This space overlaps the territories of several females that risk their safety in walking some distance to investigate the drumming males. It is also a territorial announcement that tells other males, “stay away - this territory is taken!” In good habitat, male grouse tend to space themselves so each defends an area of about 10 acres, allowing them sufficient resources to survive. However, the shock waves of drumming carry effectively through the forest.ĭrumming advertises the male’s presence to female grouse. When it’s time to attract a mate, the male lacks a singing voice, and even if he had flashy colors, they would be lost amid the vegetation. They live solitary lives for the most part. Grouse are secretive forest floor foragers that rely on cryptic coloration and the cover of dense thickets to evade a long list of predators, including foxes, coyotes, fishers, bobcats, owls, and hawks.
So why, one might ask, would a bird go to all this trouble? If you hadn’t already guessed, it’s all to do with mating. The rigors of drumming cause a male grouse to lose 10 percent of his body weight during the spring season.
#Peregrin falcon sound barrier crack
By the time the wave motion reaches the whip’s end, the tip is moving at the speed of sound and the crack is its sonic boom.
#Peregrin falcon sound barrier series
The whip moves in an up-and-down series of waves along its length that undulate with increasing speed as they approach the tip. If you’re lucky, you’ll be rewarded with an explosive crack. Take a bull whip and flail with all your might. With a bit of practice, you too can create a sonic boom. Novice males have been observed going through all the motions and not producing any sound at all. For a one-and-a-quarter-pound grouse to exert such force takes strength and perseverance.
This causes the sound waves to “pile up” into a penetrating shock wave, also known as a sonic boom. The bird stands bolt upright on a log, leans back on his tail, and fans his wings vigorously – so fast, in fact, that the wings achieve the same speed as the sound waves generated by their passage through the air. People once thought that male grouse struck their wings on a hollow log to produce this low whumping, but better observation revealed something far more astonishing. This mechanical noise, of course, is really the drumming of a male ruffed grouse. I’ve been fooled by this sound, wondering who could be trying to start a 2-cylinder engine in the middle of the woods. A distant motor thud-thud-thuds as if trying to start, then dies away.
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