The hierarchical organization of the male humpback whale song has been well documented. However, it is unknown how singers keep these intricate songs intact over multiple repetitions or how they learn variations that occur sequentially during each mating season. Rather than focus on the sequence of sounds within a song, results presented here demonstrate that the individual sounds are organized into rhythmic groups that make the production and perception of the lengthy songs tractable by yielding a set of simple groups that, although arranged in rigid order, can be repeated multiple times to generate the entire song.