An unknown tenant

It is hard to tell exactly what kind of animal is making this hollow sassafras tree its home. Squirrels keep tree den holes from growing shut by gnawing the live bark around the hole. This is a setback to the tree's attempt to heal itself. Pileated woodpeckers will sometimes chip away at a hole like this to gain entry.

Screech owls, various kinds of woodpeckers and other small woodland birds such as wrens and chickadees will use small dens like this for safety from winter cold and larger animals like raccoons. Squirrels will often pack dry leaves into such dens adding insulation and inhibiting drafts if the tree has other holes.

It is not unusual during winter's coldest nights for a den to be shared by a few different kinds of birds and possibly a few mammals such as flying squirrels and mice.

The autumn leaves in this photo are those of a sapling American Beech tree.

Through the Woods is a weekly nature photo column by Aaron Horrell. Find this column at semissourian.com to order a reprint of the photo. Find more work by him at the Painted Wren Gallery.