Collision vulnerability of marine birds within the California Current System

Four metrics were used to determine Collision Vulnerability: Diurnal and nocturnal flight activity, flight-height (defined as time spent in rotor sweep zone), and macro-avoidance. Nocturnal flight activity (NFA) and diurnal flight activity (DFA)—Nocturnal and diurnal flight activity can influence the risk of collision; therefore, we used available information to estimate the amount of time each species spent flying during night and during day. Time spent in the rotor sweep zone (RSZt)— the percentage of time each species spends flying at the same height as wind turbine blades (as opposed to above or below the sweeping zone of the blades) will influence collision vulnerability. Based on flight-height analyses and published accounts, we estimated each species’ percentage of time flying within the rotor sweep zone (RSZ; 10-200 m above the water). Macro-avoidance (MA)—The macro-avoidance values for species indicate the species-specific probability of avoidance with wind power infrastructure. For each species, we derived this value from observed macro-avoidance (via human observation and radar) at existing offshore wind power sites. In cases where species-specific data were not available, we used information from similar taxa. These data support the following publication: Adams, J., Kelsey, E.C., Felis J.J., and Pereksta, D.M., 2016, Collision and displacement vulnerability among marine birds of the California Current System associated with offshore wind energy infrastructure: U.S. Geological Survey Open-File Report 2016-1154, 116 p., http://dx.doi.org/10.3133/ofr20161154.