Nature at Five Rivers


Snags in the Woods

Now that the leaves are off the trees, we can see all the "snags" in the woods. While those of us who canoe and kayak know snags as dead wood in waterways that blocks access and traps boats, in forestry parlance, snags are dead but standing trees.

What looks like rotting timber to us is a multiuse opportunity for wild things. Birds, small mammals, and other wildlife use snags for nests, nurseries, storage areas, foraging, roosting, and perching. Snags occurring along streams and shorelines eventually may fall into the water, adding important woody debris to aquatic habitat. Decayed snags often have more and larger cavities for shelter and nesting. Snags enhance local natural areas by attracting wildlife species that may not otherwise be found there.

Any tree can become a valuable snag. The process begins with a hard snag, or a tree which is partially or totally dead but still has its bark and inner tissues largely intact. Woodpeckers are especially attracted to such trees and, as "primary nesting cavity birds", start excavating nesting cavities. Since many woodpecker species don’t nest in the same hole twice, bluebirds, swallows, chickadees, nuthatches, house wrens, wood ducks and owls, "secondary nesting cavity birds" that cannot excavate cavities themselves, move in next. At Five Rivers, an Eastern Screech-Owl, a secondary cavity nesting bird, continues to use the snag on the Woodlot Trail. Meanwhile, the tree continues to decay, creating a soft snag without limbs and often without a top. The remaining hulk eventually falls over, but still provides food and shelter on the forest floor.

Check out the exhibit about cavity nesters in the Five Rivers visitor center. It’s called “Home Sweet Hole.”

We are often much too neat! Nature would benefit if we left more rotting stumps and standing snags.

Adapted from a 2015 article by David Chinery, Cornell Cooperative Extension of Rensselaer County