Bears typically hibernate during the winter months, generally starting from October or November and lasting until April when the snow begins to melt. The exact timing and duration of hibernation can vary depending on the bear species and regional climate. For example, bears in colder northern regions may hibernate for up to seven months, while those in milder coastal areas may hibernate for shorter periods of two to five months. During hibernation, bears enter a state of torpor where their metabolism slows down, they do not eat or drink, and they rely on stored fat to survive the harsh winter conditions.

The hibernation period can also depend on food availability and the bear's reproductive status; bears that have access to food or are not pregnant might delay or reduce hibernation. Some bears in regions with milder winters may even emerge occasionally during winter thaws to forage if food is available.

In summary, bears hibernate roughly from October or November through April, with the duration adjusted by geographic location and environmental conditions.