White-tailed deer are ruminant herbivores, meaning their diet consists entirely of plant matter processed through a specialized, four-chambered stomach. Their digestive system relies on microbial fermentation to break down tough cellulose. What they consume shifts dramatically with the changing seasons and available local vegetation, reflecting the nutritional demands of growth and survival throughout the year. Understanding these seasonal dietary demands is important for maintaining deer health and managing interactions in areas shared with humans.
The Natural Diet of Deer
White-tailed deer are concentrate selectors, preferring high-quality, easily digestible plants over large quantities of low-quality forage. Their wild diet is segmented into three categories, each crucial for different times of the year.
Browse refers to the leaves, buds, and tender twigs of woody plants and shrubs. Species like sumac, maple, and dogwood provide sustenance during winter when other options are scarce. Browse offers lower nutritional density than summer forage, meaning deer must consume large amounts to meet basic caloric needs.
Forbs are broad-leafed herbaceous plants, commonly called weeds, consumed heavily during spring and summer. These plants are highly digestible and nutrient-dense, providing the high protein necessary for fawn development, lactation, and rapid antler growth in bucks.
Mast includes hard mast (acorns and hickory nuts) and soft mast (berries and apples), consumed primarily in the fall. Hard mast is rich in fats and carbohydrates, allowing deer to build the subcutaneous fat reserves needed to survive the harsh winter.
This natural shift in diet is driven by biological necessity. Spring and summer require high-protein intake for reproduction and tissue regeneration, while fall focuses on energy storage via high-calorie foods. This fluctuation ensures the specialized gut microbes in the rumen remain adapted to the current food sources, preventing digestive upset and maintaining digestive efficiency.
Foods That Harm Deer
The deer’s digestive system is highly sensitive to abrupt changes in food type, especially processed human foods. Items like bread, pastries, and candy lack necessary fiber and introduce simple carbohydrates that disrupt the delicate balance of rumen microbes. Even seemingly benign items like moldy hay or grain can be hazardous, causing severe digestive upset and potentially introducing mycotoxins.
Rumen Acidosis is a major physiological danger caused by the rapid ingestion of high-carbohydrate foods like large amounts of corn or commercial pellets. When these foods are consumed quickly, the rumen microbes produce excessive lactic acid, drastically lowering the stomach’s pH level. This acidic environment kills the necessary beneficial microbes, leading to digestive failure, dehydration, and often death within days.
Beyond processed foods, deer can suffer from consuming common garden plants that are toxic to them, such as azaleas, rhododendrons, and yew. The toxins in these plants interfere with cardiac and nervous system functions. Providing any food outside of their natural forage introduces a significant health risk.
Why Supplemental Feeding is Usually Discouraged
Providing supplemental food, even with good intentions, introduces severe ecological and health risks that extend far beyond the individual animal.
Disease Transmission
The unnatural congregation of deer at a single feeding site increases the likelihood of transmitting infectious diseases through close contact. Chronic Wasting Disease (CWD), a fatal neurological disease caused by prions, is a notable risk. CWD can spread through saliva, urine, and feces deposited at shared feeding locations. This close proximity creates a persistent reservoir of infection, accelerating the disease’s spread through the population.
Habituation and Conflict
Supplemental feeding causes deer to lose their natural wariness of humans, a process known as habituation. This loss of fear leads to increased conflicts, including vehicle collisions and damage to private property, as deer are less likely to move away from populated areas. Furthermore, concentrating deer in one place makes them easier targets for predators.
Nutritional Deficiencies
Relying on supplemental feed can also lead to long-term nutritional deficiencies, even if the supplement itself is non-toxic. Deer that rely on easy food sources may not consume the diverse array of natural forage needed to meet their full spectrum of vitamins and minerals, compromising overall health. Due to these cascading public safety and wildlife health issues, many jurisdictions have implemented legal restrictions or outright bans on feeding deer.
What Deer Forage in Suburban Landscapes
When natural food sources become limited, deer readily adapt their diets to human-introduced landscaping. These selective feeders are highly attracted to ornamental plants that provide high digestibility and minimal effort.
Favored targets include hostas, which are highly palatable and often consumed entirely down to the stem.
Spring bulbs, particularly tulips, are frequently browsed before they have a chance to bloom.
Deer also target woody ornamentals, including arborvitae, certain varieties of junipers, and young fruit trees. They often damage these plants by stripping the bark or clipping new growth tips.
This opportunistic foraging behavior is a direct result of their ability to assess the nutritional value of easily accessible food. While they prefer the high-protein forbs of the wild, they will utilize high-energy plants found in gardens and yards, causing significant frustration for homeowners attempting to maintain their landscaping.