More than 30 years ago, on December 28, 1973, President Richard Nixon signed into law the Endangered Species Act, one of the world's most comprehensive wildlife conservation measures.

VOA's Rosanne Skirble takes us to Yellowstone National Park, the nation's oldest and largest national park. It's here we witness wolves on the rebound and the captivating drama of their everyday lives.

Rick McIntyre has not taken a day off for more than four years. That is by choice. He is a wolf researcher at Yellowstone National Park and he loves his work.

On this summer morning he sets up a spotter scope on a hill overlooking the Lamar Valley. He gazes over the broad green meadow and the gently flowing Yellowstone River waiting for the wolves to make a move. His position is also just steps from the highway, although few tourists pass at this early hour.

"I checked for signals a little bit earlier and we think that most of the wolves are at their den site so we are in a position to watch the den area, as well as the pack's rendezvous site. There could be wolves in either location. So we will be looking in both directions," he explains.

Skirble: And this is the best time of day?

McIntyre: Yes, it is a little bit before sunrise. Wolves tend to be most active around dawn and dusk, less active in the middle of the day. That's why I work a split shift. I am out in the early morning hours and then take a break during the midday hours and then I am out again in the evening.

Skirble: So, your shift is much like the wolves'.

McIntyre: Yeah, that's right. They tend to sleep in the middle of the day. So, I try to do that myself!

For a century, gray wolves - once common in Yellowstone and the northern Rocky Mountain region hunted aggressively tracked down with dogs, shot from airplanes and poisoned. By 1930 they were gone from Yellowstone. It took nearly 70 years to bring wolves back to the park through a reintroduction plan that sent political shock waves through the American west.

Despite intense opposition among ranchers who feared the impact of the introduction of a top predator on their livestock, 31 Canadian wolves were captured, radio collared and relocated to Yellowstone National Park in the mid-1990s. Rick McIntyre has been monitoring them ever since.

Beeps from a portable antenna mean wolves are nearby. As he adjusts his scope to locate the pack, Rick McIntyre explains that wolves multiplied quickly in their new habitat because they have plenty of space, abundant prey and few enemies. The population - which has grown six-fold in less than ten years has also sparked some significant changes in the Yellowstone ecosystem.

"With wolves back, the elk have to be more alert," he explains. "They are constantly looking around because they are concerned about the possibility of wolves approaching them. And, all that seems to boil down to the fact that they would be spending less time in any given spot."

Which, he says, opens up the landscape for aspens and cottonwoods.

"And so people who are studying the aspens and the cottonwoods feel that they have been able to find measurable improvements in the growth and also the survivability of the seedlings. And, people are working on the same issues with the willows as well," he adds. Wolves generally hunt in packs and can overpower elk and grizzly bear. The surplus meat left behind from such kills gives scavengers like bald eagles, cougars, even grizzly bear - a free meal.

Rich McIntyre spots several wolves and confers with a network of volunteers stationed at various locations in the valley. Together they piece together a wildlife drama as it unfolds before them.

The chatter today concerns "Number 21," the male leader of the pack, who has been missing for several weeks and is presumed dead. As the story goes, "21's" son, "253," is a likely successor. The situation is complicated by "302," a male from another pack, who could challenge "253" for the top spot.

"We just don't know what the end of the story is going to be," he says. "Will 253 decisively defeat 302, and 302 will leave once and for all and not come back? Will 253 allow him to come into the pack and join it? Or will 302 draw off some of the younger wolves and start a new pack with him as the alpha male? And if that happens how will they work out the details? Will they split the territory in half? That is an on-going story that is fascinating, and that as far as we know, has never been witnessed or documented by wolf researchers in other parts of the world. So, in a sense, it is a case history that will be playing out in front of us over the next few weeks and months."

That history captivates newlyweds Lisa and Mac Rodriguez from Houston, Texas.

"We come out every day to look at them. They are absolutely stunning, beautiful animals," Lisa says.

"It is just something that you read about, see pictures of, but you actually have to see it to believe it," adds Mac.

"To see an animal in its natural habitat, to be brought back from extinction in an area where they lived before we did. It is amazing to be able to watch this animal and see it in nature," explains Lisa.

Brian Connolly expresses similar fascination. The writer who uses wolves as a backdrop in his novels for young people - spends four months each year in the park.

"The winter is the best time to be here because the wolves are much more active. They love the cold weather and all the snow, and this is the wintering ground for the elk and the mating season for the wolves and their dispersal season and the howling goes for seven or eight hours a days, trying to lure the females off from one back to the other," he says. "And the only drawback is that it is 25 degrees F below zero. So, it is very cold and you are not skiing, or on snowshoes, but you are standing still. So, you have to come prepared with foam mats to stand on and heaters in your boots, expedition-weight long underwear, but it is wonderful then."

Jeanne Muellner and her aunt, Charlene Vasilievas, make the pilgrimage to Yellowstone from Chicago several times a year. They say wolf watching has given them a deeper sense of connection with the natural world.

"They are not the big, bad wolf that the myths have made them out to be," notes Jeanne.

"I've learned that everybody should live and respect one another and the animals that live on this planet with us. There is room for everybody," Charlene says. "And, there is definitely room here for wolves, and they are just so family orientated and we as human beings if we watched them long enough and see how they care for their young and how they take care of each other, I think that we can learn a lot from them."

Most Americans, like Charlene and Jeanne want wolves to stick around. A national survey shows supporters of the Endangered Species Act outnumber opponents by two to one. While the recovery is touted as a major success under the Endangered Species Act, landowners in the region remain strongly opposed.