire farm. What this means is that the terrestrial animals are essentially free of predation in those areas. Those are the unexpected effects that we and others are discovering.”
In this regard, then, the most important thing for the clean energy community (and the anti-renewable energy community) is to understand that this research is not an argument against wind energy.
“I’m an ecologist and our paper in Nature Ecology and Evolution was designed to understand the ecological consequences of wind-farms, not make policy decisions,” explained Maria Thaker, who spoke to me via email. “It is absolutely NOT intended to protest wind energy development.”
“Many of the ecological findings I report in this paper have been found by others in various parts of the world,” she continued. “What makes our work new is that we take a multivariate look at how birds and lizards change in response. We include a study of physiology, behaviour, and morphology, and discover that the wind-turbines have cascading impacts that are direct and indirect. The results of our study do not lead us to conclude that wind turbines are bad for the environment; their effects are complicated and so cannot be considered neutral. If I have to make a policy decision, I’d say that we need to be careful not to install large wind-farms in ecological sensitive areas.”
And this is the important point that all and sundry must pay attention to — both those of us within the clean technology industry and those outside, looking in, trying to tear it down. This report does not represent any data point against wind energy. Rather, it is a data point that points to a greater need to carefully understand the impact a potential wind farm might have on an area — not just from the most obvious environmental and ecological impacts, but the trickle-down impacts that take time to develop.