Phenology Files: May 2023

phenology fi-ˈnä-lə-jē n 1 : a branch of science dealing with the relations between climate and periodic biological phenomena (such as bird migration or plant flowering) 2: periodic biological phenomena that are correlated with climatic conditions.

The Drums of Spring: Ruffed Grouse

It’s early May and you’re hiking in the woods near a river on the Olympic Peninsula. Suddenly, you hear drumming that starts off slow and speeds up coming from the brush. You think to yourself, “is someone trying to start a generator out there?” Well, maybe… but it’s much more likely that you heard a heard a male Ruffed Grouse (Bonasa umbellus).

Ruffed Grouse in the Quinault Valley by wildnettle on iNaturalist.

The Ruffed Grouse is the most widely distributed game bird in North America, with a range stretching from the Appalachian Mountains across Canada to Alaska and down to the American Pacific Northwest. Breaking down its Latin name may make you giggle. The genus, Bonansa, translates to something along the lines of “good when roasted.” The species name, umbellus, refers to the dark ruff of feathers that males show off in courting behavior. The Olympic Peninsula has its own recognized subspecies – Bonasa umbellus castanea.

Riparian areas (the habitats around streams and rivers) are generally where you will find Ruffed Grouse in the Pacific Northwest. They sometimes hang out in areas with more disturbance like logging or fire because younger stands of trees provide them with food and shelter. While you may not actually get a chance to see the secretive and well-camouflaged ground bird, you are much more likely to hear their signature engine-like drumming when the males are trying to court females during mating season.

Mating season arises in late April and lasts through May, when food resources become more abundant for the females so they can produce healthy eggs. Mature Ruffed Grouse feed almost entirely on plants, including leaves, buds, and fruits of ferns, shrubs, and woody plants. Chicks will feast on protein rich bugs. Males seek out prime habitat to claim as their territory so females and chicks will have ample food and shelter. The males then “drum” to attract females to them and their territory. Some males drum in the same territories for several years!

While it looks like the Ruffed Grouse gives its chest a hearty beating during the “drumming,” these sounds are actually created by air. Quick rotations of the wings back and forth allow air to rush under the winds and make a mini vacuum. The deep, thump of the drumming sound created by this vacuum can travel for up to a quarter of a mile. They mimic this same behavior when defending their territory. Check out the video below to see a demonstration!