While it may seem unusual to humans, the consumption of feces is a natural and often beneficial behavior observed across various animal species. This practice, known as coprophagy, serves diverse biological purposes, highlighting animal adaptation and survival strategies.
Understanding Coprophagy
Coprophagy is not a single, uniform act, but encompasses different categories based on the source of the ingested fecal matter. Autocoprophagy refers to an animal consuming its own feces. This is distinct from allocoprophagy, which involves an animal eating the feces of other individuals, either from its own species or from different species.
Reasons for Feces Consumption
Animals engage in coprophagy for several biological and behavioral reasons, primarily driven by nutritional needs and gut health. One significant motivation is nutrient recovery, especially for herbivores with less efficient digestive systems. They re-ingest partially digested food to extract additional nutrients not fully absorbed during the initial pass.
Another reason is microbial re-inoculation, which helps establish or replenish beneficial gut bacteria. This is particularly important for young animals whose digestive systems are still developing, as they acquire necessary microbes from adult feces to break down complex plant matter. For instance, foals consume maternal feces to establish fibrolytic bacteria essential for digesting fiber.
Animals may also consume feces to acquire specific compounds, such as vitamins B and K, which are often produced by gut bacteria and can be found in fecal matter. These vitamins might not be readily available in their regular diet or are better accessed through this method. Coprophagy can also be a parental behavior, where adult animals eat the feces of their young to keep dens clean and reduce disease-causing pathogens, protecting vulnerable offspring from parasites.
Coprophagy can also serve as a survival strategy, particularly in times of scarcity. When food sources are limited, consuming feces can provide residual nutrients, enabling the animal to maximize its energy intake. This behavior can also help conceal an animal’s presence from predators by removing tell-tale waste.
Animals Known to Consume Feces
Many animals engage in coprophagy, each for specific reasons tailored to their biology and environment.
Rabbits and hares practice cecotrophy, a specialized form of coprophagy where they re-ingest nutrient-rich fecal pellets called cecotropes. These soft, mucus-coated pellets are produced in the cecum, a part of their digestive system, and contain essential proteins, fatty acids, and B vitamins that would otherwise be lost.
Dung beetles are well-known for their dependency on feces, which serves as both a food source and a place to lay eggs. They primarily consume the liquid and undigested plant matter in the droppings of herbivores and omnivores. By burying and consuming dung, these beetles play a significant role in nutrient cycling and keeping environments clean.
Dogs sometimes consume feces, a behavior that can stem from various factors. While occasionally linked to nutritional deficiencies or medical conditions, it can also be an instinctual behavior, perhaps to keep den areas clean or as a scavenging behavior when food is scarce. Puppies may also engage in it out of curiosity or by mimicking their mothers.
Hamsters and guinea pigs, like rabbits, are hindgut fermenters that practice cecotrophy to recover nutrients and vitamins like B and K. Their digestive systems process fibrous plant material, and consuming these droppings ensures they absorb the maximum nutritional value from their diet.
Young elephants and other herbivores often consume the feces of their mothers or other herd members. This behavior is crucial for acquiring the necessary gut microbes to digest plant matter, as their intestines are not born with these bacteria. It helps establish a healthy digestive system as they transition from milk to a plant-based diet.
Primates, including some apes like gorillas, have also been observed engaging in coprophagy. While less common, it can occur for reasons such as nutrient recovery from partially digested food, especially when diets are low in quality, or to maintain gut health. In captive settings, boredom or social stress have also been suggested as potential contributors to this behavior.