Long-term effect of isolation rearing conditions on songs of an 'open-ended' song learner species, the canary

Among songbird species, the canary, Serinus canaria, is considered to be an ‘open-ended’ song learner because adults continue to change their syllable repertoire throughout their lives. However, it remains unclear whether the capacity to alter the syllable repertoire allows birds to acquire new song material to correct abnormal song characteristics that result from auditory isolation during development. To address this question, we reared males without any experience of typical adult conspecific song models from fledging to sexual maturity. They were then placed for at least 2 years in an aviary that included adult conspecific males. Discriminant function analyses on songs indicated that features describing the fine structure of syllables showed significant differences between isolation-reared and control birds. Analysis of syllable repertoires attributed differences to a higher proportion of multiple-element syllables in songs of isolation-reared males than in songs of control males. Isolation-reared birds were able to modify their syllable repertoire throughout their lives. However, the proportion of multiple-element syllables, instead of decreasing during the years spent in the aviary, continued to form a large part of the songs. The ability of isolation-reared canaries to change their repertoires failed to rectify, at least in large part, the syllable abnormalities caused by the lack of a song model during their first year of life. Therefore, new and previously acquired syllables might result from similar underlying processes that would set limits to the kinds of syllables produced in adulthood.