Flying northern spotted owl. USDA Forest Service photo by Julie Jenkins.
Northern spotted owls (Strix occidentalis caurina) are listed as threatened under the Endangered Species Act. They face multiple conservation challenges, including habitat availability and competition from barred owls (Strix varia). Station researchers are working with colleagues from private and public institutions to inform conservation management approaches that will support the northern spotted owl, now and into the future.
Julianna Jenkins and Damon Lesmeister, research wildlife biologists with the station, and colleagues investigated the specific habitat use of the northern spotted owl and the species’ main competitor, the barred owl.
Using a new technique that provided a 3-D analysis of forest structure, the researchers identified subtle differences in habitat use between the two owl species in the coast range of Oregon. Both species inhabited forested areas with tall trees, but spotted owls were typically found in areas with relatively lower canopy cover and a well-developed understory, as well as areas with steep slopes.
These findings underscore that spotted owl habitat is now compressed to very specific forest conditions as a result of competition with barred owls. These newly identified differences in habitat use could be used to inform targeted forest management to increase available habitat for spotted owls.
Station researchers also took a closer look at the short- and long-term conservation considerations for northern spotted owls. They found that high-quality habitat is key to both the long-term recovery of northern spotted owls and the short-term success of barred owl removals. Because wildfire can threaten the development of old-growth forest habitat, the short-term management tactic of barred owl removal is important to ensure the immediate persistence of spotted owl populations.
In the future, however, the increased availability of high-quality, oldgrowth forest habitat could eliminate the need for barred owl removals. Combining these short- and long-term conservation considerations may be an effective path forward for managers supporting the recovery of northern spotted owls.