In Missouri forests, the carrying capacity for deer is most often limited by the quantity and quality of food. Protein is deficient in winter and phosphorus is deficient year round in several preferred foods of Ozard deer. Thus, even when ample amounts of browse are available, deer may be poorly nourished. However, in winter, quantity of forage is a more important limiting factor than quality. Energy may be the most important limiting factor in the forest.
Deer are apparently in a negative energy balance and lose weight during most winter.
Feeding studies of penned deer show that deer voluntarily decrease food consumption and lose weight during winter. Deer have apparently adapted through evolutionary time to poor quality and quantity of winter foods and depend on fat reserves deposited in late summer and fall to supply much of their winter energy needs. Good summer and fall nutrition may be critical to winter survival and successful production of healthy fawns the following spring. Acorns are an important energy source during late summer and fall and this probably explains their heavy consumption rate by deer. A late summer drought followed by an acorn failure could be critical for deer in the Missouri Ozarks.