Their eyeballs aren't as moveable as ours. In the birds you have mentioned, their eyes are also at the side of the head. Their eyes, food intake system (beak/mouth - wasn't sure of the correct terminology), airway and sinuses take up most of the head so they eyes don't have much movement. It's a bit of a look around - body catches up, look around, body catches up, repeat thing. Or it's a look around, not happy, retract the head and go the other way or fly away sort of thing.