But Why: A Podcast for Curious Kids But Why turns 10!
Apr 3, 2026
Mary Holland, naturalist and nature writer who studies and photographs animals, explains hibernation in lively detail. Short, curious segments cover bear fattening, denning, birthing in winter, and the fecal 'plug'. We also hear about woodchucks, frogs, turtles, insects with antifreeze, and meet Chapin the barred owl.
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How Bears Survive Winter Without Eating
- Bears hibernate by building huge fat reserves and slowing bodily functions instead of lowering body temperature dramatically.
- Mary Holland explains black bears may double weight, breathe once every 45–60 seconds, and drop ~12°F to survive months without food.
Bears Stop Pooping With A Natural Plug
- Bears don't eat, drink, urinate, or defecate during hibernation and use a physical plug to prevent bowel movements.
- Mary Holland says a plug forms in the bear's rectum and naturally passes when the bear wakes in spring.
Mother Bears Birth And Nurse While Hibernating
- Female black bears give birth in January to tiny blind cubs while still in the den and nurse them during shallow hibernation.
- Mary Holland notes cubs weigh ~0.5 lb and are ~7 inches long, then grow and start eating spring greens after den exit.
