Abstract ID: 3.13200 | Accepted as Talk | Talk/Oral | TBA | TBA

Mountain ecosystems comprise 24% of the land-base of world and represent distinct environmental gradients that can shape biological communities. Global warming is a major biodiversity threat, which is amplified in mountain ecosystems. Mountain birds can survive, or not, by degrees. Assessing the risk and resilience of these communities is crucial under rapid change scenarios. In 2017, we initiated a temperate montane bird study aiming to: i) determine both taxonomic and functional distribution across three habitats increasing in elevation: upper montane (UM, >50% tree cover), subalpine (SA, 5-50% tree cover), and alpine (AL, <5% tree cover), ii) quantify mountain bird vulnerability to climate change (based on climate exposure, sensitivity and adaptive capacity), and iii) assess the breeding strategies of high Andean birds. We conducted 1,500 diurnal bird point counts in 10 South temperate mountains (Chile; 39°S latitude), between 1,000 and 2,200 m elevation. We found 74 bird species (in 25 families and 12 orders) inhabiting Andean temperate mountains. Species composition among mountains was highly variable (Jaccard index < 0.5), indicating potential variation in drivers such as habitat structure. Overall, we found a gradient in bird communities from predominantly habitat generalists below treeline to mainly habitat specialist in the alpine (habitat specialist: UM=3%, SA=11%, AL=87%). Functional redundancy (i.e. co-occurrence of species with similar functional roles) increased until treeline and then decreased, suggesting a lower functional resilience of the alpine bird community under the loss of a given species. Climate change effects on birds increased with elevation, with top-mountain species showing the highest vulnerability. We found an alpine breeding community using exclusively rock cavities (90 nests), strategy that might protect them from extreme temperatures in those habitats. Elucidating both risks and resilience of bird communities in southern temperate mountain ecosystems, is critical for understanding the potential conservation value of mountains under an environmental change scenario.