For the past several decades the focus on enhancing Northern Spotted Owl
populations in the West has been on preserving suitable habitat, primarily
old growth forests. Audubon and many other conservation organizations
were successful in protecting much of the remaining habitat of the Spotted
Owl – listed as an endangered species. Conserving the Spotted Owl has
been one of the most controversial and visible issues in conservation history.
This issue, enhancing the vitality and health of the Northern Spotted Owl population, has a new twist. At the very time that Spotted Owl populations have declined in the West, Barred Owls have invaded the Spotted Owl range.
The Barred Owl is non-native species to the West, including Western Washington. It has migrated across the continent into western U.S. forests from eastern states. Where the ranges of Barred Owls and Spotted Owls overlap, the Barred Owl has proven to be a more successful competitor that adversely impacts the Spotted Owl. Spotted Owl populations in Washington have been declining at a rate of 7.3% per year. On the Olympic Peninsula, the Barred Owl has increased five-fold in the past 10 years. Biologists observe that the Spotted Owl is being pushed to higher elevations on the Peninsula because of competition from the Barred Owl, which prefers lower forested areas.
What, if anything, should be done to deal with the Barred Owl’s adverse impacts on the Northern Spotted Owl? Three options are available to address Barred Owl impacts:
- Do nothing. The focus would be to continue Spotted Owl habitat protection.
- Lethal removal of Barred Owls, probably by shooting or trapping.
- Non-lethal removal of Barred Owls. Owls would be live-trapped and relocated. One sticking point is the question of where to relocate the captured Barred Owls. They are non-native throughout the West, so they likely would be unwelcome in most western states.
In a paper co-authored by OPAS member Tim Cullinan, biologists recommend two steps to guide future management decisions:
- Conduct ecological investigations of Barred Owl home range size, habitat use, prey use, and demography. Extensive studies of these factors have been conducted for Spotted Owl, but little ecological study has been done for the Barred Owl.
- Conduct experimental removal of Barred Owls in selected Spotted Owl locations. The removal experiments must be carefully designed to ensure that the Spotted Owl’s response to Barred Owl removal was caused by competition for food or space. The authors believe that direct lethal removal of Barred Owls, with appropriate ethics, would be the most cost effective and efficient method of conducting these experimental removals.
At some point, conservationists may have to debate whether, or how, to manage the Barred Owl to maintain the vitality of the Spotted Owl. In the immediate future, conservationists probably can work together to support funding for ecological studies of Barred Owls accompanied by removal experiments.