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 Mountain 2011. In 2015, after releasing one album together, Smyth left Winter Mountain and Francis opted to keep the name for his solo work. In summer of 2016 Francis performed one of his first solo shows as Winter Mountain, opening for Seal. Later that same week, a solo Winter Mountain opened for The Feeling and the lead singer of Elbow, Guy Garvey. Winter Mountain released the self-produced 'I Swear I Flew' on his 'Astral Fox Records' label in November 2016. A song from the record, 'The Lucky Ones', received radio play across the UK and Europe from multiple stations including BBC