The Space Use and Flight Behavior of Adult Golden Eagles (Aquila chrysaetos) in the Swiss Alps: Applied Implications for Mitigating Airspace Conflicts with Future Wind Energy Developments

Mountainous areas throughout Switzerland are characterized by considerably higher wind speeds in comparison to low-land areas and can therefore offer viable locations for the numerous wind energy facilities that are planned to be constructed in the coming years. However, the development of these high-altitude wind plants may lead to a hazardous airspace conflict with resident soaring birds whose energy-efficient flight dynamics may depend on the same environmental and meteorological resources that are required for cost-effective wind energy production. Among such birds, Golden Eagles (Aquila chrysaetos), which nest all throughout the Swiss Alps, may become particularly predisposed to dangerous interactions through risky subsidized and hunting flight behaviors. Consequently, in my PhD study I will develop a spatially-explicit conflict mitigation model that will rank locations throughout the Valais according to the probability that resident eagles would co-occur within the same airspace of future wind turbines, based on the estimated overlap in the selection of available resources. My first objective will be to identify recurring flight behaviors of Golden Eagles throughout the Valais. To accomplish this, I have stratified the Valais according to different conditions that may influence the flight behavior of the eagles, namely varying levels of surface aspect and wind velocity. Next, I randomly generated points at these strata, during the breeding, post-fledgling, and wintering periods. Accordingly, I am currently using an advanced laser range-finder to collect 3D locations and record continuous flight trajectories of eagles at the random locations. To compliment the range-finder data, my next objective will be to trap 20 adult Golden Eagles in the Valais during the late Fall and early winter periods and outfit them with solar-powered GPS transmitters, which will transfer the high frequency data using the cellular network. After the data collection period of the study will be completed, I will generate predictive models for different modes of recurring subsidized and hunting flight behaviors that would be expected to occur within the airspace of future wind turbines. Specifically, I will identify the habitat, topographic, and meteorological variables that can be used to model these flight behaviors. My final objective will be to produce a co-occurrence model that will rank alpine areas according to the projected probability of airspace conflict between resident adult eagles, and actual planned projects or locations characterized by varying levels of wind energy potential. I will overlay the eagle and wind energy models to rank alpine areas according to varying probabilities of co-occurrence at an above-ground-level (AGL) altitude below 180 m (the maximum height of planned turbines). The study’s deliverables will include an eagle-wind energy co-occurrence map that would identify potential high conflict risk areas throughout the Valais.