Home Forums Hunting & Shooting Hunter's Campfire Are Yellowstone grizzlies hibernating this winter?

For many years some people did not consider bears to be true hibernators. Mammals considered true, or deep hibernators, such as chipmunks and ground squirrels, experience a drastic decrease in body temperature during hibernation. Body temperature for hibernating bears remains above 88°F (31°C) which is within 12°F (11°C) of their normal body temperature of 100°–101°F (37.7°–38.3°C) (Bagget 1984). This allows bears to react to danger quicker than hibernators whose body temperature may be less than 40° F (4° C) and who have to warm up before they can move quickly (Bagget 1984). Many scientists now consider bears to be super hibernators. Due to the highly insulating pelts of bears and their lower surface area to mass ratio than smaller hibernators, body heat is lost slowly which enables bears to cut their metabolic rate by 50-60% (Craighead and Craighead 1972; Rogers 1981). Respirations in bears decrease from 6-10 breaths per minute normally, to 1 breath every 45 seconds during hibernation. They experience a drop in heart rate from 40-50 beats per minute during the summer to 8-19 beats per minute during hibernation. Mammals that experience lower body temperatures during hibernation, such as chipmunks and ground squirrels, must awaken every few days to raise their body temperature, move around, urinate, and eat (Rogers 1981). Grizzly bears and black bears generally do not eat, drink, defecate, or urinate during hibernation. Bears live off of a layer of fat built up during the summer and fall months prior to hibernation. Waste products are produced, however, instead of disposing of their metabolic waste, bears recycle it. The urea produced from fat metabolism (fatal at high levels) is broken down and the resulting nitrogen is used by the bear to build protein, which allows them to maintain muscle mass and organ tissues (Rogers 1981). Bears lose fat and may actually increase lean-body mass while hibernating due to this nitrogen recycling (Wickelgren 1988). Bears may lose 15-30 % of their body weight during hibernation (Rogers 1981).

Hey Schrap, I saw 4 wolves take down a cow elk just north of Fishing Bridge a few years ago. They had just barely gotten a mouthful each when a big griz came out and chased them off. I had a tour group on the bus and they were mortified. Everytime one of them would shriek in horror I'd ask if they wanted me to pull out and move on, but they kept telling me to stay so they could watch. It was darned interesting.

Hey Schrap, I saw 4 wolves take down a cow elk just north of Fishing Bridge a few years ago. They had just barely gotten a mouthful each when a big griz came out and chased them off. I had a tour group on the bus and they were mortified. Everytime one of them would shriek in horror I'd ask if they wanted me to pull out and move on, but they kept telling me to stay so they could watch. It was darned interesting.