Shifts in avian community composition across longleaf pine seral stages in a montane upland system

Longleaf pine ( Pinus palustris ) ecosystems historically covered much of the Southeastern United States but declined substantially due to land-use change and fire suppression, driving losses in associated avifauna. This prompted restoration efforts to reestablish frequent fire and open-forest structure. Although avian responses to longleaf restoration have been documented, responses across seral stages remain less understood, particularly in montane systems. We evaluated relationships between vegetation structure, seral stage, and avian community composition across early, late, and mature longleaf stands and compared them with reference mixed hardwood stands in Bankhead National Forest, Alabama. Breeding bird surveys and vegetation measurements were conducted from 2023 to 2025. We used distance sampling to account for imperfect detection, Hill numbers to quantify avian diversity, mixed-effects models to evaluate stage effects, and canonical correspondence analysis to relate avian community composition to vegetation structure. Mature stands supported the greatest avian richness and diversity, while late stands supported the least. Late stands showed substantial within-stage variation: some resembled open-pine conditions, whereas others retained greater midstory development, supporting different avian assemblages. Thus, seral stage alone did not consistently predict habitat conditions or avian community composition. Avian community composition was associated with structural gradients ranging from closed-canopy, high-basal-area reference conditions to open-pine conditions with greater understory development. Species of conservation concern showed contrasting associations with restored versus reference stands. These findings indicate management and monitoring should evaluate achieved vegetation structure directly while maintaining a landscape mosaic of restoration stages and remnant forest types to support avian species with differing habitat requirements.