According to new research, narwhals have delayed their seasonal migration due to the impact of the climate crisis, suggesting an ability to adapt to Arctic change but increasing the risk of them becoming trapped in ice.
Narwhals, recognizable by their long spiral tusk that earned them the nickname of “sea unicorns”, inhabit the arctic waters of Greenland, Canada and Russia. They are a migratory species that spends the summer months in ice-free coastal areas before moving to deeper waters between late September and mid-November.
Researchers from the University of Windsor, Canada, examined satellite data from 1997 to 2018 of 40 narwhals to explore how they moved into the Canadian Arctic and when they left their summer grounds. They compared these data with local and regional changes in temperature and ice formation.
The findings suggest that narwhals have delayed their migration by nearly 10 days every decade, with a total of 17 days delay since 1997. Narwhals also take an average of about four days longer in the first phase of their migratory transit, according to I study.
If you are a dying narwhal, you may not be able to account for sudden random extreme events.
Courtney Shuert, University of Windsor
The patterns in narwhal delayed departure match sea ice trends in the area, said Courtney Shuert, author of the study and researcher at the University of Windsor. For example, scholars mention other research showing that the ocean surrounding the Canadian archipelago froze about five days after a decade.
“There is this general trend [towards delaying migration]but there is also a lot of inter-annual flexibility, which highlights that they are taking this strategic approach to when they are starting and monitoring these climate trends on a large scale, ”Shuert said.
Narwhals – which live to be around 50 years old, with some as long as 100 – are more susceptible to the impacts of the climate crisis because they take longer to genetically evolve than animals with shorter lifetimes.
The suggestion that they are adapting to their changing environment was a welcome sign, Shuert said. But it could also put cetaceans at risk, especially as climate change and extreme weather events become more frequent.
Adapting to leave the coast a little later each year could leave narwhals more vulnerable to being trapped in “land ice,” sea ice that is attached to the coast and prevents animals from emerging for air. “If you are a narwhal that goes out, you may not be able to account for these sudden and random extreme events,” Shuert said. Ice trapping can kill hundreds of animals.
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Delayed migration could also lead to more encounters with predators such as killer whales, which they can reach further north, as well as ships able to access routes that would have previously been frozen, the study concluded.
More research was needed to understand the impact of change in migration patterns, Shuert said. “We don’t really understand the downstream effects of this change yet.”
The study’s findings add to research on how climate change is altering animal migration patterns, a phenomenon that has also appeared among birds and land mammals.
“The rate of change we are now seeing in the Arctic is a major concern for many animals because it may exceed the rate at which animals can adapt through evolution,” Shuert said. “But [these findings] really show this idea of behavioral flexibility and how important it can be to support these populations against change ”.