Deer are herbivores and specialized ruminants, meaning their digestive systems are built to process large quantities of plant matter like grasses, forbs, shrubs, and trees. While consuming feces (coprophagy) is rare and outside their normal diet, it does occur. These occasional instances are not driven by preference but by specific biological needs or survival instincts.
Why Deer Seek Out Feces
The primary driver for coprophagy is addressing a nutritional deficiency, often a lack of specific minerals or salts. Deer, like other grazing animals, require a complex balance of macro and micro-minerals for health, including zinc, copper, manganese, and selenium. When natural forage is depleted or lacks these elements, especially during harsh winters or in areas with poor soil quality, deer seek alternative sources.
Feces, particularly from other herbivores, can contain undigested grains, seeds, and leftover nutrients that the original animal did not fully absorb. This scavenging behavior is an adaptive strategy to access supplemental energy and minerals scarce in the environment. White-tailed deer, for instance, have been observed engaging in heterospecific coprophagy (consuming waste from a different species).
Consumption of waste from domestic livestock, such as cattle or horses, is tempting because the feces often contain remnants of high-salt feed or mineral-enriched pellets. However, this action carries risks, as consuming the feces of other animals can expose deer to parasites and diseases. The need for essential minerals often outweighs the risk when the animal is nutritionally stressed.
Post-Parturition Consumption of Afterbirth
A specific form of consumption occurs immediately following the birth of a fawn, a behavior known as placentophagy. The mother (doe) instinctively consumes the placenta and other birth materials. This act is biologically distinct from the general search for minerals and serves two primary survival purposes.
Nutritional Recovery
The first purpose is nutritional recovery. The placenta is rich in proteins, vitamins, and minerals transferred from the mother to the developing fetus. Consuming this material allows the doe to quickly reabsorb essential nutrients and calories lost during labor and delivery. This rapid replenishment is important for a nursing mother.
Predation Avoidance
The second purpose is predation avoidance for the vulnerable newborn fawn. The afterbirth, along with any blood or fluids, carries a strong scent that can easily attract predators to the birth site. By consuming the placenta, the doe removes the physical evidence and the powerful odor, reducing the likelihood that a coyote, bear, or other predator will locate the defenseless fawn. This maternal cleaning behavior ensures the immediate safety of her offspring.