The northern spotted owl (Strix occidentalis caurina) was listed as threatened under the U. S. Endangered Species Act (ESA) in 1990. We applied modern spatial conservation theory and models to evaluate several candidate critical habitat networks, and sought an efficient conservation solution that encompassed the highest value lands for spotted owl recovery rather than maximizing the total area of potential critical habitat. We created a map of relative habitat suitability, which served as input to the spatial conservation prioritization program Zonation. We used the spatially-explicit individual-based population model HexSim to estimate and compare simulated spotted owl population outcomes among a suite of candidate critical habitat networks that varied in size and spatial arrangement under alternative scenarios of future habitat suitability and barred owl (S. varia) effects. We evaluated simulated spotted owl population outcomes, including total population size, and extinction and quasi-extinction likelihoods for 108 combinations of candidate critical habitat networks by habitat change by barred owl scenarios, both range-wide and within 11 distinct portions of the owl's range. Barred owl encounter rates and the amount and suitability of habitat had substantial effects on simulated spotted owl populations. When barred owl encounter rates were high, changes in the amount and suitability of habitat had minimal impacts on population performance. Under lowered barred owl encounter rates, candidate critical habitat networks that included most existing high suitability habitat supported a high likelihood of long-term population persistence. Barred owls are currently the primary driving force behind poor population performance of NSOs; however, our models demonstrated that a sufficient area of high suitability habitat remains essential for recovery when effects of barred owls can be reduced. The modeling approach we employed is sufficiently flexible to incorporate new information about spotted owls as it becomes available and could likely be applied to conservation planning for other species.
1.Humboldt State Univ, Dept Environm Sci & Management, Arcata, CA 95521 USA 2.US Fish & Wildlife Serv, Western Golden Eagle Conservat, Corvallis, OR USA 3.US EPA, Environm Res Lab, 200 SW 35Th St, Corvallis, OR 97333 USA 4.US Fish & Wildlife Serv, Portland, OR USA 5.Nat Resources Geospatial, Smontague, CA USA 6.Oregon State Univ, Dept Fisheries & Wildlife, Corvallis, OR 97331 USA 7.US Forest Serv, Forestry Sci Lab, Corvallis, OR USA 8.US Fish & Wildlife Serv, Wenatchee, WA USA 9.US Forest Serv, USDA, Pacific Northwest Res Stn, Portland, OR USA 10.US Fish & Wildlife Serv, Reg Endangered Species Listing Div 1, Portland, OR USA 11.Colorado State Univ, Dept Fish Wildlife & Conservat Biol, Ft Collins, CO 80523 USA 12.Colorado State Univ, Grad Degree Program Ecol, Ft Collins, CO 80523 USA 13.US Forest Serv, USDA, Pacific Northwest Res Stn, Olympia, WA USA 14.Humboldt State Univ Sponsored Programs Fdn, Arcata, CA USA 15.US Fish & Wildlife Serv, USDI, Roseburg, OR USA
Recommended Citation:
Dunk, Jeffrey R.,Woodbridge, Brian,Schumaker, Nathan,et al. Conservation planning for species recovery under the Endangered Species Act: A case study with the Northern Spotted Owl[J]. PLOS ONE,2019-01-01,14(1)