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Nature’s Calendar

By Casey Smith, Naturalist

Driving down the highway, I am the person who notices every hawk on a wire, every deer in a field, and every squirrel nest in a tree. I point out every cottonwood tree in the distance, easily identified by the way their leaves flutter in the wind. I make sure everyone in the car knows when we’ve passed cows. And just the other day, I saw the first Ironweed blooming, telling me summer really is coming to an end.

Do you notice these things too? Do you notice which frogs sing at what time of year? Do you notice how the smell outside changes with the seasons? Then you might be interested in phenology. No, not studying the bumps on a person’s head, that’s phrenology. Phenology is the study of recurring biological phenomena and their relationship to weather. Think bird migration, emergence of insects, and the blooming of trees and wildflowers. In Ohio, silver maples are one of the first trees to bloom. Once the red maples bloom, tent caterpillars will start to hatch. If you get to them early, you can easily remove them before they become a problem, possibly eliminating the need for pesticide application. Serviceberry blooming tells us the winter soils have thawed. Long ago, funeral services wouldn’t be held until after the serviceberry bloomed and people knew the ground was thawed enough to dig. Ironweed blooms late in July and August.

A lot of these phenomena happen simultaneously. Instead of planting a garden based on a calendar date, using phenology – nature’s calendar – you may start to time your planting to when a certain species of bird returns to your yard. Watching trends in phenology can help scientists track climate change. Are birds migrating earlier, flowers blooming sooner, or insects emerging faster? Henry David Thoreau kept meticulous records of when local wildflowers bloomed in Massachusetts during the 1850s. Scientists can compare his data to wildflowers today. It’s also valuable for beekeepers so they can track the emergence of native bees.

You can study phenology too. Start keeping a journal of what happens to a single tree in your neighborhood. What insects are crawling on it in June, what birds do you see on it in January? Or find any nearby patch of nature and simply record what you see, hear, feel, and smell. You could also create a phenology wheel like the one pictured below. Plants and animals don’t have calendars but instead take cues from changing seasons. Let the ironweed remind you that it’s time to slow down and take in what’s happening around you.

Interested in learning more about phenology? Ohio State keeps a phenology calendar here. Put in the date and your zip code and see what’s happening in your area.

Phenology wheel
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