Disturbance effects of wind farms on birds

Abstract

Wind energy, like all renewable energy production, is a sustainable resource with a far lower carbon footprint than the burning of fossil fuels and consequently plays a role in mitigating climate change. There has been a rapid rise in its use over the last 15 years. However, there are concerns regarding the potential effects of wind turbines on wildlife, especially birds and bats. Potential effects include disturbance through direct or indirect habitat loss, or fatality through collision with turbine blades. First, I investigated the potential of using existing bird monitoring data collected by Environmental Impact Assessments (EIAs) and post-construction monitoring for developing an evidence base for the impacts of wind turbines on bird populations. As EIAs are required for wind farms to predict and mitigate potential negative effects, vast amounts of data are gathered by wind farm companies but subsequently not used to assess the effects, due to the associated logistical issues of obtaining these data (despite being officially available in the public domain). Using data from seven wind farm sites, I found that lekking black grouse (Tetrao tetrix) that were initially close to the wind turbines (up to 500m) moved locally after wind farm construction but their abundance at the wind farm sites did not change. I conclude that data from EIAs and post-construction monitoring can be used to assess potential effects of wind farms on biodiversity and should be widely available for scientists and policy-makers, ideally via a central data repository. Second, I investigated whether noise from wind farms might affect birds as bird song could be potentially masked. It is widely known that anthropogenic noise such as traffic and urban noise affects communication in birds. To investigate whether birds are affected by wind turbine noise, I modelled how song from iii birds propagates in a hypothetical environment with and without wind turbine noise. I found that songs from species where most of the energy lies in the lower frequencies are masked by wind turbine noise. As this model can predict potential disturbance effects for specific species, it could be used as a tool during EIAs by identifying which species will be affected by wind turbine noise. Third, as bird communication is masked by wind turbine noise, male-male, male-female and parent-offspring communication could be affected. I investigated if male-male interaction in European robins (Erithacus rubecula) is affected by wind turbine noise. Males responded less aggressively during simulated territorial intrusion with background wind turbine noise. This could lead to reduced breeding success as males might not be able to effectively defend their respective territories. Finally, I explored whether bioaoustic recorders could be used as a replacement for human wildlife surveys. Using the European nightjar (Caprimulgus europaeus) as an example, I found that survey methods using bioacoustic recorders are much more accurate and cheaper than surveys by humans. This could aid EIAs as they require wildlife surveys to determine which species might be affected by the development.