Modeling Nesting Habitat Selection of California Spotted Owls (Strix occidentalis occidentalis) in the Central Sierra Nevada Using Standard Forest Inventory Metrics

Abstract

Abstract California spotted owl (Strix occidentalis occidentalis) nest sites are associated with large trees, moderate-to-high tree densities, high canopy cover, and structural complexity. Therefore, forest managers need accurate estimates of these characteristics. Standard forest inventory metrics, such as those estimated from Forest Inventory and Analysis (FIA) data, are used by silviculturists to assess forest trends and condition, and are a source of data for assessing wildlife habitat. We estimated which FIA metrics best predicted California spotted owl nesting habitat by developing a nesting-habitat model comparing owl nest stands with randomly chosen forest stands in potential nesting habitat (stands dominated by 30–60.9- and ≥61-cm diameter trees and ≥40% cover) in the central Sierra Nevada. Number of large trees (≥76.2 cm) and canopy cover were the best predictors of owl nesting habitat. We present a nesting-habitat selection model based on our analysis. FIA metrics may be useful for quantifying California spotted owl habitat in our study area, but because forest conditions are highly variable in the Sierra Nevada, our results should be tested further in other geographic regions. FOR. SCI. 50(6):773–780.