Deer are herbivorous mammals that thrive in diverse environments, relying on the vegetation available in their natural habitats. Their ability to adjust foraging habits based on ecological conditions allows them to survive across various landscapes. Understanding their natural diet provides insight into their ecological role and nutritional requirements.
Primary Food Sources in the Wild
Deer primarily consume a variety of plant materials found within their ecosystems, categorized into several main types.
Browse constitutes a significant portion of their diet, referring to the leaves, twigs, and young shoots of woody plants and shrubs. Common examples include the tender branches of sumac, maple, and oak trees, as well as woody vines like greenbrier and blackberry. These provide essential fiber and nutrients, particularly when other food sources are scarce.
Forbs, which are broad-leaved herbaceous plants and wildflowers, are also a favored food source for deer. These plants, such as clover, alfalfa, wild lettuce, and asters, are often rich in protein and moisture. Deer will actively seek out these succulent plants, especially during periods of abundant growth. The consumption of forbs contributes significantly to their nutritional intake throughout much of the year.
Mast, encompassing nuts, acorns, and fruits, represents a highly nutritious component of a deer’s diet, particularly in the autumn. Oak acorns, hickory nuts, and beechnuts are carbohydrate-dense foods that help deer build fat reserves for colder months. Wild fruits like apples, berries, and persimmons also fall into this category, offering concentrated energy and vitamins.
Grasses form another part of a deer’s natural diet, though generally to a lesser extent than browse and forbs. While deer are ruminants, their digestive systems are more suited to digesting softer, more digestible plant matter. They will graze on various types of grasses, particularly new, tender growth that is easier to process. This diverse range of plant matter ensures deer receive a balanced array of nutrients from their wild environment.
Seasonal Variations in Diet
A deer’s diet changes significantly throughout the year, adapting to the seasonal availability of different plant species.
In spring and early summer, deer primarily forage on lush, new growth, including protein-rich forbs and tender young shoots. This period of abundant, highly digestible vegetation supports antler growth in males and lactation in does. The high moisture content of these plants also contributes to their hydration.
As summer progresses into fall, the availability of succulent forbs decreases, and deer shift their focus to carbohydrate-rich mast crops. Acorns, nuts, and wild fruits become a dominant part of their diet during this time. The consumption of these calorie-dense foods allows deer to accumulate significant fat reserves, which are vital for surviving the lean winter months.
During winter, when many plants are dormant and covered by snow, deer rely heavily on more fibrous and less nutritious woody browse. Twigs, bark, and evergreen foliage from plants like cedar, hemlock, and pine become important survival foods. While these provide less energy and protein than summer forage, they are accessible and provide enough sustenance to help deer endure periods of scarcity.
Foods to Never Feed Deer
Feeding deer human foods can cause serious health problems due to their specialized digestive systems. Processed items like bread, crackers, and pastries offer little nutritional value and can lead to digestive upset. Corn, especially in large quantities, can cause acidosis, a condition where the pH in the rumen, a deer’s stomach compartment, drops drastically, hindering digestion and potentially leading to death. This rapid change from a natural, high-fiber diet to a low-fiber, high-carbohydrate diet can overwhelm the deer’s digestive microbes.
Dairy products, meat products, and any moldy or spoiled food items are also highly detrimental to deer. Deer are herbivores, and their digestive systems are not designed to break down animal proteins or lactose. Moldy foods can introduce harmful toxins and bacteria, leading to illness. Providing these types of sustenance can disrupt their natural foraging behaviors and make them reliant on human feeding, which is not sustainable.
Beyond the direct health risks, feeding deer can lead to habituation, causing them to lose their natural fear of humans. This can increase their presence in residential areas, raising the risk of vehicle collisions and the spread of disease among concentrated deer populations. Artificially feeding deer can also attract predators and disrupt their natural migratory patterns. Therefore, it is important to allow deer to forage for their natural diet in the wild.