Type: report

Article abstract: We report on the fifth year’s progress in a multi-year program with the goal of developing a strategy to support the recovery of Western burrowing owls (BUOW; Athene cunicularia hypugaea) and their grassland ecosystem in San Diego County. Current BUOW management is dependent on continued human intervention and may not be self-sustaining. Because the California ground squirrel (Otospermophilus beecheyi) is a keystone species that helps engineer California grassland ecosystems and provides critical resources for BUOW, re-establishment of this species is a crucial component of any sustainable recovery plan for BUOW and the larger ecosystem. The main components of the program in 2015 consisted of work on both BUOW and California ground squirrel. For squirrels, we continued monitoring two previously established studies: (1) the experimental manipulation of grassland habitat structure and squirrel translocation to better support the persistence of ground squirrels, and (2) a pilot manipulation of natural squirrel dispersal into newly grazed pasture, using the addition of cover piles to attract squirrels into unoccupied habitat. In 2015, BUOW efforts continued to focus on understanding the ecological drivers and anthropogenic threats influencing BUOW population performance in San Diego County, as well as development of a new habitat suitability model for BUOW. These efforts were conducted collaboratively with California Department of Fish and Wildlife, San Diego Management and Monitoring Program, and other agency partners.