North America's largest forest dwelling grouse, the Sooty Grouse was split off from the Blue Grouse in 2006, and is now considered a distinct species. Found in pine forests near the Pacific coast, this relative of the turkey depends on fire to open the woodland and replenish herbaceous plants and trees. In spring, the male's deep, owl-like "hoot!" can be heard over a quarter of a mile away.
Measurements for the Sooty Grouse have not been separated from those taken for Blue Grouse, but are probably very similar, with weight averaging 2.3 pounds (males as heavy as 3.3 pounds), wingspan about 23 inches, and length about 20 inches. This fairly large, ground dwelling bird looks somewhat like a chicken. The male's body is dark gray overall with a black tail tipped with light gray. The black head and neck are accentuated by yellow combs over each eye. On both sides of the chest, the male can display a bare, yellowish air sack surrounded by bright white feathers. Female Sooty Grouse are grayish brown overall. Both sexes have small, dark bills and thick, dull yellow legs. Compared to the Dusky Grouse, the Sooty has darker plumage, a yellow rather than red vocal sac, and a louder six-note hoot, rather than a soft five-note call.
From northern California north to southeastern Alaska's Glacier Bay, the Sooty Grouse occupies a narrow range between the coast to the Cascade range. One exception is an inland range extension into California's Sierra Nevada Mountains. This grouse no longer occurs in southern California. The geographic overlap between Sooty and Dusky Grouse, the other part of the Blue Grouse split, is not well mapped, but in general, the Sooty Grouse occupies the coastal and adjacent regions of the Blue Grouse range (west of the Rockies) and the Dusky Grouse occupies the Rocky Mountain and nearby inland portions. The Sooty Grouse is locally common in its range.
Sooty Grouse habitat is often shaped by fire or severe weather, as both create openings in evergreen forests. For both cover and food, key components are grasses, herbs, and shrubs. This grouse frequents the brushy seam between meadows and forests, forest clearings in the early and middle stages of succession, and more mature stands of hemlock, cedar, spruce, and white fir in winter. For some populations, aspens are also important in winter. The Sooty Grouse occurs from sea level up to the alpine zone.
The Sooty Grouse eats a wide variety of plant material that varies with the seasons. Their warm weather diet includes the leaves of herbs, flowers, ferns, and conifer needles. Over 90% of the winter diet consists of conifer needles. The grouse clips fir, hemlock, and spruce needles from trees, and digests them with the help of a powerful gizzard, which requires grit to be effective. The Sooty Grouse also picks many fruits and seeds, including cherry, currents, forbs, huckleberry, and strawberry. For their first month of life, young Sooty Grouse depend on ants, beetles, grasshoppers, and other insects.
In late April and May, the male Sooty Grouse vigorously defends a territory and attracts multiple mates with a series of six loud hoots given from a tree. He also growls, postures conspicuously, and fights with other males. Pair bonds probably only last through mating, and the hen moves off the male's territory to construct a nest. The Sooty Grouse's nest is a simple depression in the ground, usually hidden under some cover, and variably lined with bark, feathers, leaves, pine needles, and twigs. For up to four weeks, the hen incubates one to 12 beige eggs speckled with brown. Within a day of hatching, the downy chicks can walk, hide, and feed themselves, but the hen usually attends them through August. Sooty Grouse chicks develop very quickly, and juveniles sometimes gather in small groups before migrating.
Some Sooty Grouse populations migrate short distances, usually with a significant change in elevation, while others are sedentary. Migrating grouse use powered flight as little as possible, preferring to glide downhill into valleys. Many Sooty Grouse groups migrate to lower elevations to breed, then return to higher elevations and denser forests for winter. Spring migration occurs rapidly in May, and males begin the slower "fall" migration in mid-June. Hens with broods may linger near the breeding grounds through September.
Hoffmann, Robert S. "Observations on a Sooty Grouse Population at Sage Hen Creek, California." Condor 58 (September-October 1956) 321-33.
Sibley, David Allen.
The Sibley Guide to Birds. Alfred A. Knopf, New York. 2000.
Zwickel, F. C. and James F. Bendell (2005).
Blue Grouse (Dendragapus obscurus).The Birds of North America Online (A. Poole, Ed.). Ithaca: Cornell Laboratory of Ornithology. Accessed from The Birds of North American Online database.
