The United States Air Force (USAF) is investigating whether to install wind turbines to provide a supplemental source of electricity at Vandenberg Air Force Base (VAFB) near Lompoc, California. As part of that investigation, VAFB sought assistance from the U.S. Department of Energy’s National Renewable Energy Laboratory (NREL) to provide a preliminary characterization of the potential risk to wildlife resources (mainly birds and bats) from wind turbine installations.
Although wind shows great promise as an efficient, environmentally benign renewable energy source, the installation of turbines and their required infrastructure can result in adverse impacts to wildlife and their habitat. These impacts and their significance on local wildlife populations vary greatly from site to site (AWEA 1995; Erickson et al. 2001).
With wind power development expanding throughout North America and Europe, concerns have surfaced over the number of bird fatalities associated with wind turbines (Morrison 1996; Morrison and Sinclair 1997). Guidelines developed for the wind industry by the National Wind Coordinating Committee (NWCC) recommend assessing potential impacts to birds, bats, and other potentially sensitive resources before construction (Anderson et al. 1999). The primary purpose of an assessment is to identify potential conflicts with sensitive resources, to assist developers with identifying their permitting needs, and to develop strategies to avoid impacts or to mitigate their effects.
This report provides a preliminary (Phase I) biological assessment of potential impacts to birds and bats that might result from construction and operation of the proposed wind energy facilities on VAFB. The specific objectives of the project were to
- Review available information and conduct a general site evaluation to characterize bird and bat resources at or near the proposed facilities
- Conduct preliminary field surveys to record bird species occurrence, relative abundance, and bird use at each of the sites
- Based on the preliminary findings resulting from Objectives 1 and 2 (above), assess the likelihood and extent of risk to birds and bats that might result from the proposed project
- Recommend whether additional studies, such as detailed site evaluations, pre-construction surveys, and/or post-construction monitoring are needed.
The scope of the project was limited because of funding constraints. BioResource Consultants (BRC) was initially funded to address these objectives at one proposed wind turbine location on VAFB. Because the Air Force changed the design of the wind energy project, we were asked to include in our study five potential areas located throughout VAFB. This request was later amended to a final selection of four potential sites on VAFB, with a single wind turbine installation per site.
The funding for this project was not increased, so the level of effort originally proposed for one site was distributed equally over four study sites. This resulted in a smaller sampling effort per site and a reduction in the field studies period.
The study results would have benefited from a more robust sampling effort (i.e., three to four visits per site per month over a 12-month period). In addition, the study design could have been improved if a turbine/tower hardware configuration had been selected and if the location(s) where the turbines were to be installed had been selected prior to our conducting the field surveys. With this information, we could have addressed species occurrence and relative abundance within a zone of risk. This would have facilitated a more complete analysis of the potential impacts of turbine installation and operation at each proposed site.