Fig. 5.

Amount of singing and use of multiple precursor song types during successive stages of song ontogeny in four socially tutored juveniles that precisely imitated the tutor song. (A) Each bar represents the amount of singing per day averaged over 10 days of recording (5 days a week). Black bars show the proportion of sounds not imitated from external models; the hashed bars represent the portion of time spent imitating the model heard the previous summer. Stable adult song was in place by the beginning of May. Singing surged during the plastic song stage in early spring, as repetition syntax and multisong repertoire emerged. The breeding season of chipping sparrows in our study area went from late April to early August. Male sparrows left for migration around mid-October and returned to the breeding ground during mid-April to early May. (B) In early spring, the multiple precursor songs (including the imitated song type) were sung for an approximately equal amount of time per day; the imitated song type was then sung predominantly as breeding season approached. Notice that the whistle song type was also produced more frequently in April, when it often preceded each imitated song rendition.