Sensitivity mapping for seabirds and offshore wind power farms: A case study of Slaty-backed gulls in Hokkaido

Abstract

Offshore wind energy is a renewable energy source that offers an opportunity to reduce greenhouse gas emissions while increasing energy security. However, many ecologists have suggested that offshore wind farms may have severe negative impacts on wildlife, especially seabirds. Thus, balancing seabird conservation with human energy demands is necessary when developing wind farms. Bird sensitivity mapping is a powerful and practical tool that can determine turbine collision risk within specific areas; however, sensitivity maps have seldom been generated for seabirds. Focusing on the Slaty-backed gull (Larus schistisagus), a red-listed species that often collides with wind turbines, we determined factors affecting habitat selection with the goal of reducing negative impacts of offshore wind farms. We then generated a sensitivity map using habitat modeling. GPS loggers set to record at 5-minute intervals between June and August 2018 were attached to six Slaty-backed gulls residing in Ochiishi Bay, Nemuro Prefecture, Japan. A Gaussian mixed model indicated that habitat selection was related to food availability (as determined by sea surface temperature and chlorophyll a content) and distance to the nest site. Sea surface temperature and chlorophyll a content were positively related area visitation frequency of Slaty-backed gulls, whereas distance to nest site was negatively correlated. Moreover, area visitation frequency was unchanged when the distance from the nest site was > 25 km. The sensitivity map indicated that areas both near and far from nest sites with potentially abundant food resources were high-risk areas with respect to turbine collisions for Slaty-backed gulls. Based on these results, we advocate the use of sensitivity mapping to reduce interactions between offshore wind farms and seabirds, especially for species that often forage far from their nest sites.