A bird’s digestive system differs from that of almost every other animal on the planet. As seen in the illustration below, birds have a crop, a gizzard, intestines and vent. Birds that make pets are prey animals which is why that have eyes on the side of their head. They have that design so they can see in almost all directions. Birds of prey/predators on the other hand like falcons and hawks have eyes front just like humans, cats, dogs, etc. Being a prey animal means you are always on the lookout to make sure that you don’t become someone’s lunch. For this reason, prey animals have to scarf their food quickly so they don’t become eaten themselves. Then they go off to a safe location and digest. When a prey bird eats, the food is swallowed in large portions, often whole which is stored in the crop. From there, like an assembly line, it gets passed to the gizzard which grinds up the food into a more viscous form. Then it enters the intestines to be absorbed by the body and the waste goes out the vent. The vent is the unilateral opening or hole that urine, feces and eggs pass through. Very convenient in terms of design, but like any design, it’s specific; Which means that it has advantages for making the bird lighter but disadvantages in the sense that if there’s one opening, numerous things can go wrong with any and all of the systems that utilize it.
