Extreme winter events including polar vortex outbreaks cause mass mortality in wildlife populations through hypothermia, starvation, and habitat inaccessibility.
Extreme winter cold causes prolonged hypothermic suffering in wild animals unable to shelter adequately or find food under deep snow or ice. White-tailed deer weakened by winter often succumb to predation or disease in spring when their reserves are exhausted. Sea turtles cold-stunned in shallow bays may be rescued and rehabilitated, but the vast majority of smaller animals experiencing winter mortality receive no intervention.