During winter, the diet of the spruce grouse consists almost entirely of pine or spruce needles. At other times of year, it also feeds on the shoots, leaves, flowers and berries of other plants, as well as on some fungi, insects and snails (2) (3) (4) (5). Young chicks eat mostly insects, although fungi may also be important in their diet (2) (4).
The spruce grouse forages during the day, with peaks of feeding in the early morning and late afternoon (2) (4). In summer, this species mainly forages alone and on the ground, but in winter it may gather in loose flocks of up to 30 birds, and forages almost entirely in the trees (3) (4) (5).
Both the male and female spruce grouse defend individual territories (5). The male spruce grouse may perform territorial displays which include fanning and sweeping the tail, or drumming or clapping the wings (3) (5). Males also perform elaborate courtship displays to attract a mate (4) (5), and each male may mate with several females (2) (4) (5).
Breeding usually takes place around May or June (2) (4). The nest consists of a simple depression in the ground, lined with dead needles, leaves and feathers, and concealed by overhead vegetation. It is built by the female spruce grouse, typically at the base of a pine or spruce tree (2) (3) (4) (5). Clutch size is between 4 and 7 eggs (2) (3), and the eggs are incubated by the female for 23 to 24 days (2). Females of the subspecies D. c. canadensis usually lay more eggs than those of D. c. franklinii (4) (5).
The young spruce grouse chicks are reddish-brown above and yellowish below (2) (4), and are able to leave the nest and follow the female shortly after hatching (3) (5). The young can make short flights from just 6 to 8 days old (2) (5), and become independent at around 9 to 15 weeks (4) (5). The spruce grouse may start to breed in its first year following hatching, and has been recorded living to at least 13 years old (2) (4).