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Western Burrowing Owl
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Burrowing Owls are undergoing mild to relatively severe local and regional population
declines throughout much of western North America, and have disappeared from the
far eastern and northern portions of their historic range. In Canada they are listed
as endangered, and in Mexico they are considered threatened. In the United States
they have special status designation in nearly all states in which they occur, and
are listed by USFWS as a migratory species of concern for the Southern Rockies/Colorado
Plateau region. They are listed as threatened by the state of Colorado. The Western
Burrowing Owl breeds in desert grassland, shrub-steppe, and agricultural areas in
western North America. In western Colorado, a scattered population of the Burrowing
Owl occurs in these habitat types, typically in association with white-tailed prairie
dog colonies. For unknown reasons, owl densities within the area of the Grand Junction
Field Office (GJFO) of the Bureau of Land Management (BLM) appear to have declined
severely since 1998. Given potential impacts to their breeding areas by recreation
and energy development, the BLM wanted to inventory the Burrowing Owls within their
area. Understanding use or non-use of local habitats by burrowing owls will greatly
enhance resource planning efforts, impacts analysis in NEPA documents, and help
assure avoidance of important breeding areas as well as sites that could potentially
serve as off-site mitigation locations.
In the spring of 2008 RMBO conducted Burrowing Owl surveys for the GJFO. We based
our survey locations off a survey that RMBO conducted in 2002 throughout western
Colorado where breeding season detections of Burrowing Owls had been made. The 2002
survey, coincident with a severe drought, indicated 15 potential breeding locations
for Burrowing Owls on the western slope of Colorado, eight of which were in lands
managed by the GJFO. Our 2008 survey focused on lands managed by the GJFO, including
historic sites and potentially suitable habitat (prairie dog towns). We also incorporated
visits to known historical Burrowing Owls sites on private land (n=37).
For the surveys RMBO employed a protocol recommended by the Colorado Division of
Wildlife which involved call playback methodology. Surveys were conducted from mid-April
through early-June at each historic Burrowing Owl site in our database (n=73) and
at a random selection of prairie dog towns (n≥100) on BLM lands in the GJFO management
area.
In 2008, RMBO staff located Burrowing Owls at 54 sites during surveys on private
property and on lands managed by the GJFO in Mesa County. These data suggest that
perhaps the Burrowing Owl populations were especially low in 2002 (perhaps due to
drought), that the population is undergoing an increasing trend, or that the birds
were especially numerous this year. These surveys should provide an excellent baseline
for the BLM and other conservation partners to monitor the effects of human activities
and population levels of this species of concern.
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