YELLOWSTONE NATIONAL PARK, Wyo. — We were expecting to see plenty of wildlife on a winter outing to Yellowstone National Park, but — silly us — we thought we might have to get through the entrance first.

But as we drove through the gateway community of Gardiner, Mont., toward the Roosevelt Arch, the century-old ceremonial north entrance to Yellowstone, we were distracted by the action on the gridiron at Gardiner Public School. A herd of bison covered the field.

Beyond, more bison grazed on the school's front lawn. Bison lounged on the sidewalk at its main entrance. Bison wandered among the cars in the parking lot.

"Those kids must have to be awfully careful going to and from class," my wife remarked. More people in Yellowstone are injured by bison than fall victim to grizzly bears — though numbers for both are very low.

A few snapshots, and then it was through the arch for the short drive to the entrance station. More bison grazed just inside the park boundary. Interspersed among them were bands of elk and pronghorn antelope. Within the next two hours, we also would see bighorn sheep, mule deer, coyotes, a bald eagle and more bison — all from the road.

Summer visitors to Yellowstone also expect to see wildlife. But most don't realize that winter can be prime time for wildlife viewing. Deep snow in the high country drives elk, deer and bison down into the open valleys, where the weather is milder and they can more easily paw or push snow aside to get to the dried grass beneath.

And where the grazing animals gather, predators follow — particularly the gray wolf, which has achieved star status since its reintroduction to Yellowstone in 1995. At any given moment on any winter day, dozens of binoculars and spotting scopes are sweeping the Lamar Valley in northeast Yellowstone from pullouts, looking for any sign of wolves.

This is home turf for my wife and me, since we live only a three-hour drive away, and we tend to visit Yellowstone more in winter than in summer. We enjoy telling stories of being serenaded by wolf and coyote howls echoing off the mountains, of watching a coyote stalk and pounce on a mouse by listening to it scurrying under the snow, of inadvertently skiing so close to a bison that we could watch his bloodshot eyes zero in on us — and of not exhaling until we had put a safe distance between us and the bison.

But there's more than wildlife in Yellowstone in winter. The frigid air enhances the steam spouting from its famous geysers, making them even more spectacular. Its plateaus and broad valleys are made for cross-country skiing and snowshoeing; some scenic drives in summer are designated cross-country ski trails in winter.