Rabbits are foraging herbivores, eating mostly grass and weeds. But this fibrous, cellulose rich diet isn’t the easiest to digest, and by the time their dinner has make it through their intestines it still contains many of the nutrients the bunnies need.
Rabbits and hares beat this problem with a special kind of digestion called hindgut fermentation. In short, they eat their own poop and digest it a second time. Bunnies actually make two different kinds of droppings: little black round ones and softer black ones known as cecotropes that are eaten. This process is known as coprophagy, and functions the same as cows chewing their cud.
It’s very important for a rabbit’s digestive system to keep moving fluidly, as they need to re-ingest their cecotropes in order to get the nutrients they need. If anything gets stuck in a bunny’s esophagus or intestines, they’re out of luck, since they’re incapable of vomiting.