The leaves have been rapidly changing colors and, with the help of the wind, many trees are already shedding their leaves. Through the years, I held a state game lands tour on one Sunday during the fall, which I tried to coincide with the leaves at their peak of color.

This year in Bradford County, I think the leaves will peak during the second week of October.

Predicting when leaf color will peak is a challenge because not all leaves change color at the same time. For example, the walnut tree is one of the last trees to produce their leaves in the spring and one of the first trees to shed their leaves in the fall. The leaves of the white birch and dogwood trees change early, while the beech and the oak trees will be some of the last trees to lose their leaves. Deer hunters know that young beech trees will sometimes hold their leaves well into the winter months.

The sumac trees have many different colors on the same leaf, and a combination of colors is sometimes seen on one tree.

Pennsylvania has 127 species of trees. This is because the southern forest meets the northern forest in Pennsylvania. Although many tourists travel north to Vermont to see the fall foilage, especially the sugar maple, the show does not compare with the brilliant reds, oranges and yellows of Pennsylvania’s trees.

Those that ask why a tree’s leaves change colors will receive many different answers. In my youth, I was sure the leaves changed colors due to the frost. However, frost is not the reason, but it does have some effect on the leaves. During one fall, the leaves are rich and varied in deep jewel-toned shades of color, while, in other years, the colors are faded and drab.

This is due to an early hard frost that killed the leaves before changing, preventing the trees from producing their brilliant colors.

Native Americans believed that the leaves changed their colors when the Spirit Bear, in the star constellation Ursa Major, was slain by three Spirit Indian hunters.

The star group that is known as the Big Dipper was called the Great Bear by the Native Americans. The four stars in the cup of the Big Dipper made up the body of the bear, and the three stars in the handle represented the three Native Americans. A dog, by the name of Alcor, is a faint star next to the second Native American in the handle.

Throughout the summer, the star constellations have been moving across the sky. The Native Americans believed this occurred because the three spirited natives were chasing the Spirit Bear. Every October the Native Americans caught and killed the bear.

The blood from the bear dripped from the sky and fell on the leaves, turning them red. When the bear’s meat was cooked, fat splattered out of the pot and stained some of the leaves yellow and brown. Since the bear was a spirit bear, he never died, and the hunt has been repeated year after year.

The Big Dipper is probably the most recognizable star formation in the northern hemisphere, however it is not considered a constellation but rather a group of stars called an asterism.

Credit has also been given to Jack Frost for the changing of the leaves’ colors. It was believed that he would spend the cold nights of fall painting the leaves while dashing from tree to tree. Today, botanists explain autumn’s colors using no imagination at all.

Their explanation is that the shorter days signal the tree to cut off the water supply to the leaves. Just as the birds and animals know it is time to prepare for winter, so do the trees.

A special layer of cork cells is grown at the base of each leafstalk. This blocks and weakens the connection of the leaf. Eventually, the leaf falls from the tree, due to its own weight or the wind and rain.

The leaves change color due to the carotenoid in the leaf, which was there all the time but hidden by the chlorophyll. When the chlorophyll fades away, the leaves show their real color. With clear, sunny days and temperatures dropping to 45 degrees at night, the chlorophyll disappears.

Now, three other chemicals begin to show their colors: xanthophyll (a chemical present in egg yolks) which makes the leaves yellow; Carotene, which produces the orange color in leaves; and anthocyanin, which gives the red and purple leaves their colors.

These two colors appear as stains on the leaves and are water soluble.

Lots of sunny days and cool nights are essential to produce brightly colored leaves. These conditions cause sugar to be trapped inside the leaf and when this happens, the red pigment anthocyanin is produced.

At times, a combination of colors can be seen on one tree. For example: A sugar maple tree may have red, yellow and orange leaves. The bright sunlight produces the red leaves; the yellow leaves will appear on the shaded side of the tree and the orange is a combination of the yellow and the red showing through the leaves.

Well, this fall I suggest that you become a leaf peeper and take a ride in the mountains and see one of nature’s greatest shows, the changing of the leaves.

Bill Bower is a retired Pennsylvania Game Commission Wildlife Officer. Read his blog and listen to his podcasts on the outdoors at www.onemaningreen.com.