The Origins of Music: Preface - Preface

145 The Changing Songs of Humpback Whales

Figure 9.6

Percentage of r and j units per song session versus time.The time periods (labeled 2–6 and

1–5 in the two seasons 1976–1977 and 1977–1978) are both thirty-one days.Periods having

the same number start and stop on the same dates of their calendar years.Notice that r

units replace j units.Standard error is indicated by vertical lines.Dashed lines indicate

means when aberrant songs are included in the calculations.(From Payne,Tyack,and Payne

1983.)

Fig.9.6

Figure 9.7

Alternate forms of the first subphrase of theme seven,labeled A–D.They were all common

at some point in the 1976–1977 season.Two rare alternate forms were intermediate

between forms 7B and 7C.Tracings of spectrograms to the right of alternate phrases 7A–D

are examples of each type.(From Payne,Tyack,and Payne 1983.)

Fig.9.7