A juvenile yellow-bellied sapsucker (Sphyrapicus varius) pecks at a ginkgo tree at BBG. Photo by Steven Severinghaus.
by Joe Giunta.
What do the wolf, the beaver, and the yellow-bellied sapsucker have in common? Each is a keystone species, that is, a species that by its actions may affect a whole community. In many cases, other species greatly depend upon their actions for food, shelter, and habitat.
As a predator, the wolf keeps certain animal populations, like deer, from becoming overabundant and destructive to the surrounding habitat. The beaver creates habitat for songbirds, ducks, and muskrats by building dams.
The yellow-bellied sapsucker provides not only habitat but also food for other species.
This medium-sized woodpecker is what’s known as a primary cavity-nesting bird. It makes—by drilling into a somewhat decayed tree—a cavity where it can build a nest and raise young.
The next year, secondary cavity-nesting birds like swallows, chickadees, and bluebirds can then move in to nest there and raise their own young.
The yellow-bellied sapsucker is also a great provider of food. It drills many “wells” in living trees that bleed throughout the year. The sap attracts insects, and the sapsucker feeds on those as well as the sap itself.
Other small birds like warblers and hummingbirds, as well as butterflies and bats, also come to these sap wells to feed.
Sapsucker wells have been found in over a hundred species of trees, but the sapsucker seems to prefer trees that bleed more than others, such as red maple and birch.