Abstract
California has ambitious clean energy goals designed to help mitigate the worst outcomes of climate change. Offshore wind is an important part of the solution to meet California’s clean energy goals, but has potential negative impacts on the marine environment. As offshore wind energy is new to California, this paper reviews and synthesizes existing literature from other parts of the world, looking at the real and theoretical risk of seabird collision with offshore wind turbines. Learnings from existing offshore wind projects in the U.K. as well as theoretical and modeled risk assessments are applied to California’s plans to determine the risk of seabird collision with turbines in the Humboldt and Morro Bay Wind Energy Areas. The species groups most vulnerable to collision are pelicans, terns, albatross, medium and large gulls, sea ducks, phalaropes, and jaegers/skuas. Generally, across real surveys of operating wind farms and models, collision risk is low. Seabirds tend to avoid wind energy areas completely, flying around the wind energy area at a distance. Those birds who enter the wind energy areas can most often avoid turbines by flying between them. Despite the overall low risk, several key factors impact a bird’s ability to avoid turbines: placement of turbines and wind energy areas in relation to breeding or roosting grounds and foraging locations, visibility conditions, artificial lights, and attraction to the wind energy area through food availability and roosting opportunities. More information on region specific flight behavior, migration and commuting routes, and avoidance rates should be collected in the California wind energy areas before turbines are deployed to better anticipate and avoid risk.