Winter can be a grind on all of us. This recent bout with sub-zero temperatures has had a subtle but noticeable affect on our January existence. Just two weeks ago I was seeing bundled up pedestrians and joggers on a fairly regular basis. The numbers have dwindled. Instead, folks are tucked warmly in their heated homes going about their lives indoors. When they do get out, many leave cars idling in parking lots so as to return to a relatively warm vehicle. This is all good and well, and comes with the idea of living in the northern plains. We, as humans, have a large store of ways to manipulate our surroundings and create suitable habitats for productive lives in spite of environmental conditions. But what is happening to the creatures outside our cozy windows?
I'm not one to watch a lot of television at any time, so I usually turn to other pursuits such as reading. A couple years ago I happened upon a book titled Winter World, the Ingenuity of Animal Survival by Bernd Heinrich. I wasn't familiar with this author but it turns out he's a University of Vermont biology professor who has written several books, all well received. In this particular volume, I found a treasure of information dealing with survival mechanisms from bugs to black bears.
"Because winter drastically affects the most elemental component of life--water - radical changes in a creature's physiology and behavior must take place to match the demands of the environment." That's Heinrich in the introduction to this easy-to-read book. What makes his work stand out among others in his field is the hands-on approach to science he takes. Not one to sit in a lab and stare at beakers, Heinrich is outdoors exploring the woods on his northern Maine property; all the while watching with a trained and curious eye.
He takes the reader beyond what most of us know from high school biology or from watching National Geographic specials as kids. We learn that there are certain frogs that survive the winter frozen completely solid thanks to some weird chemistry; how air-breathing snapping turtles withstand six months at the bottom of frozen ponds; that bears lose no muscle or bone tissue while hibernating and don't need water; and that hibernation itself is a moving target. He writes, "As ever more numerous and varied ways of surviving winter were discovered, an all-inclusive definition of hibernation has become out of reach."
As he deftly describes the mechanisms of animal survival, Heinrich continually returns to the mystery of the golden-crowned kinglet (Regulus satrapa). This tiny songbird is barely larger than a hummingbird yet is able to survive winters as far north as Alaska (we see the birds here in spring and fall but are usually gone by early December, likely due to our lack of preferred habitat: coniferous forest).
Just how a critter this small - it has half the body mass of a black-capped chickadee - can maintain life in the dead of winter is a puzzle. It has a huge percentage of insulating feathers vs. flight feathers but that doesn't seem enough. Might it purposefully go into a state of hypothermia? Does the bird create a microclimate by building a winter nest of sorts?
From a pure physics standpoint it is impossible. The kinglet should shed more heat energy during the night than it could possibly restore by eating bugs during short, eight-hour winter days. Heinrich surmises that something else, yet undiscovered, is at work, and bets on huddling. That is, grouping together at night to share body heat. The book ends with no answer to the kinglet riddle. He writes, "They defy the odds and the laws of physics, and prove that the fabulous is possible."
For a fascinating natural history lesson, this book is a winner. And what better way to wile away the cold, dark hours of January than by warming to the unimaginable winter survival tools wielded by the critters around us?
PS: Not long after Winter World was published, Heinrich indeed witnessed two instances of night huddling by golden-crowned kinglets.