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Monthly Nature Almanac - September
Hike of the Month - South Boulder Creek Trail
Fall colors don't just happen in the forest. In September, Boulder's rare tall grass prairie remnants display a kaleidoscope of orange and peach, pinks and yellows, reds and tans. Keep your eyes open for the deep wine-colored stalks of Big Bluestem grass, and the scarlet leaves of wild rose and sumac. South Boulder Creek Trail provides some of the best views of our prairie's changing hues. It can be accessed at many spots, including the Bobolink trailhead and the East Boulder Rec Center. Whether you walk or bike, you will be amply rewarded with spectacular views.
Many Foothills trails provide a colorful show this month. Asters are the real show-stealers. White asters include the Heath Aster and Porter's Aster, which can be distinguished by their foliage. The former has pale-green fuzzy little leaves while the latter's leaves are dark green, long and thin and the plant is less dense. The taller Smooth Aster has purple or bluish flowers, each with a yellow center. Golden Asters sprawl close to the ground. Their flowers are a lovely yellow-orange color. Curly-cup Gumweed flowers look a lot like the Golden Asters, but the plant is tall and spindly. Each flower sits in a small cup with tiny sticky appendages. Touch one and smell the resin on your finger! Dotted Gayfeather is a low plant with needle-like leaves and gorgeous magenta floral spires. Several species of Goldenrod also occur on OSMP trails. They provide nectar for late summer butterflies. And keep your eyes peeled for gentians, which often mark the end of summer. Blue Gentians are only a few inches tall, but so intensely colored that they will reward your search.
Mule deer bucks are growing their antlers this month. Deer grow antlers each fall, then shed them in late winter only to re grow them again in autumn. Antlers are bony appendages that grow from the skull. While they are growing, they are supplied with blood through a network of vessels. When the antlers are complete, the blood flow stops and their thin skin covering, called velvet, begins to come off in strips. Bucks hasten the process by rubbing and scraping their antlers against trees and bushes -- as any backyard gardener can attest! This is a good time to protect delicate saplings and ornamental shrubs with deer netting. Other animals that grow antlers include elk and moose. Bighorn sheep and bison grow horns, which are permanent structures that are not shed and re grown.
Also during September, the summer's new fawns begin to lose their white spots. During the winter they will look like smaller versions of their mothers.
The "Equal Night"
In 2023, fall starts on September 23 at 12:50 a.m. MST. At this precise moment, the tilt of the planet Earth in relationship to the sun will cause the sun to appear exactly overhead at noon on the Equator. If you could stand there, you would cast no shadow! When the sun sets, equatorial residents will experience a night that is exactly the same length as their day -- hence the term equinox, or equal night. For those of us in the Northern Hemisphere, autumn starts at that moment. Days that have become shorter since the Summer Solstice (first day of summer back in June) will continue to grow shorter, eventually culminating in the shortest day of the year, the Winter Solstice . As our days grow shorter, residents of the Southern Hemisphere will be basking in additional daylight. The tilt of the earth causes greater illumination on the southern part of the globe, hence the equal night that heralds our autumn marks their first day of spring!
Are You Putting on Winter Fat?
Seasonal variations in mood and behavior were noted as far back as the ancient Greeks. As the fall arrives and daylight becomes shorter, your body naturally prepares for the coming winter months. This involves a change in melatonin hormone levels affecting your biological clock. For some people these changes result in symptoms that cause significant distress. Such symptoms can include: sleeping and eating more, weight gain, cravings for certain foods, less desire to socialize, loss of interest in formerly pleasurable activities, feeling down or sad, being more irritated, difficulty concentrating, decreased energy or fatigue.
As a result of these changes, many people find their appetite increases during the fall. It is probably no accident that many societies mark the waning months of the year with feasting and eating (think of Thanksgiving, Halloween candy and a big Holiday dinner). Although we can now retreat from cold weather by entering our artificially heated homes, our ancestors in the not too distant past had to suffer through the lean chill months by tapping body fat reserves. People who were able to eat more in fall, and hence store more fat, were more likely to make it through the winter.
Eat, Drink and be Beary
Black bears are also putting on the winter fat they need to survive their long winter's sleep. During fall, bears must eat about 20,000 calories every day. That is the equivalent of 33 McDonald's Big Macs (at 600 calories each). Can you imagine having to eat that much every day during fall? As a result, bears spend about 20 hours a day foraging.
Because bears need a lot of high calorie food in a hurry, they are frequently drawn to human food sources like garbage cans, overflowing dumpsters and food stored outdoors in freezers or cars. Hungry bears may even try to break into homes or campers to satisfy their fall munchies. Bird feeders filled with seed or sugar solution, and pet food left on the back porch, will also attract bears to your backyard. Once bears get in the habit of visiting human neighborhoods for food, they become a safety risk to your family, pets and property. Often these bears have to be put down by wildlife officers to keep you safe.
Learn how to keep bears from visiting your home. You'll stay safe, and save a bear's life in the process!
The Last Word
"Worlds can be found by a child and an adult bending down and looking together under the grass stems or at the skittering crabs in a tidal pool."
- Mary Catherine Bateson