 Eye displays are made by exposing or covering the bare yellow patch behind the eye — when the feathers are completely <unk> the entire patch is visible , and when they are <unk> the patch is hidden . Eye displays are used in conjunction with postural displays , with the yellow patch fully displayed by dominant birds using threat <unk> , and immature birds tending to reduce the size of the eye patch when under attack from other members of the coterie . 
