SKYWATCH FRIDAY: Passing Thoughts

“Beauty has as many meanings as man has moods.
Beauty is the symbol of symbols.
Beauty reveals everything, because it expresses nothing.
When it shows us itself, it shows us the whole fiery-colored world.”
—Oscar Wilde

AutumnSunrise

“Beauty has as many meanings as man has moods.

Beauty is the symbol of symbols.

Beauty reveals everything, because it expresses nothing.

When it shows us itself, it shows us the whole fiery-colored world.”

—Oscar Wilde

In the early morning hours I stand at the kitchen window, alone with the silence and my thoughts. The last few stars fade overhead as a pale glow touches the treeline across the lake.

To my surprise, a late-feeding bat appears over the meadow, making a wide sweep at canopy level. The bat passes just a few meters in front of the window. Suddenly it lurches to the side, down, then rapidly forward. Such maneuvers make bat flight appear haphazard and clumsy, but I know better. Bats are expert fliers, rivaling birds at every turn.

I think about the amazing structure of a bat’s wing. Evolutionarily, this wing and my arm are homologous—they have the same basic skeletal structure, which can be traced back to a common (if very distant) mammalian ancestor. In x-rays this homology would become immediately apparent. The main difference, of course, is that the little flier’s finger bones are proportionately much longer. A bird’s wing has fewer, more robust bones. This sturdy framework provides easy lift, even from the ground—but far less flexibility. Bats can not only bend the elbow but move each digit independently to make rapid changes in flight direction and speed. (What about the thumb, you may wonder? This shorter digit protrudes from the leading edge of each wing, serving as a grappling hook and all-purpose tool.)

463px-Arm_skeleton_comparative_NF_0102.5-2

This image, from a 1909 book by William Leche, depicts the homology of forearm structures among eight groups of vertebrate animals.

When hunting small prey, such as micromoths or mosquitoes, a bat may simply grab the insect in its mouth. Scientists at Wake Forest University have found that large prey, such as tiger moths, are handled differently. The bat zooms up to a large insect and sweeps it up in a wing. Then the insect is dropped into the cupped tail membrane. Finally the bat bends forward and gobbles up the prey, as if eating from a bowl. Keep in mind that all of this happens in milliseconds, while the bat is midair. Scoop—gulp—swoop! The red bat, one of our local species, shaves a step off this routine. It flies under the prey and executes a forward roll, making the capture directly into the tail membrane. So efficient.

As “my” bat flutters into the shadowy woods of our neighbor’s property, I idly hope its aerobatic foraging was successful. Moments later my attention is diverted to the bottom of the hill, where robins have begun to pour from the canopy of a big maple tree. They emerge in groups of two, six, then dozens at a time. Flying low over the meadow, their dark silhouettes cross those of Canada geese on the lake.

Now my meditative silence is officially broken. Robins chuck worriedly as they settle on the lawn for breakfast, and the geese wish each other good morning with a noisy chorus of whistles and honks. Another familiar morning sound comes from within my own home: the contact call of a Blond-Haired Boy.

There’s just a moment more to gaze out the window. Golden light reflects against low clouds and back onto the water. It’s a moment of simple beauty. I can’t pass this to anyone else. But I’ll carry it with me through the day.