Wildfire has been a fundamental component of natural ecosystem dynamics for millennia. However, climate change and land use have altered fire regimes globally such that that many wildlife species are now threatened by larger, more severe, and/or more frequent wildfires. Fuels reduction treatments may be used to create landscapes that are more resilient to wildfire and lessen the impact of high-severity fire to wildlife. However, there is lingering uncertainty regarding the extent to which fire-adapted species are truly threatened by novel wildfire characteristics. The spotted owl (Strix occidentalis) has become a focal point of controversy owing to its use of forests that have been substantially impacted changing fire regimes. Here, we leveraged over three decades of surveys across 1514 historical spotted owl territories and GPS movement data from 169 individuals across seven national forests, three national parks, and privately owned land in California, USA, to answer the question: “How have spotted owls responded to changing fire regimes?”. Across the region, we found that spotted owl territories were more likely to become vacant and less likely to be colonized if they experienced recent extensive high-severity fire. Movement analysis showed that individual spotted owls were unlikely to select forest burned at high-severity. Thus, our expansive data synthesis provided an unambiguous conclusion to lingering uncertainty: Large and severe fires threaten the persistence of spotted owls across their range. If managers are charged with conserving this species in California, forest restoration and fuels reduction treatments that reduce the risk of large and severe fires without substantial degradation of suitable habitat appear to be necessary.