O. princeps has provided outsized insights about multi-taxonomic-scale resilience and vulnerability, plus governing mechanisms, amidst global change. The Columbia River Gorge (CRG) constitutes nationally unique, disjunct refugial habitats that elucidate numerous insights for informing solutions-oriented management and conservation. We sampled CRG pikas during 2011-2023 to understand trend and drivers of distribution and density, plus response to wildfire. We contextualize these results with ongoing citizen-science CRG surveys and western-USA pika results to inform conservation-management adaptation.

                  From 2011-2014 to 2019-2021, CRG-wide pika occurrence declined by 25.2%, and declined by 65.5% at separate low-elevation, longitudinal-edge sites. Similarly, pika density declined CRG-wide by 44.1%, but only 42.5% if considering only sites pika-occupied in both periods. Although declines occurred both within and outside of Eagle-Creek-Fire (burned) areas, density declines were stronger across Oregon than Washington. 2011-2014 pika-distribution and -density patterns reflected water balance (deficit, AET) far more than temperature balance or nutritional ecology. Microclimatic sensors illustrated pika-occupied sites had cooler, moister interstices than -unoccupied sites. Moss and grass cover were strongest contributors to density in a PCA. Although still possessing the lowest-elevation U.S. occurrence of pikas, apparent declines in subsurface ice, fire-driven changes in vegetative cover and composition, and habitat conversion likely catalyzed these declines.