words by willow defebaugh
photograph by daniel shea
Welcome to The Overview, a weekly newsletter in which Editor-in-Chief Willow Defebaugh offers a holistic look at life on Earth, seen from above.
“If rest is another dimension, which I think it is, I think the more we go there, the more we’re going to wake up.”
In the northern hemisphere, we are approaching the Winter Solstice. For many animals, the arrival of winter initiates a change in behavior and even biological processes. For a number of mammals including bats, rodents, and bears (the focus of this particular newsletter), the changing season means one thing: hibernation. Defined by Britannica as “a state of greatly reduced metabolic activity and lowered body temperature adopted by certain mammals as an adaptation to adverse winter conditions,” the art of hibernation offers much for us humans to learn.
While hibernation may vary from species to species—including degree of inactivity, duration, and bodily functions—the central chord is one of harmony with one’s environment. It is first and foremost a way of attuning to the season of stillness in which temperatures are too brutal to face and food sources become so scarce that futile foraging forays are not worth the energy expended. Therefore, an animal’s hibernation habits depend entirely on its climate; In the coldest parts of northern Alaska, bears will hibernate for about seven months of the year, while those in its warmer regions may hibernate for as few as two months.
Before we can go into exactly what hibernation entails, we must first examine the lead-up to it. In autumn, many bear species exhibit something known as hyperphagia—a period of excessive eating in preparation for the months of hibernation to come. During this feeding frenzy, grizzly bears may eat as many as 22,000 calories per day. Putting on up to three pounds of weight daily, this fat will serve as a reserve for the animal to live off while deep in hibernation and unable to find new food. All of this is to say: preparation is paramount when winter is on its way.
The next step in preparing for what lies ahead is a crucial one: securing a safe space. Many bears will dig their dens; others that are lucky may find a suitable one. Some begin this process far in advance, while some wait until winter is nearly upon them. A typical den consists of a short opening and entrance tunnel just large enough for the bear to squeeze through, as well as a chamber. A small opening is quickly covered by snow and prevents heat from escaping; it may even be dug at an upward angle to keep heat more efficiently trapped. Bears that find existing caverns for their dens—often pregnant females—give themselves more space to move around.
Bears’ hibernation cycles are directly intertwined with their reproduction and birth cycles. After mating during the summer months, a bear’s fertilized eggs will remain in the womb but will not implant for weeks or months, so that they can be born while their mothers are in hibernation. If enough fat has not been accumulated, the egg will abort. Cubs are relatively helpless for the first few months of their lives; while they themselves do not technically hibernate, the den provides them a safe space to grow, nursing and sleeping next to their mothers. Hibernation enables not only the survival of individual bears, but the continuation of entire species.
Hibernation itself heralds a host of bodily changes. Bears will lower their internal temperatures up to 8-12 degrees in order to conserve metabolic energy by 50-60% as they break down their fat reserves. Waste is still produced, but their bodies recycle instead of excreting it; the urea from digesting fat is turned into nitrates that help them build protein and keep their muscles and organs healthy. Their respiration changes as well, dropping from 6-10 breaths per minute to one every 45 seconds. In every way, they start to use their resources more wisely—as if deep down, their bodies know that repose is required of them.
We both know that the capitalist world we live in and the level of energy it asks of us is unsustainable. And so, this will be my last newsletter of 2021 as the Atmos team prepares to hibernate for the holidays. The time comes when we must mirror nature and rest—to find our own safe spaces to nurture and conserve our strength. Learning how to slow down is imperative not only for ourselves, but our species. And we can trust that the deepest parts of us know another way of being. In the face of the unknown, it is always possible to find stillness and return to our breath. We may need to, for what’s heading our way.
