By fixing the sensors on penguins of different species, biologists have found that they emit sounds during spearfishing, at a depth of tens and even hundreds of meters.
Gathering on land, flocks of penguins are very numerous and noisy: birds actively communicate with each other, recognizing their partners and offspring by voice. However, sooner or later they go to sea for fish and other prey, diving to depths of up to several tens and even hundreds of meters. How they communicate underwater, tells an article by scientists from the South African Nelson Mandela University, published in the journal PeerJ.
Thierry Aubin and his colleagues at the Marine Predator Research Division (MAPRU) used miniature video cameras with microphones attached to the backs of three species of penguins - royal, gentoo and macaroni. The work provided the first evidence that penguins make sounds while hunting underwater. Briefly about it is reported by the press service of the Nelson Mandela University.
The species were chosen to represent all three common penguin feeding strategies, the scientists said. The royal ones specialize in catching fish from great depths, the golden-haired ones catch shrimp near the surface, and the Papuan ones are versatile and look for any prey, at all depths. Birds were caught from colonies on the subantarctic Prince Edward Islands, on the way to the sea, and on the way back they were filmed by cameras.
For almost five hours of observation, scientists recorded a total of 203 "sessions" of vocalizations in all three species, although the golden-haired ones - only one, and as many as 168 - in the Papuan. The authors note that the majority of vocalizations (73 percent) occur in the very bottom phase of the dive, when the penguins are directly hunting, rather than during the diving and emerging phases. More than half of the vocalizations occurred during the pursuit of prey.
First evidence of underwater vocalisations in King Penguins
Previously, experts only knew that some penguins use acoustic communications, swimming on the surface of the water and coordinating with each other. However, if such communications continue under water, and in three different species, then, most likely, they are characteristic of all other penguins - and, judging by the obtained sample, they occur more often in those who prefer to fish.
“These observations raise new questions,” summarize the authors of the work in an article for The Conversation. - For example, how do penguins make sounds underwater, at a depth of high pressure? Why are they doing this? Are all signals the same or are they used differently in different circumstances? Or are they related to the physiological characteristics of a deep diving predator and are needed to correct buoyancy? Or do they perform social functions? " Scientists hope to find answers soon.