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
Ptarmigan Traverse of the trip. Today the route is a common goal of Cascade Range mountaineers. Place names are listed from north to south: Ptarmigan Traverse Ptarmigan Traverse is an alpine climbing route in the North Cascades of Washington State. The route, from Cascade Pass to Dome Peak, is generally remote, unmarked, and challenging, traversing rugged terrain and several glaciers. The first traverse took 13 days in July 1938. The group consisted of four members of the Ptarmigan Climbing Club: Bill Cox, Calder Bressler, Ray W. Clough, and Tom Myers. The second traverse was in 1953 and consisted of Dale Cole, Bob