Have you noticed that birds are losing their minds in the morning, singing their hearts out as dawn breaks? There’s a reason for that. Their avian “alarm clocks” went off a little while back and launched them into full-blown springtime behavior. Didn’t know birds carried clocks? Oh yeah, they’re just as messed up as we are. Even plants aren’t exempt. Built-in biological “clocks,” governed by the length of daylight and called photoperiod, control and affect all plant and animal life by changing their production of hormones and other biochemicals.
As their biological clocks report shortening days as summer ends, birds migrate south. Bears and ground hogs prepare to hibernate. Poultry farmers provide their inmates with artificial light so that their chickens don’t stop producing eggs. Dogs and many other mammals grow a thick layer of fine-textured undercoat for winter insulation. Green plants stop producing green chlorophyll and autumn colors begin to show.
In the spring, as days become longer, everything reverses. Bird’s chronometers trigger renewed sex drive and the first tickling urge for migration north. Plant buds swell, new green leaves and flowers emerge, while cats and dogs shed fur all over the place. Time is our tether and the birds are telling us so!
Clocks rule the world! Don’t think so? Do you believe punctuality is a measure of character, personal efficiency, and reliability? Do you strive to be on time; not too early and never late? How many clocks do you have in your home or office? Do you wear a wristwatch or carry a pocket watch, or constantly refer to the digital time on your phone? Do you have a personal planner or PDA that dictates activities for your day, week, month, and year? How many activities and appointments are sprinkled all too liberally across every week of your life? Do you sometimes wish each day could have 26 hours because you can’t fit everything in? Our lives revolve around schedules and time limits.
Lifespan, pulse rates, rates of speed, sun or moon rise and set, awakening, sleeping, appointments, and meetings are just a small sample of timed events. We even slip the nasty term “time” into everyday words - daytime, nighttime, mealtime, and local time and then adjust it with Daylight Savings Time. Most frightening of all is the dire word “deadline!”
If you watch it’s pretty apparent that beginning about December 21, days become progressively longer, reaching a maximum length about June 21. These two dates are called the winter and summer Solstices, a word meaning the time when the sun stands still, when the sun appears to slow or pause for a few days before it gradually reverses its elevation in the sky. Halfway between these two points, about March 21 and September 21, the Vernal (spring) and Autumnal (fall) Equinoxes occur when day and night are exactly equal.
We too are strongly affected by the length of day and also the intensity of the daylight. Short days and overcast skies increase feelings of anxiety and gloom. Physicians call this Seasonal Affective Dysfunction (SAD), a condition that can be alleviated by exposure to bright fluorescent lights that stretch the day as though the sun shined longer, tricking our biological clocks into the impression that it’s really spring or summer. For years, researchers thought this effect was solely a visual response, but some recent investigations show that the same effect can even be produced by shining the lights on the back of the knees! Is that strange or what?
Keeping track of time is not just of interest to modern people. The annual movement of the sun, the source of all our light, energy, and food was carefully observed by ancient people such as the Mayans, Aztecs, Toltecs, Anasazi, Druids, Celts, Romans, and Greeks. Religious ceremonies and festivals, as well as crop planting and harvest, were all correlated with the time of the year, as well as the positions of the sun, moon, and various constellations and stars.
So here we are, in the lengthening days of early spring. “Shadows of the evening steal across the sky” later each day, and the sun slips over the eastern horizon a bit earlier every morning. Take heart. Go perch on a branch and sing a little. It’ll lighten your burdens for a while before your grass gets the message and endless mowing begins again. I’d write more, but right now I have to hurry and get to an appointment!
Dr. Risk is a professor emeritus in the College of Forestry and Agriculture at Stephen F. Austin State University in Nacogdoches, Texas. Content © Paul H. Risk, Ph.D. All rights reserved, except where otherwise noted. Click firstname.lastname@example.org to send questions, comments, or request permission for use.