Arctic Alaska settlement in Arctic Alaska was driven first by discoveries of gold and later on by the extraction of petroleum. The ecosystem consists largely of tundra covering mountain ranges and coastal plains which are home to bears, wolves, sheep, oxen, reindeer, and numerous species of birds, the north coast has been defined as the Arctic coastal tundra ecoregion. Arctic Alaska is also the location of the Arctic National Wildlife Refuge, Gates of the Arctic National Park and Preserve, and the National Petroleum Reserve-Alaska. The Arctic experiences midnight sun in the summer and polar night in the winter. Arctic Alaska Arctic Alaska
Winter white dwarf hamster able to sense a directional change in photoperiod length, such as in one experiment that demonstrated a transition from 16 hours of light to 14 hours initiates a change to the winter coat. The change to the winter coat can be triggered in the summer by the short day lengths. The change occurs back to the summer coat in the autumn, when the length of the days change again. At internal temperatures hamsters in captivity start later with the changes. The winter colour is less pronounced in them. The eyes of the Winter white hamster are black, unless it is