Leopard seals, named for their spotted coats, are vocal during breeding season, which lasts from late October to early January. Males sing underwater solos, with each night lasting up to 13 hours, while females sing for only a few hours when they’re in heat.
Research analyzed the songs of 26 male leopard seals and found they share similarities with human nursery rhymes. The predictable patterns in their calls are comparable to those in traditional children’s songs like “Twinkle, Twinkle, Little Star” and “Frère Jacques.”
Leopard seal males use song to carry their call across vast stretches of icy ocean, wooing a mate. Each night’s performance is a sequence of trills and hoots performed in a particular pattern. The sounds themselves don’t vary much in pitch or duration but the order and pattern differ between individuals.
Researchers measured the “entropy” of their sequences to better understand structure and patterns. They found that leopard seal songs have five key “notes” or call types, similar to human music styles. This predictability may enable the individual to learn its song and keep singing it over multiple days.
The study’s findings suggest that leopard seals use song to set themselves apart from others and signal their fitness to reproduce. The greater structure in their songs helps ensure listeners accurately receive the message and identify who is singing.
Source: https://www.sciencealert.com/leopard-seal-mating-songs-are-eerily-like-our-nursery-rhymes