Facts on the Western Burrowing Owl (Athene cunicularia, BUOW):
Orange County has large wilderness areas that historically and currently provide favorable burrowing and foraging areas typically including wide-open and sparse vegetated areas such as grasslands and agricultural fields making it enticing to stay year-round. Such conditions are preferred by resident nonmigratory avian species such as BUOW. Our landfill properties remain suitable habitats because they include the following:
Native grassland mitigation sites in conserved areas that include large open spaces and have minimal human disturbance in restricted areas (e.g., the Segunda Grasslands restoration areas at Prima Deshecha Landfill).
Naturally occurring boulder formations and artificially placed rockpiles within both conserved areas and actively managed areas.
Open ends of stacked piping and conduit in construction/operational staging areas.
Untended disturbed vacant areas and soil stockpiles that have become inundated by ground squirrel burrows.
Eroded soil cavities below the edges of concrete paved roadways, drainage culverts, and detention basins which create non-natural burrows conducive to BUOW occupation.
Specifically, at our landfills the presence of active BUOW populations has been recorded as follows:
At Prima, BUOW individuals were observed east of the landfill in 1989 and 1990, but nesting was not confirmed. There were also observations in the landfill during the winter of 2004-2005 and again in February 2006. Most recently, from November 2019 – January 2020, two individual owls and three active burrows were observed on a boulder pile in Zone 1 (northwest of the active landfill). Owl signs here included whitewash, feathers, and pellets. Consultation with the CDFW concluded that the owls were winter residents, and measures were then implemented to close the burrows. Upon confirmation that the burrows were vacated they were collapsed.
The Frank R Bowerman (FRB) Landfill also provides habitat favorable to BUOWs. Some conserved areas of the landfill property include open grassland habitats which are conducive to BUOW breeding activities such as foraging and nesting. In fact, an individual BUOW was observed, in February 2021, briefly foraging in a remote location of the remediated East Flank landslide. Sr. Environmental Resources Specialist, Weena Dalby, and a Helix Environmental Planning crew supervisor spotted the owl several times in a small standpipe over the span of two weeks. However, this BUOW did not appear to establish a nest in the area later that spring nor was it detected again. Despite this observation and the presence of suitable habitat, there is currently no documentation confirming occupied BUOW habitats or resident populations exist within FRB property.
BUOW observations such as those listed above are recorded in the California Natural Diversity Database (CNDDB) which is an online repository managed by CDFW for statewide occurrences of all special-status species.
