Abstract
During the summer of 2008, AGE OOD (AGE), developer of the proposed St. Nikola Kavarna Wind Farm (the Project), was made aware that winter bird survey records for the region, during 2007/2008, had shown what appeared to be potentially significant winter flight activity in the general area of the proposed development. Of particular interest were the reported presence of the Red-breasted Goose within those records. Recognising the importance of the Red-breasted Goose in particular, as part of the ongoing works and environmental commitments associated with the Project, AGE undertook to carry out surveys during the 2008-2009 winter bird season prior to operation of the Project. The aim of the surveys was to:
1. record winter bird activity specific to the Project area (Whilst the 2007-2008 survey highlighted potential activity in the region the data was not sufficient with respect to the spatial and temporal distribution of geese in the development envelope of the Project);
2. ascertain whether there was potential for the Project to have a significant adverse affect on the wintering birds (with a particular focus on Red-breasted Goose); and
3. in the event that an significant adverse affect were predicted, what mitigation measures would be required to reduce the affect to an acceptable level.
As set out in the EMMP, therefore, surveys for goose activity including the IUCN Endangered Red-breasted Goose, were completed in the winter season 2008/09.
The surveys focused on goose activity within the Project area, however, some surveys were completed in the main winter roosting locations at Durankulak and Shabla lakes.
There was a strong correlation seen between the number of geese and the proximity to the two fresh water lakes used as night-time roosting locations. These lakes are the only large areas of fresh water in north-east Bulgaria and the presence of this fresh water is the main attractant to large winter populations of geese.
Daily movements to and from these lakes were recorded as birds left these sites in the morning to move to feeding grounds and returned in the evening to drink and ultimately to roost. Geese were recorded feeding in fields within the Project area; however, this activity was significantly less than that recorded closer to the lakes.
Goose movements through the Project area were recorded daily throughout the winter period; however, there was a peak of activity over a 10 day period (11-20 January 2009). Geese were recorded using a combination of fixed Vantage Points and random itinery counts across the Project area. Observers recorded a standard data set per registration that was later to be incorporated in to a Collision Risk Model. Due to some limitations in the survey, a set of assumptions were made to allow a robust ‘worse case’ assessment of the collision risk to be made.
Based on the data set and assumptions for additional parameters the Collision Risk Model predicted that, in the absence of mitigation measures, a total of 22 Red-breasted Geese could collide with turbines over the winter periods. This would equate to an increase in baseline mortality of 0.7%. This would fall just below the threshold number of collisions that would need to occur to result in a significant impact (i.e. to exceed a negligible magnitude effect, defined as a 1% increase over the existing baseline mortality, as per SNH/BWEA, 2002, assessment methodology).
A mitigation package similar to that to be employed during the autumn migration is therefore recommended for over the winter period. This will be completed in the first year post construction followed by a re-run of the CRM with the mitigation strategy being revised accordingly depending on the outcome of the results. The mitigation package to be completed includes visual observers and a radar system. All recorded information will be used to inform a turbine shut down system should birds be recorded flying in the direction of the Project area. The extent of shut down (single turbine, cluster of turbines or whole wind park) will be determined by the Project Independent Ornithological Expert (IOE) or Senior Field Ornithologist (SFO) (as defined within the Project EMMP) depending on the number and activity of observed flocks of geese.
This mitigation package was determined to reduce the potential impact of the wind farm on migration birds by a factor of 10. Assuming the same parameters the impact of the wind farm with the proposed mitigation on wintering Red-breasted Geese is calculated as an increase of 0.07% in the baseline mortality or a predicted 3.5 collisions per year. This does not exceed the threshold number of collisions that would need to occur to result in a significant impact (i.e. to exceed a negligible magnitude effect, defined as a 1% increase over the existing baseline mortality, as per SNH/BWEA, 2002, assessment methodology).