Deer are herbivores, primarily consuming plant-based foods. Their diet is diverse, adapting to environmental availability throughout the year. A specialized four-chambered stomach allows them to process fibrous plant material.
Primary Food Sources
Deer obtain sustenance from various plant materials: browse, forbs, and mast.
Browse refers to the leaves, twigs, and young shoots of woody plants like trees, shrubs, and vines. Examples include greenbrier, blackberry, young maple leaves, and cedar. These woody plants provide a consistent food source, with deer often selecting tender new growth.
Forbs are broad-leaved herbaceous plants, often called weeds, that grow in open areas. These plants are highly digestible and rich in nutrients, making them a preferred food source. Common examples include clover, ragweed, goldenrod, and wild strawberry. During summer, forbs can constitute a significant portion of a deer’s diet, sometimes up to 70%.
Mast includes nuts and fruits produced by trees and shrubs, categorized as hard or soft mast. Hard mast, such as acorns and hickory nuts, is high in fats and carbohydrates, providing concentrated energy. Soft mast consists of fruits like apples, pears, persimmons, grapes, and various berries, which offer sugars and vitamins. Mast availability varies annually, but when abundant, it is a highly sought-after food source.
Seasonal Dietary Shifts
The diet of deer changes significantly with the seasons, driven by plant availability and changing nutritional requirements.
In spring, as new growth emerges, deer primarily consume tender grasses, fresh forbs, and new buds from woody plants. This period replenishes nutrients after winter, supporting antler growth in bucks and preparing does for fawning.
During summer, deer favor nutrient-rich forbs and soft mast, such as abundant berries. The high water content in these plants also contributes to hydration. As fall approaches, their diet shifts to high-energy mast like acorns and other nuts, helping them build fat reserves for colder months and the breeding season.
Winter presents the greatest challenge for deer, as preferred food sources become scarce. Their diet relies heavily on woody browse, including twigs and stems of trees and shrubs. Deer adapt by consuming more fibrous material; their digestive system changes to process these tougher, less nutritious foods.
Beyond Plants: Essential Nutrients and Water
While plants form the bulk of a deer’s diet, other elements are essential for overall health and physiological functions. Water is a fundamental requirement for deer, crucial for bodily processes. They obtain water directly by drinking from sources like ponds and streams, and indirectly from the moisture in plants they consume, particularly succulent forbs and fruits.
Minerals are another important component of a deer’s diet, though they constitute only about 5% of their body mass. Calcium and phosphorus are important for bone development, milk production in does, and antler growth in bucks. Deer acquire these minerals from plants and natural soil sources, sometimes seeking mineral licks. Sodium is also sought, especially in spring and summer, to balance levels when consuming high-moisture plants.
Dietary Adaptations and Interaction with Human Environments
Deer are adaptable foragers, adjusting their diet when natural food sources are limited. This is evident where human development encroaches on their habitats. Deer are opportunistic feeders, readily consuming plants in suburban and agricultural landscapes.
In residential areas, deer forage in gardens, consuming ornamental plants, flowers, and vegetables. They eat cultivated crops like beans, lettuce, cabbage, apples, and strawberries. This behavior leads to conflicts with homeowners and farmers, as deer do not distinguish between native and cultivated plants. Their diet becomes a mix of natural and human-provided food sources.