My cockatiel always stretches her wings straight up in the air. She does it always when I walk over to her too. She isn't tame yet so I don't know what she's doing.

My cockatiel, Ash, isn't tamed either but the only time he stretches his wings is when he's either flying around the bathroom during a taming sesion or is stretching them in the cage. He hisses if I get close.

But she's probably trying to fly away or make herself look bigger so you don't eat her.