1, see what's the difference between the hairs on the birds' heads:
Beizi birds and males like to erect their hair, that is, crested hair; The mother of Beizi bird has no crest.
The picture below shows the male pigeon bird.
The picture below shows the mother shell bird.
2. See if Beizi Bird has bench legs:
The male bird has bench legs under his chin, while the female bird has no bench legs.
3. Look at the difference between the tail length and the head of Beizi bird:
Beizi bird has a longer tail and a bigger head; The mother bird is short-tailed and small.
The picture below shows the male pigeon bird.
The picture below shows the mother shell bird.
This is the way to distinguish between male and female shellfish.