Ellen Pero, University

Bear recovery increasingly occurs in landscapes that have undergone substantial environmental change following species extirpation, making evaluation of contemporary and future habitat quality central to restoration feasibility assessments. Food availability is a key determinant of restoration success, yet remains poorly characterized where species have been long absent. We assessed the current and future food resource landscape relevant to potential grizzly bear (Ursus arctos) recovery in the state of California within the United States where populations have been extirpated for more than a century. Using research-grade iNaturalist observations, we modeled distributions of known and key grizzly bear food taxa and mapped food-species richness across candidate restoration regions. We then projected changes under two mid-century climate scenarios (SSP2-4.5 and SSP5-8.5). Under contemporary climate conditions, all regions supported diverse but spatially heterogeneous food resources, with the Sierra Nevada consistently exhibiting the highest modeled richness. Climate projections indicated regionally divergent trajectories. While many areas showed stable or increasing food-species richness under both emission scenarios, particularly the Northwest Forest area, the Sierra Nevada region was associated with the largest projected losses, especially at lower elevations under the higher emission scenario. These results highlight potential trade-offs between regions that currently support high resource diversity and those that may offer greater resilience amidst future change. Our analysis provides a broadscale, spatially explicit assessment of food resource richness and resilience relevant to grizzly bear recovery in California. More broadly, we demonstrate how community-science data can be leveraged to reconstruct resource landscapes and inform restoration feasibility assessments for long-absent species under ongoing climate change.