Deer are adaptable herbivores. Their wild diet is diverse, reflecting what is available throughout the year. This opportunistic foraging allows them to thrive in various habitats. Deer are selective eaters, often choosing highly digestible, nutrient-rich plants.
Core Components of Deer Diet
Deer consume several main categories of food: browse, forbs, grasses, and mast. Browse refers to the leaves, twigs, and tender shoots of woody plants like shrubs and young trees. It forms a significant part of their diet, providing fiber and minerals, especially when other green vegetation is scarce. Examples of browse include honeysuckle, greenbrier, and young maple.
Forbs are broad-leafed herbaceous plants, often called “weeds.” These plants, such as clover, ragweed, and goldenrod, are highly digestible, rich in protein and energy. Deer prefer forbs for their high nutritional content.
Grasses are a less preferred food source for deer compared to browse and forbs. While deer will eat grasses, particularly young, succulent shoots, their digestive system is not as well-suited for breaking down the fibrous material in mature grasses as that of grazers like cattle. Grasses constitute a small portion of their diet, often less than 10%.
Mast includes the nuts and fruits produced by trees and shrubs. Hard mast, such as acorns and chestnuts, provides high levels of fat and carbohydrates, serving as an important energy source. Soft mast, like berries, apples, and persimmons, offers sugars and vitamins.
Seasonal Shifts in Food Sources
The diet of deer changes significantly with the seasons, adapting to plant availability and nutritional quality. In spring, as new growth emerges, deer primarily seek fresh, tender vegetation. This includes new leaves, shoots, and highly digestible forbs, which provide essential nutrients for recovery after winter, antler growth in males, and fawn development in females.
During summer, deer continue to consume lush vegetation, including a variety of forbs and the leaves and stems of woody plants. Soft mast, such as berries and early fruits like grapes, provides energy. As summer progresses, some plants become tougher and less nutritious.
In the fall, deer focus on building fat reserves in preparation for winter and the breeding season. Their diet shifts to include abundant hard mast like acorns and beechnuts, which are rich in carbohydrates and fats. They also continue to eat fruits, forbs, and browse.
Winter presents the most challenging time for deer to find food, as many plant sources become dormant or are covered by snow. During this period, deer eat woody browse, including twigs, buds, and the bark of trees and shrubs. They may also paw through snow to find dried forbs or grasses.
Foods Deer Do Not or Should Not Eat
While deer are adaptable foragers, certain foods are harmful or indigestible for them. Human processed foods, including bread, candy, and pet food, should never be fed to deer. Their digestive systems are not equipped to process these items, and consuming them can lead to severe digestive upset, illness, or even death.
Introducing new foods, especially high-carbohydrate items like corn, suddenly or in large quantities can be dangerous. Deer are ruminants, and the microorganisms in their digestive system need time to adjust to new food sources, sometimes weeks. A sudden change can disrupt this delicate balance, leading to starvation even if their stomach is full.
Some plants commonly found in gardens or wild areas are toxic to deer. Examples include rhubarb, jimsonweed, and the leaves and stems of elderberry. Certain ornamental plants like azaleas, rhododendrons, and yew are poisonous. Fruit pits from cherries, apricots, and peaches contain cyanide compounds and should be avoided.