Social environments can shape animal communication. Mutual courtship displays performed by a male and a female are often described and investigated on the assumption that they are private communications between those two individuals. However, socially monogamous birds that engage in such courtship displays often interact with other individuals as they usually communicate within the flock. Short-tailed albatrosses are socially monogamous seabirds and exhibit multimodal mutual courtship displays in the breeding colony. The courtship displays comprise several behavioral components, including body movements, vocalizations, and non-vocal sounds (e.g., bill clattering). These behaviors are exchanged and coordinated within the pairs. The conspicuous displays are frequently observed during their breeding season, but the functions remain unclear. In this study, I conducted behavioral observations of the courtship displays in short-tailed albatrosses on Torishima island. The results showed that third-party individuals often visited pairs engaged in courtship displays. Third-party individuals were observed watching the pair's display nearby or attempting to participate in the display, and they rarely showed aggressive behavior. The courting pairs also rarely engaged in aggressive behavior toward third-party individuals. The observation suggests mutual courtship displays work in a broader social context than just intra-pair interactions, as previously thought. I will introduce actual video examples and discuss possible functions of the courtship displays and the interactions with third-party individuals.