By Lee Franks
When we think of bird sounds, singing is the first thing that comes to mind. But many birds have found other ways of generating acoustical signals to serve functions usually accomplished by songs. Some bird sounds are produced with their bills, feet, wings, or tails. The best known use of bills to produce auditory displays among North American birds is the drumming of several woodpecker species. They do this by striking their bills against a hollow or dried tree branch, or, to the annoyance of many homeowners, metal gutters, drainpipes or even trashcans.
Why do woodpeckers peck wood? They want to get the insects hiding underneath the bark. Woodpeckers have extremely acute hearing and are capable of hearing bugs crawling around under bark. If they don’t hear them, they surely can feel the vibrations the insects create as they move about. Powerful muscles and a tough bill are necessary to produce the tremendous force needed to break through the bark. But while the woodpecker is pounding away at the bark, its brain is being subjected to hundreds of pounds of force. Any other bird’s brain would be turned to mush, but the woodpecker’s brain has a cushion that absorbs this pounding. The apparatus that supports the use of the bill is impressive: strong, grasping feet (2 toes pointed forward, and 2 backward) that work in concert with stiff tail feathers to form a triangular brace, allowing the bird to position itself for its strenuous pecking.
After the hole is drilled into the tree, how does the woodpecker get the bug out? It can’t grab it with its bill, because the bill is the same size as the hole. What it does is insert its long, sticky tongue, which is 3 times longer than its bill, into the hole, catch the insect, pull it out and eat it. But where does it put this long tongue when it’s not using it? It’s too long to keep in its bill, but it can’t be left hanging out. What the woodpecker does is stick its tongue into a nostril up inside its skull and wrap the tongue around its skull, under its skin. An illustration of this tongue management mechanism, can be found here: Why woodpeckers can hammer without getting headaches.