Mountains harbor a high diversity of habitats and bird species worldwide, with one-quarter of these ecosystems located in temperate latitudes. However, despite their high vulnerability to climate change, their distribution patterns and contribution to global biodiversity remain understudied. Over three breeding seasons (2017–2018, 2018–2019, and 2023–2024), we investigated bird diversity distribution across 10 volcanoes in southern Chile. We conducted 1,200 point counts to assess taxonomic diversity (species richness, Simpson index), functional diversity (functional richness, Rao index), and phylogenetic diversity (Faith index, Rao index). Mixed-effects linear regression models were used to evaluate the influence of elevation, habitat type, and structural heterogeneity on diversity patterns. Results indicate a strong positive correlation among the three diversity components, a decline in diversity with increasing elevation, and higher diversity in structurally heterogeneous habitats. This study underscores the importance of integrating multiple diversity components to understand mountain bird communities and inform conservation prioritization.