Wild deer are highly adaptable herbivores whose diet is a constant negotiation between nutritional demands and the availability of local plant life. Their survival strategy is rooted in being a “concentrate selector,” a feeding type that targets the most digestible and nutrient-dense plants or plant parts. This feeding habit is necessary because deer are ruminants with a relatively small stomach capacity, meaning their food must pass through their digestive system quickly and efficiently. The four-chambered stomach requires a steady intake of high-quality forage to meet the intense demands of reproduction, growth, and survival. Therefore, the plants a wild deer chooses to eat are not random but a precise selection of resources that maximize energy and protein intake throughout the year.
Categorizing Primary Wild Forage
The bulk of a wild deer’s diet is categorized into three main types of vegetation: browse, forbs, and, to a lesser extent, grasses and sedges. Browse consists of the leaves, buds, and tender new growth of woody plants, including trees, shrubs, and vines. This category is a consistent component of the deer diet, providing sustenance when other food sources are scarce. Deer sample a wide variety of these plants, often preferring species like greenbrier, sumac, and the new shoots of young trees.
Forbs are a highly preferred food group, referring to soft, non-woody, broad-leaved plants. These plants, such as clover, ragweed, and goldenrod, are typically low in fiber and contain high levels of easily digestible protein and nutrients. Forbs are a primary food source, especially during the warmer months when their growth is abundant. Their rapid digestibility makes them perfectly suited for the deer’s specialized stomach.
Grasses and sedges make up a small fraction of the average wild deer diet. Deer are not true grazers and generally avoid the mature, high-fiber perennial grasses that form the diet of animals like cattle. However, they readily consume young, tender grasses and cereal grains, which are more easily digested.
Seasonal Shifts in Deer Diet
The nutritional content of plants changes with the seasons, forcing a corresponding shift in the deer’s foraging habits to meet their biological needs. During spring and early summer, the diet is dominated by high-protein forage to support intense physiological processes. Bucks require protein for rapid antler growth, while does need it for late-stage pregnancy and milk production. The tender new growth of forbs and fresh browse provides the necessary protein content, which can be as high as 15 to 35 percent in some plants during this period.
As summer transitions into fall, the focus shifts toward energy-dense foods to build up fat reserves for the winter. This is the season for consuming mast crops, which are rich in concentrated carbohydrates and fats. High-energy intake is necessary to withstand the physical demands of the breeding season and prepare for the upcoming lean months. The energy stored as fat is the primary fuel source that sustains the animal when food becomes scarce.
Winter presents the most challenging time for deer, where the diet focuses on caloric maintenance rather than growth or reproduction. With most forbs and deciduous leaves gone, deer switch to a high-fiber, lower-quality diet of woody browse, including the twigs and bark of evergreen plants. Species like white cedar are important in northern regions, providing sustenance when snow covers the ground. The deer’s metabolism slows down to conserve energy, relying on stored fat and the caloric value of this coarse winter browse.
Essential Supplements and High-Value Foods
Beyond the daily bulk forage, deer actively seek out specific, high-value foods that provide concentrated energy or necessary micronutrients. Mast crops are a temporary but highly preferred food source, providing a concentrated burst of energy-rich nutrients. Hard mast, such as acorns and hickory nuts, is valuable in the fall due to its high fat and carbohydrate content. Soft mast, which includes wild fruits and berries like persimmons and wild grapes, are rich in simple sugars and vitamins, supplementing the diet in summer and early fall.
Fungi and lichens also play a role in the wild deer’s diet, often consumed opportunistically throughout the year. Mushrooms are palatable and contain high levels of protein and carbohydrates, making them a nutritious find, especially following periods of high moisture. Lichens, which are a symbiotic combination of fungus and algae, are consumed for their trace mineral content, with northern populations sometimes relying on them more heavily during winter.
The consumption of minerals is a targeted behavior that supplements the regular plant diet. Deer require essential elements like calcium, phosphorus, and sodium for bone development, antler growth, and overall body function. They obtain these by consuming mineral-rich plants or by seeking out natural mineral licks, where they ingest the necessary elements. This targeted mineral consumption ensures they meet micronutrient needs that the bulk of their forage may not provide.