Status of the Northern Spotted Owl:
Since 1990, the northern spotted owl has been listed under the Endangered Species Act as “threatened,” meaning it is likely to become “endangered” within all or a significant portion of its range in the foreseeable future. Endangered status is more serious, meaning a species is already in danger of extinction.
The most recent annual survey indicates that the spotted owl continues to decline in the majority of the 11 longterm study areas. The decline is greatest in the northern part of the range where barred owls have been present for the longest time and are in high concentrations. The overall population is declining at a rate of 2.9 percent per year.
The most important factors scientists consider in assessing the viability of the spotted owl are: 1) whether population trends are increasing; and 2) whether spotted owls are maintaining their geographic distribution throughout their range. Recovery efforts seek to promote an increasing population trend so that spotted owls are well-distributed across their range. This will ensure sufficient genetic interchange and the species’ ability to withstand catastrophic events.
There are two main threats to the northern spotted owl’s continued survival. One is habitat loss, primarily due to timber harvest and catastrophic fire. The other is competition from barred owls, a larger, more aggressive, and more adaptable relative from eastern North America that has progressively encroached into the spotted owl’s range. Spotted owl recovery can only be achieved by addressing both of these threats.
Both threats were identified when the spotted owl was listed under the Endangered Species Act in 1990, but their magnitude has changed over the years. In the early years after the spotted owl was listed, the U.S. Fish and Wildlife Service anticipated that the spotted owl would continue to decline in the short term and that it would take decades to re-grow habitat that has been lost over the last 100 years or more. As replacement habitat is grown, the habitat threat facing spotted owls should lessen. Barred owls were recognized as a threat when the spotted owl was listed, but our understanding of the magnitude of that threat has grown significantly since then as their populations continue to expand throughout the forests of the Pacific Northwest. We are concerned that the spotted owl is likely to go extinct in some or all of its range without barred owl management.
The northern spotted owl generally inhabits late-successional forest habitats with high canopy cover and larger trees (late-successional forests are dominated by stands of mature and old growth age classes of trees). The spotted owl ranges from southwest British Columbia through the Cascade Mountains and coastal ranges in Washington, Oregon, and California.
When the spotted owl was listed under the Endangered Species Act in 1990, the U.S. Fish and Wildlife Service estimated that its habitat had declined 60 to 88 percent since the early 1800s. Habitat protections put in place since that time have slowed habitat loss and are starting to increase the amount of older forest habitat available for spotted owls.
The latest data indicate there are about 8.6 million acres of nesting and roosting habitat on federal lands and about 3.5 million acres of nesting and roosting habitat on non-federal lands throughout the spotted owl’s range. Spotted owls use a broader area for foraging, but recovery efforts focus more on nesting and roosting habitat.
The U.S. Fish and Wildlife Service has identified competition from encroaching barred owls as one of two main threats to the northern spotted owl’s continued survival (habitat loss is the other).
Barred owls now outnumber spotted owls in many portions of the latter’s range. Researchers have noted that spotted owl population declines are more pronounced in areas where barred owls have moved into their range. Declines are greatest where barred owls have been present the longest. We are concerned that the spotted owl is likely to go extinct in some or all of its range without barred owl management.
Barred owls are larger, more aggressive, and more adaptable than spotted owls. They displace spotted owls, disrupt their nesting, and compete with them for food. Researchers have observed barred owls interbreeding with or attacking spotted owls in a few cases. Because the spotted owl is already struggling due to diminished habitat, the effect of the barred owl’s presence is like throwing gas on a fire. An already vulnerable population, as with the spotted owl, has a much more difficult time withstanding dramatic changes in the ecosystem such as the encroachment of a competitor.
See this fact sheet for more information on the evolution of the barred owl threat, as well as references to the most commonly cited research related to barred owl/spotted owl interactions.
Recovery of species listed under the Endangered Species Act usually occurs in three general phases. First, a listed species is prevented from going extinct. Then, initial recovery actions help a listed species’ population stabilize. The final phase is turning the trajectory around and helping the species rebound to the point it no longer needs Endangered Species Act protection. This final recovery phase is often the most difficult and time-consuming.
The northern spotted owl recovery plan outlines actions over a 30-year timeframe and envisions that recovery can be accomplished in that time if those actions are effectively implemented. Reducing competition from the encroaching barred owl is one of the major challenges in recovering the spotted owl. With strong habitat conservation and forest restoration, the U.S. Fish and Wildlife Service maintains there is a good chance of succeeding in recovering the spotted owl over the long term if we adequately address the barred owl threat in the short term.
Barred Owl / Northern Spotted Owl Interaction:
Barred owls are native to eastern North America. They began moving west of the Mississippi River around the turn of the 20th century. Barred owls reached the range of the northern spotted owl in British Columbia by about 1959, continued to expand southward, and were first documented in Washington, Oregon, and California in the 1970s. Barred owls now outnumber spotted owls in many portions of the latter’s range.
The barred owl’s movement could have been a natural range expansion or human-caused or a combination of both; we don’t have data to be sure either way. There are several theories about why barred owls progressively moved westward. The most common one is that it was caused by changes to the environment in the Great Plains as people increasingly settled there and dramatically altered the landscape. Changes in climate, fire suppression, the decimation of bison, and orchard or shelterbelt planting, among other changes, may have created patches of habitat, altering natural barriers that previously inhibited the barred owl’s expansion westward.
See this fact sheet for more information on the evolution of the barred owl threat, as well as references to the most commonly cited scientific research related to barred owl/spotted owl interactions.
About one-third of the northern spotted owl recovery plan focuses on addressing the threat of the encroaching barred owl. The most significant effort is this proposal to conduct a barred owl removal experiment to test the feasibility of barred owl removal as a management tool. The Final Environmental Impact Statement (EIS) for the experiment outlines the alternatives considered for removing barred owls from certain areas of the spotted owl’s range in an experimental approach to test whether this will have a positive effect on spotted owl populations. If the experiment yields positive results, the U.S. Fish and Wildlife Service may consider including barred owl removal on a broader scale as part of a comprehensive management strategy for barred owls. This is a separate decision and would require a separate EIS under the National Environmental Policy Act.
More information on the proposal for experimental removal of barred owls: