Vanishing sea ice in the Arctic could shake up seabird migrations

by John C. Cannon on 11 December 2019

For seabirds, an Arctic Ocean with less sea ice could provide some tantalizing alternatives to the long-haul flights that some undertake each year.

In a recent study, ecologist Manon Clairbaux and her colleagues found that at least one Arctic dweller would expend less energy by changing its route. For the little auk (Alle alle), plying a new route from the North Atlantic to the North Pacific would require only about half as much energy as their traditional migration. Little auks typically spend summers in their breeding grounds closer to the North Pole, and then fly southward to the North Atlantic in the winter.


“There are clearly new strategies for migratory birds, and those new pathways will change the shape of the global population,” Clairbaux, a doctoral student at France’s University of Montpellier, told Mongabay.



Little auks, pictured here in Greenland, are the most numerous seabirds in the Arctic. Image by Manon Clairbaux.




Clairbaux and her supervisor, biological oceanographer David Grémillet of the French National Centre for Scientific Research (CNRS), along with their colleagues in Norway and the United States, were curious about how the disappearance of sea ice would influence the movements of migratory seabirds around the Arctic. They mined the scientific literature and came up with 29 species of birds that could potentially migrate to the Pacific Ocean instead of crossing the Arctic.

The team then zeroed in on the little auk, a rotund bird that’s a bit bigger than a large songbird like a blue jay. It’s also more numerous than any other bird in the Arctic, and well-studied, Clairbaux said, so the researchers had a good idea of how they appear to be adapting to climate change and where they live.


The researchers modeled changes to the species’ distribution alongside climate models to get a sense of how the areas in which they breed and spend the winters might fit the little auk’s needs in the
future. Lastly, the team used another model to predict how much energy the birds would need for that shifted migration to the Pacific compared with flying to the Arctic or becoming a year-round “resident” at those higher latitudes.


The coast of eastern Greenland. Image by Manon Clairbaux.


Clairbaux said they weren’t expecting the new route to be so much more energetically efficient for the little auks, and it demonstrates that there’s at least the potential for the migration to shift toward an east-west route between the Atlantic and Pacific oceans. She points out, however, that this study only looked at energy costs and not other factors, such as the genetic hardwiring that drives birds to take certain routes, or the competition with other seabirds that a new
migratory destination might entail.

The team published their work Nov. 28 in the journal Scientific Reports.


Right now and in the near future, the team expects that a few birds — called “vagrants” by scientists — from the little auk population might stray toward the Pacific, or that part of the population might disperse in that direction, rather than a wholesale change in the species’ migration.

Little auks typically migrate between the high Arctic and the North Atlantic Ocean, though the loss of sea ice could change that. Image by Manon Clairbaux.



But by applying these models in the same way to other bird species, Clairbaux said that researchers could home in on the potential shifts that less sea ice could instigate. That data could further help in
planning for conservation, such as the placement of marine protected areas, she added.


“It’s really important that our conservation measures have to be dynamic,” Clairbaux said. “In fact, we have to understand that things will change. Patterns will change.”


Banner image of little auks in the Arctic by Manon Clairbaux.


Article appeared here - https://news.mongabay.com/2019/12/vanishing-sea-ice-could-shake-up-bird-migrations/

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