A model to evaluate barred owl removal strategies for the conservation of northern spotted owls

Barred owls recently expanded their range and now completely overlap that of the northern spotted owl. Current declines in northern spotted owl populations are largely attributable to this sympatry with barred owls. Lethal removal of barred owls is being considered and tested as a method of managing the negative impacts on spotted owls. The size and distribution of removal areas may influence the efficacy and efficiency with which an area can be maintained free of barred owls. I created an individual-based spatially-explicit population model to compare alternative spatial strategies for removing barred owls in a localized area. Large, continuous removal areas maintain lower barred owl occupancy and require fewer owls to be removed than smaller fragmented removal areas for a given level of removal effort. The model is most sensitive to adult and subadult survival as well as reproduction and the range over which an owl can detect a potential mate, of which the latter two parameters do not have empirical field estimates. This model could be adapted to answer further questions regarding barred owl removal and also incorporate geographic information system data to evaluate removal strategies on real-world properties.