I just got back from Yellowstone National Park. I took a class on wolves in winter though the Yellowstone Association and spent 3 days looking for and watching wolves. We saw at least 4 or 5 different packs of wolves. Most of the time we needed binoculars or spotting scopes to observe the wolves, but we did see one wolf that was on a hillside about 100 or so yards away. The wolf howled for 15 minutes or so before moving out of sight.
Elk are the primary prey of the wolves, and we saw large herds of cows and calves. The bull elk separate themselves from the cows and form bachelor herds. If it looks cold in this photo, it was. It was below zero when I took the photo.
Coyotes are killed by wolves, but they are often found not far from wolves while hunting for rodents. Mice and voles remain active through the winter under the snow. The snow forms an insulating blanket, and protects them from the wind. It also makes it hard for the coyotes to find them except by sound.
In the winter the hot springs create a lot of mist. The mist then condenses on the trees, coating them in an icy blanket.
The water from the thermal features in the park carve channels in the snow, creating beautiful patterns as the hot water flows away from the springs and geysers.