Tower Junction, Yellowstone National Park, Wyoming, USA.

Winter temperatures in Yellowstone National Park can plunge as low as -66°F (-54.5 °C), yet the bison residing here endure conditions that few other animals could survive. This photo, taken at -15F, shows a bison from the Northern Herd with his facial hair frozen solid, a striking reminder of the brutal elements he faces throughout the winter months. 

Each year, bison migrate to lower elevations between November and March, seeking more accessible and available forage beneath the snow. Their routes, part of the greater Yellowstone ecosystem, are traced from those of their ancestors, and this bull is a striking reminder of the brutal elements faced by the entire herd.