Sunday, November 11, 2018

Birds in three dimensions

The majestic bird spreads its great wings and gracefully launches itself from the cliff into powerful flight.

Or not.

More than likely the bird steps off the ledge of its high-rise home and when it reaches the correct floor opens its wings to get off its self-imagined elevator. Or, like a day-old Wood Duck chick, fledging from its nest 35 feet up in a tree cavity, it jumps out, bouncing when it hits the ground, and waddles away to the pond.

J.B.S. Haldane, On Being the Right Size (1928) wrote:
"To the mouse and any smaller animal [gravity] presents practically no dangers. You can drop a mouse down a thousand-yard mine shaft; and, on arriving at the bottom, it gets a slight shock and walks away, provided that the ground is fairly soft. A rat is killed, a man is broken, a horse splashes.
"For the resistance presented to movement by the air is proportional to the surface of the moving object. Divide an animal’s length, breadth, and height each by ten; its weight is reduced to a thousandth, but its surface only to a hundredth. So the resistance to falling in the case of the small animal is relatively ten times greater than the driving force. 
"An insect, therefore, is not afraid of gravity; it can fall without danger, and can cling to the ceiling with remarkably little trouble. It can go in for elegant and fantastic forms of support like that of the daddy-longlegs."
As humans we are strongly bound to the ground. We're not as solidly bound to the ground as an earthworm, perhaps, but our experience isn't as unbounded as a bird. We are only now starting to get used to seeing video shot from drones, floating off from the ground up over the roof tops uninterrupted. Yet that is the world that most birds live in.

Birds have the freedom of flight because of their strong breast muscles and wings. Additionally, because smaller birds don't weigh much compared to their surface cross-section, they have no fear of falling. A fall won't hurt them, because the air holds them up. Gravity is still the same 32 feet per second squared, in a vacuum, but in the open air they flutter down gently like a leaf.

Because of their ability to fly, and the lack of fear of hurting themselves in a fall, birds necessarily perceive the 3-dimensional world in a different way than we do. They live more fully in a 3-dimensional world than we can even imagine.

House Finch
House Finch

Watch this funny Suicidal Pigeon video on YouTube.

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