When male sea leopards plunge into antarctic icy waters, they “sing” structured melodies like nursery rhymes during performance that can last until 1 p.m., according to a study published Thursday in Scientific Reports.
A team of Australian researchers compared the complexity of the “song” of this seal species to that of other animals, as well as that of musicians like the Beatles or Mozart.
People are often surprised when they hear the “supernatural” hulles and sea leopards, entrusted AFP Lucinda Chambers, a doctoral student in bioacoustic at the University of South Wales and the main author of the study. “It looks like the sound effects of a SF film in the 80s,” she describes.
During the reproduction season in the spring, the male plunges and “sings” for two minutes before going up to the surface to breathe. He repeats this performance until 13 hours a day.
The researchers discovered that all sea leopards use the same five “notes”, impossible to distinguish from one individual to another. But each male suits these notes in a unique way to compose their own song.
“We think they use this structure to disseminate their identity, a bit as if they cried their names in the void,” explains Ms. Chambers.
Scientists think that males use these songs to attract females and spread the rivals.
AFP
“Rossignol de l’Océan”
The team studied the recordings of 26 sea leopards captured during the 1990s on the east coast of Antarctica by Tracey Rogers, co-author of the study.
“These are a bit like the nightingale of the southern ocean,” says Rogers, of the University of New South Gales. “During the breeding season, if you immerse a hydrophone in the water anywhere in the region, you will hear them sing.”
Analysis of the sequences of notes showed that they were less predictable than the song of the humpback whales or the whistling of the dolphins. But more than the more complex music of Beatles or Mozart.
“They are located in the human nursery area,” notes Ms. Chambers. What makes sense, because these songs must be simple enough for each leopard of the seas to remember their composition in order to repeat them every day, she explains.
A bit like “nursery rhymes that must be predictable enough for a child to be able to memorize them”.
At the same time, each song must be unique enough to distinguish itself from that of other males.
The leopards of the seas, super-predators of ancrust waters, are solitary animals which roam large expanses. Their particular song has probably evolved so that their message can also travel long distances, according to the researchers.
Varying the height or the frequency would not carry as well in such an environment, according to Ms. Chambers.
Sea leopard females also sing sometimes, although the reason is unknown. The scientist assumes that this could be a teaching song to the little ones, although this behavior has never been observed in nature. Another hypothesis is that it is a way to communicate with each other.