Mallard (Anas platyrhynchos) Interleukin-8 (IL-8), also referred to as CXCLi2 in avian species, is a key pro-inflammatory chemokine that regulates heterophil chemotaxis and activation in response to infection and tissue injury. Functionally analogous to mammalian IL-8, mallard IL-8 is produced by macrophages, epithelial cells, and other immune cells following stimulation by viral, bacterial, or parasitic pathogens and signals through CXCR1- and CXCR2-like receptors to promote recruitment of heterophils—the avian equivalent of neutrophils—to affected tissues. As natural reservoir hosts for avian influenza viruses (AIV), mallards are particularly important for studying IL-8–mediated inflammatory responses, as they often mount effective antiviral defenses while exhibiting limited clinical disease. IL-8 expression is also induced during infections with Salmonella, Campylobacter, and other waterborne pathogens, contributing to mucosal immune responses in respiratory and gastrointestinal tissues. In animal model research, mallards serve as critical models for avian influenza ecology, viral transmission dynamics, and host tolerance mechanisms, and characterization of IL-8 in this species enhances understanding of chemokine-driven innate immunity, heterophil trafficking, and inflammatory regulation relevant to both wildlife disease surveillance and comparative immunology.