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
White Mountain art his 1868 painting titled "". In all, over four hundred artists are known to have painted White Mountain views during the 19th century. They came from the Boston area, Maine, Pennsylvania, and New York. Most of the Hudson River School painters worked in the White Mountains while maintaining studios in New York City, including such well-known artists as Sanford Robinson Gifford (1823–1880) and Jasper Francis Cropsey (1823–1900). Most artists came to the White Mountains in the summer, but returned to their urban studios, or sometimes to warmer climates like Florida, in the winter. Therefore, paintings of winter scenes are not