Willow ptarmigan in favourable seasons, many juveniles may survive and the population of willow ptarmigan is prone to wide fluctuations in size. By September, families begin to form flocks. The females and young migrate to lower altitudes and may overwinter from their breeding grounds in wooded valleys and hilly country. The males also congregate in small groups but do not usually travel as far as the females. The willow ptarmigan was adopted as the state bird of Alaska in 1955. Widespread and not uncommon in its remote habitat, the willow ptarmigan is classified as a species of "Least Concern" by the IUCN.
Arctic ice pack Arctic ice pack The Arctic ice pack is the sea ice cover of the Arctic Ocean and its vicinity. The Arctic ice pack undergoes a regular seasonal cycle in which ice melts in spring and summer, reaches a minimum around mid-September, then increases during fall and winter. Summer ice cover in the Arctic is about 50% of winter cover. Some of the ice survives from one year to the next. Currently 28% of Arctic basin sea ice is multi-year ice, thicker than seasonal ice: up to thick over large areas, with ridges up to thick. As well as the regular