The Burrowing Owl occurs throughout the Great Basin and over much of the western United States. Found in expansive areas and among the rolling valley hills, Burrowing Owls prefer open landscapes and sparsely vegetated areas. As their common name indicates, these owls breed in subterranean chambers. They frequently utilize pre-existing mammal burrows, but are capable of excavating their own. The burrow's companion dirt mound offers a raised perch in terrain that may be otherwise flat, making an excellent elevated perch. Burrow entrances can be lined with materials, such as small twigs, cactus parts and/or manure chips. Usually, there is more than one burrow in the area of an active pair. Loose aggregate nests may form colonies with multiple nesting pairs spread over an area.

Burrowing Owls begin to show up in their breeding areas in the spring and soon after initiate nesting. Females incubate clutches, sometimes exceeding 10 eggs, for 28 to 30 days. The owlets fledge in the early summer, 44 days after hatching.

Utah Burrowing Owl Occupation and Nest Starts

The number of known territories, occupied territories and active nests (nest starts) represent all Burrowing Owl nests monitored in Utah from 2001 through 2005. Because of aggregate burrows, where more than a single pair of owls were observed, a territory constituted a single burrow occupied or used by a pair. A territory (burrow) was deemed occupied if crews encountered owls on multiple visits. Frequently, owls could be found perched on the burrow mound or another prominent perch in the immediate area of the nest. A nest start was assumed if a pair was present on one or more visits, evidence of predation of a suspected nest was discovered, signs at suspected nest burrow indicated the presence of larger numbers of owls, or owlets were confirmed.

Utah Burrowing Owl Success and Productivity

Nestling development and behavior cues indicate nestling age and probable fledgling dates. The pre-fledged, still somewhat downy nestlings often are active at the nest burrow entrance, standing, running in and out of the burrow, jumping or exercising their wings (hop-flapping). A nest is considered successful once nestlings have reached at least 80% of the species median fledgling age (35 days for Burrowing Owls). All nestlings reaching at least 80% of the mean species fledge age are considered to have fledged, unless observations indicate otherwise. Burrowing Owls vacate the nest burrow after fledging but remain in the general area.

Utah Burrowing Owl Trends 2001-2005

The most successful year for Burrowing over the course of the monitoring by HWI was 2004 occurring after the most dismal year on record, 2003. The decrease in 2005 may be attributable to an increase in winter and spring precipitation. Even though Burrowing Owls appeared in the region early, at the end of a relatively mild winter, overall success declined from 2004. The rains of 2005 promoted Cheat grass (Bromus tectorum), an invasive species common to sagesteppe grasslands, to grow higher and thicker, engulfing burrows historically out in the open. This vegetative encroachment on burrow areas degraded ideal nest conditions as it offered concealment for ground borne predators. Additionally, at least one burrow was known to have flooded out.

Our state-specific annual reports have more information on Burrowing Owls; Northwest Utah Nest Survey and Northeast Nevada Nest Survey.