A biologist studying bears for the past decade has captured hundreds of hours of grizzly bear behavior in Glacier National Park. This information is key to good bear exhibit design, as it allows us to understand the natural needs and instincts of these massive creatures.
Apparently, grizzly bears spend a lot of time rubbing their backs and heads on things, much like cats. This behavior is believed to be related to scent marking. Obviously, providing places for bears to do this in captivity will allow more natural behaviors to occur in front of the public, which is always entertaining and enlightening.