Deer are common mammals found across nearly all continents. Observing these animals often leads to questions about their behaviors, particularly concerning their dietary habits.
Deer’s Primary Diet: Herbivores by Nature
Deer are predominantly herbivores, meaning their diet consists almost exclusively of plant matter. They are considered browsers, consuming a wide variety of vegetation including leaves, tender shoots, bark, twigs, fruits, nuts, forbs, and fungi. The specific composition of their diet fluctuates throughout the year and across different regions, adapting to the seasonal availability of various plant foods.
A key adaptation for their plant-based diet is their digestive system. Deer are ruminants, possessing a four-chambered stomach comprising the rumen, reticulum, omasum, and abomasum. This complex system is highly specialized for breaking down tough plant cell walls, primarily cellulose, through a process of fermentation aided by a diverse community of microorganisms. This allows them to efficiently extract nutrients from fibrous plant material, supporting their high metabolic needs, particularly for processes like antler growth.
Understanding Atypical Deer Behavior
Despite their primary herbivorous classification, deer do not actively hunt or prey on animals such as squirrels. However, there are rare, documented instances where deer consume non-plant matter, a behavior that deviates from their typical diet. This includes consuming bones, shed antlers, or carrion, which refers to the remains of dead animals like fish, rabbits, or even other deer. This specific behavior is known as osteophagia, and it is primarily driven by a severe deficiency in essential minerals like calcium and phosphorus.
Observations have also included deer consuming small, helpless animals, such as baby birds found in nests. This is not considered predatory hunting, as deer lack the physical attributes and instincts of true carnivores. Instead, these instances represent opportunistic feeding behavior, especially when their regular plant-based food sources are scarce, such as during harsh winter months, or when specific nutrients are difficult to obtain from vegetation alone. Consuming these animal products provides a concentrated source of vital nutrients like calcium and protein, which are particularly important for antler development in males and overall health for all deer.
Why the Confusion Exists
The question of whether deer eat squirrels often stems from common misconceptions and occasional observations that can be misinterpreted. Witnessing a deer near a dead animal, for instance, might be mistakenly perceived as predatory behavior rather than an instance of opportunistic scavenging. Rare instances of deer consuming non-plant matter are driven by specific nutritional needs, not a shift in their fundamental dietary classification. Their occasional consumption of animal matter is a survival adaptation for essential nutrients when plant-based diets are insufficient. Such isolated incidents, when widely reported, can lead to confusion about the typical dietary habits of deer.