Bears are quite different from most hibernating mammals. They don't awaken and feed any time during their hibernation and seem to virtually shut down many of their biological systems. One system which shuts down almost entirely is the kidneys.

Once bears hibernate they cease to urinate. The blood supply to the kidneys is greatly reduced and all fluid movement in the kidneys virtually ceases. One would expect such a stoppage to damage the kidneys and produce all kinds of toxic conditions in the body, but this does not happen. Blood measurements show no measurable changes in the chemical make-up of the blood and no accumulation of waste products.

What a tremendous advantage this shut-down has to the bear. Not only does it rest the kidney and conserve energy consumption in the bear, but it also eliminates dehydration. If the bear released water and did not replace it, he would eventually die. In the deep sleep of hibernation, there is no way to replace the water.

Hibernation is a beautiful and obviously very complex way of conserving energy, protecting the bear, and protecting his potential food from over-consumption. The design and plan of such a system shows incredible wisdom. This could not have happened by accident, but it shows God's incredible design.