Many male tropical birds perform elaborate courtship displays. These displays can include visual and acoustic signaling involving Acrobatic movements combined with vocal and non-vocal sound production. Little is known about hormonal and neuromuscular adaptations underlying complex courtship displays in tropical birds. Building upon work from the 1930s/40s by Frank Chapman and Percy Lowe, we have been investigating the physiology of courtship behavior in Golden-collared Manakins (Manacus vitellinus) of Panama. Male manakins display daily on arenas within forest leks for 6 or more months. Using high-speed video, we have analyzed several courtship behaviors including multiple complex dance moves and the production of snapping sounds produced by rapid lifting of their wings. Blood levels of testosterone (T) in males are generally elevated during this reproductive period, are basal for the remainder of the year, and are low in females year round. These data suggest that T activates male manakin courtship. Consistent with this hypothesis, T-treatment of non-reproductive birds-activates several courtship behaviors. T likely stimulates courtship by actions on androgen receptors (AR). AR are expressed widely in the manakin brain and spinal cord and treatments with the AR-blocker flutamide disturb normal courtship behavior. Although T activates courtship, there is little correspondence between an individuals' circulating T level and the frequency or intensity of courtship activity. Studies are underway to understand the factors that lead to these individual differences in T and display rate.