Description:
In northwestern North America, recent warming has led to a dramatic increase in the number of days of above freezing temperatures during the migration period for the caribou (Rangifier tarandus). Thawing and subsequent re-freezing of snow results in ice layers in the snow pack which hinder travel of Rangifer and make it harder to cater for food. There have been catastrophic declines in the Peary caribou on the Arctic islands of North America and they are now considered endangered. The formation of ice layers that prevent the caribou from accessing food has been identified as the chief cause of the declines.