Changing fire regimes and nuanced impacts on a critically imperiled species

Wildfire activity throughout western North America is increasing which can have important consequences for species persistence. Native species have evolved disturbance-adapted traits that confer resilience to natural disturbance provided disturbances operate within their historical range of variability. This resilience can erode as disturbance regimes change and begin operating outside this range. We assessed wildfire impacts during 1987–2018 on the northern spotted owl, an imperiled species with complex relationships with late and early seral forest in the Pacific Northwest, USA. We analyzed population- and individual-level wildfire impacts across the frequent-fire portion of the owl's geographic range at two spatial scales and uncovered important nuances involving wildfire risk. When comparing survival of owls on burned vs unburned territories, we detected no differences in apparent survival, and owls overwhelmingly remained on burned territories indicating no measurable population-level wildfire impacts. However, when including territory-scale fire characteristics we detected negative individual-level wildfire impacts that indicated apparent survival decreased and territory displacement increased with burn severity and extent within an owl's territory. Northern spotted owls were also more sensitive to fire effects within their core use area indicating that where fire burns is important for spotted owl conservation. These findings indicate nuance is required when discussing wildfire impacts to spotted owls, and that changing fire regimes in this portion of the northern spotted owl's range have not yet translated into negative population-wide impacts. However, dwindling populations and continued fire regime changes could exceed the adaptive capacity of remaining spotted owls, thereby resulting in negative population-wide impacts.