The migratory aquatic birds that travel to the Arctic to reproduce have some capacity to anticipate their long journeys in order to coincide with the increasingly early arrival of spring at the Earth’s North Pole. However, there are limits.
In a paper published in the journal Nature Climate Change, more than two dozen scientists tracked, via GPS, the migrations of five species: the black-faced brant goose (Branta bernicla bernicla), the white-faced brant goose (Branta leucopsis), the greater white-fronted goose (Anser albifrons), the short-billed goose (Anser brachyrhynchus) and Bewick’s swan (Cygnus columbianus bewickii).
The team found that these birds are capable of reducing the time they spend feeding, and replenishing their energy and fat reserves in preparation for migration, and, in this way, launching into the skies earlier to reach the Arctic when the early spring begins to bud.
“Our results are both encouraging and worrying,” says Hans Linssen of the University of Amsterdam and the study’s lead author, cited in a press release.
“We show that these birds can migrate more quickly by adjusting the stops they make and the feeding times,” the researcher explains, but cautions that this flexibility will only be advantageous “for a few more decades,” between 18 and 28 years, more precisely. After that, advancing migrations, by themselves, will not be enough.
This is because the birds need to be well fed before traversing thousands of kilometres to the Arctic, and this requires stopovers along the way to rest and recover energy. Moreover, to depart earlier and be able to coincide their arrival with springs that are increasingly early due to climate change, the birds require high-quality food and favorable conditions, which does not always occur.
For this reason, it is possible that many birds end up arriving at the Arctic in poor health, which could affect their reproduction and, ultimately, the future of their populations.
“These birds are showing incredible adaptability,” Linssen says. “But by the middle of the century, they will need other strategies, such as changing their wintering grounds or completely altering their migratory routes, in order to stay synchronized with Arctic spring.”
