I do a great deal of paintings of birds, and am working on a painting of an eagle right now. Because of this, I do a lot of bird studies, trying to get the attitude down. If you do a lot of bird watching, you will notice that birds DO have attitudes. I had a run-in with a mockingbird once that bordered on psychotic! I happened to live in her territory, and she took great pride in defending it by dive-bombing my head every time I came home. She took a few tufts of hair out of my cat with strafing missions designed to scare off the enemy.
Hummingbirds have a lot of personality as well. The ones I feed this year are very demanding, and if they run out of nectar they let me know by hovering at my back window and peering in. I have a Carolina Wren who has consistently taunted me with her flippy little tail, bouncing about me like a ball when I go outside.
So you can see that it takes a lot of work to discover the attitude of the bird you are about to paint or draw. I do dozens of sketches to get to know them, and try to show that attitude in my finished piece. Whether it is a dignified stance or a defensive one, all birds have 'personality'.