The reasons why the cockatiel nods up and down:

1. The cockatiel is hungry. The cockatiel, which cannot speak during the lactation period, will nod up and down when it is hungry. It hopes to attract the attention of its mother and owner through this strange behavior.

2. Courtship. Eight-month-old cockatiels are in estrus. They want to attract the attention of the opposite sex by nodding up and down, which is a courtship behavior.

3. Choked. If your cockatiel nods up and down shortly after feeding it, it is most likely that it is choking on the food and is trying to relieve this symptom by nodding its head up and down.

4. When you are happier. Cockatiels will also nod up and down when eating, and they will also nod up and down when receiving rewards. This is because cockatiels are very excited.

5. When you are frightened. When a cockatiel is frightened, it will involuntarily nod up and down to relieve its emotions.