Outdoors: Ruffed grouse drumming
During the Interlochen Arts Camp Season, it’s not unusual to hear the sound of drumming in the woods. It’s usually a percussion major practicing.
In the spring at Interlochen, the sound of drumming can be heard in the woods, but technically, it is not percussion.
In music, drumming is defined making sounds by striking a membrane stretched across the opening of a hollow cylinder.
Spring drumming is created by a chicken-sized bird called a ruffed grouse.
Though the male of the species often sits on a hollow cylinder (a fallen log), he is not striking the log, his own body or anything else.
In the wonderful reference book, "The Audubon Society’s Encyclopedia of Birds," John Terres wrote, ”The drumming sound, as first proved by slow-motion pictures by Arthur A. Allen, results from the grouse’s cupped wings striking nothing more than air. The pitch of the sound produced by the wing beats has been placed between A-flat and B-flat and anyone with normal hearing [and certainly the females he is trying to attract] can detect the drumming of a grouse."
The thumping starts very slowly but accelerates to a rapid whirring sound.
One might think that a drumming grouse would be a sitting duck, but while drumming, these birds are rarely killed by owls or other predators.
According to research, an owl’s hearing ranges from 7,000- 60 cycles per second, but the drumming sound is produced at the low frequency of 40 cycles per second.
So owls can’t hear them, but we humans can celebrate the drumroll announcing spring.