Late in the fall months, black bears are in the final stretch of hyperphagia (excessive eating) to ensure they have enough fat stored for the fast-approaching winter months. Some bears will search for food up to 20 hours a day! In years where food sources are less abundant, bears have been known to den-up as early as late October. During especially mild winters, bears may not formally den and will remain active throughout the winter if food sources like acorns or beechnuts are available. Typically bears will begin denning starting in November and through December.
Bear dens can be as simple as a depression on the forest floor, but typically are small cavities in trees or under brush piles. In New York, bears have been known to den under residential porches or other outbuildings. Den sites are typically dry and afford protection from the elements during the long winter season.
Photo at top by Pete Patrick. Photo provided by the DEC.
I will guess up to an extra 100 pounds.