Deer are opportunistic herbivores, often choosing the most nutritious and easily digestible plants available. A common misconception is that these animals avoid all vegetation with sharp defenses, like thorns or spines. However, the woody, thorny vines and shrubs generally referred to as “briars,” which include species like brambles and greenbrier, are frequently consumed by deer.
Briars as a Critical Browse Component for Deer
The answer to whether deer eat briars is a definite yes, and these plants often form a significant part of their diet. Deer are classified by biologists as “concentrate selectors,” meaning they prefer forage high in nutrients and low in difficult-to-digest fiber. This preference must adapt to environmental availability, making briars a regular part of their browse. Browse refers to the woody stems, buds, and leaves of trees and shrubs, consumed when soft, herbaceous plants are scarce.
The ability to process this coarse, thorny browse comes from the deer’s specialized digestive system. As ruminants, deer possess a four-chambered stomach. The largest section, the rumen, uses microbial fermentation to break down plant material. These microbes are specifically adapted to digest the cellulose and complex carbohydrates found in tough, woody forage. This process allows the deer to extract nutrients from material that simpler-stomached animals cannot utilize effectively.
Identifying the Preferred Thorny Species
When selecting thorny plants, deer are highly selective, favoring certain species over others. The most important thorny browse species are Greenbrier (Smilax species) and the brambles, which include Blackberry and Raspberry (Rubus species). These plants are actively sought out because they provide relatively palatable woody growth. Deer primarily target the young, tender growth, such as the new leaf buds and the soft tips of the canes or vines.
Even when consuming mature thorny stems, the deer’s lack of upper incisors and the way they browse—by grasping and tearing—allows them to consume the plant without excessive damage to their mouths. The leaves of these thorny plants are also frequently eaten, even on varieties with larger thorns, as the foliage itself often lacks the sharp defenses of the main stems. Deer often prefer the younger, less-lignified growth that is easier to digest. The Smilax genus as a whole is considered a high-value food source.
Seasonal Necessity and Nutritional Value
Briars become important during the dormant season, primarily in late winter and early spring, when most other high-quality forage is unavailable. When soft, green plants are typically covered by snow or have died back, the evergreen or persistent stems and leaves of briars become a reliable food source. The nutritional content of Greenbrier, for instance, often contains crude protein levels around 11% in winter, which is higher than many other native winter browse species.
While the high fiber content of briars means they take longer to digest than summer forage, they offer a combination of calories, protein, and moisture during harsh periods. The moisture content, especially in evergreen species like Greenbrier, helps supplement the deer’s water intake when sources may be frozen. Relying on this tough browse helps the deer bridge the nutritional gap until new growth emerges.