Songbirds acquire songs by imitation, as humans do speech. Although imitation should drive convergence within a group and divergence through drift between groups, zebra finch songs sustain high diversity within a colony, but mild variation across colonies. We investigated this phenomenon by analyzing vocal learning statistics in 160 tutor-pupil pairs from a large breeding colony. Song imitation is persistently accurate in some families, but poor in others. This is not attributed to genetic differences, as fostered pupils copied their tutors’ songs as accurately or poorly as biological pupils. Rather, pupils of tutors with low song diversity make more improvisations compared to pupils of tutors with high song diversity. We suggest that a frequency dependent balanced imitation prevents extinction of rare song elements and overabundance of common ones, promoting repertoire diversity within groups, while constraining drift across groups, which together prevents the collapse of vocal culture into either complete uniformity or chaos.

鸣鸟就像人类一样，是通过模仿来获取歌曲的。尽管模仿应促使群体内的趋同并通过群体间的漂移而发散，但斑马雀科的歌曲在群体内仍保持着高度的多样性，但群体间的差异却很小。我们通过分析来自大型繁殖群体的160对学生的语音学习统计数据来调查这种现象。在某些家庭中，模仿歌曲的方法一直很准确，但在另一些家庭中，模仿效果很差。这并非归因于遗传差异，因为寄养的学生复制的导师的歌曲与生物学的学生一样准确或差强人意。相反，与歌曲多样性高的导师的学生相比，歌曲多样性低的导师的学生即兴创作。我们建议频率依赖的平衡模仿 防止稀有歌曲元素的消失和常见歌曲元素的过多，促进组内曲目的多样性，同时限制组间漂流，共同防止声音文化崩溃为完全统一或混乱的情况。