Assessing the Importance of Social Factors in Bird Song Learning: A Test Using Computer-Simulated Tutors

Passerine song learning has become a major model system for the study of vocal learning, and many parallels with human language learning have been noted (Marler 1970; Brainard & Doupe 2002). One parallel that has been appreciated only recently is the key role of social factors in vocal development (Catchpole & Slater 1995; West et al. 1996; Snowdon & Hausberger 1997; Goldstein et al. 2003; Beecher & Burt 2004). The importance of social factors in bird song learning first became apparent with the discovery that birds learn more readily from singing adult birds (live tutors) than from tape-recorded song (tape tutors) (Baptista & Petrinovich 1984). The greater potency of live tutors compared with tape tutors suggests a key role for social factors in song learning, but to date much work remains to be carried out in analyzing these presumptive social factors (Nelson 1997). The major effort to integrate social variables into song learning is a model of song learning proposed by Nelson & Marler (1994). They focus on the selective nature of song learning, on the fact that the young bird hears and memorizes many more songs during his song-learning period than he will keep for his final song repertoire. This selective process appears to operate in many species regardless of whether the species-typical repertoire size is 1, 10 or 100 song types (Marler & Peters 1982). Therefore, the bird must ‘decide’ which particular songs he will retain for his final repertoire. Nelson and Marler propose that song learning has two phases. In the first phase, occurring during the bird’s natal summer, song learning is primarily a process of listening to and memorizing the songs of adult birds. In the second phase, occurring during the next spring when the young bird attempts to establish his territory, the bird ‘selects’ the songs he will retain for his final repertoire. Nelson and Marler describe this later Correspondence John Burt, University of Washington, Box 351525, Seattle, WA 98195, USA. E-mail: [email protected]