Canaries differentially modulate solo and overlapping singing during the transition to the breeding season

Songbirds sing different song types depending on the social context. Songs can be categorized into two types based on their timing relative to other birds songs: solo and temporally-over-lapping songs. Overlapping songs have been typically characterized in the breeding season, in which they are associated with an aggressive social context. However, whether both song types occur year long, and whether they show differential modulation of their frequency and properties during the transition between the non-breeding and the breeding season has been rarely studied. Here we investigate, in a group of domesticated canaries (Serinus canaria), the variation of singing in both song types at the transition between the nonbreeding and the breeding season. We found that both song types were present outside the breeding season. Whereas for solo songs, duration and its variability, fraction of time singing and number of songs increased as the breeding season approached, overlapping songs showed opposite trends. Furthermore, both song types were distributed more homogeneously as the daylength increased. Overall, the differential changes of both song types at the seasonal time scale suggest differential underlying mechanisms and functions of these two song types found in a social setting.