The Barred Owl (Strix varia) is a large, widespread species of owl recognizable by its dark eyes and brown-and-white striped plumage. Its most common vocalization is a distinctive eight-to-nine-note hoot often translated as “Who cooks for you? Who cooks for you-all?”. This vocal signature is familiar throughout the woodlands of eastern North America, where the species historically occupied before expanding its range westward. The Barred Owl is a highly sedentary bird that maintains a territory throughout the year, with defensive behaviors intensifying during the nesting season.
Defining Barred Owl Territory
Barred Owls are strongly territorial, a behavior observed across seasons but most pronounced as the breeding period approaches. This territoriality primarily serves to secure and defend the resources necessary for successful reproduction and survival of the pair and young.
A typical territory includes the immediate area around the nest site, often a large tree cavity or an abandoned stick nest built by a hawk or crow. It also encompasses reliable roosting sites for daytime rest and a core hunting area providing a consistent food supply. Since Barred Owls are monogamous, the pair often maintains the same territory for multiple years.
Vocalizations and Active Defense
The primary tool for maintaining a territory is the owl’s vocalizations. The nine-note hoot serves as a long-range boundary warning, communicating the pair’s presence and discouraging encroachment by other owls. These territorial calls are heard year-round, but their frequency increases significantly during late winter and early spring when breeding activity begins.
If vocal warnings fail, the owls engage in active defense. Intruders, including other Barred Owls or predators, may be met with a loud, frantic series of calls known as caterwauling, often performed as a duet. This display is accompanied by physical threat behaviors, such as exaggerated wing clapping, which sounds like a sharp slap intended to intimidate the threat. If the threat persists, the owl, especially the female near the nest, may resort to physical attack using its powerful talons.
Home Range Size and Population Density
The area used by a Barred Owl pair includes a smaller, vigorously defended core territory and a larger, loosely defined home range. Home range size depends on habitat quality and prey density. Studies show annual home ranges can be as small as 273 hectares in resource-rich areas like Minnesota, or as large as 971 hectares in less favorable environments like Saskatchewan.
During the breeding season, owls constrict their activities to the immediate vicinity of the nest for hunting and foraging. Population density influences territory size; in high-quality, mature forest habitat, Barred Owls can occur at densities up to 1.0 pairs per square kilometer. The availability of large trees for nesting cavities is a strong determinant of where a breeding territory will be established.
Inter-Species Territorial Conflict
The Barred Owl’s assertive territoriality is a significant factor in its ecological impact, particularly in its expanding western range where it overlaps with the native Spotted Owl (Strix occidentalis). The Barred Owl’s slightly larger size and more aggressive nature give it a strong competitive advantage over its smaller cousin. This allows the Barred Owl to actively displace the Spotted Owl from established territories and prime nesting sites.
Barred Owls occupy territories at higher densities than Spotted Owls, meaning they require less acreage per pair and effectively saturate the habitat. Another element is the Barred Owl’s broader and more diverse diet, which includes a wider variety of prey species, including those active during the day. This dietary flexibility reduces their reliance on the specific nocturnal mammals that Spotted Owls specialize in, leading to successful competition for food resources.
This territorial and resource-based competition has caused a steep decline in Spotted Owl populations across the Pacific Northwest. When Barred Owls move into a Spotted Owl’s territory, the native species exhibits lower survival and reproduction rates. Conservation efforts, including experimental removal of Barred Owls from certain areas, have demonstrated a strong, positive effect on the survival of Northern Spotted Owls. This confirms the direct link between the Barred Owl’s aggressive behavior and the decline of the native species.