A comparative anatomical differences and similarities of the digestive tract in two birds with different food types (Aquila nipalensis and Columba livia)

The study aimed to identify the anatomical description and conduct a comparative study of the digestive tract in two types of birds that differ in nutrition, namely Aquila Nipalensis and Columba livia. The study showed the following results:
The digestive tract in the eagle is longer compared to the digestive tract in the pigeon due to the difference in body length, and begins in both types with the mouth surrounded by the beak from the front, and includes the oral cavity, pharynx and tongue, followed by the esophagus and the glandular stomach (anterior), followed by the muscular stomach (gizzard), small intestine, large intestine, rectum and ends with the cloaca.
The tongue is long, thin, and spear-shaped in pigeons and triangular in the eagle. The esophagus in the eagle is thicker and longer compared to the esophagus of the pigeon. The crop in the eagle has a single lobe, is spindle-shaped, and thick-walled compared to the pigeon, which has two lobes, is disc-shaped, and thin-walled. The glandular stomach of the eagle is elongated and larger than that of the pigeon, which is spindle-shaped. The gizzard is disc-shaped in pigeons, while it is cystic in the eagle. The small intestine of the eagle is longer than that of the pigeon. The duodenum is similar in both birds, forming two loops resembling the letter U. It shows the presence of a pair of caecums, which are short and undeveloped in pigeons and vestigial in the steppe eagle.