If alpine swifts need to catch a snooze, they do it on the fly. The birds stay airborne for at least six months without touching terra firma, a new study shows.
As their name implies, swifts are agile aerialists. Researchers have suspected for decades that the birds spend most of their lives on the wing.
After breeding in Switzerland every summer, alpine swifts, Tachymarptis melba, migrate to West Africa for the winter. They then fly across the Sahara to spend the spring in North Africa and Spain before returning north. Researchers led by Erich Bächler at the Swiss Ornithological Institute in Sempach, Switzerland adorned six alpine swifts with tiny data loggers that measured the activity of the birds through each day and night.
Three of the swifts returned the following summer, with data showing that they had remained airborne throughout the winter in West Africa and while migrating across the Sahara. They touched down after 200 days for a pit stop in the Mediterranean on their way back to Switzerland, the researchers report October 8 in Nature Communications.
The researchers propose that the birds may use “some kind of sleep” while on the wing to maintain their bodily functions without landing.