Abstract
Central-eastern Spain is characterised as being a flat and relatively open landscape, greatly used for agricultural purposes and with a high density of wind installations. This landscape also hosts a large population of the lesser kestrel (Falco naumanni), one of the species most threatened by collisions with wind turbines. During a ten-year period, we analysed bird mortality by recording deaths on three wind farms (WF), Cerro del Palo, Cerro Calderón and La Muela I, located in the province of Cuenca (Spain) and containing a total of 99 turbines. The aim of the study was to determine the variables associated with mortalities caused by these types of devices. Subsequently, the information obtained allowed a mitigation measure to be implemented for avoiding and minimising collisions. The procedure involved superficially tilling the soil around the base of turbines with a high collision rate. This measure was monitored for two years before and after implementation in order to compare its effectiveness, and involved making the areas around the turbines less attractive to kestrels by tilling and reducing the amount of vegetation and consequently the abundance of potential prey, mainly Orthoptera. If effective, the lack of prey would decrease the number of dead kestrels, as the birds of prey would need to search for food in other less dangerous areas (approximately 80 m away from the turbines). After monitoring the mitigation measure it was found that the number of collisions decreased by 75–100%. In fact, no collisions were registered during the two year period for all of the wind turbines with tilled surroundings. Based on these results it can be safely stated that this mitigation measure is an easy and inexpensive procedure that significantly and effectively reduces the number of kestrels that collide into wind turbines.