Human provisioning can shape resource availability for wildlife, but consequences for microbiota availability and exchange remain relatively unexplored. Here, we characterized microbial communities on bills and fecal material of two hummingbird species and their food resources, including hummingbird feeders and floral nectar. We experimentally manipulated bird visitation to feeders and examined effects on feeder microbial communities and sucrose solutions. Birds, feeders, and flowers hosted distinct bacterial and fungal communities. Flowers and feeders hosted remarkably different bacterial communities; Proteobacteria comprised over 80% of flower bacteria but feeders contained high relative abundance of Proteobacteria, Firmicutes and Actinobacteria. Birds hosted both bacterial taxa commonly found in other bird taxa, novel genera including Zymobacter [Proteobacteria], and Ascomycete fungi. In feeders, bird-visited and unvisited solutions both accumulated abundant microbial populations that changed solution pH and bird visitation rates, but microbial composition was largely determined by visitation treatment. Our results reveal that feeders host abundant microbial populations, including some bird-associated microbial taxa. Microbial taxa in feeders were primarily non-pathogenic bacteria and fungi but differ substantially from those in floral nectar. These results demonstrate that human provisioning influences microbial intake by free-ranging hummingbirds; however, it is unknown how these changes impact hummingbird gastrointestinal flora or health.