Boreal Owl: Its Habitat and Prey in the Superior National Forest (Final Report to USDA/Forest Service, Superior National Forest)

Abstract

Vegetation characteristics surrounding Boreal Owl (Aegolius fimereus) breeding sites in no1theastern Minnesota were examined during 2000-2001. Data collected during 1987-1990 were combined with the 2000-2001 data and all sampling methods were standardized. During nocturnal surveys, 42 individual Boreal Owl singing territories were located. Vegetation was sampled at 0.04 ha plots surrounding Boreal Owl song perches. Identical measurements were taken at one random plot, which was paired with a song plot. The majority (93%) of song perches were located in coniferous species. Boreal Owl song sites had high basal area of both live and dead trees, higher percent coniferous canopy and a taller overstory canopy than those of random locations. Using Landsat Thematic Mapper satellite imagery, I compared the proportion of 13 land cover classes within 100 m (3.13ha), 500 m (78.14 ha), 1000 m (312.57 ha), 2000 m (1,256.27 ha), and 5000 m (7,814.17 ha) radii concentric circular plots surrounding cavity trees (N = 31) with random locations (N = 41) distributed throughout the SNF. Land cover differences between cavity and random locations were significant at all buffer levels. Upland mixed and upland conifer forests were significantly higher surrounding cavity locations, pmticularly within 100 m - 1000 m (P < 0.05). Lowland conifer stands were significantly higher (P < 0.05) surrounding cavity locations, particularly at larger landscape levels (> 1000 m).