Deer are widely regarded as gentle creatures that subsist solely on plants, a perception rooted in observations of them grazing. This often leads to the assumption their diet is exclusively plant-based. However, a deer’s dietary habits are more complex. This article explores what deer consume, examining whether they ever deviate from their typical plant-based fare.
What Deer Primarily Eat
Deer are primarily herbivores, meaning their diet is overwhelmingly composed of plant matter. Their natural forage includes browse (leaves, twigs, and tender shoots of woody plants), forbs (non-woody, broad-leaved plants), and mast (nuts and fruits like acorns, berries, and apples). This diverse plant-based diet changes seasonally, with deer adapting their consumption to the availability and nutritional content of different plants throughout the year.
A deer’s digestive system is specifically adapted for processing fibrous plant material. As ruminants, deer possess a four-chambered stomach, including a large rumen where plant matter undergoes fermentation. Microorganisms in the rumen break down tough cellulose, converting it into usable nutrients. This specialized digestion allows them to extract maximum nutrition from their plant-based diet.
Deer are often described as “concentrate selectors” due to their preference for highly digestible and nutrient-rich plant parts. While they may consume grasses, particularly young, tender shoots, grasses generally constitute a smaller portion of their overall diet compared to browse and forbs. This selective feeding strategy ensures they obtain sufficient energy and protein, especially during periods of high metabolic demand like antler growth or gestation.
Instances of Animal Consumption
Despite their predominant herbivorous diet, deer have been observed consuming animal matter. These instances are opportunistic behaviors, not typically part of their regular dietary strategy. Documented examples include eating shed antlers, gnawing on bones, consuming bird eggs, or ingesting small rodents, insects, or carrion.
The primary motivation behind these unusual dietary choices is often to supplement specific nutritional deficiencies. Consuming bones and antlers can provide essential minerals like calcium and phosphorus, especially when scarce in their plant-based diet. Animal matter also offers a concentrated source of protein, sought during periods of stress, harsh winters, or pregnancy and lactation when nutritional demands are high.
These behaviors highlight deer’s adaptability in securing necessary nutrients when primary plant sources are insufficient. While documented, they are not a regular component of a deer’s daily intake. Animal matter consumption is typically a response to environmental pressures or specific physiological needs, rather than an inherent dietary preference.
Classifying Deer Diet
To classify a deer’s diet, understanding the biological definitions of herbivores and omnivores is important. A herbivore’s diet consists exclusively or primarily of plant material. An omnivore’s natural diet regularly includes both plant and animal matter as fundamental components of its nutrition.
Based on these definitions, deer are classified as herbivores. Their digestive system, foraging behaviors, and the vast majority of their dietary intake are adapted for plant consumption. While instances of deer consuming animal matter do occur, these are generally considered anomalous behaviors driven by specific, often temporary, nutritional deficiencies.
Such opportunistic consumption of animal material does not redefine deer as omnivores, as it is not a regular, inherent, or necessary part of their long-term dietary strategy. These behaviors are exceptions, serving as a means to acquire scarce nutrients when plant-based sources are insufficient. Therefore, despite these occasional deviations, deer remain firmly categorized as herbivores.