What must bison capitalize on during summer and fall to fuel their winter survival strategy?

Consuming vast quantities of energy-rich forage to build substantial fat reserves

The ability of the bison to survive the lean, high-energy-cost period of winter is fundamentally predicated on the preparatory work done during the warmer months. Bison must take full advantage of the abundance available in the summer and fall environments. This means actively consuming large amounts of energy-rich forage found during these seasons. The goal of this intensive feeding period is to accumulate substantial, robust fat reserves within the body. These banked energy stores are the critical fuel source that sustains the animal through winter. When the metabolic rate is lowered to conserve energy, these fat reserves power the slower bodily functions, allowing the bison to survive the months when the quality and quantity of available grass are significantly reduced.