The surprising secrets of hummingbird flight - Kristiina J. Hurme and Alejandro Rico-Guevara

1,018,111 views ・ 2021-04-08

TED-Ed


Please double-click on the English subtitles below to play the video.

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And the clock starts...
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now.
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Did you miss it?
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It wasn’t some bug buzzing by or a weird trick of the light.
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You just saw a hummingbird perform astonishing aerial acrobatics,
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eat lunch in midair, pollinate a flower, and then escape a threat upside down—
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all in a matter of seconds.
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So let’s slow down the action, and unpack each step in this blazing-fast feast.
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First up, their incredibly rapid flight.
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Hummingbirds typically beat their wings 30 to 40 times per second,
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creating the high-frequency hum they’re named for.
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To flap their wings at this speed,
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hummingbirds have evolved giant pectoral muscles
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that comprise over a third of some species’ bodyweight.
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But the real secret to their fine-tuned flight is all in the wrist.
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Most birds only generate lift on the downstroke of each flap,
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while using the upward recovery stroke to set up their next wing beat.
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Hummingbirds however, turn their wrists during the upstroke,
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changing their wing’s angle to flap in a figure 8 pattern
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that continually generates lift throughout their wingbeats.
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Alongside their massive muscles, this special lift-producing technique
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allows hummingbirds to achieve sustained hovering flight—
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an aerial feat no other bird can perform.
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Hovering lets hummingbirds slow to a stop almost instantly
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and assess scenarios in midair.
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Then, they can take off in any direction,
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reaching speeds faster than a fighter jet, relative to the bird’s size.
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And since they can beat each of their wings at different speeds and angles,
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the birds can perform incredible spins and turns
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all while flying backwards or even upside down.
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Of course, flying this way can be exhausting.
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Hovering is one of the most energy intensive forms of movement
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in the animal kingdom.
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And relative to their body size,
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hummingbirds have the highest metabolic rates of all vertebrates.
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This leads them to eat very frequently—
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often consuming an average of four meals an hour while flying.
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Fortunately, their hovering lets them eat at remarkable angles without perching,
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consuming food that would otherwise be impossible to reach.
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Using their long slender bills,
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they reach deep inside flowers and pump out nectar
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with their thin grooved tongues.
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This sugary liquid is a hummingbird’s most important energy source,
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and a single bird consumes six times its weight in nectar every day
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over hundreds of small meals.
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Each of these sugary snacks also pollinates the flower being visited
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with pollen left on the bird from previous meals.
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That's just a rough idea of what hummingbirds can do in several seconds.
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But if we hang around a little longer,
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we might see their aerial acrobatics put to a more dangerous test.
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Hummingbirds keep track of which flowers they've recently drained,
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as well as those they plan to drain next.
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And each bird will fight ruthlessly to defend this floral territory
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from their only real competition: other hummingbirds.
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Using their spear-like bills and blindingly fast flight,
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dueling hummingbirds chase each other through the air,
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aggressively stabbing and plucking feathers.
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The bills of some species are specialized for fighting,
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with spiny tips, hooks, or even saw-like serrations.
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Some hummingbirds employ these aerial fencing techniques
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to chase off larger birds like hawks and owls.
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But the most extreme fights are between male hummingbirds
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competing for flowers and females.
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Fortunately, these duels are rarely deadly.
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After 15 to 20 seconds, one bird will typically surrender—
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flying off to seek its breakfast elsewhere.
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After all this fighting, feeding, and flying,
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hummingbirds sometimes need to sleep off the day’s events
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in a mild form of hibernation called torpor.
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Their hearts— proportionally the largest in the animal kingdom—
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slow from 1,200 beats per minute to a mere 50.
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But when they wake up 4 to 7 hours later,
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their lightning-fast metabolism kicks back into gear.
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With all this speed and strength,
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it’s no wonder the Aztecs revered these energetic birds
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as agents of the god of war Huitzilopotchli—
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a reminder that immense power can come in the smallest packages.
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