Fastest Things on Wings

by Terry Masear

  City residents often express envy of the freedom and exhilaration that hummingbird flight symbolizes. In Los Angeles, while we struggle to extricate ourselves from freeway gridlock that takes two aggravating hours to escape, hummingbirds zoom off to distant horizons somewhere on the margins of the earth, places the wild heart flees to when the city limits our power to break free. In their global excursions, hummingbirds ignore humans’ unnatural and artificial borders. To them there are no states or countries, only clouds, wind, and the open sky. Departing from shared urban communities, they venture to far-flung destinations we cannot know but can well imagine. And our yearning to tag along and share vicariously in their enigmatic travels captures the essence of the hummingbird’s allure.

  CHAPTER 14

  She Blinded Me with Science

  FOUR WEEKS AFTER Gabriel’s arrival, on a balmy night in early May, Pepper shows up at my door at eight o’clock in a white cardboard takeout box. Hayley, a statuesque, dark-haired beauty with arresting hazel eyes, was working on a film set in Los Feliz next to Griffith Park when she discovered Pepper stranded in the jalapeño dish (hence the name) during a catered outdoor lunch. Pepper’s bright green back blended into the jalapeños so seamlessly that Hayley nearly scooped her up onto a plate before noticing the wounded Anna’s flailing around in the stainless-steel chafing dish.

  “What do you think happened to her?” I ask after Hayley laughingly describes the culinary confusion.

  “There are a lot of tall trees around the set,” Hayley says with a shrug, “so maybe she fell out of her nest.”

  I lift Pepper out of the box and examine her carefully. “She’s not a baby, though,” I point out.

  “Oh, she’s not? How can you tell?”

  “See the length of her bill? Juveniles have a shorter bill. But there’s still a lot of grooving,” I observe, examining her with my surgical loupes, “so she’s a teenager who has been out on her own, probably for about a month or two. So something happened to her.”

  Hayley frowns. “Like what?”

  “Ah!” I exclaim, noticing a few contour feathers missing from the back of her head. “Did you see another hummingbird around?”

  “Yeah, actually, one of the grips said he saw another hummingbird buzzing around the set after I found her. Then when we were going over some footage later, we noticed them zipping through a scene together.”

  “She should be in the credits, then.”

  “Absolutely,” Hayley agrees. “I’ll make sure of that.”

  “What did the other hummingbird look like?”

  “Kind of like her, but with a bright red head. We figured it was her mother.”

  “No, it wasn’t her mother. It was an adult male, probably trying to breed with her.” I point to the missing feathers on her head.

  Hayley looks at Pepper closely, then glances at me in horror.

  “But she’s just a teenager, so she isn’t ready. Still, the adult males can be pretty aggressive toward young females,” I explain.

  “What is it with males anyway?” Hayley clicks her tongue, turning her palms upward in a gesture of disbelief and disdain.

  “Right?” I say in a tone of agreement. “It’s the same all over the world.”

  “I’ve actually met a few like that myself,” she mumbles in a low, confidential tone.

  “Who hasn’t?” I ask as we both laugh.

  “Oh, the poor thing.” Hayley groans sympathetically. “Well, I fed her sugar water all afternoon like you said. I’m sorry about bringing her so late but we just wrapped up an hour ago and I’m leaving for Italy tomorrow morning.”

  “Don’t worry, this isn’t late.” I set Pepper on a faux nest in the ICU, but she hops off and begins buzzing around the bottom of the incubator in a circle. I must betray my disappointment because Hayley glances at me in alarm.

  “What’s wrong?”

  “Her right wing. See how it’s not rotating as high as the left?”

  “Yeah.” Hayley nods. “Is that bad?”

  I don’t want to say what I’m thinking. I never do in cases like this. Because a broken wing is the saddest thing. For a hummingbird, it’s the end. With larger birds, particularly hawks and owls, broken wings can often be surgically pinned and will heal over time. But a hummingbird’s light bones and complex shoulder joints fracture easily. And they cannot be put back together again. Nobody wants to hear this. Still, I try to aim for honesty because a lot of finders call weeks, sometimes months, after dropping off a bird to check on its progress.

  “She has a chance.” I turn to Hayley, who is already starting to tear up. “I’ll give her time.”

  “What happens if she can’t fly again?” she asks anxiously.

  I look at Pepper in silence, trying to find the right words to deliver such hard news. But Hayley reaches the grim conclusion on her own.

  “She just looks so perfect.” She glances at me pleadingly.

  “It’s way too early to give up,” I say encouragingly as I hand her a tissue from my Kleenex pile. “These little guys can really surprise you sometimes.” In a lot of terrifying ways, I think.

  “Thank you, Terry.” Hayley embraces me before pulling back self-consciously. “I don’t know what I would have done without you to take her. At least I know she’s getting the best care, even if . . .” She trails off.

  “I’ll do everything I can. But it may be some time before I know for sure.”

  Hayley nods bravely. “Can I call you?” She sniffles.

  “Well, I’m not going to Italy. For a while.” I motion to the collection of nestlings in the ICU whose number has climbed to fifteen in the past two weeks. Hayley laughs and then thanks me again and hurries off into the night.

  After she leaves, I lift Pepper out of the ICU and set her on a low perch in a starter cage. Pepper doesn’t head for the feeder the way Gabriel did. And unlike Gabriel, she doesn’t sit calmly on the perch. Instead, she flaps around in agitation, and I can tell by the strained look in her eyes that she’s in pain. Each time I return her to the perch, she hops off and tries to spin her wings. As she scuttles around the bottom of the cage in a circle, her rotation does not appear as limited as a broken wing. In fact, Pepper’s damaged wing tucks flush against her body when I place her on the perch. And although the rotation of her right wing is considerably slower, the range of motion is only slightly lower than the left. Although I have seen hummingbirds just like this that never recovered even after weeks of therapy, it gives me hope.

  As I watch Pepper flop around in the cage, I contemplate the wonder of the hummingbird’s wing, a miracle of micro-engineering that separates it from everything else on the planet. Other birds have wing bones that resemble those of the human arm: a long bone, or humerus, connected to two “forearm” bones attached to “finger” bones that have welded together into the manus, from which the feathers extend. The hummingbird’s wing, in contrast, has a truncated humerus and forearm bones and consists mainly of finger bones to which the feathers are attached. The wing rotates off a shortened humerus bone, which points down toward the tail and functions like a drive shaft. Most birds can morph, or bend and change, the angle of their wings while flying, but hummingbirds have stiff wings that enable them to hover for extended periods.

  Because of their capacity to brake in midair, hummingbirds inhabit a rich evolutionary niche between insects and birds. To secure this special place in the natural matrix, hummingbirds have developed aerodynamics similar to the high-frequency wing motion displayed by insects. Flying insects have nearly flat wings that travel in a figure-eight pattern, enabling them to gain altitude by using two half-strokes that produce equal lift during the downward and upward motions. When hunting in flight, hummingbirds exhibit the same agile mobility as dragonflies because they have a similar wing motion. But just as their unique wing beat distinguishes them from other birds, the hummingbird’s avian body and wing structure prevent them from flying exactly like insects.

  Over the last sev
eral years, technology has advanced enough for zoologists to transition from decades of educated guessing to verifiable scientific conclusions in their efforts to unravel the fascinating dynamics of the hummingbird wing. Using digital particle image velocimetry—which atomizes a fluid into microscopic droplets that are then illuminated with a pulsating laser as they move through the air while being captured by digital cameras—zoologists have been able to deconstruct the elements of hummingbird flight into comprehensible parts.

  While other birds produce lift with the downstroke, the hummingbird’s ball-and-socket shoulder joints allow the wings to swivel 180 degrees. This flexibility gives hummingbirds—who generate 75 percent of their lift on the forward, or downward, stroke and 25 percent on the back, or upward, stroke—the unmatched advantage of being able to remain stationary in midair for long periods. Adding to their brilliance, hummingbirds invert their wings on the backstroke, curling the leading edges upside down to gain lift. By inverting the inner edge of the wings, hummingbirds scoop air in the same way humans can get a slight lift with an upstroke underwater. And by rapidly spinning their wings in the same figure-eight pattern as insects, hummingbirds generate the high-wattage flight power necessary for sustained hovering, giving them access to nectar-laden flowers unavailable to other birds.

  But sometimes a creature’s greatest strength can also be its greatest vulnerability. And for all of the remarkable maneuverability the complex wing structure affords the hummingbird, it is also an Achilles’ heel that makes the bird highly susceptible to injury. While we cannot determine whether hummingbirds are more prone to wing injuries than other birds or if they just seem that way because adoring humans choose to rescue many of them, broken wings account for a large percentage of the calls coming in to rehab.

  After years of admiring hummingbirds’ surreal flight capacities, I contacted Douglas Altshuler, a professor of zoology at the University of British Columbia who has spent a dozen years studying all things hummingbird. Professor Altshuler measures power output by attaching a rubber harness to a hummingbird and filming it as it lifts a string with small weights in the form of color-coded beads. Through extensive research, Altshuler has discovered, among other fascinating things, that hummingbirds possess the highest mass-specific power of all birds. Simply put, a hummingbird’s power output relative to its size is greater than any other bird’s on the planet, including the mighty albatross that, with its ten- to twelve-foot wingspan, can fly thousands of miles without landing, brave formidable ocean winds, and circle the globe in less than two months.

  Altshuler’s studies also reveal that hummingbirds with shorter wings and higher wing-beat frequency have a competitive edge at lower elevations. Rufous hummingbirds normally flap their wings at a mind-bending sixty times per second, giving them superior burst power. As astonishing as that seems, smaller species like the gorgeted woodstar in Venezuela and the Esmeraldas woodstar in Ecuador have been filmed spinning their wings over one hundred and twenty times per second for short periods. This supernatural quickness allows them to execute vertical motion and gain advantage in battle by flying above bigger birds. It also explains how a diminutive rufous like Chucky is able to dominate larger, longer-winged Anna’s in low-lying regions like the Los Angeles Basin. But once hummingbirds move to higher elevations, the laws of physics prevail, and the rufous loses his advantage for the same reasons helicopters strain above certain altitudes: decreased oxygen leads to a loss of engine power and lower air density limits rotor lift. Above several thousand feet, the rufous surrenders his dominance over larger Anna’s and broad-tailed competitors as he struggles with decreased muscle-contraction frequency and less lift. In other words, when hummingbirds head for the hills, size matters, and Chucky is no longer king of the mountain.

  Since a substantial hummingbird population lives and nests in Pasadena, several professors from Cal Tech have consulted me over the years. They all speak like textbooks. The academic formality of the messages they leave on my voicemail kills me. They start out saying something like “Based on my preliminary investigations, I calculate the fledgling’s approximate age to be . . . ,” or “In researching the nutritional requirements and regional food availability, I have concluded that . . . ,” and so forth. I love chatting with these large-brained scholars. I plunge right into their high-flying diction, throwing out phrases like relative power output required for ascension and aerodynamic limitations based on oxygen availability. My cerebral bird fans eat this stuff up.

  A young research engineer from Cal Tech who called me about a fledgling some students found grounded on campus excitedly pointed out that the motion of the hummingbird’s wingtips produced the infinity symbol. He and a colleague filmed the fledgling in flight and then viewed the footage in slow motion. Of course, this investigation had already been conducted by zoologists who specialize in avian flight, but the temptation to analyze the details of a hummingbird’s poetry in motion proved irresistible to a couple of high-domed professors stuck in a cramped computer lab all day.

  “Her wing-beat frequency is unparalleled. And we’re in awe of her maneuverability,” the professor marveled.

  “So what do you think?” I asked. “Can you replicate her wing movement to design some cutting-edge, high-tech aircraft?”

  “That’s what we were hoping at first,” he answered pensively. “But after reviewing the footage in slow motion”—the professor sighed with resignation—“we realized we’re not even close.”

  “They are amazing, aren’t they?”

  “Unsurpassed flight ability,” he agreed. “She’s so far beyond anything I have ever seen.”

  “And she’s just a beginner,” I point out. “Get her to me so she can learn to execute more advanced maneuvers that will really blow you away.”

  Hummingbirds’ unique wing design enables these flying acrobats to hover, do straight verticals, barrel-roll and somersault, rotate 360 degrees in midair, and accelerate from zero to sixty in a few seconds on a dive. When going about their daily rituals of feeding and sparring, hummingbirds can fly backwards, sideways, and upside down. Because they love fast-moving food, this diversity of motion is necessary for catching fruit flies that have perfected their own quick-escape strategies. Equally important, hummingbirds’ aerial gymnastics are crucial for them to be able to feed on flowers swaying unpredictably in the wind.

  Fledglings in rehab commence practicing sophisticated flight maneuvers their first or second day in the starter cage. Beginners start by flying slowly back and forth between plastic-coated wire perches mounted eight inches apart. Within a few days of taking flight, most execute their first slow and deliberate 360-degree turn midway between perches. Their combined look of concentration and delight at pulling off this astonishing feat is enough to make anybody cry. Oddly, when beginning fledglings hear me applauding their success, they seem motivated to repeat the miracle. Some fly back and forth over and over, deliberately completing one rotation after another until I stop encouraging them.

  After being moved to a larger, two-by-three-foot flight cage a week later, fledglings learn to execute successive midair spins while covering the two-and-a-half-foot distance from one perch to the other. At this point, many stop responding to my encouragement, as if their sublime magic is old news and they cannot be bothered to further impress me. But there are always a precious few who have connected emotionally and will continue to indulge me by repeating their aerial ballet back and forth across the cage until they get exhausted or I walk away.

  By the time they graduate to the outdoor aviary a few weeks later, they have become expert spinners who can perform countless rotations in midair. For some inexplicable reason, young adults in the aviary like to place the tips of their bills on the flat bottom of a bolt that fastens the roof of the aviary to its metal peak and then rotate rapidly, like a top spinning in the air. Some are so adept at this maneuver they can continue rotating for over a minute. Others hang upside down on their perches while mining flowers I have
gathered from around the neighborhood. Once their bodies are completely inverted, they let go of the perch and somersault in midair. Since I position the flowers so they can comfortably be eaten from the perch below, this exercise strikes me as entirely superfluous. I have no idea why young hummingbirds engage in such elaborate gymnastics, other than to sharpen their skills and amuse themselves with their newly discovered acrobatic talents.

  Although most hummingbirds weigh less than a nickel, the speed and agility afforded them by their extraordinary wings give them admirable fearlessness in the wild. Because of their small size and unrivaled quickness, Southern California hummingbirds have few natural predators once they get out of the nest. While fledglings and young adults are not so bold, I sometimes see mature males harassing hawks and other predatory birds that dare enter their high-speed airspace.

  When it comes to intimidation tactics, what hummingbirds lack in size, they make up for in attitude. Recent research indicates that hummingbirds have descended from fierce, six-hundred-pound carnivorous theropods that roamed the planet 220 million years ago. Over the ensuing fifty million years, these dinosaurs began shrinking rapidly, until they evolved into the first birds around 160 million years ago. So despite having radically downsized from their prehistoric origins, hummingbirds seem to have retained their giant ferocity and continue to act as if they still rule the earth.

  Several years ago, a raptor rehabber riding her horse along the Southern California foothills described seeing a red-tailed hawk being chased by a crow that was being tailed by a mockingbird, and, to her astonishment, a determined hummingbird brought up the rear like a border collie herding the whole bunch out of his territory. Hummingbirds’ inclination to take on creatures one hundred times their size is the key to their survival. Without their oversize aggression, these mini-flyweights would not stand a chance of defending their airspace against larger birds in the wild.