Effects of wind turbines and other physical elements on field utilization by pink-footed geese (Anser brachyrhynchus): A landscape perspective

The effects of wind turbines and other physical landscape elements on field utilization by wintering pink-footed geese (Anser brachyrhynchus) were stu died in a Danish farmland landscape. Within the study area geese were feedi ng on pastures, which together with cereals were the main crop types. Apart from wind turbines a variety of potentially disturbing landscape elements was present, e.g., high-power lines, windbreaks, roads and settlements. Pat terns of field use were assessed by measuring goose dropping densities alon g transects perpendicular to wind farms (with turbines in clusters and in l ines) and other landscape elements. Local effects were expressed in terms o f 'avoidance distance', i.e., the distance from a given landscape element t o the point at which 50% of maximal dropping density was reached. The spati al distribution of landscape elements within an eight km radius from the go ose roost was determined from aerial photographs. The area occupied by vari ous elements, together with the adjacent zones which were not available to geese due to their associated avoidance distances, were quantified using Ge ographic Information System (GIS). The avoidance distance of wind farms with turbines in lines and in clusters were ca 100 m and ca 200 m, respectively. Geese did not enter the area bet ween turbines within the cluster. At the landscape level, the combined effe ct of physical elements other than wind turbines caused an effective loss o f 68% of the total field area (40 km(2)). Wind turbines caused an additiona l loss of 4% of the field area. However, of the remaining area available to geese (13 km(2)), wind turbines caused a loss of 13% of the total area. Th e habitat loss per turbine was higher for the wind farm with turbines arran ged in a large cluster than for wind farms with turbines in small clusters or lines. This difference was mainly due to the fact that wind farms in sma ll clusters or with a linear layout were generally placed close to roads or other elements with existing associated avoidance zones, whereas the large cluster was placed in the open farmland area. The avoidance zones associat ed with physical elements in the landscape do not take into account possibl e synergistic effects and, hence, actual field areas affected are likely to be minimum estimates. Implications of these findings for planning of wind farms in areas of conservation interest to geese are discussed.