Deer are commonly recognized as ruminant herbivores, with diets centered on plants like leaves, twigs, grasses, and forbs. The idea of a deer consuming a small animal like a squirrel seems to contradict this biological classification. However, nature is often more complex than simple labels suggest, and documented, albeit rare, observations confirm this behavior. Deer have an adaptable survival strategy, allowing them to seek unusual dietary items when circumstances demand it. This behavior is an occasional, opportunistic deviation from their plant-based diet.
Deer Are Not Strict Herbivores
The surprising answer is that deer have been observed consuming small mammals, including squirrels. This behavior is not characteristic of a predator, but rather an act of scavenging or opportunistic feeding. Instances of white-tailed deer and other species consuming animal matter have been documented by researchers and wildlife observers.
Deer possess the four-chambered stomach, or rumen, typical of ruminants adapted for digesting fibrous plant materials. However, their digestive system can process other substances. Consumption of non-plant food is typically limited to small, recently deceased animals or carrion they stumble upon. Deer are not actively hunting squirrels, but are taking advantage of a readily available, high-density food source.
This occasional consumption confirms that deer are not strictly herbivores, but exhibit tendencies toward opportunistic omnivory. The behavior has been documented with various small creatures, including rabbits, bird eggs, and fish. These observations challenge the traditional division between plant-eaters and meat-eaters.
Nutritional Needs Driving Unusual Behavior
The primary motivation behind a deer consuming animal matter is almost always a severe nutritional deficiency, particularly a lack of essential minerals. Deer, like many herbivores, instinctively engage in osteophagy, the consumption of bones. This practice supplements their intake of calcium and phosphorus, which are often scarce in vegetation or in specific soil types.
Calcium and phosphorus are important during periods of high physiological demand, such as gestation, lactation, and the rapid growth of antlers in males. Hardened antlers are composed of about 22% calcium and 11% phosphorus. If the diet is insufficient, a male deer will pull these minerals from its skeleton. Consuming an animal carcass provides a concentrated source of these minerals, protein, and fat, which is more accessible than finding mineral-rich plants.
When a deer consumes a small animal, it often focuses on the bones and organs, which are rich in the missing nutrients. This behavior is a survival adaptation, allowing the deer to quickly correct a dietary imbalance. The consumption of animal protein is a direct response to a biological need, not a preference for a carnivorous diet.
Contextualizing Rare Dietary Choices
The consumption of squirrels falls within a broader pattern of opportunistic feeding seen when a deer’s diet is nutritionally compromised. This is an extremely rare event, and the vast majority of a deer’s diet consists of plant material like forbs, woody browse, and mast. However, the flexibility of their diet allows them to utilize other unusual items when necessary.
In addition to small mammals, deer have been observed chewing on shed antlers, which are concentrated sources of calcium and phosphorus. They have also been seen eating the remains of fish, raiding the nests of ground-nesting birds for eggs and hatchlings, and scavenging carrion. These instances demonstrate that the deer is an adaptable creature, prepared to exploit any available source of necessary nutrients.
The image of a deer eating a squirrel, while startling, should be viewed as an example of animal resourcefulness. The deer remains fundamentally a browsing herbivore, but it will temporarily act as an omnivore when driven by the instinct to survive and meet nutritional requirements. This flexibility ensures the animal’s survival in environments where essential minerals are not consistently available through vegetation alone.