Barred owls (Strix varia varia) compete with spotted owls (Strix occidentalis caurina). The range of barred owls is expanding from the deciduous forests of eastern North America to the coniferous forests of western north America. Now the ranges of barred owls and spotted owls largely overlap. Spotted owl populations are declining, particularly where barred owl populations are most abundant. The effects of expanding ranges of barred owls on spotted owls includes: consumptive competition, displacement, and hybridization. Other major threats to the spotted owls include habitat loss, infestations of defoliating insects, and forest management practices.
The objective of this study was to obtain more information about barred owl ecology to inform management practices. The authors looked at space use patterns of barred owls, factors that determined habitat selection by barred owls, and the relationship between these factors and the probability of habitat use by the owls.
The study area was a mixed conifer vegetation zone in Chelan County WA. The site was chosen because it encompassed a range of environmental conditions. The birds were located using recorded calls. The birds were then captured and fitted with radio tracking devices. Spatial data was obtained using GIS.
The findings of this study were consistent with findings of previous studies. Barred owl habitat is moist, structurally diverse, closed canopy forests on gentile slopes. Habitat use was most strongly associated with highly productive moist forest. In contrast, spotted owls prefer dry forest habitats. The differences in ecology may be related to prey types.
Forest managers may use this information to protect areas of forest where spotted owls are most likely to be found and where barred owls are least likely to exclude them.
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