The application of chaos theory to study the movement of iconic arctic whales has revealed fascinating insights, including a 24-hour diving cycle and long-range synchronization over approximately 100 km.
Bowhead whales, among the largest and longest-lived mammals in the world, are integral to the Arctic Ocean’s marine ecosystems, yet little is known about their foraging and diving behaviors. In an upcoming publication in the journal Physical Review Research, a diverse team of scientists from Japan, Greenland, and Denmark has uncovered behavior patterns in these whales that could provide valuable clues about their foraging and social interactions.
In a groundbreaking study, Associate Professor Evgeny A. Podolskiy from the Arctic Research Center at Hokkaido University, along with Professor Jonas Teilmann from the Department of Ecoscience at Aarhus University and Professor Mads Peter Heide-Jørgensen from the Department of Birds and Mammals at the Greenland Institute of Natural Resources, conducted an in-depth analysis of 144 days of diving records of 12 bowhead whales tagged in Disko Bay, West Greenland.
By utilizing a dynamical systems chaos approach, the researchers uncovered remarkable patterns within the whales’ apparently disorderly collective behavior. Their findings revealed a fascinating 24-hour spring diving cycle, demonstrating how the whales strategically swam deepest in the afternoon to monitor the daily movement of their prey towards the surface, a phenomenon known as the diel vertical migration.
This study sheds light on the complex and intriguing behavior of bowhead whales, offering valuable insights into their foraging strategies and daily routines.
“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,” said Heide-Jørgensen. “Until now, this hasn’t been shown for spring and remained contradictory for autumn.”
The research team uncovered a remarkable finding about two bowhead whales that synchronized their diving patterns over long distances, even when they were up to one hundred kilometers apart.
Despite their separation, the female and the other whale, whose sex is unknown, would coordinate their dives and spend up to a week together, diving to different depths. This synchronized behavior was observed when they were within acoustic range of each other, spanning over 100 kilometers. However, the researchers faced technical challenges in recording the whales’ sounds to determine whether they were interacting.
“Without direct observations, such as recordings of the two whales, it isn’t possible to determine that the individuals were exchanging calls,” said Teilmann; nevertheless, “the observed subsurface behavior might be the first evidence supporting the acoustic herd theory of long-range signaling in baleen whales proposed by Payne and Webb back in 1971.”
“The possibility of acoustically connected whales, which seem to be diving alone but are actually together, is mind-bending. Our study identifies a framework for studying the sociality and behavior of such chaotically moving, unrestrained marine animals, and we encourage the research community to collect more simultaneous tag data to confirm if our interpretation is appropriate,” Podolskiy concluded.
Journal reference:
- Evgeny A. Podolskiy, Jonas Teilmann, and Mads Peter Heide-Jørgensen. Synchronization of bowhead whales. Physical Review Research, 2024.
