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Q:What happens if you wake up early from hibernation? —Anonymous, Denver, CO
A: The early bird may get the worm, but the early bear…well, we just don’t like getting up early. Depending on where we live and whether we’ve had cubs over the winter, black and brown bears may stay in our dens up until mid-April. If we had alarm clocks, we’d be smashing the snooze button, and probably the clock too.
There are three answers to your question. First: We actually wake up early all the time. You see, bears don’t hibernate the way ground squirrels or other “true hibernators” do. Instead, we enter a state called torpor, which is like true hibernation except our body temperature, metabolic rate, and breathing doesn’t drop quite as much. That also means we’re more active throughout the winter: If you were to hide a camera in my den (make sure to get my good side), you’d see me shifting positions and occasionally stirring from my slumber in response to noises or other stimuli. Female bears will even wake up to give birth to their young. But those early wake-ups are temporary—we quickly go back into torpor—and probably not what you’re talking about in the first place.
The second answer is a little grimmer. Hibernating bears don’t eat during the winter, so black and grizzly bears spend most of the fall in a state of hyperphagia, trying to pack on as much fat as possible to stay cozy and survive the snowy season. In bear-heavy places like Katmai National Park, that can involve pretty heavy competition, as we all jockey over the most productive fishing spots and berry patches. The unfortunate bears who don’t put on enough weight wake up early when their fat reserves run out, and face the difficult task of finding sustenance in the resource-poor winter. I’m sorry to say that their outlook is bleak: Starvation is one of the leading causes of death among adult bears, next to vehicle strikes.
Finally, there’s some evidence that climate change is causing bears to wake up earlier and earlier in the year. A 2017 study by the U.S. Geological Survey found that for every rise in temperature of 1°F, female black bears in Colorado came out of their dens approximately 3 days earlier. Could humans eventually warm the Earth to the point where me and my kind don’t hibernate at all? It’s possible. But for now, I’ll continue looking forward to my annual beauty sleep.