Artificial burrows for the western burrowing owl were surveyed in 2010, 2011, and 2012 by the California Department of Fish and Wildlife (CDFW). Each burrow was surveyed for evidence of burrowing owl use. Types of evidence included whitewash, prey remains, feathers, pellets, or visual confirmation of the species. Burrows with strong or multiple types of evidence were marked as used by burrowing owls. Maintenance needs were also recorded for each burrow.
Survey results: http://arcg.is/2dDPFsS