Bat occupancy model predictions for Montana from acoustic and mist net data 2008-2010

The spread of white-nose syndrome (WNS) across the eastern United States has raised conservation concerns and provided motivation for efforts to monitor the impacts of this disease. Currently, WNS has not yet been detected in Montana, or any other western state besides Washington, and it is unknown how severe it will impact species in this region once it arrives. Within an occupancy model framework, we analyzed mist netting and acoustic records for eight bat species in Montana to estimate baseline distributions across the state prior to the arrival of WNS. Heterogeneity in the probabilities of occupancy for each species was explained with covariates for forest cover (%), elevation, ruggedness, and average degree days. Our analysis provided no evidence of spatial correlation among occupancy probabilities within each species, but did suggest spatial correlation among detection probabilities likely related to timing of surveys. We incorporated spatially-correlated random effects in the model for detection probabilities to account for these patterns.