Barred owl expansion | In the last century, the barred owl (Strix varia) has expanded from eastern to western North America, having been facilitated by human actions that together led to more trees in the Great Plains and milder conditions in boreal forests. Barred owls are now ubiquitous in many forests of western Washington, western Oregon, and northwestern California. As novel predators and competitors, barred owls have the potential to negatively impact native species and ecological communities. Most notably, barred owls outcompete and displace the native and iconic spotted owl (Strix occidentalis).
USFWS Strategy | To address the threat posed to spotted owls by barred owls, the US Fish and Wildlife Service (USFWS) developed the Barred Owl Management Strategy, which lays out a voluntary framework to be adopted by landowners and managers. The Strategy is exhaustive and comprehensive, providing several levels of geographical guidance for the implementation of barred owl management. Within the range of the Northern Spotted Owl (NSO; S. o. caurina), the strategy delineates General Management Areas (GMAs) as the central organizing unit for barred owl management (alongside a handful of special interest areas). The Strategy provides explicit among-GMA prioritizations and qualitative guidelines for the placement of Focal Management Areas (FMAs) within GMAs. These prioritizations and recommendations are based on extensive knowledge of the system, including spotted owl populations and habitat, barred owl invasion status, and accessibility. Users should familiarize themselves with the Strategy before using the Barred Owl tool.
Barred Owl Tool | This tool provides quantitative prioritization results to complement the guidance offered in the USFWS Strategy. It implements modern tools from systematic conservation planning (see Methods) to help end-users decide where to implement barred owl population control with in the range of the northern spotted owl. The How-to guide walks users through the tool's many options and results, but several guiding principles should considered before using the tool and kept in mind while doing so:
- This is a decision support tool, not a decision making tool. That is to say, users should consider the results and outputs of this tool as a component of their decision making, rather than the sole information around which decisions are made. Results of the tool should be cross-referenced with on-the-ground knowledge of the system. For example, spotted and barred owl occurrence has been included in the tool via predictive methods (see Methods); users may thus wish to overlay the maps provided by this tool with up-to-date spotted owl occurrence records.
- The USFWS Strategy emphasizes that barred owl management should be geographically dispersed across the range of the northern spotted owl, in alignment with the former's recovery plan. This tool provides prioritizations at the regional (northern spotted owl range) and sub-regional (physiographic province) scales to help users identify priority patterns at broad spatial scales. However, in keeping with the USFWS Strategy, GMA-level prioritizations will be the most relevant for end-users seeking to delineate FMAs.
