Why do bears hibernate?
Show answer & explanation
Answer: Conserving energy when food scarce
Avoiding human contact — Wrong. Bears evolved hibernation long before humans. Strategy conserves energy during winter food scarcity, not human avoidance.
Growing thicker fur in dens — Wrong. Fur doesn't grow during hibernation. Bears hibernate to conserve energy—heart rate drops, metabolism slows when food unavailable.
Conserving energy when food scarce ✓ — Correct! Winter survival strategy! Bears hibernate (torpor) when food scarce: (1) Metabolic rate drops 50-60%. (2) Heart rate: 55→9 bpm. (3) Body temp drops slightly (31-34°C). (4) No eating, drinking, urinating, defecating for months! Live off fat reserves (gain 30% body weight pre-hibernation). Not true hibernation like ground squirrels (can wake quickly if threatened). Pregnant females give birth during hibernation! Den selection critical. Some bears don't hibernate (food available year-round).
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