Kansas City, Mo. – A freshly chipped, round hole in the tree limb’s outer bark led to a newly excavated cavity, revealing a woodpecker's handiwork. The woodpecker chipped inside the dead locust tree limb this spring and created a cavity, possibly for a nest site. But a thunderstorm snapped the limb from the tree. The limb broke apart at the hollow spot when it hit the ground, a loss to the woodpecker but a lucky new hideaway for a ground-dwelling creature.

Nature sometimes tears down what it builds, but nothing is ever wasted, including a hole in a tree. The Missouri Department of Conservation (MDC) suggests that observing cavities in trees alive or dead, standing or fallen, is a good way for people to spot watchable wildlife using a hole as home. Creatures use hollows created by fungi, woodpeckers, and squirrels as nesting and hiding spots.

“I’m sure if the locust limb had not fallen a woodpecker or squirrel would have used the cavity,” said Krista Noel, MDC natural history biologist.

Missouri has more than 20 species of birds that use tree cavities as nesting or roosting sites. They have neighbors. Squirrels, raccoons, bats, bees, and other creatures also use hollows in trees as a place to hide or live.

Tree cavities can be small or big enough for a bear. Fungi can enter a tree through a damaged spot and consume heartwood without killing the tree. Nutrients that keep the hollow tree’s branches and leaves alive moves up and down in the outer rings of the tree trunk, not in the center. Big trees that appear solid throughout  when standing often turn out to be hollow. A black bear may make a large, hollow oak blown down by a summer storm its winter den site.

Woodpeckers are pioneers at creating small hollows in limbs or chipping into a tree trunk. They may peck away at dead wood looking for insects to eat and keep going. Squirrels, a member of the rodentia order of wildlife, may use their strong teeth to gnaw larger the hole a woodpecker started. Other birds or small mammals finding a cavity unoccupied may move in for a season, to nest in spring or ride out the winter cold.

The hollowed locust limb that fell to the ground can be used, too. Perhaps a lizard or skink needs a hiding spot?

“Even on the ground, whether in the woods or a fencerow, a wood cavity still serves as shelter for smaller animals,” Noel said. “I can see a mouse using it for shelter on the ground or perhaps a toad.  A snake might use it to escape the heat of the day temporarily, and of course insects would use it.”

A dead limb or tree trunk that poses a possible hazard to people and property should be removed. But if a dead tree, or at least the trunk, can be safely left standing in the woods or yards, they serve watchable wildlife, such as bluebirds.

For more information about how den trees and snags serve wildlife, visit https://short.mdc.mo.gov/Z8h.