Bison in winter

Bison move to the lower elevations of the park in the winter to feed. They use their huge heads to shovel the snow and ice out of the way, and feed on dead grasses.

If the winter is very harsh they will continue to move to lower elevations which take them out of the park where they are hunted, or rounded up and killed because they have been exposed to a disease called brucellosis. This bacterial disease causes bison and cattle to abort calves, and can be transmitted if an animal eats grass near where another has given birth. Local ranchers are concerned that the bison could spread the disease to their cattle. Ironic since cattle gave the disease to bison in the first place.

Wolves

These wolf tracks were in the snow by the side of the road that traverses the Lamar Valley. This is the only road open to cars in the park during the winter. Down the road to the east we came across the male wolf below at a kill made the night before.
90% of the time when wolves are present so are ravens. Ravens can't open the body of an elk or other large mammal by themselves, but the wolves can. Ravens have been seen playing with wolf pups as they emerge from their dens in the spring. Ravens also play with adult wolves as well as the pups. Wolves don't kill ravens, but they will kill other birds and animals that approach their kills.
There is a hypothesis that ravens may even lead wolves to weak prey as they fly back and forth from the prey to the wolf pack they may be guiding wolves to specific animals the ravens have picked out as being slow, weak or ill.

More Yellowstone in Winter

There is alot more snow in the Lamar Valley this winter than last. All this snow makes it more difficult for the animals to more around, and some like wolves, bison and coyotes learn using the road makes traveling easier when they want to move along the valley.

This coyote was headed up a hillside near the road, and broke through the icy crust on the snow.

This coyote headed toward the road. I saw it in my side view mirror, so I stopped the car and waited.

It continued up the road right past the car.

This mule deer had been killed either by a mountain lion or wolves. When I saw it magpies, ravens and this coyote were scavenging the remains. Wolf kills end up feeding lots of other animals.

Winter in Yellowstone

The red fox in the foreground was hunting mice and other rodents in the snow, and did not notice the coyotes approaching it. Like wolves will kill coyotes, coyotes will kill foxes.

Once it did see the coyotes, the fox took off running toward the road with the coyotes in pursuit.

The coyotes became distracted by their own rodent hunting when they reached the area where the fox had been hunting, and the fox was able to evade them. This fox is a color variation on typical foxes and is referred to as a "black morph."

This is the typical color of the red fox. We had four days of "three dog days" in Yellowstone during which we saw wolves, coyotes and foxes.