Black bears, Georgia’s largest native terrestrial mammals, undergo a biological process each winter. This period allows them to conserve energy and survive when food becomes scarce. This natural phenomenon highlights the adaptations of these resilient creatures found across Georgia’s diverse landscapes.
Typical Hibernation Period in Georgia
Black bears in Georgia enter their winter dens between mid-November and early January, emerging around April or May. While this provides a general timeline, significant variability exists in the exact timing for individual bears. These animals do not undergo true hibernation like some other mammals, but rather a state of deep sleep known as torpor.
During torpor, a bear’s heart rate, respiration, and body temperature decrease, but not to the extreme levels seen in true hibernators. This lighter state of sleep means bears can be roused more easily if disturbed or if conditions change. Georgia Department of Natural Resources (DNR) tracking indicates that approximately 90 percent of collared female bears spend time in dens due to their reproductive cycles, while only about 40 percent of males den.
Influences on Hibernation Timing
Several environmental and biological factors dictate the precise timing of den entry and emergence for black bears in Georgia. Food availability is a primary influence; an abundance of natural food sources, like oak acorns in the fall, allows bears to build fat reserves through a process called hyperphagia. If natural food is scarce, or if human-provided food sources are readily available, bears may delay or shorten their denning period, or even forgo it entirely.
Weather patterns, particularly temperature, also play a role in signaling the onset of denning. Milder winters in Georgia can lead to shorter periods of inactivity for bears. The amount of daylight, known as photoperiod, also triggers the physiological changes that prompt bears to seek out dens.
Bear Behavior During Hibernation
While in their dens, black bears experience physiological changes. Their heart rate can drop to about 8-10 beats per minute, and their body temperature decreases by approximately 10 to 12 degrees Fahrenheit. Bears do not eat, drink, urinate, or defecate during this time, instead relying on their accumulated fat reserves and recycling waste products. They can lose between 23 to 30 percent of their body fat, with lactating females losing up to 45 percent.
Pregnant female bears give birth to their cubs during this period, typically between mid-January and mid-February. Newborn cubs are tiny, weighing less than a pound and are blind and entirely dependent on their mother’s rich milk for nourishment and growth. Mothers and their cubs are often among the last to emerge from the dens in the spring, usually in mid-April to early May. Dens can vary widely, including hollow trees, ground excavations, rock cavities, brush piles, or even secluded spots under human structures.