The first is called the proventriculus or glandular stomach, where digestive enzymes are secreted to begin the process of digestion. ... The second part of a bird's stomach (a part we humans don't have) is the gizzard or muscular stomach.

What is a gizzard in a human?

This is the secretory part of the stomach. Then the food passes into the gizzard (also known as the muscular stomach or ventriculus). The gizzard can grind the food with previously swallowed stones and pass it back to the true stomach, and vice versa.

Where is the proventriculus located?

The proventriculus is a standard part of avian anatomy, and is a rod shaped organ, located between the esophagus and the gizzard of most birds. It is generally a glandular part of the stomach that may store and/or commence digestion of food before it progresses to the gizzard.