Many bird species utter a “whisper song” at the nest site, e.g., during nest relief. However, studies on the song and its function tend to be wholly descriptive, and very few quantitative analyses have been conducted. The male Grey Thrush Turdus cardis emits the whisper whistle song immediately before and after feeding his young. In this study, the male's behavior was examined in relation to the female's presence, for four nests. The male sang on 59.5% of the occasions immediately before arrival at the nest, and on 44.6% of the occasions immediately after departure. In most males, the frequency of singing before arrival did not relate to the presence of the female at the nest. However, on occasions when the male sang before arrival, the female tended to fly away before the male's arrival, suggesting that the song was used as a sign of nest relief. The male tended to sing immediately after departure more frequently when the female was absent from the nest than when she was present, although the singing did not affect the timing of the female's next arrival. According to observations made immediately before fledging, nestling activity was synchronized with the frequency of the male's singing behavior. Thrushes might be suitable subject species to study the role of songs within the family group.