Fig 1.
Geographic extent of study area and modeling regions boundaries.
Table 1.
Name, acronym and size of modeling regions, and definitions of acronyms used throughout.
Fig 2.
Flow chart of generalized modeling phases.
NR = nesting and roosting, F = foraging, RHS = relative habitat suitability, NWFP = Northwest Forest Plan.
Table 2.
List of variables used for modeling relative habitat suitability of northern spotted owl site centers.
Table 3.
Categories of candidate variables (and order of entry), variable names of variables used in the relative habitat suitability modeling process.
Fig 3.
Flowchart of development and evaluation of MaxEnt relative habitat suitability (RHS) models within each of 11 modeling regions.
Fig 4.
Flowchart of steps using Zonation to identify alternative candidate critical habitat networks for northern spotted owls.
Fig 5.
Flowchart of generalized steps involved in the northern spotted owl HexSim model.
Table 4.
Number of alternative candidate critical habitat networks by relative habitat suitability by barred owl scenarios, inclusion of environmental stochasticity, number of replicates, and total time steps used in HexSim simulations of northern spotted owl populations.
Table 5.
Candidate critical habitat networks Composites 1 and 2 that resulted from Phase 1 modeling.
Fig 6.
Map of relative habitat suitability throughout the geographic range of the northern spotted owl.
Table 6.
Relative habitat suitability model evaluation statistics among 11 modeling regions.
Fig 7.
Northern Spotted Owl strength of selection (SOS) by relative habitat suitability (RHS) bin mid-point and modeling region.
SOS is estimated by dividing the proportion of northern spotted owl site centers within a RHS bin by the proportion of the modeling region comprised of that bin (and thus represent relative densities of site centers). For values <1, we divided the SOS value into -1 to allow values <1 and >1 the potential to vary to the same extent. Without doing this, values <1 are constrained to be between 0 and 1, whereas values >1 can grow nearly infinitely. Legend acronyms are the 11 modeling regions and the mean of all regions combined.
Table 7.
Comparison of percentage of northern spotted owl site center locations from 1996 training sites versus independent test sites from 2006 among five relative habitat suitability (RHS) bins for four modeling regions.
Table 8.
Comparison of 6 candidate critical habitat networks (we developed) by size and percent of 1996 spotted owl sites used in model development that occur within the network.
Table 9.
Phase 1 HexSim modeling results showing the percentage of the time-step 50 range-wide population size that was realized at time-step 250 (mean of 5 replicates) among 7 candidate critical habitat networks, various barred owl encounter rates, and relative habitat suitability (RHS) change scenarios.
Table 10.
Barred owl (STVA) encounter rates by modeling region.
Table 11.
Estimated northern spotted owl population responses, in modeling regions, among candidate critical habitat networks for the optimistic relative habitat suitability change scenarios.
Table 12.
Estimated northern spotted owl population responses, in modeling regions, to potential critical habitat networks for the pessimistic relative habitat suitability change scenarios.
Table 13.
Estimated range-wide northern spotted owl population responses to candidate critical habitat networks for the optimistic and pessimistic relative habitat suitability change scenarios.
Fig 8.
Mean and 95% confidence intervals of simulated northern spotted owl population sizes among 11 composite candidate critical habitat networks and the Northwest Forest Plan (NWFP) size, based on the pessimistic habitat change scenario.
Fig 9.
Maps of (a) Composite 11 (Critical Habitat designated in 2012), and (b) The Zonation scenario with 70% of habitat value, with emphasis on public lands. Although Z70PUB was more than twice the size of Composite 11, simulated spotted owl populations performed similarly.