The ptarmigan's genus name, Lagopus, is derived from Ancient Greek lagos (λαγώς lagṓs), meaning "hare", + pous (πούς poús), "foot", in reference to the bird's feathered legs.

[7] The species name, muta, comes from Neo-Latin and means "mute", referring to the simple croaking song of the male.

[7] It was for a long time misspelt mutus, in the erroneous belief that the ending of Lagopus denotes masculine gender.

The silent initial p was added in 1684 by Robert Sibbald through the influence of Greek, especially pteron (πτερόν pterón), "wing", "feather", or "pinion".

[10] The rock ptarmigan is seasonally camouflaged; its feathers moult from white in winter to brown in spring or summer.

In winter, its plumage becomes completely white except for the black outer tail feathers and eye line.

Aerial courtship rituals involve fast forward flight with rapidly-beating wings followed by an upward glide, tail fanned out.

Other signals via fanning their tails, extended necks, lowered wings and circling a receptive female are also utilized.

[16] The rock ptarmigan is a sedentary species which breeds across Arctic and Subarctic Eurasia and North America (including Greenland) on rocky mountainsides and tundra.

Rock ptarmigan have a limited capacity for fat storage,[29] which requires overwintering birds to forage frequently.

[30] Most of the minuscule mass gained over winter is to the ovary, oviduct and hypertrophy, in preparation for the spring breeding season.

[34] During winter, food availability is lower in Svalbard than in other parts of their range, which accounts for the necessary increased fat reserves not found in other sub populations.

Hunting has been allowed again since 2005, but is restricted to selected days, which are revised yearly and all trade of rock ptarmigan is illegal.

The birds feed, records Bewick, "on the wild productions of the hills, which sometimes give the flesh a bitter, but not unpalatable taste: it is dark coloured, and has somewhat the flavour of the hare.