Abstract
Impacts of wind turbines including the barrier effect can be site specific and may not occur at each site. Therefore, turbine layout and facility location should be evaluated on a site-specific basis by an experienced wildlife biologist in conjunction with available information regarding local and migratory bird and bat species in, around or passing through the proposed site to ensure that any possible barrier effects are minimized or avoided. Wind developers need to assess the potential impacts on species prior to and following development. Knowledge of spatial distribution of birds is a source for answering many fundamental questions of the evolutionary ecology and ornithology as well as for practical solutions. Here we provide a new quantitative instrument for calculation of the cumulative consequences of wind power development in large territories and we demonstrate how GPS data from tracking projects of conservational projects can be applied for evaluation of impact in respect to location and density of turbines along the Eastern fly way of white storks. We get 605 609 target points after processing of the available 1 207 130 points through the target territory. 139 597 the rest of the points were excluded from the analysis by different technical reasons mainly due to upper limit of acceptable change in height of 2 meters / sec (600 meters in 5 minutes - the interval between records) is used. Higher values are replaced by the average of their two adjacent points. In a "block" of consecutive anomalies, its values are replaced by a smooth transition between its neighbor's normal values.We have discovered variation of wind turbine density in respect to migratory flow of adult white storks in spring migration along the Eastern flyway. The density of wind turbines in specific locations varied between 0 and 20 per km2 . The number of White storks registrations in 300 m above the terrain as well as the birds flying lower than300 m over the areas with wind turbines was significantly lower than the number of storks flying over the areas without turbines We have not observed any change in the altitude of birds flying over 300 m above the terrain in the areas with wind farms in comparison to the areas where no wind turbines have been registered in our study. Birds flying in altitudes up to 300 m above the ground level have increased the altitude in the vicinity of wind farms. The observed increase was gradual and dependent on the density of the turbines at the ground. We have identified 266 registrations near the Wind turbines. Within these 266 registrations the average distance to the nearest turbine was 385 m, (min = 26 m, max = 1171 m, std=233). There are four registrations of flying White stork in less than 50 m distance from the wind turbine although we do not know if the rotor of the turbine was rotating or not. Although White storks are model species for the group of soaring birds there are many raptor species which migrate in much smaller flocks or as single individuals. For all the soaring birds we need urgently more information in order to quantify all spatial interactions between birds and wind turbines. Our results also indicate strong power of satellite and GSM tracking data obtained in last decades. We would strongly recommend new projects in collaboration between wind power energy sector and conservation policy makers to be performed with more target bird species in order to estimate quantitative limits of turbine densities for the rest of migrating birds.