Influence of heterogeneous habitats on the taxonomic and functional diversity of avifauna in an eastern Himalayan foothill landscape, India

The Eastern Himalaya in India is known for its rich avian biodiversity, often supported by the variation in habitat type and distribution. In this context, our study investigated the influence of habitat heterogeneity on avian assemblages in a foothill forest. We estimated the taxonomic and functional diversity of birds, considering species richness and abundance as species weightage. Our avian surveys, conducted from September 2021 to September 2023, recorded 2753 individuals representing 233 bird species, providing a comprehensive picture of avian diversity in the region. Taxonomic and functional diversity indices varied across the habitats. Shannon-Weiner diversity index and functional evenness were high in dense forest, while the forest edge showed high functional richness. Riparian habitat had the lowest Shannon-Weiner diversity but exhibited high functional divergence. Moreover, avian richness and abundance were significantly affected by habitat type. Indicator species analysis revealed that most habitats were associated with several invertebrate-feeding species. The foraging guild composition also significantly differed across the habitats. The presence of globally threatened and near-threatened species highlights the conservation significance of the study area. The results of our study underscore the critical role of habitat heterogeneity in the conservation of diverse bird species. In addition, our results highlight the importance of developing conservation strategies tailored to the specific needs of different bird functional groups to ensure the long-term survival of bird populations. • Eastern Himalayan foothills include dense forests, open forests, riverine areas, croplands, and scrublands. • Bird functional richness varied significantly across different habitats. • Species composition differed significantly across the heterogeneous landscape. • Habitat heterogeneity is crucial for conserving diverse bird species in the eastern Himalayan foothills.