Deer are adaptable herbivores, meaning their diet consists entirely of plants. They primarily function as browsers, which involves consuming leaves, twigs, and buds from woody plants rather than grazing on grasses. Their diet is diverse and changes based on the availability of food in their environment.
Core Diet of Deer
Deer primarily consume a variety of plant materials. They are primarily browsers, consuming leaves, buds, and the ends of twigs from woody plants such as trees, shrubs, and vines. Deer also eat forbs, which are non-woody, broad-leaved plants. These forbs are more digestible and nutrient-rich compared to other food sources. While deer can eat grass, it is not their preferred food and makes up less than 10% of their diet, typically consumed when young and tender.
Deer possess a specialized four-chambered stomach, characteristic of ruminants, which is adapted for processing fibrous plant material. This digestive system allows them to store large quantities of food, later regurgitating and re-chewing it as “cud” to aid digestion. Microorganisms within their rumen, the first stomach chamber, break down cellulose and other plant components, converting them into usable nutrients. This digestive process requires deer to consume high-quality, easily digestible forages to meet their energy and protein requirements.
Seasonal Changes in Deer Diet
Deer diets change throughout the year, adapting to available food sources. In spring, deer seek out tender new growth, including fresh grasses and various forbs. This period is important for replenishing nutrients after winter scarcity. As summer progresses, their diet shifts to lush vegetation, leaves, and protein-rich plants.
During the fall, deer focus on building fat reserves for the colder months, primarily consuming acorns, nuts, and fruits. Acorns are favored due to their lower tannin content and high fat and carbohydrate levels. Winter presents a challenging period, forcing deer to rely heavily on woody browse such as twigs, buds, and bark. Evergreen leaves also become important when other food sources are scarce.
Opportunistic Foraging
Deer consume opportunistic food sources when natural forage is limited. These opportunistic foods include fruits and berries, which provide concentrated energy and nutrients. Mushrooms and other fungi are also consumed for their nutritional value, particularly for phosphorus.
Agricultural crops, such as corn, soybeans, and alfalfa, are readily eaten by deer when accessible. These crops are nutritious and palatable, serving as significant food sources. These crops are highly digestible and nutritious.
Foods to Never Feed Deer
Feeding deer human food or non-natural supplements can cause harm to their health and natural behaviors. Items like bread, pastries, and processed snacks lack the proper nutrients and are difficult for a deer’s specialized digestive system to process. Consuming large quantities of carbohydrates can lead to severe digestive issues like acidosis, bloating, and dehydration, which can be fatal.
Feeding deer can also lead to habituation, causing them to lose their natural fear of humans and increasing the risk of vehicle collisions. Additionally, artificial feeding sites can concentrate deer populations, facilitating the spread of diseases like Chronic Wasting Disease (CWD). It is important to allow deer to forage for their own food to protect both their well-being and human communities.