MISSOULA, Mont. (AP) — The big bull came into the small round pen with its tail sticking straight up in the air.

The bison had been through this before.

Only this time, there wasn't a crowd of bystanders packed on the walkways above. There weren't any shouts from behind or poles poking at it. And there weren't any rattling cans or electric hotshots, either.

With a snort, it whirled around away from the open gate as it looked for another way out. The sound of its hoof bouncing off the side of the metal wall reverberated in the still air as all the people hovering above moved ever so slowly and quietly.

"That's right," said Darren Thomas as he waved his hand gently through the air in the direction of the gate. "Be real slow with him. Let's just slow him down and let him find the way."

Standing in the top end of an upright culvert, National Bison Range biologist Amy Lisk gently waved a plastic blue flag just behind the bull to help encourage him to step inside the gated chute, where he'd be weighed and his electronic ear implant recorded.

Eventually, he did just that.

The bull was just one of close to 350 that would find its way through the maze of chutes as a crew of biologists, wardens, veterinarians and others with the U.S. Fish and Wildlife Service took note of their general condition and took some blood samples from a smattering of the adults.

This year's crop of bison calves was fitted with an electronic chip about the size of a kernel of rice that would be used to identify them for the rest of their lives. Biologists also collected hair from the calves' tails and took a blood sample that would be used to create a DNA marker that could eventually determine their future home.

This year's roundup had a different feel than most.

Traditionally, the event brings busloads of school-aged children and carloads of interested adults to see the bison up close and learn through a variety of accompanying educational offerings.

The dangerously dry conditions that followed the summer's challenging fire season gave managers of the bison range pause and they opted to push the event back nearly a month to ensure the fences were tight and the ranges moist enough to avoid any kind of flare-up.

Lisk was among the five horseback riders who attempted to drive the estimated 350 bison that inhabit the range into holding pastures located just above the complex of chutes where the animals are worked annually.

"That's not an easy task," Lisk said. "Bison are extremely agile and fast. They tend to go whichever way they want to go and like to test the boundaries.

"You have to have some good skills on a horse to stay up with them in the steep and rough terrain here on the range. It certainly tests your horse's physical capabilities."

Lisk said they try to get all the bison rounded up, but there's always some that manage to escape.

"We didn't get everyone," she said. "While we want to see as many as possible, we also are making a concerted effort to treat them more as wildlife rather than livestock. If we don't see an animal every year, that's OK."

The focus is on preserving the genetics of the National Bison Range herd, which is considered among the best in the nation.

Lee Jones, a U.S. Fish and Wildlife Service wildlife health specialist, places her efforts on keeping that gene pool viable.

"Our goal is to keep inbreeding down as much as possible," Jones said. "The animals that are most highly related to the rest are removed from the herd."

At this point, it's been determined that the range has the capacity for about 350 bison. Every year, in an effort to keep that number relatively stable, a number of animals are moved to other bison ranges managed by either U.S. Fish and Wildlife Service or various Indian tribes.

Fifty were culled from the herd this year.

The Rocky Mountain Arsenal NWR in Colorado will receive 25. Another 10 will go to a brand new herd in the Eastern Shoshone Tribe's Wind River Reservation. The last 15 will be sold to a variety of different entities through a sealed bid process.

"Typically, the bison from the National Bison Range are highly sought after because their genetics are considered pure," said Barry Petersen, the range's acting project leader. "There are a lot of other bison herds that have cattle bred into them. The people who buy bison from here are looking to improve their genetics."

While biologists do look for any outward signs of disease, Petersen said the animals aren't vaccinated or wormed like cattle.

"We don't do any form of treatments," he said. "As far as we're concerned, they are wildlife. From the years that I've spent around them, I know that they are amazingly tough. They can withstand an awful lot and do just fine."

But that doesn't mean that they don't respond to a bit of gentleness.

Every year, Lisk said employees at the National Bison Range look for ways to handle the bison in the least intrusive manner possible. They have redesigned the chutes and found new, less stressful ways to move the bison through them.

They have also upgraded their computer system to allow them to keep better track of how well the bison are doing out on the range and to help determine which ones need to be culled to keep the herd's gene pool safe.

"There's been a shift in perception on how we should handle the bison," Lisk said. "We've tried to get away from the concept that we can force them to what it is that we want them to do. Now we try to ask them to do it and let them make the decision themselves."

As a result, there haven't been any injuries to either man or beast over the last few years.

"It's just a lot less stressful," Lisk said. "If you give them time, they'll make the right decision. They are intelligent animals. No one likes to have three or four bosses poking them with a stick at the same time. That's what we want to avoid.”