We compared home range areas and habitat selection of radio-marked Spotted Owls (Strix occidentalis) and Barred Owls (Strix varia) in an area of sympatry in the northern Cascade Range of Washington in 1986–1989. On average, home ranges of Spotted Owls were 3–4 times larger than ranges of Barred Owls, and there was little overlap of home ranges during the breeding season. Ranges of both species tended to expand during winter. Home range size of both species was negatively correlated with the amount of old forest, but the negative slope of the regression was much steeper for Spotted Owls than for Barred Owls. For both species, home ranges of individual owls typically had high overlap among seasons and years, indicating high site fidelity. Barred Owls generally occupied home ranges at lower elevations than Spotted Owls (mean  =  386 ± 27 m vs. 750 ± 68 m). Both species tended to use old forests more than expected, but Spotted Owls tended to use other cover types less than expected, whereas Barred Owls used most other cover types in proportion to their availability. We suggest that Spotted Owls may use larger ranges than Barred Owls because they prey selectively on a few species of nocturnal mammals, whereas Barred Owls forage more evenly across a broad range of prey types, including diurnal and aquatic species. The low overlap of Barred Owl and Spotted Owl home ranges suggests that territorial Barred Owls exclude Spotted Owls from their territories, at least during the breeding season, thus reducing the amount of habitat available to Spotted Owls.

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This report describes options for effectiveness monitoring of long-term status and trends to evaluate the success of the Northwest Forest Plan in maintaining and restoring marbled murrelet nesting habitat and populations on Federal lands. A two-phase approach is described that begins with developing reliable and repeatable processes for identifying nesting habitat and overcoming logistical and statistical problems before habitat and population trends can be accurately assessed. The second phase involves application of these processes to mapping and quantifying nesting habitat, and establishing populations in the Forest Plan area. The potential use of predictive models to evaluate the relation between terrestrial habitat use and conditions and population densities and trends is described along with a process for data analysis and reporting.Keywords: Northwest Forest Plan, effectiveness monitoring, marbled murrelet, nesting habitat, marine surveys, remote sensing, GIS, landscape, stand-scale, habitat assessment, predictive model. PrefaceThis report is part of a series of reports describing the approach for monitoring effectiveness of the Forest Plan that have been approved by the Intergovernmental Advisory Committee. Other reports present the plans for monitoring late-successional and old-growth forests, northern spotted owl, and aquatic and riparian ecosystems. Future reports may address survey-and-manage species and biodiversity of late-successional and aquatic ecosystems, socioeconomics, and tribal resources. These reports follow the framework for effectiveness monitoring described in "The Strategy and Design of the Effectiveness Monitoring Program for the Northwest Forest Plan." The purpose of this report is to present a range of options for monitoring the marbled murrelet from which the Federal agencies responsible for the Forest Plan could select an approach meeting their respective information needs given current and expected resource availability. This report responds to the assignment from the Federal resource agencies through the Intergovernmental Advisory Committee and incorporates responses to all comments and peer reviews, as requested. The options, recommended by the authors and the interagency Effectiveness Monitoring Team, have been selected for implementation in fiscal year 1998. Manuals, protocols, specific tasks, and annual funding allocations will be provided in individual agency work plans. All these documents, including manuals and work plans, will comprise the full set of guidance for conducting the effectiveness monitoring program for the Forest Plan. Executive SummaryThe primary goal of the marbled murrelet effectiveness monitoring plan is to evaluate the success of the Northwest Forest Plan (Forest Plan) in maintaining and restoring marbled murrelet (Brachyrhamphus marmoratus) nesting habitat and populations. Specific objectives are based on standards and guidelines in the Forest Plan and focus on monitoring the status and trends of murrelet nesting habitat and populations. Plan ApproachT...