Scientists baffled by non-stop 10-month flight of the swift
We already know that swifts are among the fastest birds on the planet. Now, researchers have discovered that some swifts also spend the majority of the year in the air. Ten months, to be exact.
The findings were published recently in the journal Current Biology. Ecologist Anders Hedenström is the lead researcher. He spoke with As It Happens host Carol Off from the Swedish island of Öland about his discovery. Here is part of their conversation.
Carol Off: Professor Hedenström, how do they do it? How do these birds spend so much time in the air?
Anders Hedenström: They breed for a short period in the summer, during two months. Then they just take off and leave for migration, wintering and return migration. It takes them about 10 months. During that period, a few individuals literally never touch ground. A few other individuals do come down to roost occasionally for a few hours during the winter period.
Maybe, if I'm allowed to speculate, when they come down in gliding flight from these ascending tours it could be then that they get a power nap, if you will.- Anders Hedenström
AH: They forage from aerial insects that they capture in the open air space. That we know from the breeding period and what kind of insects they bring back to their young. How they sleep we don't know. That remains to be found out in future studies. But if swifts are like other animals, that is they need to sleep at least some time of the day, then we believe they have to do that while they are up in the air. If they are sleeping they must do it while they are flying.
CO: How would they do that?
AH: There is one possibility. If they are like the only other species that has been studied recently — and that is a frigate bird — they are able to shut down one brain hemisphere at a time and then they probably can maneuver by having the other eye open and steer by that. We don't yet know if swifts are capable of the same thing. Swifts have another very irregular behaviour that we have observed. They climb to a very high altitude, up to about 10,000 feet. One time around dawn and another time around dusk. Maybe, if I'm allowed to speculate, when they come down in gliding flight from these ascending tours it could be then that they get a "power nap," if you will.
CO: They catch 40 winks while they're gliding down from 10,000 feet?
AH: Yes, maybe!
For more on this story, listen to our full interview with Anders Hedenström.