The adult glaucous-winged gull flew right over the boat as we drifted in Puget Sound. (G. Thomas Bancroft)
The glaucous-winged gull came flying straight toward the boat. It’s wings fixed in a steady glide into the wind. The bird’s speed and the wind created enough lift to allow the bird to close the hundred yards to me without once flapping its wings. The bird was going to fly directly over our boat, and I would be able to look right up at this marvelous example of flight.
Have you every wished that you could fly? When I was young, I dreamed about what it would be like to soar like the red-tailed hawk that flew above our farm fields or to fly like a barn swallow low over the hayfield twisting and turning to catch insects. This gull, so aerodynamic, glided right toward me. Envy seemed to be surging through my veins. As the bird approached, I almost felt weightless and imagined extending my arms to join it as it passed.
My body tensed and my heart sped up as I stared at this perfect example of aerodynamics. This bird’s feathers create a streamlined body, and its skeleton has been modified to be light but sturdy. Most bird bones are hollow, filled with air, and yet can support the torque created by muscle contraction and the pressures of flight. Large breast muscles attached to their sternum provide the power to flap their wings, and their well-developed cardiovascular system can pump large amounts of oxygenated blood to these muscles. They can sustain vigorous activity for long periods of flying, but this gull seemed to glide effortlessly.
Holding my arm in front of me, I marveled at how a bird’s wing is a modified version of my primitive vertebrate forelimb. Bird wings have a humerus, ulna, and radius. The digits are reduced to three, and some bones in the hand are fused together. The primaries — outer flight feathers — attach to the hand bones, and the secondaries attach to the ulna. These flight feathers provide the power for flight. The downward movement of the wing creates lift as well as thrust forward. The upper surface of the wing bends up, creating a convex surface and a longer distance for air to travel than it does across the bottom of the wing. Consequently, the air moves faster over the wing’s top, reducing air pressure, and creating lift.
“Wow. Look at that, amazing”, came from the crowd around me on the boat. I had just missed seeing an orca breach. The gull, however, passed directly over me, and I turned to watch it continue past our boat. I smiled wondering how many of my whale-watching colleagues thought about the wonders of flight.
