Quan sát da gốc mỏ của chim yến phụng. Nhận biết chim yến phụng trống. Nhận biết chim yến phụng mái. Xem xét tuổi của chim yến phụng. Hiểu rằng sẽ gặp phải các khó khăn nhất định khi phân biệt giới tính bằng màu sắc.

I'm interested in that, but I only have a few mins. Can you give me at most the first 500 characters of a detailed explanation in English about that?
The cere is a fleshy covering which is located directly above its beak. The budgie's nostrils are found on the cere (they look like two in-depth holes) making the cere easy to find. While most budgie's beaks are a yellowish color, the cere is a certain color depending on the bird's sex. Most male budgies in the breeding mood have a bright or royal blue cere. Sometimes, the vibrant color can appear purple-blue. This color will lighten when the budgie is not in the breeding mood. If you've identif