Impact of global change on the distribution of mountain mammals and birds.

Climate change and land-use changes are key drivers of global biodiversity loss. Many species are shifting to higher elevations or latitudes in response to global warming, often encountering unfavorable land-use conditions during the shift. These changes can lead to reduced range size and increased extinction risks, particularly for mountain species that are often confined to narrow high-altitude habitats. Predicting future distributions of mountain species requires accounting for their bioclimatic responses, topographical distribution, land-use preferences, and ability to colonize new areas via dispersal. We projected the future distribution of 34 mountain mammal and 361 nonmigratory mountain bird species in 2050 under different emission scenarios. Using species distribution models (SDMs) that incorporated topography, climate, and land-use data, we assessed the impacts of global change on species' ranges across mountain regions worldwide and compared different emission scenarios to clarify the contributions of climate, land-use change, and dispersal to shaping future distributions. Species were projected to experience greater range loss under the high-emissions scenario than under the low-emissions scenario (16% higher on average). Dispersal played a key role in range shifts: when dispersal was included in the model, the number of birds that shifted their range increased by 144%. The most severe range losses were projected for species located in Central and South America and Oceania, whereas European mountains showed fewer losses, highlighting substantial regional differences in vulnerability. When land use was also considered, range dynamics remained stable, showing climate as the primary driver of mountain species distribution change. Our findings emphasize the importance of considering dispersal capacity when assessing climatic biodiversity risks in mountains. Our results highlight the urgency of applying regional strategies to establish ecological corridors, improve connectivity, and manage habitats to conserve the unique biodiversity of mountains.