You know how damn exhausting it must be to fly? I don’t. Having never had the ability to fly without propulsion, I can’t say just exactly how hard it must be. Studying the metabolism of flying birds gives us some idea, and current evidence suggests flying is really really f**king hard.
A lot of people compare flying to swimming, which I think is a bit of a BS comparison. Water is a much more dense and heavy medium than air. Sure, it’s harder to move through water than it is to move through air, but long-distance travel through the oceans has the advantage of buoyancy to counteract the effects of gravity. Without having to spend energy from falling to the ocean bottom, all effort can be spent moving forward.
In contrast, flying truly is falling with style. Most of the forward energy generated from flight occurs because of gravity, or the downward force of the wing generating movement in the forward direction. Thus, flying animals are tasked with the mind-numbingly complex task of controlling their descent and forward travel, modifying body position as air currents change, all in an attempt to keep oneself from crashing into the ground in a puddle of crushing sadness.
Basically, it’s generally agreed that moving flying is more energetically demanding than swimming or walking. Migratory birds that choose to embark on long-distance flights typically rest for a while throughout the journey. Even the largest sea-faring gliders have to rest every few days to recover from their grueling haul.
Unless you’re the alpine swift. These aviary ass-kickers don’t stop for jack shit.
“But don’t birds have to land on the ground to eat, rest, or sleep?”. F**king nope, not the Alpine swift.
These birds are built for ass-kickery. They have a body design that’s conducive for long-distance travel, mixing flapping and gliding to travel long distances using little energy. And their yearly migration is a long one, beginning in the mountains of Western Europe across the Mediterranean and Sahara to their wintering sites in the African interior and back, a journey spanning some 2500 miles round-trip.
There have been rumors for decades that some swifts never land for any reason, which honestly sounds ridiculous and stupid. So, to resolve the stupidity, a group of Swiss researchers placed sensors on six Alpine swifts, seeking outline their migration from the Swiss Alps to western Africa for the winter. What they found, described in a paper published in the October 2013 issue of the journal Nature Communcations, ended up being so mind-blowingly balls out that I myself can hardly believe they didn’t just make it the f**k up.
The transmitters they used collected only two parameters: light level to extrapolate position, and acceleration to determine other metrics like pitch (a measure of body position, indicating whether the animal was in flight and where it was traveling), flapping rate, metabolic activity, and a few others. They were also able to tell when and where birds were breeding, wintering, or migrating based on how the birds behaved and where they were located.
Based on the distinct difference in activity between roosting and migrating metabolic activity and pitch, the researchers observed that the three birds they recaptured in Switzerland the following year had been on the wing for at least 200 days. Every bit of food they ate over the trip was snagged in the air during migration. And sleep? Well, the authors aren’t really sure whether swifts feel the harmful effects of sleep deprivation:
“In Alpine swifts there seems to be no necessity for physical inactivity to maintain any of the relevant physiological processes. However, our data indicate that there are distinct periods of increased and decreased activity, which could go along with some kind of sleep in flight.”
Such periods of decreased activity suggest swifts spend several nighttime hours gliding to conserve energy or perform other physiological functions. The researchers’ data backs this up too; swifts were most active and had highest flapping rates near sunrise and sunset, probably because they need to ascent to great heights to avoid gliding into the ground overnight, and probably had to work to recover this altitude at sunrise. How do they control their flight if they’re asleep? Nobody really knows, but they may only sleep one brain hemisphere at a time.
So, despite hours of grueling physical activity, swifts seem to recover without having to land on the ground or water. They travel huge distances over impossibly barren terrain, hauling ass with more long-term gusto than any land creature ever documented. They’re masters of endurance and champions of travel with a purpose. Also, never challenge one to a “lets’s see who can fly the longest” contest. Literally every other organism on the planet will lose.
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