How old is the three treasures that can have eggs

The three treasure birds started to calculate from the young birds and can only breed in the third year.Its reproduction period is from May to August. It usually runs on the nest of the coniferous mixed forests, and occasionally uses a woodpecker's abandoned cave for nests.This bird can breed a nest a year. Each nest has 3-4 eggs, white in color, and smooth surface.After spawning, the male and female birds will incubate in turns. After the shell is out of the shell, the parent will start breeding.