Song learning and vocal tradition in Nuttall's white-crowned sparrows

We investigated song sharing and dispersion of song types in the wild in a colour-marked population of the non-migratory Nuttall's white-crowned sparrow, Zonotrichia leucophrys nuttalli. The songs of fathers, their male progeny (sons), and the neighbours of the sons at recruitment sites were analysed spectrographically and compared qualitatively and quantitatively. To determine whether a son's song more closely matched that of his father or a neighbour at the site settled, we subjected frequency and temporal characteristics of songs within each father-son-neighbour triad to multivariate cluster analysis. The songs of 14 of 16 sons clustered with their neighbours' rather than their fathers' songs, confirming that song matching of neighbours is an integral component of territory settlement by juveniles. Principal components analysis of frequency and temporal measurements of song within a dialectal area show that songs group into neighbourhoods and are non-randomly distributed. Multivariate analysis suggests that sons may entrain on frequency and temporal characteristics of a neighbour's song without matching phrases or complex syllables. Implications for models of instructive versus selective learning are discussed. The timing of closure of the sensitive phase, the length of the silent interval between the sensory phase and plastic song stage, and the time to song crystallization remain open questions in song ontogeny. (C) 1998 The Association for the Study of Animal Behaviour.