Surprising discovery in Arctic songbird may reveal how it survives challenging migrations

Snow buntings are equipped for winter even while migrating to their breeding grounds, shows a recent study in Frontiers in Ecology and Evolution. There have been major declines in biodiversity around the world and the snow bunting population has dropped 60% over the last 45 years.

The specific cause of this drop is unknown, and this study is among the first to look at the physiological changes that occur during the different life stages of this species (ie between winter and migration). This work provides clues into the future survival of snow buntings, as well as new insights into how species generally endure the harsh cold of the Arctic.

“With the rapid warming of the Arctic, it is likely that cold specialist species like snow buntings will be hit hard if they have a limited ability to live in an increasingly warm environment – which appears to be the case for this species,” said lead author Dr Audrey Le Pogam, of the University of Québec at Rimouski in Canada. “Our study establishes a baseline for future comparative studies and, in the long term, these results may help to elucidate the causes of their decline or to anticipate the adaptive capacity of populations.”

To better understand snow bunting adaptations, Le Pogam and her collaborators collected free-living snow buntings before and during their spring migration. The researchers studied birds from two locations: on their wintering grounds near Rimouski, in Canada, and on their breeding ground at Alert, in the Canadian High-Arctic. The team measured the birds’ weight, fat stores, the thickness of their flight muscles and metabolic parameters providing information on their physiological maintenance costs and cold endurance.

‘It’s amazing how little we know about snow buntings’

Past research from the last 50 years shows that maintaining winter characteristics may come at a physiological cost for migratory birds. It is well-established that other species change according to the conditions of their destinations. Based on this, Le Pogam and her collaborators initially hypothesized that snow buntings would reduce their winter specializations when they moved to their breeding grounds. But, surprisingly, the birds’ metabolic parameters and other physiological traits were similar between the two locations.

More research is needed to confirm whether this is unique to snow buntings, or whether it is shared by other Arctic migratory species such as Lapland longspurs, Arctic redpolls and horned larks. Nevertheless, this research shows that keeping winter adaptations provides advantages to snow buntings in terms of coping with harsh weather during migration. These traits also help bunting males reach breeding grounds earlier and secure the best breeding spots.

“It is amazing how little we know about highly specialized Arctic species like snow buntings,” said Le Pogam. “By studying species like this, we quickly realized that some of the accepted patterns and mechanisms we thought were generalizable are likely not fully applicable to Arctic songbirds migrating through cold environments. Understanding these species is even more important given that high latitudes are warming up twice as fast as the rest of the world.”

###