The Hazel Grouse (Tetrastes bonasia) is the small, quiet forest grouse that startles hikers with a sudden whirring flush from a spruce thicket beside the trail — the smallest of Sweden's forest grouse and, despite being one of the country's more numerous game birds, one most people only glimpse for an instant. It measures 34–39 cm long, with a wingspan of about 48–54 cm and a weight of 300–450 grams, and its plumage is finely mottled grey, brown and white, a near-perfect camouflage against the forest floor. The crown bears a small erectile crest; the male has a black, white-edged throat patch that the female lacks, and in flight both sexes show a clear black terminal band on the grey tail.
The male's territorial call is a very thin, high-pitched, drawn-out whistle, "si-si-si-siii", so faint it is easily missed among other forest sounds, given mainly during the spring display period. Hazel Grouse nest on the ground, often hidden beneath a spruce or beside a stump, where the female lays 7–11 eggs and incubates alone for 23–27 days; the precocial chicks leave the nest almost immediately and follow her, able to flutter short distances within a couple of weeks. Diet shifts with the season — green shoots, berries, seeds and insects in summer, when growing chicks depend heavily on insect protein, switching to buds and catkins from alder, birch and sallow in winter. Found across most of Sweden's forested regions but tied to old, closed, moist coniferous and mixed forest, the species is extremely sedentary, with an estimated population of 100,000–200,000 pairs that rarely strays beyond a few hundred metres of its home territory.
Read about this species in Swedish →