Anthropogenic features influence home-range size and perch selection in Bubo virginianus (Great Horned Owl)

Anthropogenic changes providing elevated structures for nesting and hunting in grassland systems have facilitated range expansion by Bubo virginianus (Great Horned Owl). Depredation by owls may pose an additional threat to species of conservation concern. We used satellite transmitters to study how anthropogenic landscape features influence nocturnal movement, home-range size, and perch selection of 16 adult B. virginianus that nested in a variety of grassland and cropland-dominated landscapes in Saskatchewan, Canada. Regardless of grassland composition, male B. virginianus in our study had similar-sized core areas (1.0 ± 0.6 km; 50% kernel density estimate [KDE]). Owls that nested in high-percentage grassland-cover landscapes had larger home ranges (13.8 ± 6.1 km2; 95% KDE) compared to those in medium grassland-cover (11.0 ± 3.9 km2; 95% KDE), and approximately twice that of owls nesting in cropland (7.0 ± 3.4 km2; 95% KDE). The nightly flight distances were similar for owls nesting in high and medium grassland-cover landscapes (14.5 ± 0.4 km and 14.2 ± 3.9 km, respectively), but owls in cropland traveled shorter distances (11.6 ± 4.3 km). Bubo virginianus selected perches that were 5–10 m tall, typically within 400 m of the nest, and were mostly on planted trees, buildings and other human structures. Bubo virginianus movement and space use in human-dominated cropland landscapes were likely reduced due to an abundance of vertical structures for hunting. Removing elevated hunting perches may be used to discourage B. virginianus from using grassland areas occupied by vulnerable at-risk species.