The U.S. Fish and Wildlife Service identified competition from barred owls as one of two main threats to the northern spotted owl’s continued survival (habitat loss is the other). We conducted an experiment to test the effects of removing barred owls from certain areas of spotted owl habitat to see if it would benefit spotted owls. The Barred Owl Removal Experiment has demonstrated success with reduced and declining populations of barred owls and a strong, positive effect on survival of northern spotted owls, which arrested the long-term population declines of northern spotted owls within the removal areas. This collection contains information related to the Barred Owl Removal Experiment.