Roles of syntax information in directing song development in white-crowned sparrows (Zonotrichia leucophrys)

Syntactical cues play an important role in song learning in songbirds. White-crowned sparrows (Zonotrichia leucophrys), whose song typically consists of four to five different phrases, fail to construct normal songs if exposed to all phrase types presented singly (Plamondon, Goller, & Rose, 2008; Soha & Marler 2001b). The specific role of acquired syntax information in guiding ontogenetic trajectories of syntax, however, and the respective contributions of instructive and selective processes to syntax ontogeny remain unknown. We tutored white-crowned sparrows with syntax information ranging from acoustic isolation to full song. Manipulation of tutor syntax influenced developmental trajectories of syntax assembly, suggesting that instructive processes contribute to syntax ontogeny. Early in development, birds tutored with full song or phrase pairs preferentially produced phrase pairings matching tutor syntax. Birds tutored with single phrases showed decreased diversity of pairwise syntactical combinations immediately after tutoring compared with other tutor groups, further illustrating the role of instructive processes. Overproduction of song material was also observed, suggesting that selective forces play a role in syntax development as well. Finally, consistent with the notion that innate influences guide syntax ontogeny, birds from all groups exhibited many similarities in trajectories of syntax assembly.