Lagopus term is of feminine gender, and the specific epithet has to agree with that, the feminine "muta" and "leucura" are correct. The English name "ptarmigan" comes from the Scottish Gaelic name for the bird, , whose origin is unknown. The p- was added due to a mistaken belief in a Greek origin, as if the word were related to the Greek word ("pterón"), 'wing'. The three species are all sedentary specialists of cold regions. Willow ptarmigan is a circumpolar boreal forest species, white-tailed ptarmigan is a North American alpine bird, and rock ptarmigan breeds in both Arctic and mountain habitats
Winter white dwarf hamster able to sense a directional change in photoperiod length, such as in one experiment that demonstrated a transition from 16 hours of light to 14 hours initiates a change to the winter coat. The change to the winter coat can be triggered in the summer by the short day lengths. The change occurs back to the summer coat in the autumn, when the length of the days change again. At internal temperatures hamsters in captivity start later with the changes. The winter colour is less pronounced in them. The eyes of the Winter white hamster are black, unless it is