The Barred Owl (Strix varia) is a distinctive raptor known for its large, round head and dark eyes. Its brown and white plumage is striped horizontally across the chest, giving the bird its common name. The species is most easily identified by its loud, recognizable call, often vocalized as “Who cooks for you? Who cooks for you-all?” Historically, this owl was a common resident across the eastern half of North America. Despite being native, the Barred Owl has become the subject of intense conservation debate due to its successful range expansion into new territories, where its presence is altering established ecosystems.
A Native Species Expanding Its Range
The historical distribution of the Barred Owl was confined to forests east of the Great Plains, a vast expanse of treeless prairie known as the “Great Plains filter.” This natural barrier prevented westward movement. The species began a range shift around the turn of the 20th century, facilitated by human modifications to the landscape.
Post-colonial land use changes, such as suppressing natural wildfires and planting trees in riparian areas, allowed forests to connect along river systems. These wooded corridors enabled the Barred Owl to cross the Great Plains. The expansion continued rapidly, reaching the Pacific Northwest by the 1960s and 1970s, establishing populations from British Columbia down into California.
The term “invasive” is applied because its establishment in this new region is ecologically detrimental. An invasive species causes harm where it did not historically occur, and the Barred Owl’s arrival has disrupted the western forest ecosystem. It acts as a novel competitor and predator, introducing new pressures to native wildlife.
Direct Competition with the Northern Spotted Owl
The most significant consequence of the Barred Owl’s westward march is the severe competitive conflict with the federally threatened Northern Spotted Owl (Strix occidentalis caurina). Both species rely heavily on the dense canopy and complex structure of old-growth forests for nesting and foraging, resulting in a near-complete overlap of habitat requirements.
The Barred Owl possesses traits that give it a superior competitive edge over its smaller relative. It is physically larger and displays higher vocal and physical aggression, frequently displacing Spotted Owls from their established nesting and roosting sites. Studies show that the annual production of young by Spotted Owls fails entirely in territories within 1.5 kilometers of a Barred Owl nest site.
Beyond physical dominance, the Barred Owl exhibits broader ecological flexibility, particularly in its diet. The Spotted Owl is a specialist predator, focusing primarily on arboreal prey like the northern flying squirrel, while the Barred Owl is a generalist. Its wide-ranging diet, including terrestrial mammals, aquatic organisms, and diurnal species, allows it to thrive in fragmented habitats where the Spotted Owl struggles.
This adaptability translates to higher reproductive success; Barred Owl pairs produce 4.4 times more young over three years than their Spotted Owl counterparts. The Barred Owl has become the primary factor driving the continued decline of Northern Spotted Owl populations, surpassing the threat of habitat loss. The intense competition involves displacement, occasional hybridization, and even predation upon the Spotted Owl. This combination of superior aggression, reproductive capability, and dietary flexibility threatens the long-term survival of the Northern Spotted Owl.
Current Conservation and Management Efforts
The severe Barred Owl threat prompted the U.S. Fish and Wildlife Service (USFWS) to implement an intensive and controversial conservation response. The agency initiated large-scale experimental removal studies across Washington, Oregon, and California to determine if reducing Barred Owl numbers would benefit the struggling Spotted Owl population. This research involved the lethal control of Barred Owls in designated areas, sparking significant ethical debate.
The findings were clear: where Barred Owls were removed, Northern Spotted Owl survival rates increased significantly, and population declines stabilized or were arrested entirely. In contrast, Spotted Owl populations in control areas continued to decline sharply, often exceeding 12 percent annually.
These results provided the scientific basis for the USFWS to develop a final Barred Owl Management Strategy. The strategy calls for the targeted reduction of Barred Owl populations in specific, collaboratively selected areas to improve the survival and recovery prospects of the Northern Spotted Owl. Implementation is voluntary and depends on available resources, but it recognizes the necessity of active management.
While habitat protection remains foundational, studies demonstrate that strategies focused solely on preserving old-growth forest are insufficient to reverse the Spotted Owl’s decline. Ongoing management involves a two-pronged approach: continued protection of old-growth habitat combined with localized Barred Owl population reduction to create competitive release for the native species.