Buffalo may look slow, clumsy and docile, but they're not. They are unpredictable, as swift as a horse and, at a full run, can stop on a dime, spin and charge without warning.

With that in mind, riders on horseback set off to round up buffalo on Antelope Island a few weeks back, roughly 750 head — young-of-the-year, old bulls and young bulls, and cows ripe with next summer's calves.

It was a scene pulled from the pages of the Old West 150 years ago — riders on horseback, wild buffalo, wide open range — were it not for the puffy parkas, duck-bill baseball caps and the iPods.

Roughly 65 horses and riders showed up on the first day, which was cold and wet, and twice that number showed up on the second day, which was warmer and sunny.

About 60 buffalo managed to slip through the riders, some by accident and some by choice.

The really big bulls, said Ron Taylor, as he watched one particularly large bull standing outside a fenced enclosure holding the herd, are left alone.

Island staff call them the Beasty Boys. The one he singled out was nicknamed Grumpy for what he said were obvious reasons.

"We choose to keep them out of the roundup. They're hard on equipment, hard on the staff and the other animals," said Taylor, island manager for the Utah Division of Parks and Recreation

"It's funny, but on past roundups they haven't wanted to be with the other buffalo. This year they do. They're hanging around, outside the fences, trying to get in. One tore out a section of fence after we had the herd in pens, and about 100 animals got out. He had to herd them back into the pens."

On past roundups, helicopters were used to herd the buffalo. Horses and riders swept the island looking for stragglers. For them it was actually more of a ride than a roundup.

Last year it was decided to ground the helicopter and round up the buffalo the old-fashioned way. It worked, said Taylor, "So we tried it again this year."

By the end of the second day, two-thirds of the bison were in pens. By the end of the third day, fewer than 60 stragglers were free, and a number of those were the Beasty Boys.

"We were convinced we could move the animals with riders on horseback, and we were right. I know the riders enjoyed the roundup a lot more," confirmed Steve Bates, island biologist for the DPR.

The island herd is one of the oldest and most productive in the country. Roughly 85 percent of the cows checked last year were pregnant.

The rate on the free-roaming herd on the Henry Mountains is only around 25 percent.