Even the best distant runners and long-distance swimmers on the planet need a break every once in a while, but scientists have found a species of bird which fly during exceptionally long periods of time during its annual migration without needing to stop and catch its breath.
According to NPR and National Geographic, researchers from Lund University in Sweden have monitored the flight patterns of the common swift (Apus apus) and found that the birds can spend nearly their entire 10-month nonbreeding period soaring through the skies without stopping.
Specifically, the husband-and-wife team of Anders Hedenström and Susanne Åkesson fitted 19 swifts with lightweight data loggers in 2013, which they were able to use to identify the position of the birds and which recorded their body position, activity, and acceleration levels to determine if they were flying or resting at any given time.
This bird don’t stop to eat, drink, or maybe even sleep.
As they reported this week in the journal Current Biology, they found that the birds spent at most 0.64% of their migration on the ground, and that some of the birds were almost constantly active during this time. In fact, one of them rested for just four days total between September 2013 and April 2014 and stopped for just two hours during the same time period the following year.
“They feed in the air, they mate in the air, they get nest material in the air,” Åkesson explained to Nat Geo on Thursday. “They can land on nest boxes, branches, or houses, but they can’t really land on the ground” because their wings are too long and their legs too short to take flight from a flat surface, she added.
Study findings suggest that swifts sleep while in midair
Some of the swifts were forced to take breaks more frequently, Åkesson and Hedenström noted. They believe that this was because their tail and wing feathers had not been completely replaced following their annual molt, compromising their ability to remain airborne. Even so, not one of them spent even 1% of their 10-month nonbreeding period on the ground.
Common swifts are known to fly south from Europe to sub-Saharan Africa, NPR said, but they apparently do not land there, as scientists have yet to discover any roosting sites in that region of the world. The rarity of the stops, the authors told Nat Geo, suggests that they typically stop only for bad weather – indicating that the species may not need to land in order to sleep.
In fact, Åkesson and Hedenström wrote that it is unclear “when and to what extent swifts need to sleep,” and they’re not alone in that regard, according to reports. Earlier studies have discovered that alpine swifts (which are twice the size of common swifts) may have flown from Switzerland to Africa without stopping for 200 days. These lengthy nonstop flights indicate that swifts might be able to sleep while flying, much like frigate birds have been proven to do.
The researchers also found that the birds appeared to be less active during the day than they were at nighttime, which they explained was “most likely due to prolonged gliding episodes during the daytime when soaring in thermals.” They also wrote that the results “have important implications for understanding physiological adaptations to endure prolonged periods of flight, including the need to sleep while airborne.”
—–
Image credit: Stefan Berndtsson
Comments