Habitat and Nest-Site Selection by Burrowing Owls in the Sagebrush Steppe of Idaho

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Abstract
The local topography and vegetation around 80 occupied burrowing owl (Athene cunicularia) nest sites in the sagebrush steppe of southcentral Idaho were quantitied. Several additional topographical variables within a 1-km radius and habitat variables within a 693-m radius of these sites were then compared with data for an equal number of randomly chosen sites. Owls used burrows provided by badgers (Taxidea taxus) in open soil and by yellow-bellied marmots (Marmota flaviventris) in small lava outcrops; the latter were chosen significantly more often (P < 0.005) than expected on the basis of availability. Cover within a 50-m radius of 80 occupied burrows was mainly bare earth, cheatgrass brome (Bromus tectorum), rock, and annual forbs. In comparison to randomly chosen sites, occupied sites had a greater cover of cheatgrass brome, had a greater habitat diversity, werree lower in elevation, and were more frequently located on southerly aspects. Farmland occurred on 30 occupied sites and 33 randomly chosen sites but averaged significantly less (P < 0.05) acreage on occupied sites. Big sagebrush (Artemisia tridentata) occurred on 48 occupied sites and 32 randomly chosen sites and also averaged significantly less (P < 0.05) acreage on occupied sites. Surface water was present on 14 (18%) occupied sites but on only 2 (3%) randomly chosen sites. Burrow security and prey availability, especially the proximity to populations of montane voles (Microtus montanus) on farmland, may explain some of the habitat selection observed.

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