Rare winter sighting of Yellowstone Grizzly Bear on January 26th, 2026 скачать в хорошем качестве

Rare winter sighting of Yellowstone Grizzly Bear on January 26th, 2026

Every winter, grizzly bears enter a state known as hibernation-like torpor, not true hibernation. Their heart rate drops from ~40 beats per minute to as low as 8–10, body temperature declines modestly (not to near-freezing), and metabolism slows dramatically—allowing them to survive for months without eating, drinking, urinating, or defecating. But torpor is flexible, not absolute. During late winter, especially in years with warm spells or shallow snowpack, some grizzlies—most often adult males—may briefly emerge from their dens. These short outings can involve changing den sites, clearing snow, or limited movement nearby. This does not mean the bear is fully “awake” or actively foraging. It is a temporary arousal driven by temperature, hormonal state, and energy balance. Females with cubs are different. They almost always remain denned until consistent spring conditions arrive, because leaving the den would expose newborn cubs—often weighing less than a pound—to lethal cold and predation risk. Physiologically, these brief arousals are expected. Bears can raise their metabolism and heart rate rapidly, then re-enter torpor without the energetic cost that would cripple smaller hibernators. This metabolic control is one reason bears are studied for insights into muscle preservation, insulin sensitivity, and bone density in humans. Nelson et al. (1983). Behavior, biochemistry, and hibernation in black, grizzly, and polar bears. International Conference on Bear Research and Management, 5, 284–290.