Protected by packed layers of down-like feathers, the Ku'sikuk is able to withstand the harsh winds and biting cold of its arctic habitat. Their sluggish, lumbering movements on land starkly contrast their surprising speed and grace underwater. Males are highly territorial and protective of their flock; their aggression often peak during mating season and after the birth of their offspring. A single peck or snap of their beak can lead to grievous injury.