Trim. The mouth width of budgerigar only needs to be trimmed, and the trimming method is as follows:

1. First, hold the budgerigar's body with one hand and gently fix its head with the other. Be careful not to use too much force to avoid hurting the bird's neck.

2. Secondly, observe the budgerigar's mouth and determine the parts that need pruning. It is usually necessary to trim off the long tip or side of the mouth.

3. Then divide the pruning process into several times, and cut off a small amount of corners at a time. Cut off the budgerigar's mouth with scissors, and trim its cross section with grindstone and fine sandpaper to make it smooth.

4. Finally, after trimming the budgerigar's mouth, relax your arms and gently loosen your grip on the budgerigar to let it move freely.