Deer are highly adaptable herbivores, consuming a wide variety of plant material to meet their nutritional needs. Their diverse diet, encompassing hundreds of species, adjusts based on availability and physiological requirements, allowing them to thrive in diverse habitats. Deer are known as “concentrate selectors,” prioritizing nutrient-rich and easily digestible foods.
Wild Forage Favorites
In their natural habitats, deer primarily seek browse, forbs, and mast. Browse refers to the leaves, buds, and tender twigs of woody plants like maple, oak, and greenbrier. They select the youngest shoots and leaves, which are higher in digestible energy. Forbs are broad-leaved herbaceous plants, such as clover and ragweed, that are highly digestible and nutrient-rich, making them a significant part of a deer’s diet, especially in spring and summer.
Mast includes hard mast like acorns and beechnuts, and soft mast such as berries and apples. Acorns are a crucial energy source due to their high fat and carbohydrate content. Deer also consume fungi and mushrooms, which provide protein, carbohydrates, and minerals, especially after rainfall.
Seasonal Dietary Shifts
Deer diets undergo significant seasonal changes, driven by food availability and metabolic demands. In spring and early summer, deer prioritize new, green growth, focusing on forbs and tender browse. These are rich in protein and easily digestible, supporting lactation and antler development. Their digestive systems are optimized for these succulent plants.
As fall approaches, deer shift to mast crops, particularly acorns, to build fat reserves for winter. These foods provide energy for the rut and colder months. In winter, when other food sources become scarce, their diet consists of woody browse, such as twigs and evergreen leaves, and any remaining mast or agricultural remnants. Their digestive system adapts to process this higher-fiber material.
Agricultural Allure
Deer are drawn to agricultural fields due to the abundance and high nutritional value of cultivated crops. These crops offer concentrated sources of energy and nutrients. Favorites include corn, high in carbohydrates and fat, and soybeans, known for their high protein content.
Deer also consume alfalfa and cereal grains like oats and wheat. These cultivated foods provide a significant caloric boost when natural forage is less abundant. The ease of access to these crops makes farmlands attractive foraging grounds for deer.
Harmful and Unsuitable Foods
While adaptable, many human-provided foods are harmful to deer. Feeding them can lead to serious health problems, including rumen acidosis, a potentially fatal condition caused by their digestive system struggling with large amounts of carbohydrates like corn. Their four-chambered stomach relies on a specific balance of microorganisms that adapt slowly, so sudden dietary changes can disrupt digestion and lead to starvation.
Beyond digestive issues, supplemental feeding can concentrate deer, increasing the risk of disease transmission like Chronic Wasting Disease (CWD). It can also habituate deer to humans, making them less fearful and more prone to vehicle collisions. Certain common garden plants, such as daffodils, foxglove, and yew, are toxic or irritating to deer, which they generally avoid.