Dusky Grouse Life History

Habitat

During the breeding season, Dusky Grouse are usually found in or near mountain forests, especially those dominated by firs, ponderosa pine, quaking aspen, and Douglas-fir. Their foraging takes them out of the forests well into surrounding grasslands, shrubsteppe habitats of bitterbrush and sagebrush, and high-elevation subalpine and alpine habitats in summer. Females with young seek out more open environments rich in both seeds and insects. In some parts of the range, Dusky Grouse remain at high elevations year-round, but in other places, they move to lower elevations to winter among white fir, Douglas-fir, Engelmann spruce, western hemlock, mountain hemlock, and lodgepole pine. Individual Dusky Grouse have been found as much as 10 miles from the nearest forest in winter, which suggests that some perhaps winter in shrubby habitats as well.

Food

Dusky Grouse eat mostly plants, but also eat large quantities of grasshoppers and beetles in summer and early autumn. Young birds also eat ants, spittle bugs, and other small insects. Dusky Grouse feed most heavily very early in the morning and again near dusk, mostly on the ground except when eating buds, shoots, leaves, or fruit from taller trees. Like many other birds, Dusky Grouse eat small amounts of grit, which helps them grind foods in the gizzard. In winter, the diet may consist almost entirely of conifer needles and buds, of which they usually eat the outer portion. Hemlocks, grand fir, noble fir, white fir, and Douglas-fir are principal foods. In spring and summer, they take buds and leaves of deciduous plants as well as herbs such as buckwheat, vetch, and clover. Berries such as hawthorn, serviceberry, cherry, currants, bearbeary, blackberry, rose, strawberry, and buffaloberry are eaten when ripe.

Nesting

Nest Placement

Hundreds of nests have been studied by ornithologists, who have found them in very hot shrubsteppe habitats all the way up to cold alpine krummholz (stunted or twisted trees at high elevations) at the top edge of the treeline. Females build ground nests, usually well away from males’ spring territories and away from other females’ nests. Most have some overhead cover, often provided by a shrub but sometimes by rocks, logs, or grasses. A minority of nests are completely exposed to the elements.

Nest Description

Females make a shallow scrape about 6.7 inches across and 1.8 inches deep. They line the scrape with materials close by: leaves, twigs, needles, moss, bark, and a few feathers.

Nesting Facts

Behavior

Early in spring, when snow is still present, males call and begin to perform some initial “flutter flights,” to advertise to females. These are usually short fluttering flights or circular flights from a perch. Males at this time of year drive other males from well-spaced territories, but they are not territorial at other times of year. Male Dusky Grouse are promiscuous and court any female that appears on the territory during the spring. However, no study has revealed whether females mate with more than one male. If a female approaches a male’s spring territory, and especially if she vocalizes, males begin courtship displays, involving hooting calls, strutting, exposing the purplish red skin of the neck sac, fanning the tail feathers, bobbing and drawing in the head, and drooping the wings. Males have no role in nest building or rearing of young. Females with young are aggressive against other females. Females sometimes attempt a distraction display, in which they feign injury and attempt to draw a predator (wolf, bear, human, dog) away from their brood. If this is unsuccessful, they have been known to fly at, and strike, large mammals in order to protect young. Young birds are fully grown in autumn and become independent in their first winter. Both males and females are solitary except when breeding or with dependent young.

Conservation

Overall, Dusky Grouse populations have been stable since 1966, according to estimates from the North American Breeding Bird Survey. Partners in Flight estimates a global breeding population of 200,000 and rates the species rates an 11 out of 20 on its Continental Concern Score, indicating it is a species of low conservation concern. The chief negative impacts on this species probably result from hunting, logging, and grazing, but studies are needed to support these suppositions.

Credits

Partners in Flight (2017). Avian Conservation Assessment Database. 2017.

Sauer, J. R., D. K. Niven, J. E. Hines, D. J. Ziolkowski Jr., K. L. Pardieck, J. E. Fallon, and W. A. Link (2017). The North American Breeding Bird Survey, Results and Analysis 1966–2015. Version 2.07.2017. USGS Patuxent Wildlife Research Center, Laurel, MD, USA.

Sibley, D. A. (2014). The Sibley Guide to Birds, second edition. Alfred A. Knopf, New York, NY, USA.

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