Mallard IL-17F (Interleukin-17F) is a pro-inflammatory cytokine belonging to the IL-17 family that contributes to host defense and inflammatory regulation in mallards (Anas platyrhynchos). IL-17F is produced primarily by Th17-like CD4⁺ T cells, γδ T cells, and other innate lymphoid populations in response to microbial infection and immune stimulation. It signals through IL-17 receptor complexes to induce expression of pro-inflammatory cytokines, chemokines such as CXCLi1 and CXCLi2 (avian functional homologs of IL-8), and antimicrobial peptides, thereby promoting heterophil recruitment and enhancing mucosal immunity in respiratory and gastrointestinal tissues. In healthy mallards, basal IL-17F expression is generally low but increases during bacterial, viral, and parasitic infections. Given that mallards serve as natural reservoir hosts for multiple influenza A virus strains, IL-17F is of particular interest in studies of avian influenza pathogenesis and immune tolerance. In avian and wildlife immunology research, mallard IL-17F provides insight into Th17-like immune responses, mucosal defense mechanisms, and host–pathogen interactions in wild and domestic waterfowl populations.