Population trends in northern spotted owls: Associations with climate in the Pacific Northwest

Biological Conservation
By: , and 



We used reverse time capture-mark-recapture models to describe associations between rate of population change (??) and climate for northern spotted owls (Strix occidentalis caurina) at six long-term study areas in Washington and Oregon, USA. Populations in three of six areas showed strong evidence of declining populations, while populations in two additional areas were likely declining as well. At four areas, ?? was positively associated with wetter-than-normal conditions during the growing season, which likely affects prey availability. Lambda was also negatively associated with cold, wet winters and nesting seasons, and the number of hot summer days. The amount of annual variation in ?? accounted for by climate varied across study areas (3-85%). Rate of population change was more sensitive to adult survival than to recruitment; however, there was considerable variation among years and across study areas for all demographic rates. While annual survival was more closely related to regional climate conditions, recruitment was often associated with local weather. In addition to climate, declines in recruitment at four of six areas were associated with increased presence of barred owls. Climate change models predict warmer, wetter winters and hotter, drier summers for the Pacific Northwest in the first half of the 21st century. Our results indicate that these conditions have the potential to negatively affect annual survival, recruitment, and consequently population growth rates for northern spotted owls. ?? 2010 Elsevier Ltd.
Publication type Article
Publication Subtype Journal Article
Title Population trends in northern spotted owls: Associations with climate in the Pacific Northwest
Series title Biological Conservation
DOI 10.1016/j.biocon.2010.06.021
Volume 143
Issue 11
Year Published 2010
Language English
Larger Work Type Article
Larger Work Subtype Journal Article
Larger Work Title Biological Conservation
First page 2543
Last page 2552
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