* Excitement - Cockatiels often rock back and forth when they are excited, such as when they are about to get a treat or when they see their favorite person. This is a normal behavior that is nothing to be concerned about.
* Nervousness - Cockatiels may also rock back and forth when they are feeling nervous or anxious. This could be due to a change in their environment, such as a new person or pet in the house, or it could be a sign of a medical problem. If you think your cockatiel is rocking back and forth due to nervousness, try to identify the source of the stress and remove it if possible.
* Illness - In some cases, rocking back and forth can be a sign of illness. If your cockatiel is also exhibiting other symptoms of illness, such as lethargy, loss of appetite, or diarrhea, it is important to take them to the vet to rule out any medical problems.
If you are not sure why your cockatiel is rocking back and forth, it is always best to err on the side of caution and take them to the vet for a checkup.