Pre-construction Risk Assessment and Post Construction On-site Surveys and Mitigation for Bird-Wind Turbine Interactions

Abstract

Pre-construction risk assessment and postconstruction on-site surveys and mitigation are important components of understanding and addressing wildlife interactions with wind facilities. This presentation will cover all of these topics in detail. Pre-construction risk assessment can be a 3-phase process. Phase 1 involves preliminary site assessment, often done remotely, and is based especially on literature review. If this review suggests at-risk species may be present, then phase 2 involves verification of their presence at the site and assessment of site-specific features (topography, land cover) that may influence risk from turbines. Finally, phase 3 should involve quantitative studies to count numbers and assess potential risk. Additional surveys similar to those conducted postconstruction are also important. Post-construction surveys are typically focused on counting numbers of individuals and, more recently, estimating population-level consequences of fatalities. Counting fatalities requires surveys at and around individual wind turbines. Critical to this effort is defining the search area correctly (a small bird can fall far from turbines), accurate species identification establishing useful search intervals that vary with the size of the target species, and estimating rates of both searcher efficiency and scavenger removal. Best practices call for standardizing survey methodology across facilities to facilitate comparison and to making data public. Estimating population-level consequences of fatalities requires identifying the population of origin of affected animals, estimation of the size of the population in those origin areas, and building demographic models to estimate populationlevel consequences. Mitigation also typically follows a threestep hierarchy, with (1) avoidance; (2) minimization; and (3) compensation. Avoidance of collision is typically achieved with either macro- or micro-siting, typically underpinned by risk modeling or expert opinion. Minimization of numbers of collisions can be accomplished by detection and deterrence or operational or responsive curtailment. Compensation involves replacement of animals killed and can be achieved by habitat improvement, food supplementation, or reduction of other threats to a species. Effective replacement requires identifying the population of origin of affected animals and the factors limiting that population.