Abstract
A cadre of environmental regulations and the associated permits and authorizations require offshore wind (OSW) energy to be planned, constructed, and operated in ways that avoid, minimize, and mitigate environmental impacts, including potential harm to wildlife. Wind energy areas (WEAs) are often rich with birds under protection by the Migratory Bird Treaty Act (MBTA) and some species are also protected by the Endangered Species Act (ESA). Some birds (e.g., albatross, shearwaters, and petrels) may be more vulnerable to collision with OSW turbines because of their reliance on wind-rich areas to propel their long-distance movements from distant breeding areas to foraging grounds offshore of the West Coast of the U.S.; flight can occur during the day or night, and at heights overlapping rotor-swept zones. In cases where OSW has the potential to kill or injure birds and/or bats, consultation and authorization by the U.S. Fish and Wildlife Service is required. For birds protected by the ESA, proposed wind energy projects will likely be required to generate collision risk models (CRMs) capable of estimating species-specific impacts anticipated over the permit term and recognizing uncertainty about these estimates.
CRMs are most sensitive to avoidance rate, which must be calculated from interactions occurring at the following three scales: macro (avoidance of the wind farm as a whole), meso (avoidance of individual turbines or rotor-swept zones either through active detection and avoidance or as the result of species-specific flight and habitat use patterns), and micro (last-second measures taken to avoid collision) (Figure 1).To generate CRMs prior to construction requires extensive species-specific metrics from the project site such as: passage rate through the wind facility and rotor-swept zones; interannual variability in passage rates; turbine avoidance and attraction at multiple scales (macro, meso, and micro) (Cook et al. 2018); seabird or bat behaviors (foraging, transiting, seasonal migration, nocturnal activity, etc.); seabird and bat flight characteristics (speed over ground, position in rotor-swept zones, direction relative to wind, maneuverability, style of flight); seabird and bat size; and additional considerations of environmental covariates of collision (i.e., conditions that modify collision risk).
Developing technology that can address this critical knowledge gap for most of the seabirds that occur off the U.S. west coast where floating OSW projects are proposed will allow wind energy proponents to avoid or minimize detrimental scenarios and achieve renewable energy generation targets. Real-time, automated monitoring technologies for seabird and bat detection, identification, and characterization at multiple scales will increase understanding and reduce uncertainties associated with potential interactions between seabirds and bats with OSW technologies, and reduce the timeline and costs associated with environmental permitting.