Rabbits eat their own soft droppings, called cecotropes, to absorb essential nutrients their bodies cannot extract on the first pass.

This biological process is called cecotrophy, a form of hindgut fermentation. Rabbits have a large organ called the cecum, roughly ten times the size of their stomach, containing a complex ecosystem of bacteria and enzymes that break down tough plant cellulose into digestible nutrients. Since fermentation occurs at the end of the digestive tract, many nutrients would be lost without re-ingestion.Cecotropes differ markedly from normal hard fecal pellets. They are soft, moist, and coated with a protective mucus layer that shields bacteria from stomach acid during the second pass. Research from the University of California, Davis has shown that these pellets contain high concentrations of vitamin B12 and vitamin K, along with essential amino acids that rabbits cannot synthesize on their own.If a rabbit cannot consume its cecotropes, it rapidly becomes malnourished and may develop severe digestive problems. This behavior typically occurs at night or early morning, which is why it is rarely observed by casual observers. It is an evolutionary adaptation that enables rabbits to thrive on low-quality forage in the wild, ensuring that almost no nutritional value from their food is wasted.