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Chukars are a type of ground-dwelling partridge, and about five years ago Dial's research team was doing an intense investigation on how they grow and learn to fly. Dial is an experimental functional morphologist -- a biologist who studies animal design -- and he wanted to know how baby chukars use their undeveloped wings before they learn to fly. What good are such proto-wings at that stage? What the heck are they flapping for?
Using high-speed digital cameras that shoot 1,000 frames per second, Dial's two high school assistants -- his son, Terry, and family friend Ross Randall -- measured the daily development of the birds. They recorded how far they could fly and run each day.
At first the researchers placed the chukars on an elevated perch, and they would take one down and watch it flap back to its siblings. Then Dial and the teenagers started doing an experiment nicknamed "the Evel Knievel." They placed a flock of chicks on a table and then moved one to another table and watched it return to the group. At first the table was 2 inches apart. In a week it was 3 yards. (Foam pads between the tables protected the young chicks if they fell.) By the end the birds were flying 100 yards between tables.
"The point was we were trying to document on a daily basis how these animals develop performance in flying -- vertically and horizontally -- from the day they hatched until they were adults," Dial says.
Then came a big surprise. Dial went away to Harvard to do some research, and upon returning home his son told him the past week of chukar research had gone terribly.
"They aren't flying anymore," Terry said. "They are cheating."
researchers had just changed their elevated perch experiment. In the past they
had sent the birds up slick cardboard with grids, which helped gauge distance
while the chukars were filmed. Now they were letting the birds perch on bales
of hay, giving the chukars something natural to get their claws into as they
"It was an epiphany," the older Dial says. "Exactly when it happened I knew it would be big. We had a new story that nobody had seen before. The birds were doing something that had never been documented."
Using high-speed cameras, Dial showed how ground birds use their wings like the spoiler on a race car to stick their feet to the ground. It's a behavior used by chickens, pheasants, chukars and many other ground birds to climb straight up a hay bale, rock, tree or almost any other structure to reach safety. The cameras had slowed down the explosion of wings enough to reveal the birds were actually running straight up instead of flying.
Dial calls the bird behavior WAIR -- wing-assisted incline running.
"We filmed a number of tests with different types of textures, substrates and angles," Dial says, "and we found out definitively that the birds don't use their wings in the standard way that birds use their wings to fly. They are using their wings in a novel way, which is much more primitive and reptilian-like ... dinosaur-like!"
Figuring out how birds evolved into flying creatures has been a Holy Grail for evolutionary biologists since the dawn of the discipline. Dial says that for nearly 150 years scientists have been divided into two bickering, theoretical camps regarding the evolution of flight.
The arborealists, who generally are ornithologists, think avian ancestors took wing by climbing and gliding from trees. Many modern snakes, lizards and flying squirrels exhibit this behavior -- climbing and then leaping from trees. The cursorialists, however -- usually paleontologists who note the similarities between dinosaur and bird fossils -- believe early birds ran along the ground, beat their feathered forelimbs and eventually took off.
Dial's research offers another alternative: Bird ancestors flapped their proto-wings to help them run up extremely steep surfaces, giving them a survival advantage. And eventually these wings evolved to the point they became strong enough to allow true flight.
"This also offers an explanation for birds without fully functioning wings," Dial says. "You don't need a wing to support your body up in the air for it to be effective."
Dial seems to relish causing upheaval in the staid arboreal and cursorial worlds. In fact, he got into his chukar research after holding a UM graduate seminar on the origin of flight seven years ago. Students read books on the evolution of flight and then actually talked to the authors in class via speakerphone.
"Our seminar group found out that people have such strong convictions one way or the other that it's almost a religious conviction," he says. "They weren't questioning anymore, and good scientists are supposed to be questioning all the time. We found people were so entrenched in their ideology of cursorial or arboreal that nobody was looking for new data. Sure, paleontologists might be digging up a new fossil, but there was no one looking at behavior of living animals, no one looking at the structures that are required for flight ... so we decided to go looking and generate some new data."
Dial focused on chukars because they could easily be raised from egg to adult. He also had noticed that chicken-like ground birds move around right away, while birds protected in nests grow to adult size before they leave the nest. He suspected something magical might be revealed in ground birds that transition to flying "through an awkward teenage phase."
Pointing to a slow-motion video of a three-day old chukar chick running up a steep incline, Dial says they found that even baby birds use WAIR. However, experiments conducted on large flightless birds such as ostriches, rheas and emus show they don't use their wings for incline running. Their wings remain an enigma.
"I thought maybe we could explain that large flightless birds really have functional wings," Dial says, "but that didn't turn out to be the case."
Later experiments showed that birds running vertically move their wings differently than flying birds, Dial says. Birds running up inclines move their wings from head to rear, while flying birds flap from back to belly. Dial and his doctoral student Matt Bundle discovered this by using sophisticated gadgets such as force plates, which the birds run over, and accelerometers, which actually were affixed to the birds' backs to measure the contribution from their legs and the thrust of their wing strokes.
The researchers learned that newly hatched chukars could master slopes of 45 degrees or more by flapping their baby wings. They conquered steeper slopes as they grew, and adults could sprint up 105-degree overhangs. If their feathers were clipped or removed, these skills declined.
Dial published his research in the January 2003 issue of Science, and the news hit the scientific community like a bomb. Stories about WAIR were published worldwide, and Dial found himself doing interviews with USA Today, the New York Times, the London Times, the Washington Post, CNN, BBC and many other major media outlets.
Dial, a 16-year veteran of UM's Division of Biological Sciences, is no stranger to the spotlight. As one of the nation's leading bird experts, he has been published four times in Science and Nature, the top research journals. He also became a minor celebrity while hosting "All Bird TV" on Animal Planet, and has done other television programs with National Geographic, CNN and Nova. The license plate on his car says "Flight," and he is a commercial-rated multi-engine pilot who flies at least once a week.
Dial is on sabbatical this year -- catching up on research projects and grant proposals -- but he usually teaches Vertebrate Design and Evolution, a class for UM seniors in zoology. He also instructs the Ecology of East Africa, a class actually taught in Tanzania to select graduate students.
The researcher works at the Field Station at Fort Missoula, a former U.S. Cavalry horse stable built in 1907 that has been converted to a state-of-the-art lab facility. The building includes aviaries with a swan, geese, chukars and "the Earth's biggest pigeons." The flight laboratory also has a wind tunnel where you can stand still next to a bird flying 30 mph. Sometimes the researchers take high-speed X-rays of the flying animals, creating videos of flying skeletons. A surgery room lets scientists implant devices into animals to record the workings of their muscles and nervous systems.
Dial says most of his research involves quantifying animal performance. He is interested in how flight operates in animals from the inside out. "I want to know what's under the hood," he says. Using high-tech equipment such as devices implanted on birds, he studies power-to-mass relationships in the animals. He can tell you why -- because of gravity and the viscosity of air -- the upper weight limit for flying birds is about 25 pounds, and the biggest flier is a swan.
He says such interfacing of bird biology with engineering may lead to better planes, more aerodynamic cars and many other applications.
"Biology is the study of life, and it's the most exciting story," Dial says. "There are an infinite number of biology stories out there, and they are more bizarre than science fiction. I'm pretty excited to be a biologist, actually."
-- By Cary Shimek