What is the impact of wind farms on birds? A case study in southern Spain

Wind farming is a relatively new form of obtaining energy that does not cause air pollution or other forms of environmental degradation associated with fossil fuel technologies. However, their use impacts on the environment, and the current rate at which they are being put into operation, combined with poor understanding of their medium- and long-term impact, is a cause of concern. Wind farms represent a new source of impact and disturbance for birds that adds to the long list of disturbance factors caused by human activity, such as power lines, radio and television towers, highways, glass windows, the practice of poisoning, illegal hunting and overexploitation. Due to the precarious situation of several bird species and their decline, any additional cause of mortality may be significant and should give rise to increased attention and research. The aim of the present work is to analyse the effect of the “Sierra de Aguas” wind farm on bird density and abundance, flight behaviour, and bird mortality. Mortality rates did not increase due to the presence of the wind turbines. The results suggest that the presence and operation of the wind turbines did not have a clearly negative effect on passerine birds present in the region where wind farm is located. However, raptors used the space around the wind farm with lower frequency than prior to its existence, which represented a displacement of the home range of these species.