The Ganges floodplain of Bangladesh is one of the prominent bio-ecological zones that is enriched with wildlife resources. The natural wetlands and modified habitat in this area sustain a diverse range of avifauna. To uncover the present status, seasonality, habitat usages, existing threats, and conservation issues of avifauna, an eight year-long (2016–2023) scientific study was conducted in the Ganges floodplain of Bangladesh by direct field observation along with reviewing the published literatures of the research team of the area. A total of 260 avian species were observed under 20 orders and 62 families. Non-passerine bird species (167 species, 64.23%) specially wetland specialist birds were dominant in this area. From the study area, 98 (37.69%) migratory bird species were observed. In the avian communities among three study sites, wetland specialist bird species and individuals under the order Charadriformes, Anseriformes, Accipitriformes and Pelecaniformes was higher in the wetlands and associated habitat, whereas in terrestrial habitat Passeriformes was higher. A significant difference was found among the species richness in five types of major habitats. The highest number of bird species richness and abundance was observed during the winter season with the highest number of season-specific unique species. The wetland habitats are more important for holding the highest number of threatened bird species and important bird species. The 19 nationally threatened species along with 11 newly recorded bird species reflect the conservation necessity of this area. The observation status of avifauna from the study area shows that 116 species (44.61%) were very common, 15 (5.76%) common, 88 (33.84%) uncommon and 41 (15.76%) were few. At present, illegal bird hunting, trade of wild birds, water pollution, agricultural nets, tourism, and existing fishing practices are major threats to birds. This study will help take future conservation initiatives for the conservation of birds in the study area.