The ongoing range expansion and rapid population growth of barred owls is rapidly driving northern spotted owls NSO extinct throughout their range

California coast range forests effectively constitute the leading edge of the range expansion and are among the few remaining areas harboring functional NSO populations. If barred owls are allowed to achieve higher densities in this area NSO populations will almost certainly go extinct. Here we propose to conduct barred OWL removals in the strategically located mendocino national forest to prevent NSO extinction and promote the recovery of remaining populations of NSO. This 913306ACRE landscape was selected based on four CRITERIA1 contains recoverable NSO populations 2 is large enough to function as a standalone barred owlfree refuge for NSO 3 occurs close to limited ongoing barred OWL removal projects and 4 has reasonable information on the distribution of barred and spotted owls. Our project will create a key barred owlfree refuge for NSO that will serve as an essential bridge to the forthcoming barred OWL management strategy being developed by the united states fish and wildlife service USFWS and thus has a high probability of contributing substantially to the recovery of this iconic threatened species. The effectiveness of barred OWL removals and the recovery of NSO will be monitoring using callbased surveys and a powerful beforeaftercontrol impact design for a minimum of two years using preremoval occupancy data we have already collected. Repeated surveys and removals will be required over the twoyear project period to remove colonizing barred owls and assess spotted OWL recovery. However we are confident these removals will reduce barred OWL densities to levels that help maintain a viable NSO population within our study area until the longerterm USFWS barred OWL management strategy can be implemented.