Alpine forest ecosystems have increasingly experienced extreme disturbances due to climate-related events. In October 2018, Storm Vaia struck the Italian Alps, followed by widespread outbreaks of the bark beetle Ips typographus. These events impacted forest structure, offering the opportunity to study post-disturbance bird community dynamics.

We investigated species richness, diversity, and turnover in bird assemblages in an 8 x 2 km area in the upper Valtellina valley (Central Alps), using 51 standardised point counts. The study area is elongated mainly south-north, with open areas in the south and closed forest in the north. The altitudinal gradient ranges from the anthropised valley floor (1164 m above sea level) to the east to coniferous woods (1839 m a.s.l) to the west. Point counts were performed between 5:00 and 10:00 am, recording for 10 min all individuals heard or seen within 100 m.

Environmental predictors included land cover proportions (from classified raster data) within 100 m of point counts, altitude, latitude, longitude, and the extent of forest damage (bark beetle and tree felling). For each point count, we computed biodiversity indices from the maximum observed abundances.

Results showed 55 bird species, with richness ranging from 6 to 18 per point count. Species richness and Shannon diversity were positively associated with built-up areas. Shannon diversity was also positively associated with tree cover and negatively with latitude. A distance-based redundancy analysis model on Bray-Curtis distances explained 28.4% of community variation, with tree cover, built-up areas, altitude, and latitude as the most important predictors. A variation partitioning analysis showed that land cover variables explained 24.6% of community variability, 8.6% was explained by the spatial variation in land cover, and only 2.7% by spatial variation in bird communities. Turnover was the dominant beta-diversity component (β_SIM = 0.63).

These findings suggest that moderate disturbance, like the presence of open areas in the south and around built-up areas at lower elevation, can support diverse avian communities by promoting habitat heterogeneity. Community variation was primarily driven by species replacement along these gradients. Post-disturbance management should therefore aim to preserve structural complexity to maintain bird diversity.