INTRODUCTION

In the mid-1960s Klaus Immelmann began a series of experiments with domesticated zebra finches (Taeniopygia guttata) that led to seminal contributions to two related fields, song learning and sexual imprinting. Immelmann (1969) manipulated the auditory and social experiences of young males in their first 100 days of life and found that those denied any contact with singing males failed to sing the normal zebra finch song at adulthood. He concluded that song in this species, like that of most songbirds, must be learned. When he isolated young from foster parents (Bengalese finches (Lonchura striata var. domesticaj) at different ages he found that the sensitive phase for song acquisition began as early as 25 days of age, about a week after fledging, and ended around 80 days of age, around the onset of sexual maturity. Furthermore, young males did not learn from just any singing adult, but preferred to copy from the male with whom they formed a personal bond. In most instances this was the father or foster father and the bond was based primarily on the provisioning relationship, the most basic filial bond. Immelmann (1969) hypothesized that wild zebra finches would be likely to learn the songs of their fathers, and an early end to the sensitive phase was necessary in order to prevent learning from heterospecific estrildines.

The experimental possibilities raised by Immelmann's intriguing study of song eventually stimulated a steady series of follow-up experiments by other researchers, in particular, by P. J. B. Slater and coworkers, who used song learning in domesticated zebra finches as a model for teasing apart the subtle interactions involved in the development of behaviour (for a review, see Slater et al. 1988).