Deer are widely recognized as common herbivores, primarily grazing on vegetation. While their diet overwhelmingly consists of plant matter, the answer to whether they consume insects or other non-plant items is complex. Deer exhibit a surprising degree of dietary flexibility, and their food choices are ultimately driven by immediate nutritional requirements.
Occasional Insect Consumption
Deer are highly opportunistic and selective feeders, meaning their diet is not strictly limited to plants. They occasionally consume insects, such as grasshoppers, though this is typically incidental to regular foraging. Insects contain high concentrations of protein and fat, which can be appealing when primary food sources lack quality.
Instances of deer intentionally consuming insects, bird eggs, or small animals are rare but documented. This usually links to periods of nutritional stress, such as harsh winters or droughts. This behavior supplements a diet temporarily deficient in certain nutrients, particularly protein. An invertebrate may be consumed accidentally while browsing, or sometimes deliberately when the nutritional incentive outweighs herbivorous instincts.
Deer as Ruminants: The Typical Herbivorous Diet
Despite the occasional consumption of invertebrates, deer are classified as ruminants. They possess a specialized four-chambered stomach designed for processing plant matter. The largest chamber, the rumen, uses fermentation by microorganisms to efficiently break down cellulose and complex carbohydrates found in vegetation. This digestive system is perfectly optimized for a diet of easily digestible shoots, leaves, forbs, and soft twigs, which are higher in quality than the fibrous grasses eaten by many other ruminants like cattle.
Because of their relatively smaller rumen capacity, deer are highly selective feeders, choosing the most nutritious and palatable plant parts available. Their anatomy, including a narrow snout and long tongue, allows them to browse selectively for the best forage. This specialization reinforces that the bulk of their sustenance comes from vegetation, and their system is not suited for digesting large quantities of animal protein.
Other Unexpected Items in a Deer’s Diet
The opportunistic nature of deer extends beyond insects when specific minerals are scarce. A well-documented behavior is osteophagia, the act of chewing on bones or shed antlers. This action is driven by a strong need for calcium and phosphorus, which are necessary for bone and antler growth, as well as for pregnant or lactating does.
In extreme cases, deer have been observed consuming small carrion, dead fish, or the nests of ground-dwelling birds to acquire these hard-to-find minerals. For example, deer have been seen gnawing on the bones of sea turtles or sampling dead alewives washed up on lake shores. This flexibility illustrates that while deer are primarily herbivores, they are not strictly vegetarian when survival or the requirement for specific nutrients dictates otherwise.