Assessing California’s Relocation Guidelines for Burrowing Owls Affected by Renewable Energy Development

Once common and widespread throughout the western United States and Canada, the western burrowing owl (Athene cunicularia hypugaea) population has declined to the point where the species is now designated as a Species of Special Concern in California. Their presence in development areas, including renewable energy facilities, necessitates an effective strategy for protecting them. This study is the first of its kind to test both passive and active relocation techniques with burrowing owls and evaluate their relative effectiveness with and without the addition of conspecific cues (such as acoustic playback of owl calls and imitation whitewash to attract the owls).
The goal of this large-scale study on active and passive relocation was to develop management recommendations for maximizing the effectiveness of burrowing owl mitigation methods from the potential impacts of renewable energy development. A combination of satellite telemetry and field monitoring techniques was used to monitor relocated birds for longer than is generally implemented. Burrowing owl dispersal, mortality, and reproductive output were recorded in an experimental framework for both passive and active relocations and evaluated against a control group.
Results showed that short-term post-relocation owl survival is relatively high, with no apparent reproductive penalty for relocated burrowing owls. The use of conspecific cues was also effective for encouraging the owls’ settlement at release sites. However, while initial survival was lower after active translocations (relative to passive), uncertainty remains without more complete long-term data. Coordinated long-term pre- and post-impact monitoring with federal, state, and local regulatory agencies is needed to achieve effective mitigation outcomes. The development of better translocation methods will benefit electricity ratepayers by improving mitigation strategies when renewable energy facilities are built in burrowing owl habitat. The results of this study will additionally enable conformance with California laws and conservation strategies while simultaneously enabling future renewable energy development.