Free American Buffalo by Steven Rinella Page A

and willows that help to hold it in place.
    I’m struck by the lunar appearance of the river, its stark grayness. Essentially, the river’s floodplain is composed of a vast, deep expanse of glacial debris. Eighteen percent of the Copper Basin is covered in glaciers, which pulverize the surrounding mountains into something known to geologists as glacial till. The finest glacial till is called rock flour, particles so small and fine that they turn the water the color of potter’s clay. Every year, the Copper River carries about sixty-nine million tons of debris to the ocean, or about thirty-five times the total amount of debris that was hauled away during cleanup after the destruction of the World Trade Center.
    In places, the meandering channels of the Copper River are eating away at the steep hillsides, which border the floodplain. The river takes away slices of the hillsides in vertical chunks—think of cutting a meat loaf into slices that fall away intact or else crumble into the pan. Some of the eroded slopes are one hundred or more feet high. Within the first few miles of our float, I watch erosion happen several times. As we float along, little pebbles and puffs of dirt fall away from the banks and trail into the river. Sometimes the falling debris knocks off more rocks and dirt, creating miniature landslides. Above these eroded banks, the vegetative mats of the forest hang over the precipices like heads of foam tilting over the lips of overfilled glasses of beer. Trees that reach too far over the cliffs tend to lose their footing and plunge down into the river en masse. We pass several places where dozens of trees have come down at once in great tangles of wood. The limbs, still springy with life, wave in the current and emit swishing sounds. Trees that have spent a season or two in the river are stripped of their limbs and bark. They look like perfect telephone poles, except they are still attached to their root wads. If you sank one of these trees in the ground upside down, it would look like a long-stemmed flower with a wooden blossom.
    In part, the buffalo chose to live in this specific area because of the erosion. There are steep bluffs a half mile away from the water, evidence that the river has changed its course and volume many times over the millennia; with the river no longer sloughing away at their bases, the cliffs taper off and vegetation takes hold. Sedges, grasses, and wildflowers carpet the soft soil of the hillsides, but trees don’t hold as easily. The lack of trees exposes the bluffs to the sun and wind. In the winter, the wind carries the snow away, and the sun helps to melt it. While the buffalo might prefer to winter among the thick stands of willows along the river, at times these bluffs provide the only food for many miles that is not encased in snow and ice.
    When it comes to the cold, buffalo have a lot of anatomical tricks up their sleeves. Proportionate to body size, the buffalo’s trachea is larger than that of any other large land mammal; when it takes a breath of cold air, the air is pre-warmed inside the trachea before it moves down to the animal’s lungs. This way, ambient air temperatures have a diminished effect on the animal’s core body temperature, which is 101.6 degrees Fahrenheit. A buffalo’s coat of hair is another handy adaptation. The hair above its eyes is so short that it looks like someone buzzed it with an electric clipper. This shortness prevents freezing water from accumulating against sensitive eye tissues. Domestic cattle have longer hair around their eyeballs and are commonly blinded by gobs of ice. With dark hair growing out of black skin, buffalo can absorb much more warmth from the sun than light-skinned and light-haired critters. And their hair is thick. On their mid-rib, female buffalo calves have about 2,992 hair fibers per square centimeter, while males have a bit fewer, at 2,182. (The total number of hair follicles on an animal is constant throughout