Slide 1
Hibernation reduces a bear’s winter energy use
A hibernating bear reduces energy use during a period of scarce food. Its winter state is more than ordinary sleep.
More to Read
Bears can remain responsive and may leave a den under some conditions. Hibernation describes a physiological strategy, not a guarantee of continuous unconsciousness for an entire season.
Slide 2
Autumn feeding builds the fat reserve
Before denning, bears can feed intensively and build fat stores. Those reserves supply much of the energy used during winter.
More to Read
Food availability before winter influences condition later in the den. Seasonal survival links events separated by months, rather than beginning only when the animal disappears from view.
Slide 3
Heart rate and metabolism fall during winter
Heart rate and metabolic activity decline during bear hibernation. Temperature falls less dramatically than in many small hibernating mammals.
More to Read
A large body loses heat relatively slowly. Size and insulation help explain why strong energy savings do not require the same temperature pattern seen in a small ground squirrel.
Slide 4
A denning mother can also feed newborn cubs
Pregnant female bears can give birth in the den and nurse cubs. The mother's stored resources support herself and the young.
More to Read
Cubs begin small and dependent, so den conditions offer shelter during early development. Apparent inactivity outside can conceal a demanding stage of the reproductive cycle.
Slide 5
Species and conditions change the denning calendar
Bear denning dates vary with species, location, weather and food. A single winter timetable does not describe every bear population.
More to Read
Studying local patterns avoids confusing a normal regional difference with an anomaly. Hibernation is an adaptation to seasonal conditions, so its timing connects to conditions animals actually encounter.
Sources
- Hibernation in Bears
National Park Service
- Bear Ecology
National Park Service