The social factor in song learning in american sparrows  (Page 4/9)

Juveniles have many different choices of tutors. Usually, juveniles choose many adults to be their tutors, each with varying importance. In song sparrows, for instance, the number of tutors for each juvenile can vary from two to five (Beecher et al. 1994; Nordby et al. 1999; Nordby et al. 2000). According to Wheelwright et al. (2008), male savannah sparrows choose social fathers to be their most important tutor 12% of the time, natal neighbors (neighbors when the learner hatched) 35% of the time, 1-year-old breeding-year neighbors (neighbors when the learner first begins to breed) 26% of the time, and older-breeding neighbors (neighbors long after the learner began to breed) 26% of the time. In this case, the most important tutor is defined as the tutor that shares the most number of songs with the subject. Such variations in importance of tutor, especially among the different types of neighbors, suggest that learning allows songbirds to adapt to their social environment.

There are many reasons why a juvenile bird may choose a particular tutor to be his primary tutor over another. One may be the repertoire size of the tutor. Soma et al. (2009) has found that juvenile Bengalese finches ( Lonchura striata domestica ) learn from both their father and a subtutor when the two models have small repertoire sizes; but when the father has a smaller repertoire size, they tend to learn from the subtutor; in either case, the presence of a subtutor led to a larger repertoire. This is in accordance with the repertoire hypothesis of song learning. In Wheelwright et al. (2008)’s study, the juveniles tend to pick neighbors as the most important tutor. This result is in accordance with the sharing hypothesis of song learning, and is explained further in the following subsections.

Learning from fathers

Although fathers are a logical choice as tutors for juvenile songbirds, since chicks are exposed to the songs of their fathers from birth; however, fathers are often not important tutors at all. Baptista (1985, described in Petrinovich&Baptista 1987) found that songbirds usually do not sing the songs of their fathers. Instead, as described above, neighbors are much more important tutors. This suggests that juvenile birds choose tutors not simply to learn how to sing, but to learn how to communicate with an individual. Juvenile songbirds leave their natal nests just a few weeks after hatching, so they never need to communicate with their fathers as adults. On the other hand, communicating with neighbors is important to territory possession (described below) and breeding (recall earlier discussion on sedentary versus migratory white-crowned sparrows).

Learning from neighbors

Neighbors are one of the most important tutors to sparrows and can be much more important than fathers. [link] shows that song sharing increases the closer two neighbors are to each other, suggesting that song learning from neighbors is important for social interactions with those neighbors. Social interaction, in turn, is important to learning from neighbors. DeWolfe et al. (1989) show that juvenile white-crowned sparrows that socially interact with adult territorial neighbors develop songs faster than those that do not.