The Influence of Different Tutor Types on Song Learning in a Natural Bird Population

Male Savannah sparrows, Passerculus sandwichensis, sing a single, individually distinctive song their entire life, which they presumably learn from other males in the same population. We took advantage of a strongly philopatric, known-age and known-parentage island population to examine the influence of five tutor types on song learning: a bird\u27s social father, genetic father, natal neighbours, older breeding-year neighbours and 1-year-old breeding-year neighbours. Of 57 males banded as nestlings, there was wide variation in the tutor type with the greatest influence on song learning. Based on pairwise visual comparisons of spectrograms of all co-occurring males plus quantitative measures of similarity of digitized songs, only 12% of males sang songs that were most strongly influenced by their social father, as inferred by overall similarity of entire songs. About 45% of males were the product of extrapair paternity, but no male sang a song that was most similar to his genetic (versus social) father. Thirty-five per cent of males produced songs that were most similar to those of natal neighbours, 26% sang songs most like older breeding-year neighbours and 26% sang songs most like 1-year-old breeding-year neighbours. Neither a male\u27s body condition at fledging nor his fledging date was related to tutor type, and tutors did not differ from nontutors in morphology, longevity or reproductive success. Savannah sparrows apparently draw upon a wide set of models heard in both their hatching and their breeding years, incorporating specific song elements into their own song rather than copying in its entirety any particular tutor\u27s song