Have you seen the ad on TV where an owl is talking to a face on a tree? I have seen magazine ads where one can order a kit containing face parts (like Mr. Potato Head), which are used to decorate a tree. This got me thinking about trees that I have seen in the woods, with distorted growth that appears to be faces.

Many trees produce lumpy swellings that are known as burls. Black walnut, black cherry and other tree burls are highly prized due to their colors and unusual distorted grains. A burl is produced by innumerable buds that have failed to develop due to either old injuries, insects or tumors, all of which can cause abnormal growth.

Although a burl can disfigure a tree, it seldom causes the tree to die.

Another unusual sight appearing in trees is that of holes in the tree trunks. Although these holes open the interior of the tree to weather and diseases, they are very important to many types of wildlife.

The openings are caused by the tree’s self-pruning. This happens frequently in stands of old, dense timber, where the lower limbs are shaded by the forest canopy. Without adequate light, these limbs eventually die and break away from the trunk.

The shaded limbs literally starve, which is why so many trees in a dense forest have straight, clean trunks and grow in height rather than girth. Trees in the open can produce more food than those in a dense forest; however, because they do get sunlight their lower limbs neither die nor form hollows.

After a limb dies, the living tissue of the tree’s bark grows around the limb’s base in the shape of a collar. Decay eats into the tree trunk at the spot where the limb fell off. This rotten wood is removed by squirrels, woodpeckers and a host of other birds and animals, and a cavity is formed. The living bark’s tissue around the mouth of the cavity tries to heal the wound.

Each spring, which is the period of a tree’s greatest growth, the tree will try to close the opening by laying down a new layer of scar tissue over the rim of the old wound. To keep the cavity open, animals, such as squirrels, will continue to gnaw at the fresh growth as fast as it appears. Each year, the tree tries to close the opening, and each year the animals keep it open. The five- or six-scar layers on a den’s entrance are visible until the animals finally win.

The center of the tree remains open to the weather and insects, and finally, the tree begins to rot.

White oak trees make ideal den trees because their dead limbs hold the bark, absorb moisture and rot quickly. Some trees, such as hickory, form very few cavities; however, when cavities are formed, it seems that animals do not try to keep them open. This is probably because the wood is so hard.

Other dens are formed when trees are subjected to storm damage, lightning, heavy snow, etc.

Some trees are damaged by the falling of other trees. If a young sapling is bent over from the weight of a fallen tree, the young sapling will grow in a bent over fashion.

For many years, with much pressure from Mary Alice, I decorated our front yard spruce tree with outdoor Christmas lights. I planted the spruce as a seedling, and each year this task became more difficult as the tree grew. Before long, a step ladder was needed.

One year after the holidays, instead of taking the time to get the ladder, I simply pulled on the strings of lights to take them off. The top string became entangled. So, I yanked the string hard. You guessed it, the wire broke and the terminal sprout of the tree bent to one side.

I had a tough time trying to explain to Mary Alice that the line would soon decay, and the tree would straighten. However, many, many years later and the top of the tree still leans toward the house.

Snag trees have always fascinated me, and usually, I stop to check when I see one. Snag trees provide sanctuaries for a variety of wildlife. They are standing dead trees in various forms of decay. According to the National Wildlife Association, they provide habitat for as many as 1200 species of wildlife. Even after these trees fall to the forest floor, many invertebrates thrive in the decaying wood.

For example, ants and other animals, such as mice, can be found living in decaying wood. Mosses and lichens form on these snags and aid in the decaying by returning vital nutrients back into the soil. A decaying log also acts as a nurse log, a place where seeds find it easy to germinate and grow and ensures a next generation of trees. Despite this information from the National Wildlife Association, modern forestry practices encourage the removal of these dead snags.

Whenever I see a tree with an unusual burl or shape, I stop and take a picture. The next time you take a walk in the woods, look closely at the trees and you too will find many unusual tree markings.

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.