Wind turbines aren’t quite ‘apex predators’, but the truth is far more interesting

November 7, 2018 | Jeroen Minderman|

In some ways, it may indeed seem as if wind turbines act similarly to the introduction of an “apex predator” into the food chain: by reducing the number and activity of intermediate predators such as birds of prey, predation pressure on smaller animals may be reduced. However, it is of course important to stress that almost all biological predators are, in the end, limited by the availability of prey. By contrast, turbines are not limited in this way and will continue to be present regardless of whether their “prey” goes locally extinct.

Perhaps more important is the non-lethal effects on the wider ecosystem that is highlighted by Thaker and colleagues. By reducing predation or reducing the activity of predators, the physiology, behaviour and population density of prey populations can be changed in unpredictable and subtle ways.

Looking beyond the collision casualties

What this work really highlights is that wind farms can have effects that are indirect or not immediately visible. This poses a huge challenge for impact assessments and survey work. Perhaps understandably, many assessments of wind turbines focus on vulnerable species, which tend to be the birds and bats most at risk of direct collision. Similarly, where carried out, post-construction monitoring often focuses on collision casualties. These are things that can be directly measured or counted, over clearly defined periods.

By contrast, assessing the longer-term effects on indirectly impacted species such as lizards takes a lot more time and money. Unfortunately, this luxury is typically not available for commercial impact assessment studies. What is more, it is likely to be significantly harder to convince regulators that impact assessments should be broadened to consider wider ecosystems, particularly where these cannot be immediately seen or counted as dead animals.

At least in the UK, there is some evidence that consideration of such “synergistic” effects of developments is now increasingly expected in impact assessments. While this is encouraging, more work along the lines of study by Thaker and colleagues is needed to build up a better understanding of the extent and importance of similar effects in different areas. From a pragmatic perspective, it may well be that in the future impact assessments will move away from focusing on direct collision mortality and towards more targeted and in-depth assessments of “downstream” ecological impacts


Related Post: Predator Effect of Turbines