Environmental disturbances, such as wildfire, drought, and fuel management, are reshaping wildlife habitats in western forests and threatening forest-dependent species like the spotted owl (Strix occidentalis). Here, we used 35 years (1987–2022) of spotted owl detections across the southernmost extent of their geographic range in Southern California to model owl nesting and prey acquisition habitats and evaluate the effects of wildfire, drought, and fuel treatments. We found a 54% decline in nesting habitat and a 40% decline in prey acquisition habitat. Notably, 91% of suitable nesting habitat across years occurred within the San Bernardino Mountains. Wildfires were the main driver of nesting habitat loss, responsible for approximately 30% of the decline, with most large, severe fires occurring after 2003. In contrast, fuel management contributed to only 4% of the loss. The number of potential territories containing sufficient nesting habitat (48 ha) declined by 53%, whereas territories containing sufficient prey acquisition habitat (48 ha) declined by 47%. The number of potential territories with sufficient nesting and prey acquisition habitat decreased by 73%. Our research demonstrates the pronounced impact of wildfires on spotted owl habitat, particularly in the San Bernardino National Forest, while emphasizing the minor negative effect of fuel management.