This past weekend, my brother and I went traipsing around on top of Mt. Sentinel above Missoula, sniffing ponderosas, arguing about who was more out of breath, and generally frolicking in the cool autumn air. As we walked through an area thick with deadfall and brushy debris near the summit, a thunderous whoosh rocketed from behind a burned log at our feet, exploding into the branches of a nearby Douglas-fir. Startled, we jumped back and reached for the bear spray (we didn’t have any). Then, peering through the dark green branches of the fir, I laughed. A grouse! Smaller than a chicken, and twitching its head at me as I tiptoed towards the base of the fir to get a better look. It was a ruffed grouse, crowned with a mottled mohawk and dappled white and brown and soft orange and tan—near-perfect camouflage among the fall colors.
I’ve always been fascinated by ruffed grouse (known otherwise as partridge, or thunder chickens, or fool chickens). For such a small, skittish-seeming bird, they have a hugely outsized presence in the soundscape of the forest. Prone to hiding stockstill in thick brush until you, potentially one of their many predators, are nearly on top of them, as a last resort they will flush into the treetops with a furious roar of beating wings. But this heart-attack-inducing surprise isn’t the only sound they are known for in the woods.
If you sit quietly enough in good ruffed grouse habitat—typically, mixed-conifer woodlands where fire or other disturbances have created a mix of clearings and denser brush amidst the larger trees—you’re likely to hear the other sound they’re known for, especially in the spring. A low, beating rhythm that starts slow and staccato and then crescendos into a continuous, chopping thrum not unlike the blades of a tiny helicopter. The sound reverberates in your chest like a subwoofer, and is so low that when I first heard it, wandering the forest in early spring as a boy, I thought it was my own heart speeding into arrhythmia.
The sound remained a mystery to me until I was a teenager. On a snowy April walk with my grandfather, we paused near a thick patch of fir and young, brushy birch. I heard that strange, beating thrum: boom… boom… boom, boom, boomboomboom.
What is that? I asked my grandfather. He chuckled, leaning on a walking stick as tall as he was and smiling at me from beneath his orange Stormy Kromer cap.
That’s a partridge out lookin’ for a girlfriend, he said.
Turns out, spring is the breeding season for ruffed grouse. After the long winter, during which grouse escape the cold by burrowing under the snow, the males perch on logs or exposed rocks and try to attract a female. They strut and fan their tails and puff their chests and erect their dark, distinctive neck feathers, fully displaying the “ruff” for which they are named. And they drum, beating that strange, deep rhythm into the surrounding forest.
Early ornithologists believed that the grouse created the sound by thumping their wings together, or against their sides or puffed up chests. The drumming was too fast to see clearly with the naked eye, or with standard film. It wasn’t until 1929 when film technology advanced enough to allow Cornell University’s Arthur Allen to use frame-by-frame video analysis to determine the truth. The drumming grouse was simply beating his wings against air, faster than the speed of sound, essentially creating a series of mini sonic booms that can be heard from up to half a mile away.
So next time you’re enjoying the first sunshine of spring, walking quiet mountain trails through melting snow and patches of brushy young trees and older conifers, pause and listen for a while. If you’re lucky, you’ll hear it. That low, beating crescendo that seems to come from your own chest. If you’re very sneaky, you can try to follow its eerie rhythm through the trees, to a small clearing somewhere, where a little, strutting thunder chicken will be beating sonic booms into the air to attract a mate.
Today’s Field Note was written in the Environmental Writing class at the University of Montana. I’m Lars Chinburg for Field Notes, brought to you by the Montana Natural History Center, providing natural history education for schools and the public throughout Montana. For information on upcoming events and programs at the Center, call 406.327.0405 or visit our website at MontanaNaturalist.org.
