Black-tailed deer are adaptable herbivores whose dietary habits are shaped by their environment and the changing seasons. These members of the deer family, which include the Columbian black-tailed deer and Sitka black-tailed deer subspecies, inhabit diverse landscapes across western North America. Their diet is primarily plant-based, allowing them to thrive in various forest and brushland ecosystems.
Primary Food Sources
Black-tailed deer consume a wide array of plant materials, broadly categorized into browse, forbs, grasses, and mast. Browse refers to the leaves, twigs, and young shoots of woody plants and shrubs. Common browse items include:
Thimbleberry
Vine maple
Salmonberry
Blackberry species
Hazelnut
Cascara
Salal
Greenbrier
Forbs are broad-leaved herbaceous plants that constitute a significant part of their diet. Examples include:
Skunk cabbage
Bunchberry
Five-leaf bramble
Clover
Ragweed
Goldenrod
Sword fern
Pokeweed
Beggar’s lice
Plantain
These plants are often high in protein and readily digestible, particularly new growth in spring and summer.
While deer are considered browsers, some subspecies, like the Columbian black-tailed deer, will consume grasses. They may eat types such as orchardgrass, brome grass, and bluegrass, along with sedges. However, grasses form a smaller portion of their diet compared to browse and forbs, and deer prefer young, tender grass shoots.
Mast includes nuts, acorns, fruits, and berries. Acorns provide energy-rich carbohydrates and fats. Soft mast includes blackberries, blueberries, huckleberries, salmonberries, and apples. Black-tailed deer also consume fungi and lichens.
Seasonal Dietary Shifts
The diet of black-tailed deer changes throughout the year, adapting to food availability. In spring, their diet shifts to capitalize on new, tender plant growth. They seek out herbaceous plants and forbs like skunk cabbage, providing a high-energy food source. This fresh vegetation helps them regain body weight lost during winter.
Summer brings abundant foliage from shrubs and herbs. Deer consume leaves from plants like thimbleberry, vine maple, and salmonberry. Berries also become a part of their diet.
As fall approaches, mast like acorns and berries become a dominant food source. These nutrient-dense foods allow deer to build up fat reserves in preparation for the winter months. They also continue to forage on remaining browse.
During winter, food availability decreases, and black-tailed deer rely on woody browse, twigs, and buds. Evergreen forbs, such as bunchberry and five-leaf bramble, remain accessible when other foods are scarce. Blackberry leaves can form a substantial portion of their winter diet. Their digestive systems adapt to process this higher-fiber woody browse, which is less nutritious than spring and summer forage.
Hydration and Essential Minerals
Water is obtained by black-tailed deer through direct consumption from streams, ponds, and puddles. They also acquire moisture from the vegetation they eat. Metabolic water, produced during the breakdown of fats, carbohydrates, and proteins in their food, also contributes to their hydration. The need for direct surface water can vary, with deer requiring less if their forage has high moisture content. During drier periods, they may travel up to three miles to find water sources.
Essential minerals are obtained by deer through their diet, by consuming soil, or by visiting natural mineral licks. Calcium and phosphorus are important for antler growth in bucks and for bone health and milk production in does. Deer also require sodium, which they often crave in spring and summer due to the high potassium content in fresh green vegetation. Other minerals like magnesium, zinc, iron, and copper are necessary for their health. These minerals support immune response and metabolism.