Resource partitioning is a critical mechanism underlying the coexistence of close relative species that feed on similar resources. Based on foraging data, we built a plant–seedeater interaction network for three sympatric species of Neotropical seedeaters – namely Tropeiro Seedeater Sporophila beltoni, Black-bellied Seedeater Sporophila melanogaster, and Tawny-bellied Seedeater Sporophila hypoxantha, and tested to what extent the three species shared resources. The interaction network was non-nested and modular, forming three modules, each one comprising one seedeater species and their most consumed plants, indicating the existence of resource partitioning. Modules may result from multiple non-exclusive factors, including differences among seedeater species in habitat use, bill sizes, feeding habits, structure of vegetation for nesting, and abiotic factors that influence plant composition. Our results indicate that the effective conservation of these species requires the protection of areas that include the three distinct subsets of plants used by these birds during the breeding season and also indicates which plants may be used for the restoration of grasslands in the region.