The sensitive period for auditory-vocal learning in the zebra finch: Consequences of limited-model availability and multiple-tutor paradigms on song imitation

Male zebra finches, Taeniopygia guttata, acquire their song during a sensitive period for auditory-vocal learning by imitating conspecific birds. Laboratory studies have shown that the sensitive period for song acquisition covers a developmental phase lasting from 25 to 65 days post hatch (dph); formation of auditory memory primarily occurs between 25 and 35 dph. The duration of the sensitive period is, however, dependent upon model availability. If a tutor is not available early in development, birds will learn from an adult male introduced to their cage even after they reach 65 dph. Birds who are exposed to a second tutor as late as 63 dph can successfully adjust their song 'template' to learn a new song model. However, if second-tutor song exposure occurs after 65 dph, learning of a new tutor's song will not occur for most individuals. Here, we review the literature as well as novel studies from our own laboratory concerning sensitive periods for auditory memory formation in zebra finches; these behavioral studies indicate that there are developmental constraints on imitative learning in zebra finches.