Young naturalists Thunder ▼ on the Plains American bison have returned from the edge of extinction to roam North American grasslands. by Christine Petersen In 1540, Spanish soldier and kept as farm animals in many parts explorer Francisco Vázquez de of the world. But these were not Coronado led an army out of cattle. They were wild bison, also Mexico in search of gold. They known as buffalo—the largest land traveled north and east, across animals in North America. mountains and deserts. The men “The country was covered with eventually came to a flat region them,” one observer recalled. Na- covered in grasses and wildflow- tive American people also lived ers but hardly any trees. on the grasslands, following and They found few landmarks to hunting bison as their ancestors guide them across this wide-open had for thousands of years. landscape. But the vast grasslands Bison thrived in North America were not empty. Huge, shaggy- until the 1800s, when they nearly furred animals roamed in herds too went extinct. Today, these amazing large to count. Coronado thought giants of the plains still roam some they looked like cattle, which were Minnesota prairie lands. JIM BRANDENBURG A herd of American bison wanders the prairie at dusk at Blue Mounds State Park. September–October 2019 49 Ancient Grass Eaters American bison are mammals in the years ago. Most large mammals died Chew and chew again. Tallgrass prairie A bison cow (left) feeds her calf. A bull (right) rolls same family as cattle, sheep, and goats. off as the climate became warmer and is a type of grassland found in regions on the prairie to get rid of insects. Their only close relative, the wisent, lives drier. Grasslands replaced forests across with more rain and snowfall. This habitat in Europe. All the members of this fam- the heart of North America. Bison sur- once covered more than 18 million acres plants are hard to digest. Bison can get ily are grazers. They have long legs, split vived and spread across this sea of grass. in Minnesota—that’s about one-third of enough nutrition only by ruminating, or hooves, and large, flat teeth for chomping American bison look like they still be- the state. In the prairie, grasses and flow- chewing repeatedly. and grinding tough plant foods. long in the ice ages. Woolly, chocolate- ers can grow more than 6 feet tall. Trees As it wanders, a bison pulls or bites off Bison have been in North America for at brown fur grows thickly over the animal’s and shrubs thrive along streambanks plants and swallows them whole. The least 130,000 years. They moved from Asia upper back, front legs, and massive head. and may spread into open spaces. food is stored in the animal’s four-part to North America during a cold period in A beard dangles from its chin. The shoul- Wandering the prairie, bison eat grasses stomach. Acids and microscopic or- the Earth’s history when northern oceans ders rise into a muscular hump, which and similar-looking plants called sedges. ganisms begin to break down the plant were frozen and the sea level was lower. slopes down to narrow hips. They spend much of the day in search of material. When a bison stops to rest in Ancient bison lived alongside mammoths, A male bison is bigger than a moose or food. There are many grasses and sedges the afternoon, it spits up food and chews camels, and giant ground sloths. They had even a grizzly bear, and sometimes as fierce. to choose from—big bluestem, prairie until this cud is soft and mushy. Rumi- thick fur to stay warm and wide horns to The bull may stand 6 feet tall at the shoulder dropseed, sideoats grama, porcupine nating helps the bison’s digestive system fight off fearsome saber-toothed cats. and weigh up to 2,000 pounds. Females, grass, prairie sedge, and dozens more. But absorb nutrients from even the toughest The last ice age ended about 10,000 called cows, are smaller but still impressive. JIM BRANDENBURG even when they’re fresh and green, these old grasses. 50 Minnesota Conservation Volunteer September–October 2019 51 Bison, Prairies, and People Bison don’t just live on the prairie. They help er variety of food for prairie animals. don’t die in a fire. Their roots are deep and Moving across the prairie at Blue Mounds State keep the prairie healthy. Like natural lawn- Insects, worms, and fungi feed on bi- remain safe belowground. Soon the plants Park, bison eat grasses and wildflowers. mowers, bison clear away grass and make son waste, returning nutrients to the soil begin to grow again, feeding the bison. space for wildflowers to flourish. They stay for reuse. Songbirds swoop down to catch Native Americans knew this. They children of the Plains; it is our home and in one area for a while and then move on. insects that rise from the grass where bi- sometimes set fires to create fresh graz- the buffalo has been our food always.” The plants quickly sprout new growth. son walk. Sick, old, and very young bison ing land for bison herds, or to clear for- A Lakota Indian leader named Red On hot summer days, bison wallow— are prey for wolves. Vultures and other est on the edges of the prairie. Cloud listed everyday uses for bison. Its they flop down into wet spots and roll. scavengers clean up the remains. hoofs were used for glue. The hide was Mud cools the skin, and it prevents in- Children of the Plains. For dozens of Na- used in clothing, ropes, and the water- sect bites. Shallow, bare holes called wal- A fresh start. Fires may start when light- tive American tribes, hunting bison was a proof lining of boats and tipis. Tools were lows form wherever bison do this, and ning strikes the prairie during summer way of life. In 1887, Chief Crowfoot of the made from bison bones, and tendons be- these wallows fill with rainwater. Dif- thunderstorms. Fire burns away dead Blackfoot tribe spoke about the impor- came bowstrings. But bison were more ferent plants grow here than on the sur- plants. It clears young trees that would tance of bison to his people. “The Plains than a resource to Native Americans. rounding prairie. That provides a great- block sunlight. Grasses and wildflowers JIM BRANDENBURG are large and wide,” he said. “We are the They were honored and respected. 52 Minnesota Conservation Volunteer September–October 2019 53 54 Minnesota Conservation Volunteer September–OctoberPHOTOGRAPH BY JIM BRANDENBURG 2019 55 Bison Seasons For much of the year, bison live in small the ground or scrapes them against trees, bison can use its strong sense of smell to Bison live on the prairie in all seasons. Their calves groups spread across the prairie. Cows, stamps his hooves, and bellows with a locate grasses buried under snow. Thick are born in springtime. calves, and young bulls stick together while deep and growling voice. If a challenger muscles inside its shoulder hump allow the older males go off on their own. As sum- doesn’t back off, the bull may run forward animal to move its massive head from side birth. She has one baby per year, which mer approaches, these groups walk long and lock horns in a wrestling match. One to side, pushing snow out of the way. Win- weighs between 35 and 55 pounds. The distances to find each other. They may of the males usually gives up before these ter is a slower time, too. The bison saves en- calf stands up within a few minutes and swim across rivers. And if one bison is star- contests become bloody. And the bison ergy by moving less. When blizzards bring in several hours can walk back to the herd tled, the whole group begins to run. Stam- cow may still walk away from the winner. strong wind and heavy snow, the bison with its mother. Its reddish-orange fur peding bison make a sound like thunder turns to face the storm and waits it out. blends with the prairie grasses, providing that seems to shake the earth. Great clouds Cooler to cold. Autumn is a time of change camouflage against predators. of dust rise up behind them. The animals on the prairie. Summer-green grasses fade New life. Winter turns to spring, bring- Young bison play and run while adult are agile despite their size. Bison can turn as the last wildflowers bloom. The days -be ing new life to the prairie. Bison no lon- animals feed. If a little one strays too far, quickly, cross rough ground, and gallop come shorter and cooler, and bison begin ger need their woolly winter coat. They its mother grunts to call it back. Rich longer than horses without tiring. to fatten up. As winter sets in, fat provides rub against trees and rocks to peel away milk helps the calf grow quickly. Within a insulation for their bodies, with help from the itchy fur. There are boulders on the month, it also begins to eat some grass. By Pairing up. Summer is the mating sea- extra layers of fur—a dense undercoat for Minnesota prairie worn smooth by gen- summer, the calf has begun to sprout tiny son. A bull bison stands close to his cho- warmth, with longer guard hairs to keep erations of passing bison. horns and a hump. Its fur turns brown. sen herd, threatening any other male rain and snow off the animal’s skin.