Difference between digestive system of mammal and bird?

The digestive system of mammals typically includes a single-chambered stomach, where food is broken down and nutrients are absorbed in the intestines. In contrast, birds have a unique two-part stomach consisting of the proventriculus, which secretes digestive enzymes, and the gizzard, which grinds food, often aided by ingested stones. Additionally, birds possess a cloaca, a multifunctional cavity for excretion and reproduction, while mammals have separate openings for these functions. Overall, these adaptations reflect their differing dietary needs and feeding habits.