Bird and bat vulnerability to wind farms

26 Sep 2017

A new study, funded by the CCI Collaborative Fund, has shown the potential vulnerability of birds and bats around the world to collide with wind turbines. The paper, recently published in Proceedings of the Royal Society of London B: Biological Sciences, was prepared by the team working on the Collaborative Fund project ‘Impacts of renewable energy on global biodiversity – an overlooked cost of climate change mitigation?’.

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, a collaboration between seven CCI partners, 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.

The team reviewed published papers documenting collision rates with onshore wind turbines. 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, Dr Chris Thaxter, of the British Trust for Ornithology (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."

Read the paper in full here.