Climate change and fire suppression are leading to an increased prevalence of ‘mega-disturbances’ such as drought and wildfire in terrestrial ecosystems. We studied the occurrence dynamics of an iconic old-forest species, the spotted owl (Strix occidentalis), on a long-term study area in the Sierra Nevada, CA, USA from 1989 to 2020 to evaluate their multi-scale population response following a 2014 megafire (the ‘King’ Fire) that affected a portion of our study area. We found that extensive severe fire within spotted owl sites resulted in both immediate site abandonment and prolonged lack of re-colonization by owls six years post-fire. Sites that experienced high pyrodiversity – a mosaic of burn severities – were more likely to persist after the fire, but this effect was only apparent at finer spatial scales. A potentially confounding factor, post-fire salvage logging, did not explain variability in the probability of either owls persisting at sites or sites becoming re-colonized; effects could be attributed only to severe fire extent and pyrodiversity. Our study demonstrates the prolonged effects of severe fire on the occupancy of this forest-dependent species, suggesting that forest restoration that reduces megafires could benefit spotted owls.