It's a brilliant fall morning and instead of being holed up in my stuffy office cube, I'm out stalking grizzly bears. I've come to Yellowstone National Park to learn more about the wildlife here, particularly its two top predators: grizzlies and wolves.

My guides are MacNeil Lyons, a naturalist with the Yellowstone Association Institute, and his partner, Institute program manager Nick Derene. As we travel together, it becomes evident that their knowledge of wildlife — and the park in general — is nearly encyclopedic.

Today's destination is Lamar Valley, a beautiful, rolling and rumpled swath of the Rockies that sprawls across the northeastern corner of this 2.2-million-acre park. Overhead the sky is a deep, periwinkle blue as we wind our way into the valley, the sun just beginning to peer over the rugged Absaroka mountains that rise above Yellowstone's eastern boundary. We spot bison grazing and the occasional elk in the flats that rim the Lamar River before Mr. Lyons pulls the van over and quickly jumps out. Training his binoculars towards the horizon, he points out a tawny lump barely discernible among the rocks.

“Look, over there. Do you see it?” he whispers, our group gazing into the middle distance. “That's a grizzly bear.”

I can hardly believe our luck.

Approximately 150 grizzlies live within the park boundaries and the bears have been particularly active this year. With hibernation just weeks away, their foraging has taken on a sense of urgency. I watch through the spotting scope as the impressive bruin upends boulder after boulder in search of grubs or moths, intent on sniffing out something for breakfast.

“What do you think a grizzly eats?” Mr. Lyons asks.

This time of year it is grubs, though that diet varies according to the season, he notes. Bears are omnivores, so their food choices are vast and include berries, roots and moths, rodents, fish, and elk and even bison.

The naturalist holds up a grizzly skull he cradles in his arms. It's roughly the size of a football on steroids.

“He's at the top of the food chain here at Yellowstone,” Mr. Lyons says of Ursus arctos horribilis.

Even the wolves won't challenge a grizzly bear for food. Though often seen lumbering, grizzlies can hit top speeds of 30 miles an hour when chasing prey. Once down, a grizzly kill of elk or bison will provide sustenance for a host of other animals as well: Coyotes, wolves, ravens, bald eagles, mice, badgers, magpies, even the occasional mountain lion, all benefit from the grizzly's hunt.

As predators, bears and wolves play an important role in the delicate balance of life here. But it is a balance that is constantly shifting.

“Yellowstone is always in a state of flux,” says Mr. Lyons.

Change, it seems, is the only constant in nature, the only thing that remains certain.

Wolf alert

Now that we've seen a grizzly, our minds are dancing with wolves. “Is that one over there?” someone calls out as we all turn in unison. But we've been fooled. A closer look reveals two coyotes who trot along the perimeter of a bison herd.

As we scan the group with our binoculars, Nick Derene tells us the coyotes know that the pounding of hooves often flush out voles and field mice from the brush, so they're alert and ready. We watch as one coyote crouches, then leaps straight up in the air as he pounces on his prey. No luck this time, though. Mealtime will have to wait, and he lopes off to catch up with his mate.

Around the bend, we finally come upon a bevy of spotting scopes and long-lensed cameras, which can mean only one thing: Wolves. Biologist technician Rick McIntyre with the Yellowstone Wolf Project sits attentively as a group of 10 people chat and take turns looking through the spotting scopes.

“Who hasn't seen the wolves yet?” he asks as we approach.

The scopes are trained on the lodgepole pine forest several football fields away where three wolves saunter in and out of the afternoon shadows. Mr. McIntyre remains patient, focused. He's been observing wolves every day since they were first reintroduced to Yellowstone in 1995 and remains fascinated by their behavior.
The animals we see today are part of the newly formed Lamar Canyon pack, he tells us.

The female, bred by two males, gave birth to four pups last spring. Now that the youngsters are more mature, the pack has been roaming this region of the valley. The three adults will likely stay together for life, says the biologist, while the pups will eventually move on to join other packs.

The Lamar Canyon group is one of approximately 11 to 15 packs that have staked out territories at Yellowstone. All are the progeny of the original 31 Canadian wolves brought here from Alberta, Canada to repopulate the park.

I watch as Colby Anton steadies an antenna and points it towards the glade where the gray wolves have gathered. About 20 percent of park wolves wear collars fixed with small, portable radio transmitters. Each transmitter is set to a different radio frequency, so that individual animals can be followed by a signal that beeps from the collar. Mr. Anton, a field technician with YWP, assists Mr. McIntyre in tracking the wolves using telemetry, a data collection method that makes observing these elusive canines easier. While a somewhat inexact science (since radio waves can bounce off rock walls giving false readings), telemetry provides biologists with a much better picture of where animals travel and how they behave.

Mr. McIntyre became interested in wolves while working summers in Denali National Park and Preserve in Alaska. It was research for a book on wolves that led him to Yellowstone and the Wolf Project, which is funded in part by the Yellowstone Park Foundation. Now, he spends every day adding to the body of knowledge about wolves, helping scientists unravel their mysteries.

Understanding Our Past

Back at the van, Mr. Lyons passes around old photographs to illustrate how changes in wildlife management at the park have evolved over time. The story of the wolf is a good example. The canines, once considered a dangerous threat to the park's wildlife, were aggressively hunted and eradicated from Yellowstone during the first half of the 20th century. Now, they've successfully (if controversially) been returned to the park and are thriving. While their success has been celebrated, the steady decline of elk in recent years is raising questions and writing a new chapter in this continually unfolding story. The images lead to a discussion of the importance of conservation and how best to manage the park's natural resources.

Whether participating in wildlife observations or hiking to see the park's many natural wonders, a more informed experience is what the Yellowstone Association works to deliver.

The nonprofit “wants people to understand and enjoy the park,” says Jeff Brown, YA's director of education. “We like to say we're helping people fall in love with Yellowstone.”

Encouraging preservation through education, that's their mission, by helping the public learn more about the majesty and mystery that is Yellowstone National Park.