In many bird species of temperate zones, singing of males is restricted to the breeding season. Singing plays a crucial role in male-male interactions during the establishment and maintenance of territories and in mate attraction. Seasonal patterns of song characteristics have been thoroughly studied, but little is known about how these patterns vary with mating status and phases of the breeding season. In this study, we investigated whether and how seasonal patterns of different song characteristics were related to mating status and to the breeding status of females in the Common nightingale, Luscinia megarhynchos. We examined several measures of song based, as part of a long-term field study, on 23 males of a Berlin population. In addition, we investigated whether a male’s behaviour in simulated vocal interactions would vary along with breeding season and would be influenced by its prospective mating status. Our results imply that mating status is a key factor affecting singing behaviour in vocal interactions and that singing patterns like song overlapping and matching are used flexibly during vocal interactions. Additionally, individual differences in response suggest that the motivational state and/or quality of a territorial male are important for decisions on how it responds vocally. Furthermore, we found that specific song characteristics like song versatility, transition versatility or song and pause duration do indeed change during the breeding season. Differences between paired and unpaired males shed further light on the dual function of song and might help to identify song characteristics that might be crucial in territory defence from those that mainly serve to attract females.