DUBOIS - Dan Bjornlie cocks his ear toward the gaping mouth of the bear den.

Around him the forest is silent - save for a faint scratching coming from beneath the earth.

The female black bear he tranquilized only moments before isn't going to sleep.

Scratch, scratch, scratch.

She disappears from view in her den. Her cranky hissing and growling subsides - for the moment.

Scratch, scratch, scratch.

Then he realizes what's happening.

She's coming out the top.

He looks at the crowd gathered behind him. They stare, unable to look away from what is about to happen.

In a barely audible whisper, he commands them.

"Everyone get the hell out of here."

The previous day, Bjornlie and three other biologists from the Wyoming Game and Fish Department snowmobile to another den.

The project is part of a long-term study of the correlation between body condition and reproduction in Wyoming black bears - a sort of "side project" for biologists who spend most of their time collecting data on grizzly bears.

During the summer, a few female black bears are caught in snares set up for grizzlies. They are then fit with VHF collars and tracked through the year.

In the winter, the biologists visit three to five dens to collect information on the bears' body condition and whether they have cubs.

"It's just a way to use the information with the chances we are getting," Bjornlie says.

The study has been ongoing for about 15 to 20 years, and to this point the data has yet to be analyzed. But in his time doing it, Bjornlie has drawn a few conclusions.

"What we're finding is the lower body fat bears obviously are in poorer condition, and it's those bears who don't have cubs," he said. "The female body condition plays a lot into whether they have cubs and cub survival."

The black bear they are seeking this time is known to have at least two cubs.

She also is known to be a runner, fleeing the den after being drugged.

They pack up their sleds and head up the trail.

Word has come from various sources that the snow is packed clear to the turnaround point.

The day promises some warmth, and the snowmobiles zip through the trees, having only minor upsets before making it to the turnaround.

The group snowshoes into the forest and sets up shop on a steep slope above the den.

Dan Thompson, trophy game biologist for Game and Fish, prepares the drug in a jab stick. Bjornlie gets the data sheets ready.

Everything is prepared in advance in an effort to minimize the bear's time out of the den.

Approaching the opening, Bjornlie flips his hat backward and shines a flashlight into the dark hole.

One swift move, and he injects the drug.

Or he thinks he does.

Maybe he doesn't.

It's hard to tell.

"I got her right here," he whispers, pointing to his left shoulder.

They check their watches, waiting for the drug's effects to set in.

The tranquilizer is called Telazol - a combination of a hallucinogen and a muscle relaxant. It calms the bears and causes them to be unaware of what is going on around them.

It's a favorite for bear biologists because of its relative safety. It's hard to overdose with Telazol.

The only difficulty is getting the drug in the bear - as seems to be the case here.

Justin Clapp, trophy game biologist for Game and Fish, peers into the den.

The bear gives a hiss and a small, aggressive swipe. Definitely not sleeping.

Clapp jumps back, eyes wide.

"She's pissed," he mouths.

About five minutes pass, and they realize the bear didn't get enough of the drug. Now they must resort to the dart gun.

A small "pop" from the gun, and they check their watches again. A few minutes pass, and they peer into the den.

She's down.

They crawl into the darkness, a cavernous space for a black bear den, and pull her out onto a tarp, taking care as they lower her down the hill. Pads are placed underneath her to keep her insulated from the snow.

Bjornlie crawls back into the den and produces two cubs, one black, one brown. They mew, a metallic, almost robotic sound, as they are carried down the slope tucked into the coat of one of the biologists. They cling to his shirt, nuzzling in the darkness and warmth.

Back on the tarp, the bear's temperature, body fat and weight are all taken. She is inspected for wounds, mites and broken limbs, teeth or jaws to make sure she is in good condition.

At 11 years old, she comes in at about 178 pounds, and from the looks of it, she has had a good year.

With the work-up complete, they pull her back into her den, curling her up on her side and placing her cubs on her belly.

Back at the trucks, Bjornlie gives a sigh of relief. As far as black bears go, she was relatively cooperative - an easy job considering the variables.

But some bears don't go down as easily.

A brown paw breaks through the snow.

Three-inch claws fan out, swiping like a cat at the three obstacles that stand before her.

"Everyone get the hell out of here," Bjornlie whispers to the crowd behind him.

What first appeared to be an earthen den actually is a snow cave.

The bear claws at the roof, carving out a hole.

The biologists place small shovels in front of her, trying to deter her escape.

They need more time before the drug sets in.

Just a little more time.

If she would only go back in her den and lie down.

She continues digging, making the hole in the roof of her den bigger.

She bites the shovels, swatting them away.

The snow gives way, and the bear pulls herself out of the top of her den.

The biologists retreat.

She surveys the crowd now staring at her in awe.

And then … she runs.

Her gait is slow: Some of the drug has begun to take effect. She lumbers, quietly.

For all the excitement, the forest remains silent.

Bjornlie straps on his snowshoes and takes the dart gun, following her into the woods.

He can't leave her out by herself. He must give her more of the tranquilizer to put her to sleep before returning her to the den.

They do-si-do around the woods.

The bear walks in circles.

Bjornlie chases.

Finally, he gets a shot in. She goes down on the side of a hill.

The crew carries her sleeping body back to the den, spreading her out on the padded tarp.

They work quickly, taking data, changing her collar.

This one has lost weight since the last time they saw her. At age 4, she was 140 pounds. At 6, she is only 110.

Watching from the edge of the tarp is Susan Stewart.

She stands quietly, bundling up in her Game and Fish coat.

Finally, when the activity lulls, she asks, "Can I touch her?"

Sure, they say.

She hands her camera to someone in the group and kneels at the bear's side.

Unlike the bear from the previous day, the years have not been kind to this girl; her sides feel bony to the touch. Her body appears small and helpless while laid out on the ground. If she had cubs, they are now gone.

Even at the top of the food chain, the wilderness can be an unforgiving place to an animal.

Stewart places her hands in the bear's coat, gasping at the feel.

She rubs the bear's back, softly strokes her fur, bowing her head over the animal for a moment.

Then, placing the giant paw in her hand, she looks up at the camera and wipes the tears out of her eyes.