Because it is difficult to find food under the deep snow, bison depend on stored fat to help them survive the harsh weather. Even so, it is a lack of food, not predators, that is the greatest threat to a full-grown bison. As the snow melts and the ground thaws, the vegetation renews itself. Springtime also means new calves. The nutrient-rich plants help the mothers produce ample amounts of milk for their growing calves.
Calves remain under their mother's care for about a year.
They must then prepare for the upcoming winter by themselves. Cud is partially digested vegetation, previously swallowed and then regurgitated from the bison's rumen for further processing. A part of the stomach. Bacteria here break down tough grasses and plants. While it may look ragged, shedding helps them stay cool.