Satellite telemetry data shows narwhals altering seasonal migration patterns in response to climate change

A team of researchers affiliated with several institutions in Canada and Denmark has found evidence that narwhals have been altering their seasonal migration patterns in response to global warming. In their paper published in Proceedings of the National Academy of Sciences, the group describes how they compared satellite data showing narwhal movements, with ice and temperature data in the Arctic over a 21-year period and what they learned by doing so.

Prior research has shown that many land animals and birds have been altering their migration patterns as the planet grows warmer. But, as the researchers with this new effort note, little research has been done to find out if sea creatures are doing the same. To find out, they conducted a study of narwhals, which live in ice-free areas near the coasts of Russia, Canada and Greenland during the warm months and then move to deeper water in the fall, where they spend the winter.

The work by the researchers involved studying satellite imagery that showed a pod of 40 narwhals migrating over the years 1997 to 2018. Doing so showed that the little whales with the unicorn-like horns have been altering their migration patterns. They have been moving their summer migration dates to later in the summer by approximately 10 days for each of the decades studied.

For the period as a whole, they have delayed their migrations by 17 days. Suspecting that the changes in migration patterns were due to global warming, the researchers then looked at the degree of warming in the Arctic and the changes that have been wrought due to global warming. They found reductions in sea ice patterns matched with the delays by the narwhals.

The researchers note that narwhals are long-lived creatures, which generally means that they are less suited to adapting to rapidly changing conditions—at least from an evolutionary perspective. But, because they live from 50 to 100 years, they also have the ability to learn over time. Most of those they studied were the same whales, and they very clearly learned to adapt on the fly.

That suggests that they have some degree of ability to change in ways to meet the changes yet to come. But, the researchers also note, they may face other problems. Leaving the coastlines later in summer could lead to becoming trapped and suffocating in landfast ice, for example. It could also put them at more risk from predators, such as orca.

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