Abundance and behavior of little egrets (Egretta garzetta) near an onshore wind farm in Chongming Dongtan, China

Abstract Wind energy development has complex ecological consequences for many bird species. Previous environmental impact assessments (EIAs) for avian taxa mainly focused on the direct and indirect impacts of wind farm, such as collision mortality, flight changes, and habitat displacement. Their impact on waterbird behavior is less studied, especially foraging behaviors, which determine their energy budget and, thus, their reproduction and survival. In this study, we examined the effect of wind farms and the surrounding landscape on the abundance and energy budget-related behaviors of little egrets (Egretta garzetta), a dominant resident waterbird species near wind farms along the East China coast, from June to October 2019. Three egret behavioral categories were recorded, i.e., rest, locomotion, and foraging, and three foraging subcategories, i.e., stand-and-wait, walk slowly, and walk quickly. We also measured the distance to the wind farm and five landscape variables (aquaculture pond edge, ditch, marsh grassland, marsh open water, and river) within each quadrat. We found no significant effect of the distance to the wind farm on the abundance of little egrets, although their abundance was positively and negatively related to the aquaculture pond edge and marsh open water, respectively. The distance to the wind farm was positively correlated with stand-and-wait foraging. In addition, the river was negatively correlated with locomotion. Marsh open water was negatively correlated with walk slowly foraging. Therefore, the abundance of little egrets in Chongming Dongtan was not affected by the wind farm, although the wind farm resulted in changes to some of their behavior. Overall, the effect of this wind farm on little egrets was limited. We suggest aquaculture ponds mainly inhabited by egrets as alternatives for coastal wind farm development. We also highlight the behavioral evaluation of waterbirds as a complementary technique for EIAs of wind farm developments.