Deer are widely recognized as herbivores, subsisting primarily on plant matter. This often leads to the assumption their diet is exclusively vegetarian. However, evidence reveals a more nuanced reality. Under specific circumstances, deer have been documented consuming meat, challenging the strict herbivore label and highlighting their adaptability. This flexibility allows them to meet various nutritional demands.
The Typical Deer Diet
Deer are classified as ruminants, possessing a specialized four-chambered stomach designed to efficiently digest fibrous plant materials. Their natural diet predominantly consists of a wide array of vegetation, varying seasonally based on availability. They are primarily browsers, feeding on leaves, buds, and tender shoots from woody plants like trees and shrubs.
Forbs, broad-leaved herbaceous plants, are also a significant component of their diet, especially during spring and summer when they are highly digestible and nutrient-rich. Deer consume various fruits, berries, and nuts, known as mast, which provide crucial energy and fat, particularly in the fall as they prepare for winter. While they do eat grasses, especially young, tender growth or agricultural crops like alfalfa and clover, grasses are generally less preferred due to lower digestibility and nutrient content compared to other plant sources.
Unusual Dietary Habits
Despite their primary herbivorous nature, deer occasionally exhibit opportunistic omnivorous tendencies, consuming animal matter when the chance arises. This behavior is not a regular part of their diet but has been documented through observations. Deer have been observed scavenging on carrion, including the carcasses of dead animals, sometimes even other deer. They are not active hunters but will consume meat if encountered.
Specific instances include bird eggs and nestlings, often taken from ground nests. Deer have been captured deliberately taking eggs and baby birds. They have also been seen consuming small rodents like mice, squirrels, and rabbits, usually when already dead or injured. This opportunistic feeding extends to other animal matter, such as fish and insects.
Why Deer Deviate
Deer deviate from a purely herbivorous diet primarily due to specific nutritional needs that plant matter alone may not adequately provide. They require various minerals, including calcium, phosphorus, and protein, for their overall health, bone growth, and, in males, antler development. Plant-based diets can sometimes be deficient in these essential nutrients, particularly calcium and phosphorus. Consuming animal matter offers a concentrated source of these minerals, abundant in bones and flesh.
This opportunistic feeding behavior is more common during periods of high nutritional demand or scarcity of preferred plant foods. For example, during harsh winters when vegetation is sparse, or for pregnant and lactating does, or bucks undergoing antler growth, the need for protein and minerals increases significantly. While deer are not predators, their scavenging allows them to supplement their diet and meet these heightened physiological requirements.