Nesting Success and Habitat Relationships of Burrowing Owls in the Columbia Basin, Oregon

Burrowing Owls (Athene cunicularia) were studied to determine their nesting success and patterns of nest-site selection in northcentral Oregon during the breeding seasons of 1980 and 1981. Nest success was 57% for 63 nests in 1980 and 50% for 76 nests in 1981. Desertion was the major cause (32%) of nest failures and was related to the proximity of other nesting pairs. Depredation of nests by badgers (Taxidea taxus) was the next most frequent cause (14%) of nest failure. Nests lined with livestock dung were significantly less prone to predation than unlined nests. Burrowing Owls occupied three of the five habitats surveyed for pairs. Burrows with good horizontal visibility and little grass coverage were preferred. Elevated perches were used in habitats with average vegetation height >5 cm and not in habitats with vegetation <5 cm. Elevated perches presumably improved the Burrowing Owl's ability to detect both predators and prey by increasing their horizontal visibility. Low grass cover may be indicative of a high availability of prey preferred by Burrowing Owls. The nesting ecology of Columbia Basin Burrowing Owls appears to be strongly influenced by the availability of badger burrows for nesting and, in turn, on predation pressures by badgers.