Taste receptor cells (TRCs) in the mouth act as gatekeepers for feeding behaviour.Taste system in man and animals has evolved to serve as leading regulator of feeding behaviour in animals. The feeding behaviour is a natural trait, a beneficial attribute for their survival. Gustation is a specialized chemosensory system that detects nutritionally relevant and harmful compounds in food. Otopeterin (OTOP1), an ion channel, regulates the flow of proton currents in acid-sensing taste receptor cells. OTOP1 is evolutionary conserved and expressed in various tissues, indicating a broad physiological role. Sour taste likely evolved in ancient fish and has not been lost in most of the vertebrate species, including birds. Valence reaction to acidic food varies with some species; some are more tolerant to sour taste so they like it and some dislike. Canaries are more acid-tolerant than pigeons. It is now known that tastes to sweet, bitter, sour, umami, and sodium are mediated by a separate set of taste receptor cells. Sour tolerance or in other words, taste preference for sour food, provides survival advantages to birds, avoiding competition on the same fruit.