1. This report presents the comparative results of four autumn seasons’ study of birds at the St Nikola Wind Farm (SNWF), with an especial focus on the possible impact of SNWF on migrating birds.
2. Spatial and temporal dynamics in the numbers of different species passing through the wind park territory during autumn migration 2011 (15 August to 30 September) are presented.
3. The data gathered from visual observations are analysed.
4. The data from the autumn monitoring in 2008, 2009, 2010 and 2011 are used to test whether, through a ‘barrier effect’ there has been a statistically significant change in species composition, numbers, altitude or the flight direction of passing birds in autumn, as a result of SNWF’s presence. 5. There was no evidence for barrier effect of the constructed wind farm on autumn seasonal bird migration through the territory. The numbers of species, absolute number of birds, overall altitu
des of flight and migratory direction varied by years with no obvious effect after the wind farm was constructed and started its operation.
6. Taking all preliminary available information into account, a system for reduction of collision risk was applied successfully through a Turbine Shutdown System, in a short period of intensive soaring bird migration through the wind park territory.
7. No victims of collision were found, despite numerous searches for casualties under the turbines.
8. The data to date indicate that SNWF does not constitute a major obstacle or threat, either physically or demographically, to important populations of diurnal autumn migrants.