Lagopus muta
Slightly smaller and less heavy than Willow Ptarmigan. Overall greyer plumage, and a more delicate bill. Male summer with grey upperparts and white underparts. Female summer with browner upperparts than male. Both sexes completely white in winter plumage, except for black lores in males. Wings white and tail feathers black in all plumages in both sexes.
Call of male a very distinct "rrrrrrr", being a rattling rapid pulse of clicks, like running a stick along a picket fence. Female has similar sounds, but is higher pitched and not so coarse as male.
Wikipedia: map (se also Xeno-canto below)
Birdlife ecology
