483 



two songs sung by each of three whales 

 (I, II, and III). No sounds have been 

 omitted, changed in order, or shifted 

 in time (although we have cut our 

 traced record into pieces, we present 

 the pieces in their original sequence and 

 have omitted none of them). 



Before discussing song type A, we 

 must make one final point Some 

 phrases in humpback songs are further 

 complicated by being inexact replicas 

 within a theme. That is, the phrases 

 systematically change, or "evolve," 

 with each successive repetition during 

 a theme. The phrases in theme 1 of 

 song A are a good example of this. 

 The six themes of song type A are as 

 follows. 



Theme 1: Figure 6 shows that 

 each phrase in this theme consists of 

 three principal units — unit 1, a sound 

 like a motor running [a pulse train in 

 which the number of pulses (subunits) 

 per second changes during the train], 

 followed by units 2 and 3, a pair of 

 sustained or wavering tones. (Some- 

 times each sustained tone is followed 

 by a faint pulse, and sometimes the 

 phrase ends with a very low grunt.) 

 With each repetition of this phrase, 

 unit 1 becomes longer, and, toward 

 the end of the theme, each sustained 

 tone tends to occur at a higher fre- 

 quency than the previous one. (In 

 song type B, the pulse trains are given 

 without sustained tones between them 

 or with just a brief tone tacked on to 

 the end of the train of pulses — see 

 whale IV.) Thus, in song type A, 



theme 1 consists of a series of se- 

 quentially modified phrases changing 

 in a predictable fashion. 



Theme 2: We arbitrarily designate 

 the onset of theme 2 as the moment 

 when sustained tones give way to short- 

 er tones, or rapidly ascending fre- 

 quency sweeps. Theme 2 is one of the 

 most variable in our sample. It may 

 consist of a great variety of sounds, 

 but all, or most, of them are ascending 

 frequency sweeps or brief (less than 1 

 second) high-frequency squeaks or 

 chirps. The theme has no obvious sub- 

 sets that repeat predictably. Theme 2 

 is quicker in tempo and less rhythmic 

 than the rest of the song, which is com- 

 posed of more measured, drawn-out 

 phrases. 



Theme 3: The phrases in theme 3 

 have as their first unit a loud, ascend- 

 ing frequency sweep, which is emitted 

 from one to three times and is fol- 

 lowed by several fainter, high-fre- 

 quency harmonic arpeggios. In some 

 cases, the arpeggios become more elab- 

 orate with each repetition of this 

 phrase, until, by the end of the theme, 

 the component notes become more sus- 

 tained. (See Fig. 10 for an expanded, 

 scale view of arpeggios from the songs 

 of whale U and whale TV.) The loud, 

 ascending frequency sweep, marking 

 the beginning of each phrase 3, usually 

 occurs twice (only once in case of 

 whale III) at the outset, but in the 

 course of the theme changes to three 

 repetitions and stays at three. When 

 there is a transition from two to three. 



it is as irreversible as the basic se- 

 quence of phrases in a song. 



Theme 4: Theme 4 is one phrase 

 long. It starts with a loud, ascending 

 sweep that is similar to unit 1 in theme 

 3. Each successive unit in this theme 

 rises and falls in frequency, but returns 

 each time to a lower frequency than 

 the preceding unit. (This gives the im- 

 pression of a deepening series of roars 

 or bellows.) The last units of theme 4 

 are low-frequency grunts (which may 

 be descending pulse trains). 



Theme 5: The phrases of this theme 

 typically have six units. Unit 1 is a 

 downward sweeping note; unit 2, a 

 loud, low, rising or slightly warbling 

 note (followed sometimes by one or 

 more brief, descending, pulsive notes 

 that are hard to detect in poor record- 

 ings). Units 3 and 4 are very like 

 units 1 and 2. Units 5 and 6 are 

 grunts. Since there are usually two 

 such grunts, each phrase in theme 5 

 usually consists of six units. However, 

 there may be three (rarely more) 

 grunts, and sometimes one or even 

 none. This whole phrase is usually re- 

 peated once; thus, theme 5 is usually 

 two phrases long. 



Theme 6: The components of this 

 theme are unit 1, a loud, sustained 

 tone; unit 2, a descending note (some- 

 times in the form of a slowly falling 

 warble); unit 3, another sustained tone 

 similar to unit 1; unit 4, a descending 

 note similar to unit 2 (sometimes there 

 are faint pulsive notes after units 2 

 or 4, or both); and a series of one to 



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/ / 



/ / / LJ^ 



WHALE I 



ly 



2 b J .J^J 



f / / > ' / r 



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WHALE 1 1 



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WHALE II I 



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Fig. 8. (Left) Theme 3. Note the evolution of the phrases comprising this theme from two loud sweeps rising in frequency, fol- 

 lowed by short, high, harmonic arpeggios, to three loud sweeps rising in frequency, followed by more sustained, rising notes; 

 (right) theme 4 (only one phrase long) is the shortest theme in song type A. 



