Willow ptarmigan complicated changes in plumage several times a year and the differing colour and pattern of the summer plumage: The willow ptarmigan often hybridises with the black grouse ("Tetrao tetrix") and the hazel grouse ("Tetrastes bonasia") and occasionally with the western capercaillie ("Tetrao urogallus"), the spruce grouse ("Falcipennis canadensis") and the rock ptarmigan ("Lagopus muta"). During the Pleistocene, the willow ptarmigan widely occurred in continental Europe. Authors who recognize paleosubspecies have named the Pleistocene willow ptarmigan "L. l. noaillensis" (though the older name "medius" might be the correct one). These marginally different birds are said to have gradually changed from the
Winter white dwarf hamster white is known to be one of the most tameable types of hamsters. The hamster has no fully accepted common name, Winter white dwarf hamster and Russian dwarf hamster are among the most often used. Confusion arises because of their physical similarity to the Campbell's dwarf hamster, consequently the name Djungarian hamster and Russian dwarf can refer to both Winter white and Campbell's dwarf hamsters. The term "Winter white" derives from the fact that in the wild the hamster changes it's fur colour to white for the winter months, this camouflages the hamster and reduces predation when snow is on