Abstract
During their breeding season, male leopard seals (Hydrurga leptonyx) spend
hours perfecting their solo performance: singing unique sequences of
stereotyped calls underwater to create their ‘song’. These song bouts are
made up of discrete call types common across leopard seals within a
region, which begs the question – what determines the individually unique
patterns of these calls? Information entropy quantifies the amount of
randomness in a sequence, providing insight into the statistical patterns
governing a sequence. The songs produced by 26 different Eastern Antarctic
leopard seals have more predictable temporal structure than humpback whale
songs and dolphin whistle sequences. The estimated information entropy of
the leopard seal songs is comparable to nursery rhymes but unsurprisingly,
lower than contemporary, classical, and baroque music. The greater
structure of the leopard seal’s song improves the ability of distant
listeners to accurately receive signals and identify singers, which is
essential for this widely dispersed species. Future studies examining
animal mating song would benefit from incorporating entropy analysis to
question if information is conveyed through temporal structure alongside
other acoustic variables.