Plains song: bison and life on the "American serengeti"

Natural History, Oct, 2002 by Dale F. Lott

Bison don't just graze and eliminate on a prairie; they also wallow. Wallowing probably gets rid of some insects, possibly reduces the bison's heat load, and certainly alters 75 to 150 square feet of habitat for the prairie plants. Wallowing also lays the soil bare and compacts it. The compacted bowl of soil holds rainwater, creating a microenvironment in which seedlings that are otherwise rare in tallgrass prairie--sedges and rushes--can grow. Some of these seeds are blown in by prairie winds; others are carried there in the coats of the wallowing bison--perhaps picked up in another wallow.

The Hunt

Be a bison. A bison cow on the run, adrenaline soaring, heart racing, hooves flying. On the run from what? From whatever the bison all around you are fleeing. Running with the herd has meant safety for thousands of generations.

But not this time. This time the predator is man, and unlike all the other predators, he wants you to notice him before he is beside you, wants you not to lag behind the running herd. This morning, men waved and shouted as they approached the herd and started the cows and young bulls around you running from them, and as you ran with the herd, more men rose to the left and right, guiding the running herd down a funnel of strange sounds and movements. This predator has turned your ancestor's hard-earned knowledge of predators to its own advantage. It has turned your best defense into a deadly weapon. Your escaping will be the death of you.

But that's not what your phylogeny whispers, and so you follow the cow in front to.... Suddenly, where she ran, there is only empty ground, and in a moment, not even that. The plain has ended mid-stride and you are running in space. Your feet flail at the sky as your body tumbles; then your breath is gone and your ribs and spine are breaking as the cow behind you falls on you, the way you fell on the cow in front. Your body becomes part of the maimed mass at the bottom of a cliff.

Bison react to things they can see, hear, or smell that seem dangerous. The stand hunter--so called because he pursued standing bison--nullified smell by coming from downwind. He crawled on his belly and kept his distance. But then he fired his .50-caliber Sharps rifle. A sudden cloud of black smoke rose on the crest of the hill where he lay, followed in an instant by a boom that would reach any ear within half a mile.

Nearly every wild thing fears the unknown and flees from it. It's a reasonable rule of thumb. If the unknown thing was not deadly dangerous, you've wasted a bit of time and energy. If it was deadly dangerous, you've saved your life. The possibility of one huge payoff like that justifies a lot of small investments. Call it the lottery principle of predation prevention. It's sometimes called the life-dinner principle. The predator's dinner is at stake; the prey's life is at stake.

Why, then, did the herd stand for the slaughter? Perhaps because the rifle's report filled the ear too much like a thunderclap. A grazing herd is as indifferent to thunder as it is to the rain that usually follows. They simply graze on, their ears filled with thunderclaps and their coats filling with raindrops. Thunderclaps signaled rain, not death, and maybe that's why, while the rifle boomed, they grazed on ... and died.