Fire gives avian populations a rapid and enduring boost in protected forests of California

Abstract Background Fire can impact ecosystems and species over both short and long timeframes, resulting in pervasive impacts on the structure of avian communities. While recent research has highlighted the strong impact of fire on bird communities in the short term, there remains a need for understanding long-term population processes following fire, particularly in forested landscapes that are burning more frequently than in the past century. We analyzed avian response to fire using point-count data from 1999–2019 within national parks of the Sierra Nevada Inventory & Monitoring Network, combined with high-resolution estimates of burn severity from fires that burned up to 35 years prior to each count. We used a hierarchical Bayesian framework to account for imperfect detection of birds while estimating the potentially divergent effects of fire on population density over time for each of 42 species. Our models integrated time-varying data on habitat characteristics that would otherwise be confounded with fire history, such as canopy cover and height. Results In aggregate, bird population density increased rapidly after fire and remained higher in burned areas for at least 35 years relative to unburned areas. Moderate-severity burns typically resulted in more immediate and enduring positive effects than burns of lower severity. Of 42 bird species analyzed, only 13 showed little response to fire, eight responded positively for less than 20 years, 10 showed responses (nine positive) persisting longer than 20 years, and 11 showed positive responses with little or no sign of attenuation even 35 years after a fire. Responses did not align with broad migratory, nesting or foraging traits. Conclusions A wide variety of birds appeared to benefit—immediately or eventually—from burns at bird point-count stations in two fire-prone parks of the Sierra Nevada. These results offer a rare perspective on long-term avian response to fire and postfire successional processes, in some of the few western forests where effects of fire are relatively unconfounded by anthropogenic habitat loss and resource extraction.