Black bears, Connecticut’s only bear species, enter a state of reduced activity known as denning during colder months. This process conserves energy and helps them survive periods of scarce food. While not “true hibernators,” black bears undergo significant physiological changes, crucial for their survival in the state’s changing seasons.
The Onset of Hibernation in Connecticut
Black bears in Connecticut typically begin denning in late November or early December, continuing until mid-March. This timing is influenced by colder weather and decreasing natural food sources. Before denning, bears engage in intense foraging, known as hyperphagia, to build fat reserves. They can spend up to 20 hours a day searching for food, consuming around 20,000 calories daily to prepare for winter rest. They seek suitable den sites, including brush piles, hollow logs, rock crevices, or spaces under decks and sheds.
The Hibernation Period and Its Influences
The denning period for black bears in Connecticut generally lasts three to five months. Its exact timing and duration vary based on several factors. Food availability, particularly fall mast crops like acorns, influences when bears enter dens. Milder winter temperatures and minimal snow cover might lead some bears, especially males, to remain active or forgo denning if food is accessible. Pregnant females, known as sows, den longer than males, needing a protected space to give birth and care for cubs.
Life Inside the Den
During denning, black bears undergo notable physiological adjustments. Their heart rate and breathing slow significantly, and their metabolic rate decreases by about 50%. Unlike smaller hibernators, their body temperature drops only slightly, typically by 10-14 degrees Fahrenheit. Bears do not eat, drink, urinate, or defecate in their dens, relying on accumulated fat reserves. Despite this dormancy, they can wake up if disturbed.
Cub Birth and Care
Female bears give birth to tiny, blind, and toothless cubs in the den during late December or early January, with litter sizes commonly ranging from two to three. The sow rests while her cubs nurse and grow.
Emergence and Post-Hibernation Activity
Black bears in Connecticut emerge from dens in late March through April. Rising temperatures and reappearing natural food sources signal the end of their denning period. Upon emergence, bears are hungry and immediately search for food. Their initial activities involve seeking fresh vegetation and water, increasing activity as they replenish energy. This period marks the start of their active season, where they forage and move about the landscape.