We use field and laboratory studies to identify the mechanisms and functions of colorful ornaments in birds. These colors often serve as indicators of an individuals worth as a mate or their ability to compete for access to mates. We are interested in how color signals reliably communicate this information. Bright coloration often reveals the nutritional condition, health state, or aggressive ability of birds, and we employ a variety of biochemical, nutritional, physiological, immunological, and behavioral methods to determine the factors that control color intensity. Techniques such as high-performance liquid chromatography (HPLC), for example, allow us to track the types and amounts of pigments that birds accumulate and the physiological causes and consequences of variability in pigmentation. Brilliant colors are by no means restricted to birds, and we are anxious to expand our focal studies on birds to other vertebrates and invertebrates to determine if, how, and why other animal colors play valuable roles as visual signals of quality.