Post-Fire Abundance Trajectories of Bird Species and Functional Groups Within an Atlantic–Mediterranean Ecotone

The Atlantic–Mediterranean ecotone of northwestern Iberia is one of the most fire-prone regions in Europe, yet post-fire avian dynamics there remain poorly documented. To characterise short- to mid-term post-fire avian trajectories in this ecotone, we combined a 16-year fire record with six consecutive breeding seasons of annual point-count surveys. Between 2020 and 2025, we recorded 13,770 individuals of 67 bird species across 210 fixed locations in a mountain protected area of NW Spain dominated by frequent small- to medium-sized wildfires. We contextualised trajectories against both contemporary unburned reference conditions and historical baselines representing contrasting fire regimes. Community-level species richness and total abundance converged rapidly toward reference levels within 3–5 years, whereas functional-group responses showed marked divergence: shrubland and open-habitat species consistently overshot unburned reference abundances, while forest-associated guilds showed persistent deficits—most pronounced among canopy foragers. Conservation value peaked during early post-fire stages and remained above reference levels for at least 9 years. This study provides the first integrated characterisation of post-fire avian trajectories at the species, functional-group, and community levels in this Atlantic–Mediterranean transitional system, offering an empirical baseline for future mechanistic research and evidence-based fire management in fire-prone landscapes.