Exposure of the species of the genus Hemitriccus (Aves, Rhynchocyclidae) to future climate change

Human-induced climate change (CC) may cause global mean temperature to rise from 1.5-4.5°C before 21st century ends. CC will have far-reaching impacts on biodiversity, including changes in species distributions and extinction rates. Ecologic Niche Models provide a useful tool for assessing exposure to CC, particularly in tropical regions that will be highly affected by CC and harbour most of the endemic and threatened species. Here, we applied ENM to assess the exposure of Hemitriccus species to future CC and implications for their conservation status. Endemic from South America, this genus presents 22 species in different biomes. We used eight algorithms in an ensemble forecasting approach to model current and future suitability. Occurrence data (from scientific collections, literature and online databases) were associated to current climatic variables and scenarios for 2050 (RCP 8.5: CCSM4, HadGEM, MIROC). Predictors were selected based on Variance Inflation Factor. Consensus models indicated loss of suitable area in 2050 for most species (16 from 21). Estimated losses indicated worsening in conservation status for 10 species. Contraction was predicted for Andean, Western Amazon and Atlantic Forest species (except H. kaempferi), while gains were predicted for Eastern Amazon species and generalists. Species can develop four responses to CC: dispersion, acclimation, adaptation and extirpation. For Hemitriccus, small non-migratory birds with low dispersal ability, dispersion is restricted to neighboring areas. Acclimation may be a response in areas with mild climatic variations, whilst there is no time for genetic adaptation. Therefore, in no longer suitable areas, the most likely response would be extirpation.