U.S. Department of Agriculture: Animal and Plant Health Inspection Service



Jeremy T. Rockweit, Oregon State UniversityFollow
Julianna M. Jenkins, USDA ARS Corvallis Forestry Sciences Laboratory
James E. Hines, United States Geological Survey
James D. Nichols, University of Florida
Katie M. Dugger, Oregon State University
Alan B. Franklin, USDA APHIS National Wildlife Research Center
Peter C. Carlson, Colorado State University
William L. Kendall, Warner College of Natural Resources
Damon B. Lesmeister, USDA ARS Corvallis Forestry Sciences Laboratory
Christopher McCafferty, USDA ARS Corvallis Forestry Sciences Laboratory
Steven H. Ackers, Oregon State University
L. Steven Andrews, Oregon State University
Larissa L. Bailey, Colorado State University
Jesse Burgher, USDA ARS Corvallis Forestry Sciences Laboratory
Kenneth P. Burnham, Colorado State University
Tara Chestnut, US National Park Service
Mary M. Conner, Utah State University
Raymond J. Davis, USDA Forest Service
Krista E. Dilione, USGS Forest and Rangeland Ecosystem Science Center
Eric D. Forsman, USDA ARS Corvallis Forestry Sciences Laboratory
Elizabeth M. Glenn, United States Geological Survey
Scott A. Gremel, Olympic National Park
Keith A. Hamm, Green Diamond Resource Company
Dale R. Herter, Raedeke Associates, Inc.
J. Mark Higley, Forestry Division
Rob B. Horn, U.S. Bureau of Land Management
David W. Lamphear, Green Diamond Resource Company
Trent L. McDonald, LLC
Janice A. Reid, USDA ARS Corvallis Forestry Sciences Laboratory
Carl J. Schwarz, Simon Fraser University
David C. Simon, USGS Forest and Rangeland Ecosystem Science Center
Stan G. Sovern, Oregon State University
James K. Swingle, USDA ARS Corvallis Forestry Sciences Laboratory
J. David Wiens, USGS Forest and Rangeland Ecosystem Science Center
Heather Wise, U.S. Bureau of Land Management
Charles B. Yackulic, United States Geological Survey

Date of this Version



Ecological Applications. 2023;33:e2726.



CC-NC; U.S. government work


We conducted a range-wide investigation of the dynamics of site-level reproductive rate of northern spotted owls using survey data from 11 study areas across the subspecies geographic range collected during 1993–2018. Our analytical approach accounted for imperfect detection of owl pairs and misclassification of successful reproduction (i.e., at least one young fledged) and contributed further insights into northern spotted owl population ecology and dynamics. Both nondetection and state misclassification were important, especially because factors affecting these sources of error also affected focal ecological parameters. Annual probabilities of site occupancy were greatest at sites with successful reproduction in the previous year and lowest for sites not occupied by a pair in the previous year. Site-specific occupancy transition probabilities declined over time and were negatively affected by barred owl presence. Overall, the site-specific probability of successful reproduction showed substantial year-to-year fluctuations and was similar for occupied sites that did or did not experience successful reproduction the previous year. Site-specific probabilities for successful reproduction were very small for sites that were unoccupied the previous year. Barred owl presence negatively affected the probability of successful reproduction by northern spotted owls in Washington and California, as predicted, but the effect in Oregon was mixed. The proportions of sites occupied by northern spotted owl pairs showed steep, near-monotonic declines over the study period, with all study areas showing the lowest observed levels of occupancy to date. If trends continue it is likely that northern spotted owls will become extirpated throughout large portions of their range in the coming decades.