Hummingbirds are specially equipped to perform these feats. In most birds, 15 to 25 percent of the body is given over to flying muscles. In a hummingbird’s body, flight muscles account for 35 percent. An enormous heart constitutes up to 2.5 percent of its body weight — the largest per body weight of all vertebrates. At rest, the hummingbird pumps blood at a rate fifteen times as fast as that of a resting ostrich, and that blood is exceptionally rich in oxygen-carrying hemoglobin.
Alone among the world’s ten thousand avian species, only those in the hummingbird family, Trochilidae, can hover in midair. For centuries, nobody knew how they did it. They were considered pure magic.
Even the scientists succumbed to hummingbirds’ intoxicating mysteries: they classified them in an order called Apodiformes, which means “without feet” — for it was believed (incorrectly) for many years that a hummingbird had no need for feet. It was thought that no hummingbird ever perched, accounting in part for its sun-washed brilliance: as the comte de Buffon, Georges-Louis Leclerc, wrote in his 1775 Histoire naturelle, “The emerald, the ruby, and the topaz glitter in its garb, which is never soiled with the dust of the earth.”
Churning beneath these feats of vigor is a Herculean metabolism that demands a greater volume of food per bodyweight than any other vertebrate. If a human were to sustain the activity level of a hummingbird, they would have to consume 155,000 calories per day — nearly 80 times what the United States government recommends for an average adult — and would ultimately self-combust as their body temperature rises to 370 degrees Celsius, or around 700 Fahrenheit. Montgomery furthers the marvelous mathematics of equivalency:
As if the evolution of ordinary bird flight weren’t miracle enough — scales transfigured into feathers, jaws transfigured into beaks, arms transfigured into wings — the hummingbird, like no other bird among the thousands of known avian species, can fly backward and upside-down, and can hover. It is hovering that most defiantly subverts the standard physics of bird flight: head practically still as the tiny turbine of feather and bone suspends the body mid-air — not by flapping up and down, as wings do in ordinary bird flight, but by swiveling rapidly along the invisible curvature of an infinity symbol. Millions of living, breathing gravity-defying space stations, right here on Earth, capable of slicing through the atmosphere at 385 body-lengths per second — faster than a falcon, faster than the Space Shuttle itself.
Meanwhile, we have The Hummingbirds’ Gift to widen us with wonder at the seeming impossibility of these fragile, fierce marvels of nature — and to render us wondersmitten with the hope that if individual humans are capable of bring individual hummingbirds back to life from the brink of death, then perhaps our entire species is capable of rehabilitating an entire planet; perhaps we are capable of a great deal more care and tenderness than we realize toward the myriad marvelous creatures with whom we share the ultimate cosmic miracle of life, this staggering improbability that is — somehow, somehow — possible.
That supranatural marvel of nature is what Sy Montgomery — the naturalist who so memorably celebrated the otherworldly marvel of the octopus — celebrates in The Hummingbirds’ Gift: Wonder, Beauty, and Renewal on Wings (public library). She writes:
Hummingbirds are the lightest birds in the sky. Of their roughly 240 species, all confined to the Western Hemisphere, the largest, an Andean “giant,” is only eight inches long; the smallest, the bee hummingbird of Cuba, is just over two inches long and weighs a single gram.
Science, being the supreme human implement of self-correction, eventually caught up to the reality of the hummingbird’s wispy feet, then unpeeled a thousand subtler and more astonishing realities about the extraordinary feats of which this flying jewel is capable. Montgomery writes:
Essential as pollinators and essential as muses to poets, hummingbirds animate every indigenous spiritual mythology of their native habitats and are sold as wearable trinkets on Etsy, to be worn as symbols — of joy, of levity, of magic — by modern secular humans across every imaginable habitat on our improbable planet.
This fragility is why tender armies of humans have taken it upon themselves to help hummingbirds survive the gauntlet of an increasingly perilous world. The book is as much a love letter to these uncommon feathered creatures — by a human who learned everything she knows about how to be a good creature from a lifetime of working with non-human animals — as it is a love letter to the uncommon human animals toiling as hummingbird rehabilitators in kitchens and backyards, each “a Mother Teresa, a Saint George, a little Dutch boy with his finger in the dike — desperately trying to fend off the hordes of monstrous perils facing these tiniest of all birds.” Montgomery quotes one such hero — a Pennsylvanian named Mary Birney:
At its large heart, this slender book — like all of Montgomery’s books, composed in the tradition of Rachel Carson — is as much a love letter to a particular creature as a clarion call to our entire ecological conscience: Hummingbirds occupy that singularly ominous Venn diagram between the pollinators whose populations are collapsing by the minute and the 2.8 billion birds that have vanished from the North American sky since the founding of Earth Day half a century ago. With her spare poetics, Montgomery offers an admonition radiating an invitation:
Their feet are like thread… Touching them damages their feathers. Yes, they are made of air — air and a humongous heart. That’s all they are. It floors me I’m able to work with them.
Frida Kahlo painted a hummingbird into her fiercest self-portrait. Technology historian Steven Johnson drew on hummingbirds as the perfect metaphor for revolutionary innovation. Walt Whitman found great joy and solace in watching a hummingbird “coming and going, daintily balancing and shimmering about,” as he was learning anew how to balance a body coming and going in the world after his paralytic stroke. For poet and gardener Ross Gay, “the hummingbird hovering there with its green-gold breast shimmering, slipping its needle nose in the zinnia,” is indispensable to the “exercise in supreme attentiveness” that gardening offers.
Today, perhaps more than ever before, we thirst for community; we hanker for transformation; we long to reconnect with the incandescence of life. We need to make those inner journeys. But what if there are no bees or butterflies or hummingbirds to accompany us? It’s a growing possibility.
And yet for all their fragility, hummingbirds are endowed with strength that, when adjusted for bodyweight, would render its human analogue superhuman. Montgomery details the physiology and physics of their infinity-symbol hover wingbeat:
Delicacy is the trade-off that hummingbirds have made for their unrivaled powers of flight. Alone among birds, they can hover, fly backward, even fly upside down. For such small birds their speed is astonishing: in his courtship display to impress a female, a male Allen’s hummingbird, for instance, can dive out of the sky reaching sixty-one miles per hour, plunging from fifty feet at a rate of more than sixty feet per second — and pulling out of his plunge, he experiences more than nine times the force of gravity. Adjusted for body length, the Allen’s is the fastest bird in the world.
There is, indeed, something almost magical to the creaturely reality of the hummingbird — something not supernatural but supranatural, hovering above the ordinary limits of what biology and physics conspire to render possible.
Since what we call magic is the eternal instinct of the human mind to mistake the boundaries of its understanding for the boundaries of reality, it is hardly a surprise that hummingbird flight was seen as magic for centuries; since science is the best tool we have for expanding the boundaries of our understanding, it wasn’t until the invention of photography and the invention of the stroboscope in the 1830s that the blur of the hummingbird hover was revealed to be wings beating at sixty times per second. The camera captured what was far too rapid for the human eye to register, liberating the human mind to probe the physics beneath the phantasm. Montgomery observes:
Hummingbirds are less flesh than fairies. They are little more than bubbles fringed with iridescent feathers — air wrapped in light. No wonder even experts who are experienced with other birds are intimidated by this fragility.
The upstroke as well as downstroke require enormous strength; every stroke is a power stroke. Like insects and helicopters, hummingbirds can fly backward by slanting the angle of the wings; they can fly upside down by spreading the tail to lead the body into a backward somersault. Hovering becomes so natural to a hummingbird that a mother who wants to turn in her nest does it by lifting straight up into the air, twirling, then coming back down. A hummer can stay suspended in the air for up to an hour.
To fuel the furious pace of its life — even resting, it breathes 250 times a minute, and its heart pounds at five hundred beats per minute — a hummer must daily visit fifteen hundred flowers and eat six hundred to seven hundred insects. If the nectar alone were converted to its human equivalent, that would be fifteen gallons a day.