I think that the animals can be sensitive to the early tremors of earthquakes, and there used to be someone who actually predicted quakes in California by reading the lost and found ads. he claimed that when more animals went missing, or were found somewhere other than their home; they seemed to be sensing a quake and tried to get away from it. Apparently, his percentage rate of prediction was actually pretty good.
As for the Yellowstone Bison and elk; they were probably just moving to lower elevations as the snow became too deep in higher elevations for them to forage. In the spring, as the snows melt, and grass comes back to the mountainsides; they will probably go back up.
Even in North Idaho, the animals are looking for places to forage closer to towns, as shown by these moose walking through the Main Street of downtown Sandpoint, Idaho today.
I think these guys probably just wanted huckleberry pie and coffee for breakfast, don't you ??