Deer, widely recognized as plant-eaters, have occasionally been observed consuming animal matter. While primarily herbivores, their diet is not exclusively plant-based. This rare behavior challenges common perceptions and highlights their adaptability in the wild.
Understanding a Deer’s Usual Diet
Deer are ruminants, possessing a four-compartmented stomach system adapted for digesting fibrous plant materials. Their digestive process involves chewing cud, where partially digested food is regurgitated and re-chewed to break down tough plant cell walls. This system allows them to efficiently extract nutrients from a diet primarily consisting of browse, including leaves, twigs, and buds from woody plants.
Their typical diet also incorporates forbs (non-woody broad-leaved plants), fruits, nuts (mast), and grasses, depending on seasonal availability and geographical location. Their digestive system is designed for high-quality, easily digestible plant matter.
Explaining Occasional Carnivorous Behavior
Deer exhibit occasional carnivorous behavior primarily due to specific nutritional deficiencies, rather than a predatory instinct. This opportunistic consumption of animal matter helps them acquire essential minerals and proteins that might be scarce in their plant-based diet. Calcium, phosphorus, and protein are particularly important during periods of high physiological demand.
Male deer, for example, require substantial amounts of calcium and phosphorus for antler growth, with hardened antlers being about 22% calcium and 11% phosphorus. Pregnant and lactating does also have elevated protein and mineral needs to support gestation and milk production for their fawns. Plant sources, while providing energy, often lack sufficient concentrations of these nutrients, especially calcium.
When faced with these deficiencies, deer may resort to consuming various animal materials. This includes gnawing on bones, eating carrion, or consuming small animals like birds. Documented instances include deer eating bird nestlings directly from nests or even birds caught in mist nets. This behavior supplements their diet to meet specific metabolic requirements, particularly when natural forage quality is low, such as during winter months or in areas with nutrient-poor soils.
How Common is This Behavior?
While documented, the consumption of animal matter by deer is not a regular or primary component of their diet. Deer remain herbivores by classification, and their bodies are predominantly adapted for processing plant material. This behavior is considered exceptional and opportunistic, occurring under specific circumstances rather than being a consistent dietary habit.
Observations of deer eating birds or other animal matter are infrequent but have been recorded by researchers and through trail cameras. This dietary flexibility, though rare, underscores their ability to adapt to environmental challenges and nutritional stresses. It is a survival mechanism rather than a fundamental shift in their dietary nature.