The Mystery of Narwhal Behavior, Solved by Chaos Theory

  • The researchers used mathematical models based on chaos theory to analyze the movements of a group of satellite-tagged narwhals.
  • Around solar noon, narwhals rest closer to the surface and dive deep. At night, their dives are shallower but with faster and more intense movements, likely to hunt squid. The behavior of narwhals also changed depending on the amount of sea ice present.
  • The narwhal’s life cycle is closely tied to ice. The researchers say this new method could be useful in understanding the challenges faced by narwhals and other Arctic animals due to sea ice loss due to climate change.
  • Narwhals are among the most endangered animals in the Arctic due to hunting, predation, climate change, shipping, and noise pollution associated with oil and gas development and exploration.

Narwhals are chaotic. Or so the researchers thought until they developed a new math-based method to detect patterns in their seemingly irregular movements.

Narwhals (monodon monoceros) are known as unicorns of the sea because of their distinctive single tusk, which is actually an enlarged tooth with up to 10 million nerve endings. These tiny whales live in the Arctic seas and like to take long, deep dives, diving to depths of more than 1,800 meters (5,900 feet) below sea level.

Scientists have long been baffled by the whales’ behavior, but now researchers have used mathematical models based on chaos theory to analyze the movements of a group of satellite-tagged narwhals over an 83-day period.

They found that around solar noon, narwhals rest closer to the surface, but when they dive, they dive very deep. At night, their dives are shallower, but with faster and more intense movements. Scientists believe they may be hunting squid, which come close to the surface at night.

A group of adult male narwhals, Greenland, September 2019. Photo by Carsten Egevang
Attaching a satellite-linked transmitter (biotag) to a live-captured narwhal, Scoresby Sound, East Greenland. Photo courtesy of Greenland Institute of Natural Resources

“While animal-based ocean sensors continue to advance and collect more data, there is a lack of adequate methods to analyze irregular behavior records,” said Evgeny Podolskiy, a geophysicist at the University of Arctic Research Center. ‘Hokkaido and first author of the research. statement.

This new procedure used to find patterns of behavior amid complex movements was developed by Podolskiy with Mads Peter Heide-Jørgensen at the Greenland Institute of Natural Resources and was published in the journal Computational Biology PLOS.

“Our approach is relatively simple to implement and can map and label long-term data, identifying differences between the behavior of individual animals and different species,” the authors suggest.

Narwhals are among the most endangered animals in the Arctic due to hunting, predation, climate change, shipping, and noise pollution associated with oil and gas development and exploration. The authors hope their methods will inform policies to protect endangered species.

The life cycles of narwhals are closely linked to the sea ice, which is an important hunting ground and refuge. When there is more ice, whales dive more intensely, the study reports.

Sea ice is down about 13% per decade due to warming from climate change, according to NASA. The researchers said this new method could be useful in understanding the challenges that narwhals and other Arctic animals face due to loss of sea ice.

Banner image: A Narwhal by Газпром нефть via Wikimedia Commons (CC BY-SA 4.0).

Liz Kimbrough is a writer for Mongabay. Find her on Twitter: @lizkimbrough_

Quote:

Podolskiy, EA, and Heide-Jørgensen, MP (2022). Narwhal’s strange attractor (monodon monoceros). Computational Biology PLOS, 18(9), e1010432. do I:10.1371/log.pcbi.1010432

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Sharon D. Cole