Salivary glands located here, secrete a very limited amount of amylase, which hydrolyses starch to maltose, and maltase which hydrolyses maltose to glucose. The salivary glands main purpose is to lubricate the bolus, which is the portion of food swallowed at one time, so that it can move down the digestive tract. Very little digestion takes place in the mouth because food passage is so fast. Chickens lack a soft palate in their mouths and the hard palate is divided by a long, narrow slit in the center, opening into the nasal passage. This opening and the lack of soft palate makes it impossible for the bird to create a vacuum to draw water into the mouth, therefore the bird has to scoop water when drinking and then let it run down the gullet by gravity.
Beaks become colored due to deposits of carotenoid pigments, collectively known as xanthophylls.
Laying birds can divert this pigment to the egg yolks which results in their beaks bleaching out. Birds with short beaks are generally seed eaters. The Esophagus , or the gullet, is the main tube that connects the mouth to the crop and the crop to the proventriculus. The esophagus secretes mucus which further lubricates the bolus and aids in swallowing. The Crop is a modification of the esophagus which forms a pouch that can store food when the bird is eating rapidly.