Spruce Grouse — A bird of the boreal forest

The Seward Peninsula’s spruce forests are home to another well-adapted winter resident, the aptly named spruce grouse. These handsome and hardy grouse are found throughout the boreal and montane forests of northern North America, where they embrace cold winters with fascinating adaptations and seasonal changes to their diet and lifestyle.
Spruce grouse will be most familiar to people living in or near the forested areas of eastern Norton Sound. From Nome, a drive to Council can put us in their domain, and on rare occasions a stray may make a surprise landing in the Nome area.
Fall is a time of behavioral and physiological change for these grouse, and that can be an especially good time to spot them. As they switch from a summer diet of soft plant materials to a fibrous winter diet of spruce needles, a grouse must greatly increase its grit consumption to grind the tough food in its gizzard. This need draws them out of the forest and onto roads and trails in search of grit.
In summer, spruce grouse forage on the forest floor, eating mainly berries, flowers, fungi and leaves.
In late fall, regardless of snow cover, the birds transition into an arboreal life in the spruce trees. They tend to forage in the upper tree branches to eat newer needles or growing tips.
Spruce needles are less energy-packed and nutritious than the grouse’s summer diet, so they must eat more to sustain themselves. As a result, their gizzard—which grinds up hard-to-digest needles—grows by 75 percent, and the length of their intestines increases by about 40 percent.
Also, in preparation for an arboreal life, spruce grouse grow horny scales (pectinations) along the edges of their toes, which give them added traction for maneuvering on tree branches. These protrusions also increase the surface area of their feet and act as snowshoes, which are shed in the spring. For added warmth, their feet are feathered to the base of their toes.
During winter nights the grouse may roost in a spruce tree, hidden by branches, or beneath a protective shroud of boughs on the snow at its base. Or, like ptarmigan, they may burrow into the snow for extra insulation and protection.
A spruce grouse can store up to 10 percent of its body weight in food in its crop—a pouch between its throat and stomach. This allows the bird to digest food in safety or during long, cold nights.
As spring comes, spruce grouse spend more time on the ground, foraging silently as they walk along the forest floor. They seldom fly unless flushed into a nearby tree, or when males perform short courtship displays.
In the light and warmth of spring, cocks begin displaying to attract hens. They strut boldly on the ground or along a tree branch with their crimson eye combs erect, and raise their chest and neck feathers, making themselves appear large and imposing.
Cocks fan and flick their raised tails, making swishing and whooshing sounds with their tail feathers. They also perform “flutter-flight displays,” producing a fluttering or muffled drumming sound with their wings while making near-vertical flights up and down between low branches and the ground. The sounds made by these wing and tail movements lure hens into the cock’s territory, and ward off trespassing males.
Hens are usually monogamous, while cocks often have more than one mate. Both sexes defend their own territories against others of the same sex.
A hen lays five to nine eggs in a well concealed nest on the ground. She incubates and rears the brood without help from her mate. The hen broods and protects her downy chicks, who leave the nest soon after hatch and are able to find their own food. Unlike their vegetarian parents, the chicks eat a high protein diet of insects to maximize growth during the first few weeks after hatch.
Many spruce grouse stay year-round on their territory. Others may move short distances—usually less than ten miles, and mainly on foot—between their breeding and winter ranges. In winter, spruce grouse may form loose flocks after a summer of solitude.
Spruce grouse numbers fluctuate between periods of abundance and scarcity. Their population cycles are believed to be driven largely by changes in the forest resulting from natural succession, or disturbances such as insect infestations, fire, management practices, or from climate change.
A study in Yukon, Canada, also found that scarcity of spruce grouse coincides with a scarcity of snowshoe hares, but that grouse numbers tend to decline one year ahead of snowshoe hare declines. Declining grouse density was correlated with increased predation, rather than changes in body condition or productively. Researchers speculate that high numbers of predators, bolstered by an abundance of hares, increases opportunistic predation on grouse.
For those living near spruce grouse habitat, these grouse can be a valued subsistence resource. The succulent, berry-fed birds in fall are savored. Once the grouse shift to their winter diet of needles, their meat is said to become tougher and stronger tasting, and not to everyone’s liking. But for others, spruce grouse can be a welcome addition to one’s winter diet.