Assessing California's Mitigation Guidelines for Burrowing Owls Impacted by Renewable Energy

Improving mitigation actions for burrowing owls impacted by renewable energy development.

Zoological Society of San Diego dba San Diego Zoo Global


Escondido, CA

Recipient Location


Senate District


Assembly District



Amount Spent



Project Status

Project Result

The project was completed in 2019, and the final report was received. The researchers captured the targeted number of burrowing owls at development sites for three treatment groups. They released the active translocation group of owls at conservation areas and monitored their mortality and reproductive success. Short-term survival after translocation was relatively high, with no apparent reduction in reproduction. In collaboration with the Technical Advisory Committee, the project team refined the study design and research protocols and made recommendations to wildlife regulatory agencies about translocation protocols. In addition, they tested GPS units and modified their design for use with burrowing owls. The team shared sample material from captured owls with researchers in EPC-14-061 and EPC-15-043 to extend the data used for isotopic and genetic analyses in those projects.

The Issue

In California, western burrowing owls ([i]Athene cunicularia hypugaea[/i]) have been designated with the conservation status of Species of Special Concern, mainly due to habitat loss. With planned facility expansions in burrowing owl habitat, renewable energy projects represent a possible stressor for the species. Translocation away from project sites is an important mitigation method for owls impacted by development, but there has been significant uncertainty around the effectiveness of the main two approaches (active and passive translocation) due to the difficulty of tracking owls long enough to determine their fates after they were released.

Project Innovation

The project analyzed the consequences of both passive and active relocation methods for burrowing owls (a California Species of Special Concern), and filled an existing need for robust scientific data on the relative effectiveness of relocation as a conservation method. Secondary goals were to provide data on owl movements and habitat use that could inform collision risk models and site selection decisions for renewable energy-generating facilities. The project team fit more than 50 owls with GPS tracking devices and divided them into three study groups--active translocation, passive relocation, and a control group. Frequent site visits provided information on mortality rates and reproductive output.

Project Benefits

This project will increase the effectiveness of conservation actions designed to mitigate renewable energy impacts on burrowing owls. This was achieved by evaluating the relative effectiveness of primary translocation methods in an experimental framework. Improvements to the effectiveness of existing translocation methods were tested experimentally. Long-term GPS tracking of individuals in the active and passive relocation groups and a control group provided the critical, previously missing, information to judge the effectiveness of each method. The management recommendations and proposed translocation protocols from this study should improve the success of mitigation and facilitate new permitting of renewable energy.

Environmental & Public Health

Environmental Sustainability

The project measured the relative effectiveness of alternative methods for translocation of burrowing owls that are displaced from renewable energy development areas, leading to better guidelines for mitigating impacts.

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