Why is the crow vomiting?

The crow vomits because I eat too much.Raising this bird requires a relatively large and solid bird cage, but it cannot be mixed with other birds in the cage, otherwise it is easy to be eaten by it.The water can in the cage must be iron, and the porcelain is easily damaged.Usually feed foods such as peas, wheat, sorghum, etc., but also with meat foam, corn surface, fruits, etc.In addition, the cage should be cleaned regularly, and the birds need to prevent the birds from running away during the period.