Northern Spotted Owl
Photo Credit: Courtesy of Oregon State University
Scientific Frontline: Extended "At a Glance" Summary: Northern Spotted Owl Functional Extinction Assessment
The Core Concept: An extensive, artificial intelligence-driven acoustic monitoring study has determined that northern spotted owl (Strix occidentalis caurina) populations in the Pacific Northwest have crossed or are rapidly approaching functional extinction thresholds.
Key Distinction/Mechanism: The research utilizes widespread passive acoustic monitoring combined with advanced machine learning algorithms to process millions of hours of ecosystem audio, accurately differentiating the calls of the native northern spotted owl from the competing barred owl (Strix varia).
Origin/History: The northern spotted owl was listed as threatened under the Endangered Species Act in 1990, prompting the adoption of the Northwest Forest Plan in 1994. The current study is based on passive acoustic data collected between February and September 2023.
Major Frameworks/Components:
- Deployment of passive acoustic recording devices across 1,027 randomly selected, 5-kilometer hexagon sampling units, representing over 38,000 square miles of federally managed habitat.
- Application of machine learning models to efficiently analyze more than 2.1 million hours of bioacoustic data for species-specific vocalizations.
- Evaluation of interspecific competition dynamics, revealing that barred owls are detected at a rate eight times higher than northern spotted owls.
- Assessment of functional extinction thresholds, indicating populations in regions such as the Washington Cascades are now too low to perform meaningful ecological roles or sustain reproductive viability.
Branch of Science: Conservation Biology, Bioacoustics, Population Ecology, Wildlife Ecology, and Data Science.
Future Application: The integration of artificial intelligence and passive acoustic monitoring can direct highly localized conservation interventions, including targeted barred owl removal, precise nesting habitat preservation, and potential captive breeding initiatives.
Why It Matters: The findings definitively document the functional extinction of a deeply protected species across large portions of its historic range, underscoring the urgent need for active management intervention while validating a scalable, highly effective method for broad ecological monitoring.
Populations of the northern spotted owl (Strix occidentalis caurina) are approaching, or have already crossed, functional extinction across large areas of the Pacific Northwest, a new study found. Researchers used artificial intelligence and advanced monitoring methods to assess long-term trends at an unprecedented scale.
While northern spotted owl populations have declined for decades, this study identifies where populations are at or near functional extinction—meaning numbers are so low that the owls no longer play a meaningful ecological role or cannot reproduce sufficiently to persist. It also provides detailed population data on the barred owl (Strix varia), which outcompetes the northern spotted owl for prey and habitat.
“These findings demonstrate that passive acoustic monitoring and machine learning can be used for large-scale ecological monitoring,” said Damon Lesmeister, a wildlife biologist at the US Forest Service’s Pacific Northwest Research Station and a courtesy faculty member at Oregon State University. “Our hope is that they can help shape conservation strategies and improve conservation outcomes for the northern spotted owl.”
Study findings include the following:
- Barred owl calls were heard eight times more frequently than those of northern spotted owls across the entire study area in Oregon, Washington, and northwestern California.
- Northern spotted owls are approaching functional extinction thresholds in Washington and on the Oregon coast.
- Northern spotted owls were not detected in the Washington Cascades at latitudes north of Seattle.
The conservation and management of northern spotted owls became one of the largest and most visible wildlife conservation issues in US history after the species was listed as threatened under the Endangered Species Act in 1990 due to rapid declines in the owl’s old-growth forest habitats. Four years later, the Northwest Forest Plan was adopted, reducing the rate of logging in old-growth forests on federal lands.
Despite more than thirty years of protection, northern spotted owl populations have continued to decline due to ongoing habitat loss from logging and wildfires, as well as competition from barred owls, whose range in recent decades has increasingly intersected with spotted owl territory.
For the new study, scientists, led by teams at the US Forest Service and Oregon State University’s Department of Fisheries, Wildlife, and Conservation Sciences, divided more than 38,000 square miles of federally managed northern spotted owl habitat in Oregon, Washington, and northwestern California into 5-kilometer hexagonal sampling units meant to replicate the typical territory of a northern spotted owl.
They randomly selected 1,027 (3 percent) of those hexagons and deployed four passive acoustic recording devices in each for a six- to eight-week period between February and September 2023. The devices collected more than 2.1 million hours of recordings.
Research computers at Oregon State University’s Center for Quantitative Life Sciences analyzed those recordings using machine learning models developed by the researchers. Findings from that analysis include the following:
Northern spotted owl calls were confirmed in 261 of the 1,027 hexagonal sampling areas, and barred owl calls were confirmed in 891 of the sampling areas.
A total of 34,341 northern spotted owl clips and 279,439 barred owl clips were recorded, meaning barred owls were heard over eight times more frequently than northern spotted owls.
More northern spotted owls were observed during sampling in the southern portions of the range. Detection rates ranged from 13 to 17 percent in Washington and on the Oregon coast, to 44 percent in the Oregon and California Klamath Mountains, and up to 91 percent on the California coast.
Barred owls were heard more frequently in northern sampling areas. They were detected in 100 percent of sampling areas on the Oregon coast, 94 percent on the Washington coast and in the western Cascades, 72 percent in the Oregon and California Klamath Mountains, and 45 percent on the California coast.
This monitoring has continued since the 2023 period analyzed in the study, and preliminary findings from the additional monitoring mirror those outlined in the paper, Lesmeister said.
Lesmeister believes the findings can help focus northern spotted owl conservation strategies on specific geographic areas. The authors cite several conservation strategies, including ongoing barred owl removal efforts, conserving landscapes well suited for northern spotted owl nesting, and bringing northern spotted owls into captivity for breeding—a strategy that has already been adopted in Canada.
“Northern spotted owls are already functionally extinct in large swaths of their range. It’s not a thing that’s happening in the future; it has happened,” Lesmeister said. “That doesn’t mean we can’t do anything. There is still an opportunity for carefully considered management actions.”
Published in journal: Ecological Applications
Authors: Damon B. Lesmeister, Julianna M. A. Jenkins, Raymond J. Davis, Natalie M. Rugg, Cara L. Appel, Larissa L. Bailey, Erin Bayne, Tara Chestnut, Leila S. Duchac, Katie M. Dugger, Taylor D. Ellis, Alan B. Franklin, Scott A. Gremel, Aaron Henderson, Edward Henson, J. Mark Higley, James E. Hines, Bruce Hollen, William L. Kendall, Taal Levi, Darryl I. MacKenzie, Christopher E. McCafferty, Thomas Munger, David T. Press, Caroline Provost, Suzanne Reffler, Zachary J. Ruff, James K. Swingle, Erica Tevini, Alaina D. Thomas, Matthew J. Weldy, Kirsten Wert, Angela White, and Charles B. Yackulic
Source/Credit: Oregon State University | Sean Nealon
Edited by: Scientific Frontline
Reference Number: cons082526_01