Predicting occurrence of mexican spotted owls in arid canyonlands of southern utah

Abstract

The Mexican Spotted Owl (Strix occidentalis lucida) was listed as "threatened" by the U.S. Fish and Wildlife Service in 1993. Predicting the distribution of suitable habitat is an important step in the owl's recovery, and Geographic Information Systems (GIS) provide appropriate spatial and analytic tools. We developed and validated a GIS-based occurrence model for Mexican Spotted Owls in arid canyon environments in Utah. We generated a set of competing models with topographic and vegetation covariates, and ranked models using information theory. Our top-ranked models indicated slope and variation in elevation were important predictors for the occurrence of Mexican Spotted Owls in rocky habitats, and we averaged coefficients from the top models to estimate probability of owl occurrence. During a model validation survey, we detected Spotted Owls in 22 test plots, where mean estimated probability of occurrence, an index to habitat suitability, was 0.68 (SE = 0.03). In addition, we evaluated model performance at 30 known Mexican Spotted Owl use sites from outside our model development areas, and observed an overall mean probability of occurrence equal to 0.78 (95% CI = 0.71-0.81). For the 30 known owl use sites, estimated probability of occurrence using our top model ranged from 0.54-0.90. Our results suggest that GIS modeling can be an important tool for predicting the potential distribution of Mexican Spotted Owls and their habitat in arid canyonlands in Utah. © 2014 The Raptor Research Foundation, Inc.