Abstract
Recently, to help curb anthropogenic climate change and fossil fuel depletion, there has been a rapid increase in the number of wind farms being built worldwide. However, the construction of wind farms in the foraging areas of raptors or along the routes of migratory birds raises concerns about avian collisions and habitat loss. Here, we present an additional situation in which avian collisions may present a problem. That is, when wind farms are built between roosting and foraging areas of over wintering migratory birds, the bird flocks are forced to pass through the farm each morning and evening. Indeed, at the Awara Wind Farm in Fukui Prefecture, Japan, approximately three thousand White-fronted Geese Anser albifrons frontalis inhabit the site where the installation of 10 wind turbines has recently been completed. The collision risk posed by these turbines may affect the goose population. However, few studies have examined the effects of wind farms on the flight patterns of geese, making it difficult for stakeholders to achieve a consensus. The purpose of this study was to evaluate the collision risk for geese in the planning phase of the Awara Wind Farm. A collision model based on goose avoidance behavior was developed to predict collision mortality, and an applied potential biological removal (PBR) analysis was used to determine the maximum allowable collision mortality (ACM) whilst maintaining a sustainable goose population. The estimated annual collision mortality was 0-2 geese, whereas the allowable collision mortality was 75 geese per year, suggesting that the collision risk is sufficiently small for the population to persist. We also include a discussion of adaptive management plans for regulating wind turbine operations when the actual collision mortality exceeds the socially acceptable level.