Translator Disclaimer
1 August 2011 Reproduction of Northern Spotted Owls: The Role of Local Weather and Regional Climate
Elizabeth M. Glenn, Robert G. Anthony, Eric D. Forsman, Gail S. Olson
Author Affiliations +

We examined associations between annual reproduction and climate for 6 populations of individually marked northern spotted owls (Strix occidentalis caurina) in Washington and Oregon. We used an information-theoretical approach and mixed models to evaluate statistical models representing a priori hypotheses about the effects of weather and climate on reproduction. Reproduction was higher for adult than subadult owls and declined as the proportion of spotted owl territories with barred owl (Strix varia) detections increased. Similar to other spotted owl studies, we found that reproduction was negatively associated with cold, wet winters and nesting seasons at 3 of 6 study areas. In addition, we identified new relationships between reproduction, annual precipitation, storms, and regional climate cycles. For 3 of 6 areas, we found a quadratic relation between precipitation (rain and snow) and reproduction, with the number of young fledged per pair per year declining as precipitation in the previous year deviated from average levels. A meta-analysis conducted across all 6 areas indicated that reproduction at the regional level had a quadratic association with total winter snowfall in the preceding winter and was positively related to temperatures during the previous summer and fall. The amount of annual variation in reproduction accounted for by weather and climate varied widely across the 6 areas (4–79%), whereas variation in weather and climate across owl territories accounted for little of the spatial variation in reproduction (0–4%). Our results suggest that across the range of the species climate factors affecting prey abundance may have a greater effect on reproduction than direct effects of weather on nestlings.

© 2011 The Wildlife Society.
Elizabeth M. Glenn, Robert G. Anthony, Eric D. Forsman, and Gail S. Olson "Reproduction of Northern Spotted Owls: The Role of Local Weather and Regional Climate," Journal of Wildlife Management 75(6), 1279-1294, (1 August 2011).
Received: 2 July 2010; Accepted: 16 January 2011; Published: 1 August 2011

This article is only available to subscribers.
It is not available for individual sale.

mixed models
Northern Spotted Owl
Pacific Northwest
Strix occidentalis caurina
Get copyright permission
Back to Top