Working towards safer onshore windfarms

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A new study, published in ‘Proceedings of the Royal Society B – Biological Sciences’ could provide the answer to making onshore windfarms safer for birds and bats.

There is no doubting the urgent requirement for renewable energy production if climate change is to be brought under control. However, the challenge is to develop solutions whilst being sensitive to potential impacts on biodiversity. Birds and bats in particular can be placed at risk due to collisions with wind turbines at onshore windfarms.


Onshore windfarms
Onshore windfarm © Dawn Balmer/BTO


In this pioneering study, the British Trust for Ornithology (BTO) has identified the key risks related to how and why these collisions occur and suggested means for reducing such impacts. Until now, little was known about the extent of the problem of outside of Europe and North America. It was therefore crucial to understand the issue from a global perspective, given the rapid expansion of windfarms in other regions.


“It is vital to consider the impacts of wind farms on populations of both bats and birds…”

The BTO, funded by Cambridge Conservation Initiative (CCI), led a review of published papers which documented the collision rates with onshore windfarms, identifying which species are most vulnerable and where these species are concentrated. Modelling the rate of collisions in relation to factors such as migratory behaviour and ecology, and wind turbine height and capacity provided a clear insight into the potential hazards faced by the birds and bats.

Lead author, Dr. Chris Thaxter of the BTO said, “It is vital to consider the impacts of wind farms on populations of both bats and birds, especially for migrants and wide-ranging species. Considering where to place wind farms, for example, avoiding migratory flyways could greatly reduce the risk of collisions.”


Golden Eagle are at risk from onshore windfarms
Birds of prey such as the Golden Eagle are at risk from onshore windfarms – © Tom Wallis/BTO


Some of the key findings of the study were:

  • Collision rates of the 769 bird-species tested were affected by habitat, migratory strategy and dispersal distance.
  • Birds using artificial habitat, such as farmland, had a higher risk of collision with wind turbines, potentially because more wind farms are placed there than in other habitats, and because such habitats tend to be more open.
  • Migrant birds and bats that dispersed further had a higher risk of collision.
  • Birds of prey were the most vulnerable, which is problematic as many of these species are slow to reproduce and have populations that are highly sensitive to reductions in survival rates.
  • Collision rates in general were predicted to be higher for bats than for birds, with a number of North American species such as hoary bat and Eastern red bat particularly vulnerable.


Hoary Bat at risk from onshore windfarms
Hoary Bat – Paul Cryan/U.S. Geological Survey

Amongst the solutions suggested by the study, was that building fewer large turbines may actually reduce the risk of collision for birds and bats.

Dr. James Pearce-Higgins, Director of Science of the BTO and author of the paper said, “This study provides an important way forward to facilitate renewable energy to combat climate change whilst minimising the impacts on vulnerable species.

By identifying which species are most vulnerable, and where those species are found, these results can inform strategic spatial planning to indicate where wind farms may be least damaging, and to identify the priority species for impact assessment by individual developments. The use of appropriately sized turbines may also minimise collision risk.”

Dr Chris Thaxter concluded, “Future research should prioritise work in developing countries where wind power may soon become an alternative to fossil fuel as these countries try to meet climate mitigation goals, as well as off-shore wind farms. This will help to find the delicate balance between a greener future and healthy biodiversity.”



Related article on talk: Wildlife: Assessing windfarm risks

Thumbnail image: Red Kite – © Jill Packenham/BTO

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