A male Dusky grouse in display mode on the Hunter Creek Cutoff.

Among birds on Pitkin County’s open spaces, the Dusky grouse has a reputation like no other. Encounters with this upland game bird can be memorable.

Trail users escaping the wrath of a male Dusky grouse tend to break into a panicked run, shrieking in alarm at a pursuer they will later describe to friends as a “crazy chicken” (if they admit to being scared witless by a bird at all). Some communities have actually posted warning signs to give trail users a heads-up about a particularly hostile grouse.

Hens with chicks can be equally fierce, prompting many a hiker to shamelessly back away.

One of our encounters with a male Dusky on Smuggler Mountain Open Space began peacefully enough but ended with the requisite chase. While we remained stationary in the woods along the Smuggler Loop Trail, the grouse circled curiously, offering a series of low clucks. Once we began walking away, the bird gave chase. The retreat turned into a 50-yard dash with a furious, pecking bird in hot pursuit.

“They can be highly territorial – against everybody,” wildlife biologist Jonathan Lowsky confirmed. Lowsky, with Colorado Wildlife Science, monitors wildlife on various Pitkin County open spaces and has found Dusky grouse at Sky Mountain Park, North Star Nature Preserve and Filoha Meadows Nature Preserve, as well as Smuggler. They likely inhabit other open spaces, as well.

Dusky grouse are “generalists,” meaning they can eat a variety of foods and thrive in a range of habitats. They are doing well in Colorado, as a result, while the Gunnison sage grouse, for example, is federally listed as threatened due to loss of habitat. The rare and localized bird is found only in southwest Colorado and a small part of adjacent Utah. Meanwhile, Greater sage grouse numbers are also in decline and the species is no longer found in the Roaring Fork Valley, though old-timers can recall its former presence here.

The Dusky grouse, Merriam wild turkey and White-tailed ptarmigan are all members of the same family of heavy ground birds (Phasianidae). Pitkin County is home to all three species.

Like many ground birds, Dusky grouse (Dendragapus obscurus) sport inconspicuous plumage that allows them to blend in with the forest. Males, however, will “display” during courtship – a trait shared by most grouse. In spring and early summer, the male will strut about with its tail raised and fanned, and reveal reddish-purple air sacks on its neck as he tries to attract a mate. His muted-yellow eye comb will swell to a rich yellow, orange or red.

The mating spectacle offers a unique opportunity to spot this otherwise well-camouflaged bird, but if a chicken-sized, mottled brown bird chases you down the trail or shoots suddenly upward out of the underbrush, you have likely met the Dusky grouse.

More to know about Dusky grouse

• Dusky grouse and Sooty grouse were first identified separately by Lewis and Clark in the 1800s, but were later combined into a single species – Blue grouse. Ornithologists split them back into two separate species in 2006 after DNA research indicated they are, indeed, two different birds.
• Dusky grouse do migrate for the winter months – by walking uphill, sometimes interspersed with short flights. It is an unusual, altitudinal migration. They spend winters in the trees of spruce-fir forests, where their diet consists of conifer needles and buds.
• In summer, Dusky grouse move to slightly lower altitudes, hang out on the ground and eat mostly plants (berries and buds), along with grasshoppers and beetles. Among their favorites is the fruit of grouse whortleberry, or grouseberry.
• Weighing 2 to 3 pounds, they are the second largest grouse in North America behind the sage grouse varieties.
• Females generally lay 7-10 eggs in the spring. Hatchlings are precocial, meaning they hatch in an advanced state that makes them able to feed and move about almost immediately, even though they are itty-bitty at half an ounce in size. Only hens tend to the young.
• A baby grouse is called a cheeper, or squealer.
• There is a fall hunting season for Dusky grouse in Colorado.
• The patch of bare skin on the male air sack, visible during display, is an apterium (a bare space between the feathered areas of a bird). The plural is apteria.

– By Pitkin County Open Space and Trails

A male dusky grouse blends into the forest on Smuggler Mountain Open Space. The faint eye comb is visible.