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Understanding long-term patterns of bill-row occupancy for the Western Burrowing Owl (Athene cunicularia hypugaea) is necessary for the conservation of this species, especially in and, desert ecosystems where burrow occupancy data tire lacking. Monthly borrow monitoring was conducted over it 4-year period (1997-2001) in southern Nevada to determine borrow occupancy patterns of Borrowing Owls and to evaluate the effects of burrow type and desert region on borrow occupancy. Burrow occupancy occurred Near-round and was most consistent in the Transition region and tended to be lowest ill the Mojave Desert region. Peak burrow occupancy occurred during March through May, followed by it gradual decline in Occupancy through the summer and fall until January and February, when occupancy was lowest. Occupancy was significantly higher at sites with both culvert and pipe burrows than at sites with earthen borrows in disturbed habitat or earthen borrows in natural habitat. Breeding-season occupancy wits not significantly higher in wetter, cooler portions (e.g., Great Basin desert region) of the study area. Results suggest that occupancy is influenced by habitat features-such as suitable borrows in open areas with low vegetation-and climatic regime.