Bears – Birthing
JM: It’s common knowledge that bears can do something that we humans sometimes wish we could do — they can sleep through a long cold winter. But that’s not all. Bears can literally snooze their way through pregnancy and birth. I’m Jim Metzner, and this is the Pulse of the Planet. David Schirokauer is a biologist with the National Parks Service. We’re listening to the sounds of a bear cub.
DS: “The females give birth while they’re in hibernation. They wake up to give birth but barely. Imagine the human birthing experience of a human female that weighs 150 pounds giving birth to a 9 pound child. A bear on the other hand a 300 pound female bear gives birth to a cub that weighs only 1 pound and can fit in a teacup. And so she might not have to wake up that would be a relatively painless experience.”
JM: A hibernating bear has to support not only herself, but also her newborn cubs. She does this by transforming her fat into mother’s milk and into energy to stay alive. For the remainder of the winter her tiny cubs will remain close to her, feeding from her milk until it’s time to leave the den and learn about the world outside.
DS: “After they’re born she goes back into hibernation and the baby bears nurse from when they’re born in February, until when they come out of the den in May. And the mother bear has no source of water or nutrition and she can support up to three cubs in the den easily just by metabolizing the fat that she stored up.”
Pulse of the Planet is made possible in part by the National Science Foundation and Virginia Tech, inventing the future through a hands-on approach to education and research.