Birds in flight possess flawless instinct. I don’t believe that – after thirty years of daily soaring activity and twice that many on the ground looking up, I know it. What vultures do best is a glorious airborne form of languor. These avians know how to fly S L O W. They commonly glide to windward in search of carrion, inching along very low at hardly more than a walking pace, oddly rocking their wings in frequent stall recovery. No one would attribute that to lousy flying skills. It’s simply the way to fly As Slow As Possible. That’s how the experts do it. They know all this aerodynamic stuff at birth, and in every circumstance the brilliance of instinct is central to their behavior. I’ve seen too many examples to even remember, so let’s settle for the latest.
Two vultures gliding slowly by displayed a subtlety they surely mastered a million years ago, that I’d just never happened to see before. Their staggered formation was loose by airmen’s standards, but the longer I watched the more it seemed ideal for their purpose – they are birds, after all.
The bigger one, older and more experienced, was flying ‘lead’ while the ‘wing’ held position at eight o’clock a few yards back. Mother and son perhaps? Doubt it matters. They were a couple hundred feet up, creeping into a stiff breeze and using periodic boundary layer turbulence for lift. Their ground speed was close to zero when pulling up in it, and maybe double that while ‘diving’ through the associated sink.
In a straight glide, number 2 could not keep up with number 1, who held advantages in wing loading and general proficiency. But as number 1 bore on into the headwind scarcely moving a feather, its ups and downs gave evidence of lift and sink before number 2 entered that same air. Genius lay in what 2 did with this information.
Each time 1 entered lift, 2 would edge toward it and pull up when it reached the lift. Once that was behind them, 2 would slide back to its prior separation. When 1 hit sink, 2 would immediately veer away, and avoid at least some of it. In this way a bird who was demonstrably less efficient managed to keep pace despite flying a longer path.
And all the while, neither of those two avatars once flapped a wing, and altogether expended less energy than you do simply holding your head up to read these words. If people could fly like that without being tongue lashed, CFIGs would be out of work.