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
Arctic Report Card video that summarizes the Report Card. In 2015, Arctic sea extent at the end of the winter was the lowest during the satellite record and the winter maximum occurred 15 days earlier than in the past. The sea ice minimum at the end of summer was the 4th lowest extent on record. These changes are having profound impacts in both the marine and terrestrial ecosystems and in sea surface temperatures. Arctic Report Card The National Oceanic and Atmospheric Administration's Arctic Report Card presents annually updated, peer-reviewed information on recent observations of environmental conditions in the Arctic relative to historical records.