Journal article
Meta-analysis of California Spotted Owl (Strix occidentalis occidentalis) territory occupancy in the Sierra Nevada: Habitat associations and their implications for forest management
The Condor (Los Angeles, Calif.), Vol.118(4), pp.747-765
11/01/2016
DOI: 10.1650/CONDOR-16-66.1
Abstract
We assessed the occupancy dynamics of 275 California Spotted Owl (Strix occidentalis occidentalis) territories in 4 study areas in the Sierra Nevada, California, USA, from 1993 to 2011. We used Landsat data to develop maps of canopy cover for each study area, which we then used to quantify annual territory-specific habitat covariates. We modeled the relationships between territory extinction and colonization using predictor variables of habitat, disturbance (logging, fire), climate, and elevation. We found that forests with medium (40-69%) and high (>= 70%) canopy cover were the most important predictors of territory occupancy in all study areas, and that both canopy cover categories were positively correlated with occupancy. We used analysis of deviance to estimate the amount of variation explained by the habitat covariates (primarily medium and high canopy cover) and found that these covariates explained from 35% to 67% of the variation in occupancy. Climatic covariates were not correlated with occupancy dynamics and explained little of the variation in occupancy. We also conducted a post hoc analysis in which we partitioned canopy cover into 10% classes, because our original partitioning into 3 classes may have lacked sufficient resolution to identify canopy cover levels where occupancy changed abruptly. In this post hoc analysis, occupancy declined sharply when territories contained more area with <40% canopy cover, and the amount of 50-59% and 60-69% canopy cover had a more positive association with occupancy than did 40-49% canopy cover. Our results suggest that some fuels treatments intended to reduce fire risk and improve forest resilience could be located within Spotted Owl territories without adversely impacting territory occupancy if such treatments do not consistently reduce canopy cover below 50%. We suggest that future work quantify components of forest structure (e.g., large tree density, vertical complexity) known to be selected by owls and relate these characteristics to occupancy and fitness metrics.
Details
- Title: Subtitle
- Meta-analysis of California Spotted Owl (Strix occidentalis occidentalis) territory occupancy in the Sierra Nevada: Habitat associations and their implications for forest management
- Creators
- Douglas J. Tempel - University of Wisconsin–MadisonJohn J. Keane - Pacific Southwest Research StationR. J. Gutierrez - University of MinnesotaJared D. Wolfe - Pacific Southwest Research StationGavin M. Jones - University of Wisconsin–MadisonAlexander Koltunov - University of California, DavisCarlos M. Ramirez - US Forest ServiceWilliam J. Berigan - University of Wisconsin–MadisonClaire V. Gallagher - Pacific Southwest Research StationThomas E. Munton - Pacific Southwest Research StationPaula A. Shaklee - Pacific Southwest Research StationSheila A. Whitmore - University of Wisconsin–MadisonM. Zachariah Peery - University of Wisconsin–Madison
- Resource Type
- Journal article
- Publication Details
- The Condor (Los Angeles, Calif.), Vol.118(4), pp.747-765
- DOI
- 10.1650/CONDOR-16-66.1
- ISSN
- 0010-5422
- eISSN
- 1938-5129
- Publisher
- Oxford Univ Press
- Number of pages
- 19
- Grant note
- USDA Forest Service Region 5 University of Minnesota Agricultural Experiment Station U.S. Fish and Wildlife Service; US Fish & Wildlife Service California Department of Water Resources Resources Agency of California University of Wisconsin-Madison; University of Wisconsin Madison California Department of Forestry and Fire Protection Sierra Nevada Conservancy USDA Forest Service Pacific Southwest Research Station; United States Department of Agriculture (USDA); United States Forest Service California Department of Fish and Wildlife
- Language
- English
- Date published
- 11/01/2016
- Academic Unit
- School of Earth, Environment, and Sustainability
- Record Identifier
- 9985219860602771
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