Résumé
Global trends in ice mass loss imply important changes on biodiversity. Glacier regression is expected to be more pronounced in narrow-sized glaciers with relatively small accumulation zones, particularly in tropical mountains. The effects of these changes further affect glacier-related ecosystems that strongly depend on glacier runoffs and count for important aquatic and terrestrial biodiversity. Wetlands in the dry landscapes of high-altitude Andes support a unique avifauna, providing resources for adapted species and stopover during migration, particularly during the dry season. There is increasing evidence of changes in glaciers affecting bird communities through direct and indirect effects on area, heterogeneity and quality of habitats, but few studies concern tropical mountains.We aimed to study the relationships between bird diversity and glacier-influenced environmental conditions under the context of glacier retreat in Andean high-altitude wetlands. We surveyed bird communities and environmental characteristics of 40 wetlands of the Cordillera Real of Bolivia along a gradient of glacier influence. We studied taxonomic, phylogenetic and functional diversity in relation to wetland area and further explored environmental factors influencing bird diversity, as elevation, glacier cover, heterogeneity and productivity and we assessed bird assemblages associated with wetter or drier habitats within wetlands.Birds’ diversity was strongly influenced by wetland's area, productivity and elevation, while maximized at intermediate levels of glacier influence. Within wetlands, productivity and humidity determined bird community composition along a gradient of glacier influence, potentially reflecting ongoing changes on wetland habitats under glacier retreat trends. Wetland-related ponds and cushions may be affected by precipitation and glacier runoff trends, changing in turn substantial portions of aquatic habitats. Thus, glacier retreat in these high-altitude ecosystems might affect particularly birds associated to wetter habitats and threaten uncommon species depending on aquatic resources.Owing to global change processes, glacier retreat and extinction is expected to have important consequences on biodiversity and human livelihoods, especially in highly water-dependent systems. High-altitude wetlands of tropical Andes provide an unique opportunity to broadly monitor effects of glacier decrease on biodiversity.