Ecological and Morphological Traits Determine Community‐Wide Responses of Birds to Climate Change in a Tropical Dry Forest

Aim We evaluate the potential consequences of climate change on the Caatinga Dry Forest, asking how the future climate would affect its avifauna under three different carbon emission scenarios. First, we evaluate potential climate‐induced distributional changes. We evaluate how these potential changes (predicted area loss or gain) are distributed across the avian tree of life and among feeding guilds to understand whether particular trophic guilds or lineages will be differentially affected. We then investigate if predicted changes in species distributions are correlated to key morphological traits and current geographic range. Finally, we describe current patterns of species richness in the Caatinga and assess how these patterns may change throughout the century. Location Caatinga Dry Forests, northeastern Brazil. Time Period 2024–2100. Major Taxa Studied Birds. Methods We built ecological niche models for the entire Caatinga resident avifauna (445 species) and examined the effects of climate change on avian communities. We used morphological traits to understand whether they are related to species responses to climate, including: (i) body mass (weight), (ii) three beak measurements (length, height and width); (iii) kipp index (calculated using the difference between the longest primary and longest secondary feathers); (iv) tarsus length and (v) tail length. Results Our models predict that by 2060, ~75% of the species analysed may have their spatial distribution reduced in the Caatinga, and up to 5% may be extirpated altogether, including five global extinctions. We found no phylogenetic signal; the potential impacts of climate change will be widespread throughout the avian tree of life and across most trophic guilds. Larger reductions in climatically suitable areas are significantly associated with smaller geographic ranges and lower dispersal ability (smaller tarsi and lower kipp index). Main Conclusions Our models predict severe changes in the structure of the Caatinga avian community due to climate change, which could lead to the collapse of this ecosystem. All tested scenarios coincide with the negative impacts of the novel climate, but an immediate and drastic reduction in carbon emissions (optimistic scenario) could reduce these impacts.