What happened to the birthplaces of birds without breeding

There are many reasons why the birds do not reproduce. For example, there are problems with the gender of birds. One male and one mother must be paired. The second is the age of age.There is also a problem of climate, and the right season is more likely to make birds estrus.Usually it can produce 2-5 eggs per nest. After 13-15 days of incubation, the chicks will break out of the shell.