This dataset contains bird survey data (Appedenix 2) and bird trait data (Appedenix 1) in the paper: “He et al. (2022) Seasonal elevational patterns and the underlying mechanisms of avian diversity and community structure on the eastern slope of Mt. Gongga. Diversity and Distributions”. Main results of the paper are that TD, PD and FD showed similar hump-shaped elevational patterns in both seasons. In the breeding season, TD, PD and FD for small-ranged species, were highly correlated with climatic factors (mean daily temperature, seasonal temperature range) and vegetation factors (enhanced vegetation index), while large-ranged species were correlated with spatial factors (mid-domain effect). In the non-breeding season, TD, PD and FD for all species groupings were positively correlated with climate factors. For small-ranged species in both seasons, community structure was more overdispersed at low and high elevations, and more clustered at middle elevations. For large-ranged species, community structure differed between seasons, showing a general trend toward clustering as elevations increase in the breeding season and trends toward overdispersion and/or evenness as elevations increase in the non-breeding season.