What happened to the parrot vomiting food

There are three reasons for parrot vomiting.The first is to feed the young birds. When the parrot young bird was born, there was a lack of predation. Therefore, it was fed by the parent, and the birds would spit out what they eaten to eat the young birds.The second is intestinal inflammation. After the birds are sick, they often vomit white or green liquid, and they are not mentally weak.The third is to eat too much. This situation occurs. Generally, the birds will control the amount of food by themselves.