What types of bear hibernate?

Most bear species, including American black bears, grizzly bears, and polar bears, exhibit hibernation behaviors. During hibernation, these bears enter a state of torpor, significantly reducing their metabolic rate and conserving energy throughout the winter months when food is scarce. It's important to note that not all bears hibernate in the same way; for instance, polar bears do not hibernate in the traditional sense but may enter a denning phase during the harshest winter conditions.