Expert: Walter Hintz - 2/14/2007

Question
Hello!

I've returned with more questions about bear hibernation. More specifically, I'm interested in finding out more about how bears recycle the wastes that their bodies produce while they hibernate. For instance I've heard that the ketones that result from the burning of hydrocarbons are somehow recycled into new fat. How do bears do that? Also from what i've researched, the urea that bears produce gets converted to nitrogen in their gut (by bacteria). Is that true? Which bacteria are these? Is that all that happens to the urea?
Additionally, I've been able to find very little about why bear skeletons and muscles don't atrophy after such long periods of disuse. Do you have any information about that?

Sorry if my questions seem a bit narrow, i've just been researching these specific things and am not having much luck. Any answers, theories, or references you can provide (the more specific the better!) would be greatly appreciated. Thank you very much!!!

~Kami  

Answer
Hi Kami
 I cannot answer all of these questions about the physiology of the bear.  I can tell you that bears do not undergo deep hibernate but undergo a variation of the process called "winter sleep". Their body temperature only drops about 10 degrees and they will occasionally wake up and wander around during this period.  They also tend to move and this would answer the question regarding atrophy.  Google