Landscape composition and pattern around northern spotted owl nest sites in southwest Oregon

Landscape characteristics near 20 northern spotted owl (Strix occidentalis caurina) nests were compared with 20 paired random sites for 4 concentric circular plot sizes in southwestern Oregon. Nest sites contained significantly more old-conifer forest than random sites at all 4 plot sizes of 118, 471, 1,057, and 1,826 ha. With the exception of open canopy old-conifer at the 1,826-ha plot size, we found no significant differences between nest and random sites in the proportion of open sapling, hardwood mix, pole/young, and open canopy old-conifer forest for all plot sizes, but the tests have a low power due to the small sample sizes. Nest patches were larger than the largest old conifer patches found in each random plot. Conclusions regarding most landscape pattern variables and owl nest site selection were not possible because landscape pattern variables were highly correlated with the amount of old-conifer forest. We developed a reproductive index (RI) that should be useful for comparing reproductive rates among nests where the reproductive outcomes for individual nests are not available for the exact same years. Our preliminary results suggest that spotted owl reproductive rates may be directly related to the proportion of old-conifer forest in the landscape.