By Ranger Steve Mueller
The sun is directly east everywhere on Earth during the first day of Spring. It is a most dangerous time to drive east shortly after sunrise and west shortly before sunset. Many people have been injured or killed during travel due the Earth’s position on its annual trip around the sun.
Wildlife make hazardous trips at this time of year, when hormone levels rise to stimulate seasonal movement. This week a muskrat and an opossum were killed at Ody Brook as they crossed the road.
Whether you are at the North Pole, South Pole, equator, or at home on this date, the big warming ball of gas is about 93 million miles east at sunrise and west at sunset. The sun does not rise and set. The Earth is spinning one rotation every 24 hours to make the sun appear to rise and set.
The 24-hour spinning rotation is different than the Earth’s revolution around the sun that takes 365 days for one trip. The Earth is held by the sun’s gravity as it is moves in a large loop around the hot gaseous ball. Put your palm toward the sun and feel the warmth. The sun not only warms your hand, it warms your spirit. Attitudes and behavior change as daylight hours lengthen. Like people, animals experience hormone changes in response to day length changes. Animal migration to breeding grounds is under way.
Monarch butterflies are departing wintering habitat in Mexico and are heading north.
It is not just warmer temperatures that influence animal activity. The position of the Earth and sun are important. A North and South Pole line through Earth is not at a right angle with sun. The imaginary pole that extends from the most northern point of Earth to the most southern is tilted at an angle to the sun. The Earth is spinning like a top around that imaginary pole once every 24 hours.
Interestingly, when the northern hemisphere is leaning toward the sun in summer, the Earth is farther from the sun than it is in midwinter when the hemisphere is leaning away from the sun. We are about 91.5 million miles from the sun in winter and about 94.5 million miles from the sun in summer. One would think we would be warmer when closer but the angle of tilt compared to the sun makes the difference. The northern hemisphere is tipped toward the sun in summer when we are farther away causing more direct sunrays to warm us more.
Locally, many birds have arrived from the south by the first day of spring but others are still far south. Some, like Mourning Doves, may already be on nests. American Woodcocks are performing their mating display of dancing on the ground and aerial acrobatic flights high into the sky. Bluebirds claim nest boxes. Eastern Comma and Mourning Cloak butterflies hidden as adults all winter are venturing out on warm days. Woollybear caterpillars not seen since fall crawl in the leaf litter.
During February and March as the equinox approaches, sap in trees and shrubs flows, causing buds to swell. Damaged twigs leak sap. Squirrels and birds tend the wounds to lap the sugar rich sap. Freezing temperatures create sapsickles that hang as icicles when liquid flows from stems but freezes in air. I always enjoy sucking on these frozen sugary treats offered free for the taking by nature.
Look around your yard for nature niche signs of spring that would not occur if the Earth did not revolve around the sun. Near the equator, day length and warmth remains fairly stable all year with a continuous growing season. Daylight length stays close to 12 hours as does darkness. Organisms near the equator do not get to experience shorter day light hours we have in winter or the wonderfully long lighted hours of summer. Enjoy the change of seasons with snow and rain, cold and warmth and animal movements during spring transition as plant growth bursts.
Natural history questions or topic suggestions can be directed to Ranger Steve (Mueller) at firstname.lastname@example.org – Ody Brook Nature Sanctuary, 13010 Northland Dr. Cedar Springs, MI 49319 or call 616-696-1753.