Wale kommunizieren möglicherweise über weite Entfernungen | Neue Beweise für synchronisiertes Tauchen zwischen zwei Walen im Abstand von 100 Kilometern stützen die Theorie

Some excerpts from the article:

>At first blush, bowhead whale diving behavior looks “pretty chaotic and unpredictable,” says Evgeny Podolskiy, an environmental scientist at Hokkaido University in Japan and lead author of the new research. The cetaceans will engage in hours-long bouts of diving, only to stop for no apparent reason, he says.
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>Podolskiy and his team wanted to extract some order from all that apparent randomness. Using satellite tags, they pulled together diving-depth and location data from 12 bowhead whales in the Arctic over 144 days. Then they applied complex algorithms based on chaos theory—a branch of mathematics that untangles underlying mechanisms behind seemingly erratic systems. As they crunched the numbers, patterns emerged.
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>First, the researchers noticed the whales’ dives tend to follow a 24-hour cycle, starting shallower in the mornings and getting deeper in the afternoon. This lines up with a phenomenon known as diel vertical migration (DVM)—the daily commute by plankton and other small creatures from the ocean’s surface down to the abyss and back. They also found that the whales execute their deepest dives in spring, which is when DVM tends to be most extreme in Arctic regions.
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>It isn’t surprising to see large ocean creatures following their prey, Podolskiy says, but what did surprise him was the second pattern. Two of the whales in Qeqertarsuaq Tunua—whose relationship is unknown—synchronized bouts of diving for as many as seven days on end whenever they were within 100 kilometers of each other. According to the team’s calculations, that would be about the maximum acoustic range for whales in the area. “This is very, very peculiar underwater behavior,” Podolskiy says. “It was very exciting.”
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>Podolskiy adds that it’s possible that the synchrony was a mere coincidence—that ocean conditions were conducive to the whales diving simultaneously in different locations. But, given the persistent behavior for days on end, that explanation seems statistically unlikely. “Our current belief is that it’s related to communication somehow,” he says.
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>Proving whale calls are meant for other whales is a difficult feat because low-frequency sound waves travel very slowly through cold water, Clark says. Sound waves could take over an hour to reach another whale, so it would be hard for scientists to observe the creatures exchanging calls. “It’s operating over a scale that is unobservable to humans,” he says. Not only do researchers need the proper equipment to even notice the exchange, but they also need sophisticated analysis to connect the dots between one whale’s signal and another’s apparent reaction.

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Link to research paper: [Synchronization of bowhead whales](https://journals.aps.org/prresearch/abstract/10.1103/PhysRevResearch.6.033174)

Abstract:

>Inferring animal behavior from irregular tracking data is a challenging area of research. It is particularly difficult to determine if whales, who intermittently explore different depths while staying in the same acoustic medium, synchronize their days with their prey and each other over kilometer-scale distances. Here, we aim to better understand the diving behavior of bowhead whales (Balaena mysticetus) in Disko Bay, West Greenland, using the largest high-frequency dive-depth dataset to date (144 days at 1 Hz from 12 different whales) and nonlinear dynamics, whereby we consider the whales to be chaotic (aperiodic) oscillators. We find that foraging whales dive deeper during the daytime in spring, with this diving behavior being in apparent synchrony with their vertically migrating prey. Furthermore, we demonstrate that bowhead whales can synchronize their behavior with each other for up to a week while staying within a range of up to ∼100km. This discovery agrees with the acoustic herd theory of long-range signaling in baleen whales. On the other hand, the synchrony might emerge when animals experience similar ecological conditions, which are, however, difficult to name because targeted depths and locations were separated for hundreds of meters and tens of kilometers, respectively. In this paper, we identify a framework for studying the sociality and behavior of such chaotically moving, unrestrained marine animals and call for more simultaneous tagging campaigns.