by Sarah Wilson, MA
Our Ruby-Throated Hummingbirds clock over 50 wing beats a second. And that’s their casual “running errands” speed. Courtship can crank things up to around 200.
How is that possible?
First, they have to take in a lot of oxygen. They do that by breathing 4 times a second and having a heart that pounds out about 20 beats a second. And that rapidly-beating heart is enormous for their size. If your heart was the size of a hummingbird’s proportionally, it would weigh 3.5 pounds and not the 8-10 ounces typical for an adult human.
Next, they need to fuel their muscles. To do that they consume vast amount of calories. To fuel such a system in our own bodies, we’d need to consume some 150,000 calories a day. We cannot.
How can they handle that firehose of fuel? By having the fastest metabolism on earth which is some 77 times more efficient than ours.
Once the fuel is in their bloodstream, how do they get it into their muscles? By developing bigger cellular engines. Their mitochondria (think vroom, vroom) take up about 30% of their muscle cells by volume. In mammals, that percentage ranges from 2-10%.
Add to that their flight muscles are about 30% of their body weight. If that were true for us, we’d be walking around with about 45 pounds of “flight” muscle.
With all those superpowers, hummingbirds have another adaptation up their fast-moving sleeves: how the move their wings.
Next time you’re in up to your neck in water, flap your arms up and down as fast as you can underwater. Feel the resistance? At both the top and the bottom of your “wing beat” you have to fight pressures in order to reverse course.Those pressures slow you down. Air acts in similar ways.
Now, move your arm in a figure 8 motion parallel to the bottom, pivoting your hand into the movement. Feel how much less resistance there is? How much easier that is?That’s what hummingbirds do.
These are just a few of the factors that allow Ruby-throated Hummingbirds to move their wings so fast. And all of this in a bird that weighs less than a US nickel.
Nature is amazing.