Collision Risk Model for “RUFA” Red Knots (Calidris canutus rufa) Interacting With a Proposed Offshore Wind Energy Facility in Nantucket Sound, Massachusetts.

摘要

The objective of the present study was to produce a robust, quantitative prediction of fatality rates of “rufa” Red Knots (Calidris canutus rufa) resulting from collisions with the physical structures of a yet-to-be-constructed offshore wind energy facility (the “Facility”) that has been approved for construction in federal waters of Nantucket Sound, Massachusetts. To accomplish this objective, we assembled a technical team consisting of field leading experts in offshore wind bird collision risk assessment, collision risk modeling, and Red Knot biology to synthesize existing technical information on this subject, and to use this synthesis as the basis for developing an original quantitative collision risk modeling effort. A comprehensive review of technical literature related to bird collision risk modeling at offshore wind energy facilities was performed as an initial step in this process. On the basis of this review, we adopted a modeling approach that included the Band (2012) model to represent a subset of collision dynamics, with various additional elements incorporated to represent the most important biological and meteorological dynamics of the system of interest, as hypothesized and conceived by the Project’s technical team on the basis of best available scientific information. We developed an original simulation model to represent this system, and conducted a series of simulations with the model in order to produce quantitative predictions of Red Knot fatality rates resulting from collisions with the structures of the approved Facility. These simulations included variation in several of the model’s inputs in order to characterize the sensitivity of the model’s fatality rate predictions to changes in these inputs. The overall average collision fatality rate for rufa Red Knots at the approved Facility predicted by our model was 0.16 Red Knots per year equivalent to one fatality every 6.25 years, composed of 0.10 predicted fatalities per fall migration season and 0.060 predicted fatalities per spring migration season, under baseline, or default model inputs. Predicted fatalities scaled linearly with population size, such that under the assumption of a “recovered” population three times the size of the current population, the predicted fatality rates were exactly three times higher. Collision fatality rates were largely driven by collisions of Red Knots with stationary structures, and particularly turbine towers, in our modeled results, with turbine towers accounting for roughly 90% of all collision fatalities in most simulations. The influence of collisions with turbine towers was also evidenced by the result that for all model iterations in which at least one collision occurred, the average number of collisions was approximately eight, corresponding to the number of Red Knot wingspan lengths in the tower’s diameter. Red Knots were represented flying in chevron-shaped flocks, aligned wingtip to wingtip in our model, hence when the path of a flock intercepted a turbine tower, seven or eight collisions typically resulted, depending on the elevation at which the flock encountered the tapered, cylindrical towers. Biologically realistic