Gizzard is a muscular organ of the digestive system of birds and a few other animals. It breaks up and grinds hard, solid foods. The gizzard in birds is associated with the stomach and is lined with thick, tough plates. The breakdown of food in the gizzard is aided by gravel that the bird has swallowed. Food enters a pouch of the gullet called the crop and is moistened there. It passes from the crop to the glandular part of the stomach, where it is mixed with gastric juices. The food then passes into the gizzard, where it is crushed by the movements of the muscular walls and the gravel. Gizzards of grain-eating birds are well developed, and those of fruit-eating birds are often poorly developed.
