Fig. 4.

Graph of song stereotypy as a function of age in intact adults. Stereotypy here was measured using the song analysis algorithm developed by Tchernichovski et al. (2000) (see Materials and Methods). Each bird was scored on the variability it showed in repeating 15–25 renditions of its song motif. Had all repetitions been identical, the similarity score would have been 98–99%. For each bird, each rendering of that bird's motif was compared against each of the other renderings using the “compare two songs” feature in the song analysis software; as a result, each data point shown in this graph represents the mean of 91–300 comparisons of a total of 21 birds recorded at the ages shown. Error bars indicate SEMs.