Winter World_ The Ingenuity of Animal Survival - Bernd Heinrich [1]
Each species experiences the world differently, and many species have capacities that are far different from ours. They can show us the unimaginable. Thus, the greater our empathy with a variety of animals, the more we can learn. For example, nobody on their own would seek to collect a fluid that is practically indistinguishable from water out of a specific kind of tree, then evaporate it to produce sugar. But the Iroquois, the native people of New York State, say that maple syrup was discovered by a boy who noticed a squirrel licking some maple sap at a wound where the water had evaporated. He had discovered a squirrel’s winter food. Curious, the boy tried the sap himself. Finding it sweet, he began the tribe’s use of a new resource. Similarly, prior to actually observing by eavesdropping with sophisticated electronic equipment, nobody would have suspected that bats see the world with their ears, that elephant seals dive down to a mile in depth and can stay down an hour, that moths can smell a mate from a mile away, or that birds fly nonstop across oceans.
One of the early theories (by nineteenth-century German biologist Carl Bergmann) that relates to the winter world, which is now enshrined as Bergmann’s Rule, is that northern animals are larger in size than their southern congeners, to allow them to better conserve the body heat that is generally costly to produce. It is therefore perhaps not surprising that the world’s largest of the Passeriformes (the most common and species-rich group of birds), the common raven (Corvus corax), is a northern bird, and the largest individuals of this species live from Maine to Alaska. But as with most rules, Bergmann’s applies only if everything else is equal. It never is; the world’s smallest perching bird shares the raven’s northern range, even in winter, and it weighs as little as 1/325 the weight of a large raven. This northern companion to ravens, the golden-crowned kinglet (Regulus satrapa) weighs in at about 5 grams—the same as two pennies. It is scarcely larger than a ruby-throated hummingbird or a pygmy shrew, yet it appears to thrive in the northern winter woods. I saw these tiny birds on my boyhood excursions into the winter woods of Maine—and I see them now, and am still amazed when I step out in the morning after a cold night and I’m greeted by them. Our fragility in the cold makes the survival of these tiny creatures all the more miraculous.
Golden-crowned kinglets.
Sigund F. Olson wrote in Reflections from the North Country: “If I knew all there is to know about a golden arctic poppy growing on a rocky ledge in the Far North, I would know the whole story of evolution and creation.” He could have substituted the kinglet for the poppy. Kinglets are drab-colored birds with a flaming red, yellow, or orange crest. When excited, kinglets can suddenly flash their bright crest out of their olive-colored head feathers. They are one of the most common yet least-known forest birds living in the Northern Hemisphere. When I see a kinglet hopping through a densely branched spruce tree covered with pillows of snow, I often imagine myself in its place, wondering how it experiences its world. Having a circumference of about the size of a walnut, the rate of heat flow from the body is increased over a hundredfold from what it is in my human state. The world is suddenly that much colder, and a fate of freezing to death in the northern winter becomes an almost nightly possibility. However, the wonder and the marvel of how kinglets survive cannot be understood or appreciated except when viewed through the window of the adaptations found in the numerous other animals that share its winter world. It is their special means of coping that form context and continuity for the mystery of how