What's wrong with waxing birds without breeding?

There are many reasons for waxing birds that do not reproduce. It may be that they are less than age, or they may be the same, or they have no breeding nests.The breeding period of this bird is from May-June each year. It will build the nest on the branches. The shape is deep cup-shaped, and the inner wall is relatively smooth. It is usually composed of hair, tender branches, and roots.It can produce 3-4 eggs without noise, the color is blue, with spots on it.