Editor's note: Bill Amos shared the following essay (which appeared in his Vermont newspaper column) with me, and I asked him if I could share it in turn with readers of Micscape as a reminder of our own natural twilight treasures, and to remind ourselves to take the time to appreciate them. It covers wider aspects of nature than microscopy which we hope you enjoy reading.

Now the day is over, Night is drawing nigh. Shadows of the evening Steal across the sky.

 

When I was a boy, our family occasionally attended services known as Evening Prayer, which I remember as a time of winding down, a delicious feeling of relaxation at the end of a long and busy day. It was a time to be alone with one's thoughts, a time for that small inner voice to be heard. Now, at the end of our century, opportunities for near-solitary quietude, for thankful completion of a day drawing to a close, seem lost in the millennial shuffle. Nevertheless, in the "evening of life" (a phrase I saw in a recent magazine), the first verse of a hymn sung in childhood returns to me.

Today when I sense the need, that feeling of long ago is recaptured by walking—or just sitting—outdoors as shadows of the evening steal across the sky. It is a time when the comfort of being in repose, alone or in the company of a loved one, stirs senses at full alert to the dusky changes slowly enveloping us. Bird song is stilled and crickets begin their nightly chorus. Day flowers close as those of the dark slowly open. The whispered passage of a bat tells it is out on the first of its nightly forays in pursuit of mosquitoes and moths flying invisibly overhead.

A cerulean sky turns dark and deepens further into blackness that is only a little paler than the pitch black of nearby forest. The night lights up, first with brilliant planets, then with bright stars, followed by those of diminishing magnitude. A sweater feels good.

For most of us, night is a mysterious pause when our conscious lives are temporarily suspended. We go to sleep and wake the following day, aware there has been a gap in experience, an intervening period when we were absent from the world, that time has somehow stopped. Reality is daytime or its simulation. But this is a mistaken sense, educed from being creatures of the light.

Reality is quite different, of course. "Night" and "day" are no more than periods of shadow and light as the planet rotates on its axis, half the time bathed by the sun, half the time blanketed in the dark. Time is continuous, not interrupted. Nevertheless, what we see as the shutting-down of day and its resumption at the other end of night are interpreted as signals to alter our behavior, to prepare for something different in inherited recollection of a distant creature past. This is the rhythm that orders our lives.

The cadenced pulse of this spinning globe underlies our pendulating concept of day and night, of pleasure and fear, adventure and seclusion, of the very nature of thought processes within a regulated twenty-four hour cycle. We speak in terms of black and white, rarely in shades.

A curious aspect to our governed lives is this: although we live in two worlds, one of light, the other dark, we have almost dispensed with that gentle interval between the two, that period of winding down. Technology and our frenetic existence extend the one side, delay the other, and we neglect the natural transition. It is said we need 8.4 hours of sleep a night, but it seems we begrudge even that, allowing lights to remain on far into that natural and essential bridging of behavior.

As in almost everything else, animals have more sense. And so do plants. Anomalies we may be, but at least we are granted a means of contemplation (which sometimes gets us into trouble). With small effort we are able to reflect upon the meaning of twilight, and much of our understanding comes from observing the life that surrounds us.

In "the hush of evening" before retiring to their underground bed chambers, chipmunks stuff their cheeks with one last load of seed fallen from bird feeders—which in turn are visited in the waning light by the last flurry of chickadees. Off in the woods a barred owl says, "who hunts for you? Who hunts for you-all?" And small animals take note.

Long before they developed elaborate culture and a means of bringing day to night, our distant ancestors, although fully evolved from their hominid forebears, in patterned habit still emulated their animal cousins. When the day's work was done and evening drew on, squatting around a fire to tell stories of legend took only a little time, and before long they went to their rest in darkness and slept for a greater span than our own prescribed eight-plus hours. They awoke with the dawn, took a little while to stretch and eat and rev up, then put in another long, hard day scrabbling out a living, still following the habits of fellow daytime creatures they knew well. But these people of prehistory also populated the night with real and imagined monsters, fearsome in their readiness to do harm. An evil spirit of the dark was as real as a sabretooth cat dragging off a sleeping child in the middle of the night.

Circadian rhythms are how we biologists refer to cyclical day-night activities. Within this periodicity the crepuscular intervals of morning and evening are integral links. But we prefer studies in simpler terms, perhaps the diurnal-nocturnal business of fiddler crabs and earthworms, rather than attending to ourselves, even though by understanding more we might alleviate the almighty disturbance to our own built-in rhythms that result from frenzied lifestyles and intercontinental air travel. By paying greater attention to lesser lives around us, we might learn what it is like to be properly and sanely regulated by light and dark and shades between.

A darkening sky sends bees and butterflies to their rest out of harm's way. Evening twilight is the stimulus for slugs to emerge from daytime inactivity to course over lawn and garden, laying trails of slime that lessen friction between their soft bodies and abrasive soil. During the night their file-like tongues rasp tender leaves, leaving damaged foliage to dismay gardeners the next morning who want the most out of a closing season.

The interval between day and night tells some of the larger beetles to crawl up stems and trunks, split wide their hard protective wing covers that lend shape to their bodies, snap open delicate wings hidden underneath, and fly off into the dark with a buzz. As light fades, moths cluster around porch lights in increasing abundance and astonishing variety. Frogs begin their insistent clamor, and salamanders come out of hiding to hunt upon dew-wet ground. It is time for a changing of the guard.

Twilight is when raccoons, skunks, foxes, porcupines, and woodchucks emerge to forage most busily, to hunt and seek one another. Most of them do well in both dim light and darkness, because keen senses other than vision are more than sufficient to determine where they are going and what they need to do. We should envy them, because we aren't very good finding our way through the woods at night, although I remember reading that when slaves escaped in the South and headed north to liberty, they dared not reveal their presence with lanterns and felt their way through the forest with arms outstretched, lightly touching trunks to determine the direction where freedom lay by the heavier growth of small encrusting plants on the northern side of trees.

Although night in nature can be threatening to us, it's not to many other creatures. Just looking at a thoroughly nocturnal mammal identifies it as a creature of the night with its large protruding eyes, long tactile whiskers, and sound-collecting ears. Tarsiers and aye-ayes, hardly familiar even where they live in Southeast Asia and Madagascar, are epitomes of nocturnal adaptation. And I have watched a slow loris come awake at twilight after a bright and intolerable day even more sluggishly than is usual for its prosimian kind.

Although they fly through much of the night, dusk is the time to see bats as they emerge in waning daylight. I admire bats, partly because of their skillful flight, partly because of their extraordinary ability to locate obstacles and prey by picking up with enormous ears the echoes of their high-pitched squeaks, but mainly I like them because I find them appealing. That puts me at odds with most people.

Lingering daylight is when you can watch these aerial masters at work as they scoop up insects to devour on the wing. If you enter the woods at dusk, you'll notice how a bat flies at full speed through branch openings narrower than its wingspan, as echo-location tells it precisely how much it must bank and tilt to get through. It "sees" with sound, and never blunders into barriers.

And if you prefer the sea to land's perils, you'll find that marine creatures living in the ocean's upper regions are just as regulated by the day-night cycle. Plankton and mid-water fish begin rising close to the surface in twilight and remain there through the night when sighted predators are not so active, then descend to safer, darker regions as the first streaks of dawn filter through the surface. The mini-monsters I've collected at midnight in South Pacific waters could not be taken easily in full daylight. They are enough to make one doubtful about personal swims in the vast ocean darkness.

For the less adventuresome, less traveled, nevertheless curious observer, the same vertical migration of plankton occurs in lakes, even in ponds. In one favorite pond, night was the only time I could capture an extraordinary insect larva, one with huge hooked beak, gas-filled organs of hydrostasis that enabled it to rise and fall in watery strata like a tiny submarine as it pursued prey with nervous vibrating energy.

At the other end of night, when the sky begins to lighten in the east, moths and slugs disappear, crickets grow silent, the bullfrog gives a last jug-o-rum, and owls return to their forest lodging. After being tucked away during the night, small beetles start replacing the big nocturnal ones, and early tentative bird song is heard. Bees and butterflies shiver in the weak sunlight, forcing their chilled metabolism to higher levels. It is a time before most people are stirring, before domestic animals start anticipating attention from their human masters, and before birds burst forth fully in their morning chorus. Go to a magical spot in the mountain forests of Trinidad to be awakened when the sun's rim first breaks over the horizon at the far end of a narrow valley, because it is then that an avian cacophony, beautiful and raucous at the same time, dispels the deepest sleep.

Shadows of the evening, shadows of the dawn, each brings an interim distinct from stygian night and radiant day. For hundreds of millions of years, in every part of the world, on land and in water, each plant and animal has grown attuned to an inner rhythm set by twilight.

Then we come along and try to change things, at least for ourselves, and can't understand why we suffer the consequences.

 

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Comments to the author Bill Amos welcomed.

© 1999 William H. Amos

Bill Amos, a retired biologist and frequent contributor to Micscape, is an active microscopist, naturalist and author. He lives in northern Vermont's forested hill country colloquially known as the Northeast Kingdom.

Editor's notes: Other articles by Bill Amos are in the Micscape library (link below). Use the Library search button with the author's surname as a keyword to locate them.

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Published in the November 1999 edition of Micscape Magazine.

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