Deer are herbivores, adapting their feeding habits to seasonal changes and available food sources. Their anatomy, behavior, and physiology are specifically adapted to selecting certain types of forage.
Do Deer Eat Grass?
While deer can consume grass, it is not their primary or preferred food source. Grasses are low in crude protein and contain a high amount of fiber, making them difficult for deer to digest efficiently. Unlike cattle, which are grazers with large rumens adapted to processing vast quantities of fibrous grass, deer have a smaller digestive system designed for more easily digestible forage. A deer relying solely on a grass diet would likely face starvation due to its inability to extract sufficient nutrition.
Deer observed in grassy areas are often seeking other plants, such as forbs or tender shoots, that grow among the grass. They may eat young, succulent grass, particularly during early growth stages when it is more digestible. However, perennial grasses are rarely a significant part of their diet. This preference for less fibrous plants highlights their specialization as “browsers” rather than “grazers.”
What Else Do Deer Eat?
Deer are classified as “browsers,” meaning they primarily consume the leaves, twigs, and buds of woody plants, along with broad-leaved herbaceous plants known as forbs. This diet contrasts with grazers, which focus on grasses. Over 85% of a deer’s overall diet consists of browse, forbs, and mast. Their narrow snout and long tongue allow them to precisely select specific plant parts, avoiding less palatable or nutritious sections.
Their diet changes significantly with the seasons. In spring and summer, deer favor forbs, which are highly digestible and rich in energy, minerals, and antioxidants. During these warmer months, they also consume new growth from trees and shrubs, along with soft mast like berries and fruits.
As autumn approaches, deer seek carbohydrate-rich foods to build fat reserves for winter, heavily consuming hard mast such as acorns and chestnuts. In winter, when other foods are scarce, woody browse, twigs, and buds become more important, as do evergreen leaves. Additionally, deer readily consume agricultural crops like corn and soybeans when available, as these are highly nutritious and digestible.
How Deer Process Their Food
Deer are ruminants, equipped with a four-chambered stomach system that enables them to digest fibrous plant material. This specialized digestive process begins when deer rapidly consume vegetation, chewing it just enough to swallow. The food then enters the first and largest chamber, the rumen, which functions as a fermentation vat. Billions of microorganisms within the rumen break down tough cellulose and other complex carbohydrates into compounds and nutrients.
After initial fermentation, deer regurgitate partially digested food, known as cud, back into their mouths to chew it more thoroughly. This process, called rumination, further reduces particle size, increasing the surface area for microbial action and stimulating saliva production. The re-chewed cud is re-swallowed, passing through the reticulum, omasum, and finally into the abomasum, which is considered the “true” stomach where most nutrient absorption occurs. This multi-stage digestion allows deer to extract maximum nutrients from their diverse plant-based diet, supporting their energy needs and overall health.