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Bowhead Whales Exhibit Synchronization in Diving Behavior

From January to May, Qeqertarsuaq Tunua, a vast bay on Greenland’s west coast, becomes a hotspot for plankton, attracting various baleen whales seeking nourishment. In 2010, a pair of bowhead whales entered the bay to feast. Although visually out of range, when they came within approximately 60 miles of each other, they displayed an unexpected behavior—synchronizing their diving patterns. This phenomenon had never been scientifically observed before and strengthens a long-held hypothesis regarding whale communication across distances.

While baleen whales are typically regarded as solitary creatures, some researchers propose that they might form diffuse groups, communicating over vast stretches of ocean. The concept of acoustic herd theory was initially introduced in 1971 by renowned biologist Roger Payne and oceanographer Douglas Webb.

Payne, recognized for his pioneering work in analyzing humpback whale songs, noted the strong social structures of toothed whales like dolphins and killer whales. These species often operate in close-knit family units, which help protect against predators and facilitate communal rearing of young. He speculated that larger baleen whales could exhibit similar behaviors but on a much larger scale, potentially using vocalizations to maintain contact over long distances.

In their seminal paper on acoustic herd theory, Payne and Webb revealed that the vocalizations of fin whales could theoretically transmit up to 430 miles under optimal oceanic conditions. However, demonstrating that one whale’s call effectively reaches another at such distances has proven challenging, as pointed out by Susan Parks, a behavioral ecologist at Syracuse University.

For five decades, researchers have accumulated anecdotal evidence suggesting that baleen whales can coordinate their actions over long ranges, yet these accounts remained largely unverified until a comprehensive study of bowhead diving behavior provided concrete evidence.

Initially, the diving activities of bowhead whales appeared erratic and unpredictable, according to Evgeny Podolskiy, an environmental scientist at Hokkaido University in Japan and the lead author of the study. To investigate further, Podolskiy and his team employed satellite tags to monitor diving depth and location data from 12 bowhead whales over a span of 144 days, using algorithms based on chaos theory to analyze potential patterns in their behavior.

What emerged was a striking 24-hour diving cycle, where the whales commenced shallower dives in the morning that progressively deepened throughout the day, corresponding to a phenomenon known as diel vertical migration (DVM), during which prey species like plankton migrate between the ocean’s surface and deeper waters. The researchers noted that the whales tended to undertake their deepest dives during spring, synchronizing with heightened DVM activity typical of Arctic regions.

However, the study’s most surprising finding was that when two of the bowhead whales were within 60 miles of each other, they exhibited synchronized diving behaviors for up to seven consecutive days. This distance correlates to what is believed to be the maximum acoustic communication range for whales in that region. Podolskiy expressed his excitement at uncovering this unusual behavior, although he acknowledged the possibility of chance playing a role given the ocean’s variables.

Christopher Clark, a bioacoustics researcher at Cornell University, praised the findings, highlighting how they resonate with existing anecdotes regarding whales coordinating activities over significant distances. Yet, he cautioned that fully confirming acoustic communication between the whales remains elusive. Sound waves in cold water travel slowly, complicating efforts to observe real-time interactions.

According to Parks, the integration of mathematical modeling with animal behavior in Podolskiy’s research is particularly fascinating. She expressed hope that future studies might incorporate sound recordings along with satellite tracking to definitively determine whether whales can successfully communicate in the murky acoustics of the Arctic.

Ultimately, the synchronized diving of these two bowhead whales provides compelling evidence supporting Payne and Webb’s theory, although the specifics of their communication remain shrouded in mystery. It raises intriguing possibilities about what information might have been exchanged—could they have been alerting each other to abundant food sources or coordinating to minimize encounters with human activities? Perhaps, like humans, they simply value the assurance of not being alone.

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www.smithsonianmag.com