A predictive model for improving placement of wind turbines to minimise collision risk potential for a large soaring raptor

Each year, Journal of Applied Ecology awards the Southwood Prize to the best paper in the journal by an author at the start of their career. In this post, Megan Murgatroyd (HawkWatch International/FitzPatrick Institute of African Ornithology at the University of Cape Town) discusses her shortlisted paper which used GPS tracking data together with a digital elevation model to classify the spatial likelihood of wind turbine collisions for adult Verreaux’s eagles.

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Photo: Megan Murgatroyd

The impacts of climate change have been severe in Africa, and the growing population needs better access to energy. South Africa is the largest consumer of energy in Africa and most of the electricity generated currently comes from burning coal. However, this is set to change and the renewable energy sector is growing in South Africa. There are already 26 fully operational wind farms producing over 2 gigawatts of power, and several more are about to come online. By the end of 2030, the country aims to produce around 20% of energy demand from wind power alone. 

So why aren’t we all rejoicing? While wind power may be ‘clean’, it is not without environmental challenges. A major concern is the mortality of birds which collide with the moving blades. This problem has already been seen worldwide, and some birds are more vulnerable to this threat than others. Raptors, such as eagles, buzzards and vultures, use the same wind resources that turbines need to operate. These large soaring birds use the wind to help power their own flight, by using up-draughts to glide or gain height. Whether they don’t perceive wind turbines as a threat, can’t manoeuvre away in time or simply don’t see them isn’t understood.

Since many raptors species also have long lifespans and produce few young each year, even a small increase in deaths via turbine collisions can cause populations to decline. Verreaux’s Eagles live in mountainous areas of sub-Saharan Africa and have a considerable range overlap with the areas being targeted for wind energy development. As such they have quickly become the most frequently killed large raptor at wind farms in South Africa.

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Photo: Megan Murgatroyd

This wind-wildlife conflict is a green-green dilemma: more clean energy and healthy bird populations are both desirable environmental goals, but one negatively impacts the other. Our research aimed to address this by reducing the risk of eagles colliding with wind turbines, while facilitating the development of wind energy in a more sustainable way.

To do this we built a predictive model which can calculate the likelihood of eagle collisions before they happen. The model uses simple landscape-based variables to understand eagle flight which was recorded by GPS devices. The end product of this research is a tool which can map collision risk potential for energy developers and guide safer placement of wind turbines for eagles.

In addition to this, the model also provides space saving incentives for developers. Until now, circular no-go zones for development have been implemented around eagle nests, but in order for these to adequately protect an eagle’s territory buffers would need to be very large. They also exclude areas which might not actually be used by eagles, since home ranges are not circular. By providing landscape-based predictions, our collision risk potential model can free up around 20% more land to be developed for wind energy while maintaining a high level of eagle protection. This moves the green-green dilemma into the realm of a win-win solution.

Since the publication of our model, it has been applied to over 20 proposed wind farms in South Africa, helping to secure futures for nearly 200 pairs of eagles, while giving robust assessments of collision risk to help streamline sustainable development. This is a big step forward for improving energy access in an environmentally friendly way.

Read the full paper A predictive model for improving placement of wind turbines to minimise collision risk potential for a large soaring raptor in Journal of Applied Ecology.

Find out more about the Southwood Prize early career researcher award here.

Megan Murgatroyd is a conservation scientist at HawkWatch International and a research associate at the FitzPatrick Institute of African Ornithology at the University of Cape Town, South Africa, where she also spent her post-doc and published this paper in the Journal of Applied Ecology. Her research focuses on the conservation of African raptors, with a specific interest in mitigating the growing impacts of energy developments on biodiversity. The paper has been a significant contribution to improving conservation of eagles in South Africa, and has paved the way for similar risk mitigation for other vulnerable raptors. Megan is thankful for the invaluable contributions from her PhD and post-doc supervisor, Arjun Amar, and coauthor Willem Bouten, without whom this paper would not have been possible.

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