[Bernard]

My budgie Sheik is about 5 months old. Nowadays he flies around my home from room to room. When he perches on one place I've noticed that he suddenly lifts one wing and starts chirping at it like he does when he is angry with something. He may even give it a little bite.
At first I thought his muscles were getting used to his flying so much but it has
been more then a month since he started flying.
What might it be?

 

[FaeryBee]

It's hard to say -- perhaps he is simply stretching his wing or perhaps that wing has been strained in some manner.

Have you examined his wing to see if there are any signs of visible injury?

 

[Bernard]

No. I've only looked at it while he sits on my hand, I mean, I haven't opened it up to get a good look.

Might it be the sharp feathers that first come out when molting?

Could it be mites?