What birds can teach us about flight
Researchers in Montana study birds — even ground birds — to understand more about the power of flight.
Ken Dial is a veteran pilot, qualified to fly a range of jets and other aircraft.
But the fliers this biologist admires most are the birds he studies at the University of Montana Bird Flight Lab.
"The 'aha' moments for me are when I realize I am looking at 10 different gauges to allow me to fly nice and steady and stay coordinated. I'm doing so with the help of so many different sensors," says Dial. "And, I'm just amazed at how a bird does the same thing but can actually make such extraordinary maneuvers, and keep its 'cockpit' perfectly fixed in space while its whole body is twisting around it."
With support from the National Science Foundation (NSF) for more than 25 years, Dial and his team in Missoula, Mont., have revealed more about the origin of flight. Many findings come with the help of sophisticated equipment, such as wind tunnels, lasers and cameras that can record 1,000 frames per second! But a lot of knowledge comes from keen observation, both inside the lab and out in the field.
Some of Dial's discoveries have come from comparing various species of ground birds, which are often on their own from the day they hatch, with bird species that receive a lot more parental attention, such as common songbirds.
With songbirds, for example, "Their kids are born thermally susceptible, they have to be warmed by the parents, they have to be fed by the parents, protected; the parents build a nest for them, tell them to shut up, and stay there 'till I come back with food, and don't let somebody eat you!" Dial explains, with a laugh.
Ground birds, on the other hand, have to deal with the vagaries of the environment the day they hatch. "That is, they better pick up and run or they become someone's dinner. And so they have a proclivity to just get up and run, or if they find an elevated refuge — a slope, it could be a boulder, it could be a tree trunk, it could be a cliff ledge — they'll tend to try to get up there," continues Dial. "So there's some behavior going on there that we didn't appreciate."
That behavior involves how the birds use their wings, even before the wings are capable of flight. Dial describes it as "Wing Assisted Incline Running," or WAIR.
"So they employ their little baby wings to effectively just stick to the substrate as it gets steeper and steeper and steeper. So their hind legs are doing much of the work, but their forelimbs are complementing their hind limbs like a spoiler in a racecar. And, with these little wings, they are able to accomplish very important behaviors. That is, to get to a safe place to live to see tomorrow," he explains.
Dial and his colleagues have videotaped more than 20 species of birds, from hatchlings to adults, showing that they all employed the same WAIR strategy of using their wings from day one, whether pigeons or quail or parakeets.
Bret Tobalske, who has taken over for Dial as director of the Flight Lab, bikes to work in the rugged terrain and temperature of Missoula. He, too, understands and appreciates the sheer physical abilities of the birds he studies.
"Birds are remarkable athletes," Tobalske says as he places a perch with a parakeet into the lab's wind tunnel. "It's got an air speed of 10 meters a second, that's about 22 or so miles per hour, so it is extremely fast. It is beating its wings approximately 18 times per second. And then you'll notice small hitches that we can see with our eyes, which is when it is tucking its wings in. Those are called bounds, kind of like how a kangaroo bounds. The idea being they are bulleting through the air or bounding."
As a biomechanist, Tobalske blends physics and biology to understand the mechanics of flight, such as the intermittent flight style of the parakeet. "While birds inspired early human flight, supersonic flight has little to do with animal flight," he notes.
"In the last 15 years, there has been a growing interest in drones, slow flying robots that imitate large insects and small birds. Hummingbirds are a prime model for that," says Tobalske. "So, there's an incredible amount of effort going on to develop miniature autonomous vehicles. They're self-powered, and they imitate living organisms."
According to Tobalske, another practical application in studying bird morphology might come from a fuller understanding of muscle performance. Realizing how birds can fly thousands of miles without stopping could assist in developing better physical and occupational therapies for humans, or more effective treatments for neuromuscular disorders.
Tobalske says technology has improved dramatically for doing fieldwork as well as work in the lab.
"I'm very excited that the technology has come so far, that we are able to get cameras outdoors and study three-dimensional motion, meaning not just a single point-and-shoot video camera, but multiple cameras, staged so we can watch an animal moving, we can monitor air speed, and come up with a full resolution. Remarkable high quality compared to what was possible even 10 years ago," he says.
Over the years, Tobalske and Dial have also become familiar with bird personalities, with a few real surprises.
"We see a hummingbird or a teeny songbird as being so delicate and cute and inquisitive, and so lovely and fragile," says Dial. "And we're always blown away that sometimes a hummingbird will come right up to you and start to investigate, usually something red on your shirt. And it does so because it sees you or me as a sloth. It has extraordinary power, big muscles moving these wings at extraordinary speeds, so that it sees us, even if we have intentions to grab it, and it can go and fly away."
On the other hand, in spite of their fierce demeanor, big birds are not always so tough.
"An eagle, furrowed brows, big talons; tough looking animal, killing-looking machine is actually a kind of a crybaby, a scared little bird. If you approach, an eagle will fly away immediately because it's threatened by you. In its mind, you could advance on him," says Dial. "So there's a wonderful world of investigation into how size influences behavior, not the other way around. That's a new perspective of how to look at animals, and we're excited about that."
It's not just living birds that are part of studies at the Flight Lab. Research includes efforts to better understand how fossils relate to modern birds. Dial looks for the developmental correlation between the baby birds he's studying now and fossils from millions of years ago.
"Just looking at the anatomy of most of the theropod dinosaurs, we see these monstrous hind limbs. And they've committed a tremendous amount of their anatomy to their hind limbs and tail. We know that they, for the most part, stood upright and ran like the wind, as many birds do," he says.
Dial works and lectures around the globe, speaking to everyone from kindergarten students to neurosurgeons to NASA, Boeing and the Air Force about flight, air safety and evolution.
"I want to share with them what we are discovering, so they can take it down avenues that I can't. So I am hoping to be a spark plug for some new ideas. We are confident that the data we are generating will help us better understand basic elements of the aerodynamics, ecology and evolution of avian flight," says Dial. "Investigations into the development of flight among various species, has provided a wealth of new questions as well as solid answers about the fantastic adaptations of natures' flying machines at each stage of development."
The research in this episode was funded by NSF through the American Recovery and Reinvestment Act of 2009.