What's wrong with the four happy birds not breeding

The four happy birds may not reproduce because they have not yet matured, or they have not yet reached the breeding season.The breeding period of this bird is from April to July, and some will be August.It uses dry grass, grassroots, thin branches and other nests with pine needles and moss.After the nest is built, the female birds begin to lay their eggs. There are 4-6 pieces of each nest. After delivery, the male and female birds are hatched together. Generally, it takes 12-14 days. After that, the birds will be brought together.