 <unk> displays include tall and low poses , pointing , open bill , and wing waving . The ' tall posture ' is used when in close contact with another bird and is a mild threat . The bird holds itself upright with neck and legs stretched , and it faces the other bird . The ' low posture ' is a submissive gesture ; the bird sits low on the perch with legs obscured by <unk> feathers and often faces away from the other bird . Fledglings threatened by adult birds will adopt a low posture and open their bill widely . ' Pointing ' is a threat display where the bird stretches out horizontally , with feathers <unk> and the bill pointed at the target of the aggression . A bill snap will sometimes accompany pointing . An ' open bill display ' is used by subordinates in encounters between two birds , and by a female on the nest when other birds approach . The ' trident bill display ' involves a fully open bill with the tongue raised and protruding and is a higher @-@ intensity submissive display . ' Wing waving ' is often performed at the same time as an open bill display . The wings are <unk> and held slightly away from the body , and <unk> out and up around three to six times . Wing waving may be accompanied by a yammer call . ' Eagle ' displays involve holding the wings and tail spread out , in either a vertical or horizontal position . 
