Influence of Burn Severity on Avifaunal Communities in Southern Tropical Dry Deciduous Forest, Western Ghats

Climate change has exacerbated the extent and severity of forest fire in biodiversity hotspots. The variation in fire regime attributes creates diverse successional stages and structures, thus offering ecological niches for species occupancy and increasing the biodiversity, thereby supporting the pyrodiversity-biodiversity hypothesis. Understanding the effects of postfire burn severity and landscape heterogeneity on bird communities is essential for developing forest fire mitigation measures in tropical protected areas. We systematically surveyed birds in 120 point counts, 5 years postfire, to represent burn severity classes (unburned, low, moderate, and high severity). We assessed the influence of burn severity (a single-fire component of pyrodiversity) on bird communities in a southern tropical dry deciduous forest of Bandipur Tiger Reserve, Nilgiri Biosphere Reserve in the Western Ghats. We calculated delta normalized burn ratio (dNBR) to classify burn severity using Landsat data. Richness, evenness, and Simpson diversity were not significant across burn severity. While Shannon diversity was marginally significant before testing the Bonferroni's correction, no individual burn severity class showed a significant difference in Shannon diversity after applying the correction. Bird community composition was significantly dissimilar between all burn severity classes (F = 4.52, p = 0.001). Among the foraging substrate guild, abundance of ground and generalist species was significantly higher in high burn severity than that of unburned. We found a significant positive relationship between burn severity (dNBR) and abundance (β = 1.41, p = 0.009) corroborating with the pyrodiversity-biodiversity hypothesis. Forest fire management should account for the landscape heterogeneity created by fire. Implementing prescribed fires in highly vulnerable areas reduces fuel loads and prevents large, high burn severity areas within the reserve. In tropical environments, this study establishes a foundational understanding of the pyrodiversity-avian diversity relationship, underscoring the necessity for future investigations employing multi-taxa and multi-scale approaches to discern underlying patterns for improving forest fire management.