What's wrong with the sparrow buttocks sticky shit

Most of the sparrow butt sticky shit is related to diet. This will occur if you eat it clean. You need to change the feed in time.Because this bird lives in a place where humans gather, they also eat foods discarded by humans, and they have a relatively mixed food nature.It has a small body shape, but it is very widely distributed, and has good adaptability, and has a strong breeding ability. It will prey in insects during the brooding period, and at other times, plant seeds are eaten.