Wind farms and biodiversity: are they on a collision course?

Published on 13 September 2017 in News and comment

A newly published study, funded by the Cambridge Conservation Initiative (CCI), has shown the potential vulnerability of birds and bats around the world to collide with wind turbines. In order to help reduce the potential for conflict between solutions for a greener future and healthy biodiversity, the results identify which species are most vulnerable and where these species are concentrated.

As part of efforts to combat climate change, there is a rapid growth in renewable energy production around the world. However, one of the major forms of renewable energy, wind farms, can have negative impacts on biodiversity through mortality associated with turbines. Although known about from studies in Europe and North America, there is little information from other regions where wind farms are expanding rapidly. This new study, published in Proceedings Of The Royal Society B identifies for the first time the potential vulnerability to collision mortality of bird and bat species around the world and suggests how collisions may be avoided. To achieve the British Trust for Ornithology (BTO) led a review of published papers documenting collision rates with onshore wind turbines. In order to extrapolate these observations to less-well studied species, rates of collision were modelled in relation to factors including birds’ migratory behaviour and ecology, and wind turbine height and capacity.

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 (Accipitriformes) were the most vulnerable birds, which is problematic as many such 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 bird, with a number of North American species such as hoary bat and Eastern red bat particularly vulnerable.

Importantly, the results suggest that building fewer, large turbines may actually reduce the risk of collision for birds for a given amount of energy generated, although turbines with a capacity over 1.25MW were associated with higher collision rates for bats.

Lead author, 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 (e.g. avoiding migratory flyways) could greatly reduce the risk of collisions. 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 surely help to find the delicate balance between a greener future and healthy biodiversity.’

James Pearce-Higgins, Director of Science of the BTO and author of the paper said ‘Although these results may seem to infer that wind farms are bad for biodiversity and should be opposed, this study actually 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.’

Stuart Butchart, Chief Scientist, Birdlife International, said: ‘Wind farms have a key role to play in reducing our reliance on fossil fuels. This new study provides essential information to help ensure that wind energy development takes account of potential impacts on birds and bats, and that turbines are not placed in the most sensitive locations.’