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Understanding bird diversity in seasonally dry tropical forests: The role of landscape anthropization and chronic disturbance

Abstract:

Understanding how species respond to human-induced habitat modification is essential for effective conservation and management. Among these modifications, forest chronic disturbance and landscape anthropization are key drivers threatening biodiversity. While these alterations are often associated with biodiversity loss, their effects are not always direct; rather, they frequently operate through indirect pathways, such as changes in vegetation structure. We used the bird community of seasonally dry tropical forest (SDTF) as a model system to evaluate both direct and indirect effects of these habitat modifications on biodiversity. SDTF provide an ideal context for this research, as they are simultaneously impacted by chronic degradation and landscape anthropization. Bird surveys were conducted across 51 point-counts, each visited nine times between February 2018 and March 2019, in Zapotillo, southwestern Ecuador. A total of 11,012 birds from 110 species, 39 families, and 18 orders were recorded. Our results reveal that landscape anthropization was the primary driver, influencing species richness and evenness, while chronic disturbance enhanced taxonomic distinctness. At the feeding guild level, chronic disturbance influenced the guilds in contrasting ways, both directly and indirectly, through changes in vegetation, such as reductions in canopy height and structural complexity. Our results underscore the importance of conserving well-preserved forest patches within heterogeneous mosaic of anthropized landscapes to support greater bird diversity and abundance while maintaining essential ecosystem services of different functional bird feeding guilds. This study underscores the need for tailored management strategies in SDTFs to address increasing anthropogenic pressures and ensure the long-term resilience of these unique ecosystems.