[All]: Heiðrekr’s response is (Heiðr 1960, 40): Þat eru rjúpur; þær eru hvítar um vetr, en svartar um sumar ‘Those are ptarmigans; they are white during winter, but black during summer’. The ptarmigan (Lagopus mutus) is seasonally camouflaged, with white plumage (except for a black tail) in winter and brown in summer.