Much like in northern regions, deer in the south rely heavily on green forbs and grasses in the early spring. However, the dietary proportion of each forage depends greatly on climate and geographic range; southeastern deer generally have access to more forbs, whereas deer living in Texas or the southern plains states consume more grasses. Overall, 90% of the spring diet of southern deer can be comprised of herbaceous plants; forbs typically make up the highest proportion (23-68%), followed by grasses (8-58%), cacti when available(18-21%), and browse (5%). Agricultural plants, such as corn, sorghum, soybeans, lespedeza and clover, are also used extremely heavily (40-50%) when available.
During the summer months, southern deer instinctively consume new tender shoots, leaves and twigs of trees, fungi, shrubs and vines, and many different kinds of broad-leafed herbaceous plants. Deer in the southeast typically have access to ample amounts of succulent vegetation. In especially arid regions, although summer foods tend to be 1.5 times more digestible than winter foods, nutrient levels may fluctuate and the quality and quantity of forage produced by local plant communities may be grossly inadequate as a result of a reduction in rainfall. In fact, during severe drought conditions it has been documented that certain plant species may be eliminated over extended periods of concentrated grazing pressure and, consequently, local deer populations suffer.
In autumn, southern deer begin to focus less on herbaceous food sources and concentrate their feeding efforts on ripened soft and hard mast. When available, acorns, are by far the most preferred food item to deer and many other wildlife species (including several species of insect) across the south. Even during years of low acorn production, acorns still manage to comprise a minimum of 15-20% of an individual deer’s diet, and at times, may represent over 50% of the total amount of food a deer consumes each day. In areas that lack the presence of mast bearing tree species (e.g., oak, beech), deer maintain diets that consist mainly of browse, grasses, forbs, and mushrooms (1%).
Between January and April, when green forage is scarce, most southern deer will consume browse, any remaining mast, and perennial plants that remain green during winter. However, a study in south Texas reported that some deer had an affinity towards available grasses and forbs during this time period, with consumption rates of each peaking in February. Regardless, general observations indicate that deer in the south will consume preferred grasses and forbs when available, and rely on browse throughout the year.