THE ERECT POSTURE. 
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This has teen something of a problem. There are times when 
it precedes attack, and seems largely aggressive. At other times 
it precedes flight, and seems to "be primarily du® to the escape 
drive. Still other times, it seems obvious that both drives are 
highly activated. 
In fact, what we have been calling the Erect Posture probably 
includes the homologues of both the Upright Threat Posture and 
the "Anxiety Posture" of the Herring Gull. There seems to be no 
rigid division between the two in L. ridibundus . 
The Erect Posture would seem "Eo be primarily an intention 
movement of flying. This is shown by the raised carpi, the 
occasionally raised tail, and probably by the extended neck. 
On this basic "skeleton”, elements of both the attack and the 
escape drive may be superimposed. Elements of attack include 
facing or running toward the opponent, the downward pointing bill, 
the occasional inclining forward of the neck, and the thickening 
of the neck (?). Elements of the escape drive include facing 
away or running from the opponent, Head— flagging, the head bent 
away from the opponent, the bill horizontal, the neck feathers 
smooth, etc. 
