You are right, Nooey, the chest feathers do quiver and that is normal as is the holding up one foot clenched. That is how they rest their feet, one at a time.
I don't know what else you are asking, Zohair, so give us a little more information, or ask a specific question.
And please do introduce yourself in the welcome room, let us know a little more about you and your greys, and post a picture if you have one.