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Just like disturbances wake you up, they wake up the animal kingdom -- often with dire results.
Hibernation, simply, is a state of inactivity in animals. It is typically characterized by a drop in metabolic activity—a physical slowing of the body—in addition to lower body temperature and slower breathing.
Indeed, hibernation is a sleep deeper than most humans could imagine, but it is not impervious to interruption. Increasingly, changes brought into nature by the modern world are unsettling hibernating animals during a time of the year when they are most vulnerable.