Bears and hibernation

[Ken Kinman]

Robin,
     I think it depends on how strictly you define hibernation.  It's sort of like a continuum where it is difficult to draw a define line.  Generally, black bears and brown bears are said to truly hibernate.  Polar bears are said to exhibit varying degrees of "walking hibernation" when food is scarce, and even a mother polar bear in her den is generally not regarded as being in "true" deep hibernation (because she is very easily aroused compared to black and brown bears that are hibernating).  I'd have to check to make sure, but I don't think a denning polar bear's body temperature drops as much as brown and black bears do.
  ----Cheers,
          Ken