ANTELOPE ISLAND, Utah — "How do you move a 2,000-pound bison?" a rider on a horse next to me asked. The punch line to this joke: "You don't."

Buffaloes don't herd easily. If pushed too fast, they lower their heads and charge at anyone dumb enough to get in the way.

But that is exactly what we were trying to do — about 150 riders as we trotted across a flat field on Antelope Island in the middle of Utah's Great Salt Lake. Ahead of us, a herd of about 250 bison — a woolly, snorting blanket of black shoulders and rising dust — shuffled toward the corrals on the north end of the island. To move the animals, riders whooped like warriors. One rider snapped a bullwhip.

In all the commotion, at least eight riders were thrown to the ground, and one suffered a broken wrist.

Still, that's the kind of excitement that draws riders to the annual Bison Roundup on Antelope Island, one of the country's few buffalo roundups that allow untrained volunteers to herd these surly 1-ton creatures.

At other roundups — the most famous takes place every September at Custer State Park in South Dakota — visitors stand behind fences as professional cowboys do the hard work. But on Antelope Island each fall, any adult with a horse and the $25 admission fee can help herd bison into corrals.

As a kid, I fell in love with these beasts. Since then, I've been mesmerized by the sight of brawny bison rumbling across open fields — a timeless image, like thunder clouds forming or whales breaching the surface of the sea.

I thought I was alone in my buffalo fascination until I arrived on this 28,000-acre island in mid-October and watched a stream of pickup trucks, horse trailers and RVs roll onto a grass field. Some of these fellow bison fanatics traveled as many as 600 miles to spend three days enduring freezing temperatures, choking dust clouds and sore keisters to marvel at this iconic symbol of the American West.

In the mid-1800s, millions of buffalo roamed the plains from Mexico to Canada — so many that the pounding of their feet echoed like rolling thunder. When herds crossed railroad tracks, trains were delayed for up to half a day. The railroad companies responded by allowing passengers to shoot the buffaloes from the rail cars.

"The moving multitude ... darkened the whole plains," wrote Meriwether Lewis, who along with William Clark encountered a herd at South Dakota's White River in 1806.

But in a few short decades hunters had slaughtered so many buffaloes that the once-thriving herds dwindled to only 800 animals.

Eventually, preservation efforts rescued the bison from the brink of extinction. Today, about half a million bison roam public and private lands; the biggest herd, about 4,000 bison, grazes in Yellowstone National Park. (The terms "bison" and "buffalo" are used interchangeably, although biologists note that the American bison is only distantly related to the water buffalo and African buffalo.)

BEWARE LONE BULLS

The night before the roundup, I shivered in a tiny tent on a lumpy grass field near Fielding Garr Ranch, the horse rental concession on the south end of the island.

Before I arrived, Utah state park officials told me most bison wranglers camp on the island during the three-day event. Clearly, I didn't understand their definition of "camping."

As I pitched my tent, I watched a caravan of expensive RVs, campers and trailers roll onto the island to form a makeshift village. That night I listened to the rumble of gas generators and neighing horses.

The roundup began early the next morning with a mandatory briefing. An assistant park ranger warned us that bison are not as docile as their bovine cousins. When buffaloes get angry, they lift their tails straight up and charge. Among the island's bison, the ranger told us, are several lone bulls — mean, stubborn beasts that won't associate with the herd. Those rebels that aren't corralled on the first two days will be herded later by helicopter. At the end of the briefing, each rider signed a liability waiver, an indication of what was to come.

Atop my rented steed, I followed other riders to an open field where about 250 bison had been grazing.

The riders formed a semicircle about half a mile long and advanced on the bison, herding them north. The experienced riders took the lead, riding only a few yards from the trotting animals. I stayed back and watched them move without protest. The sky was crystalline blue, and the breath from the animals dissipated like steam in the chilly morning air.

For several miles, I rode alongside Massie Tillman, a retired federal judge from Fort Worth, Texas, who learned about the roundup during a previous visit to the island. Like Tillman, I was awestruck by the assembly of hulking, wedge-shaped animals.

"The most overused adjective in the English language is 'awesome,' " Tillman said as we rode. "But there is no other way to describe this."

Up to that point, the ride was easy. Maybe too easy.

Within an hour, the bison began to rebel. Every few minutes, a random buffalo charged out of the herd, apparently frustrated by being pushed too far, too fast. Horses and riders dodged the horned attacks in a cloud of dust.

The lead riders continued to whoop and holler. A bullwhip cracked like a rifle.

Amid the commotion, I saw an ambulance, its cherry-top lights flashing, speeding along a road in the distance. I learned later that several riders had been thrown from their horses and one had broken a wrist. The ambulance took the injured rider away via a causeway on the north end of the island.

AN AWESOME SIGHT

After about two hours of riding, we gave the herd a much-needed break at a watering trough. This is where I got my first close look at Antelope Island's bison. These were plains bison, the shorter relative of the wood bison. Still, I marveled at the sheer size. The males weigh up to 2,100 pounds and stand as tall as 6 feet at the shoulders, lumpy mounds of muscle covered in black woolly fur. The heads were enormous but the torsos ended in narrow, almost delicate, hips. The calves stayed close to the adults, never straying from the protection of the herd.

When the break ended, we mounted up and pushed the herd over the ridgeline that bisects the island like a spine. Once we cleared the crest, our herd trotted downhill, joining up with bison that had been grazing on the other side. Now our herd numbered nearly 600 — a rolling expanse of dust and black humpbacks. The scene couldn't compare to the one Lewis and Clark encountered but, for a greenhorn city slicker like me, it was truly, well, awesome.

Our final destination lay at the bottom of the hill: a large corral and several stalls.

The buffaloes sped down the mountainside, with our horses trotting to keep up. But when the herd reached the open gates, the bison stopped cold. They wouldn't enter the corrals, unwilling to exchange free-range grazing for fences and gates. We shouted. The bullwhip cracked, but the bison wouldn't budge.

The standoff lasted several minutes until a few reluctant buffaloes marched through the gates and the rest followed.

The gates slammed shut. We were elated but also saddle-sore, hungry and thirsty, it had taken us four hours to move the bison just 15 miles.

At the next morning briefing, we heard that about a dozen bison still roamed the island. We would split up into small groups and track them down. A helicopter would search out any buffaloes we could not find.

I joined a group of about six riders and we headed out to the island's western slopes. During a rest stop we noticed something bulky and black under a tree about 50 yards away. A large bull, more than 6 feet tall, saw us and trotted away until it reached the crest of a nearby hill. No one suggested herding that bison back to the corrals. We could tell by the look in its eyes that it wouldn't easily be fenced in. Maybe it would just run free until we return next year.