Abstract
1. This report presents the comparative results of five autumn seasons’ study of birds at the St Nikola Wind Farm (SNWF), with a special 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 2012 (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, 2011 and 2012 are used to test the potential change in species composition, numbers, altitude or the flight direction of passing birds in autumn, as a result of SNWF’s presence.
5. The variations in numbers of species, absolute number of birds, overall altitudes of flight and migratory direction do not indicate an adverse effect of the wind farm on diurnal migrating birds.
6. The Turbine Shutdown System probably contributed to a reduced risk of collision during all years of operation within infrequent periods of intensive soaring bird migration and provided a safety mechanism to reduce collision risk for both single birds of endangered target bird species and/or flocks passing through the wind park territory.
7. The low number of victims of collision found in four autumn seasons in systematic 7 day (or less) interval searches for casualties under every turbine does not provide evidence for additional mortality caused by SNWF as a threat to populations of any bird species migrating through the territory.
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.