Aim Changes in climatic conditions are predicted to impact species distribution and hence alter their diversity patterns. Modifications in the composition of biological communities are expected as a result of the loss and replacement of species due to global warming. Forest frugivorous birds already suffer from habitat loss and may disappear locally due to suitable area contraction or range shifts to novel areas, disrupting seed dispersal and consequently the functioning of natural ecosystems. Here, we investigate the impacts of different climate scenarios on alpha and beta diversities of forest frugivorous birds. Location Central Corridor of the Atlantic Forest (CCAF), Brazil. Methods We used ecological niche models to project species distribution of 68 frugivorous birds for the baseline and future (2050 and 2070) scenarios. We generated binary maps of suitable areas for each species by climate scenario to calculate alpha and beta diversities. Results Most forest frugivorous birds were projected to lose suitable area, as a consequence of climate change, reducing alpha diversity in future scenarios and increasing temporal beta diversity, which is dominated by the nestedness component. In addition, species richness decreased from the east to the west portion of the CCAF, while differentiation of bird communities increased in the same direction, a pattern consistent across all climate scenarios evaluated. Main conclusions Climate change may exert drastic alterations in the composition of frugivorous bird communities in the CCAF. As forest frugivorous birds are critical to seed dispersal of forest plant species, impoverishment of their communities can drastically affect forest regeneration, diversity, and structure in the decades to come. Therefore, a better comprehension of spatio-temporal changes in diversity patterns of frugivorous birds can help us to avoid the disruption of seed dispersal and its consequences, such as cascading effects that will trigger biodiversity loss in the CCAF.