The Rock Ptarmigan (Lagopus muta) is the grey-mottled game bird of the high fells, a master of camouflage that changes its plumage with the seasons and lives year-round on barren alpine tundra above the treeline. It is a medium-sized game bird, 31–35 cm long with a wingspan of around 54–60 cm and a weight of 400–550 g, with a round, compact body and a small head. The plumage is strongly seasonal: in winter the bird is almost entirely white with a black tail, while the summer dress is grey and mottled with a paler belly. The legs are feathered all the way to the toes, the trait behind the genus name Lagopus, roughly "hare-foot", and the most reliable field mark is the male's thin black line between bill and eye, which persists even in winter plumage; both sexes carry a fleshy red comb above the eye that becomes prominent during display.
Its call is a hard, dry, rattling croak, often rendered "arr-arr-arr-ka-ka-ka", mechanical and slightly frog-like, heard mainly from displaying males in spring and carrying well across the open fell terrain. Rock Ptarmigan breed on bare, often stony ground above the treeline throughout the Swedish mountain range, from the Dala fells in the south to Lappland in the north; the population is put at tens of thousands up to around 200,000 pairs but varies greatly between years and shows a long-term declining trend, linked to a warming climate that pushes the treeline upward and shrinks the alpine habitat the species depends on. The nest is a simple scrape sparsely lined by the female, who alone incubates 5–9 eggs; the precocial chicks leave the nest soon after hatching and forage for themselves under her watch, protected by their camouflaged plumage. The diet is entirely vegetarian, dominated by buds, shoots and leaves of dwarf birch and willow, supplemented with berries, seeds and herbs, while chicks take insects during their first weeks.
Read about this species in Swedish →