Ukrainian scientists presented recordings of orcas voices for the first time

Ukrainian scientists have presented recordings of the voices of killer whales (orcas) for the first time. The audio mainly contains impulse cries, which are the means by which these animals communicate.

This is stated on the page of the National Antarctic Science Center.

Also among the main types of their sounds are whistles and echolocation clicks. These predators create impulse sounds not with their vocal cords, but by blowing air through special structures in their noses. Scientists still do not fully understand how this mechanism works and why orcas and other marine mammals make such a variety of sounds. Therefore, Ukrainian biologists are very carefully studying these sounds in Antarctica.

"On February 10, 2024, we were working in Collins Bay and saw 11 leopard seals on the ice floes. So when we landed on the island, we left an acoustic recorder turned on near the moored boat so as not to miss the opportunity to record the underwater vocalizations of these predators. But then the recording unexpectedly revealed the sounds of a group of type "B" (large) orcas, which mainly hunt seals," said biologist Vadym Tkachenko.

There are several ways to record marine mammal sounds. One way is to conduct continuous passive monitoring in one location. This can be done for a short period of time or for a whole year. This method allows us to understand how the presence of different species in an area changes throughout the year.

Another method is to record sounds during the movement of vessels, such as the Noosphere, or motorboats as they go out to sea from the station. But most often, Ukrainian biologists recorded sounds when the boats stopped to observe animals or for other research. This is how the sounds of killer whales were recorded.

From the sounds, scientists found out that a group of orcas, consisting of at least three animals, periodically approached the abandoned boat very close. They were probably looking for seals to feast on. Biologist of the National Academy of Sciences Oksana Savenko explained that orcas near the Akademik Vernadsky Station can be seen rarely — usually up to 10 times a year. But the sound recordings show that orcas are often nearby, even if they are not visible due to icebergs and ice.

Spectrograms and oscillograms are used to analyze sounds. A spectrogram shows what frequencies are in the sounds at a particular moment (in kilohertz), and an oscillogram shows how the sound strength changes (in micropascals). The color on the spectrogram shows the loudness of the sound in decibels. The sounds that were recorded are very short — they last a fraction of a second. Therefore, they were slowed down to 10–12% of their original speed so that they could be heard.

Most of these sounds are in the ultrasonic range, which is inaudible to the human ear. But what we hear in the recording are those sounds that fall into the range up to 20 kHz, along with various echoes and other vibrations that occur when killer whales communicate.

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