What happened to the baldness without breeding

Blackwhal is not sexually mature or not reached the reproductive period, naturally does not breed, and breeding must be mated first and one mother, so that female birds will lay their eggs, otherwise the female will be an ovulation that has not been fertilized even if they spawn.This bird is breeding in April to July each year. It usually builds the nest across the branch or trunk branch. Each nest has 4-6 pieces. The color is blue and gray, and there are spots on it.