THREAT BEHAVIOR (on the Ground) , Three main types 
Pattern A. ERECT POSTURE# With (and sometimes without?) 
greatly thickened neck. Head-flagging. Bent head and neck. 
Sometimes this looks like a pure intention movement of attack; 
and it is sometimes the prelude to an actual attack. I think, 
however, that we must presume that Both the attack and escape drives 
are activated. Most of the time, for instance, an attack does not 
actually materialize after the E, During Mutual Displays and FB 
a gull in the E posture often runs away from its mate. During 
disputes a gull in the E posture sometimes runs away from its 
opponent. The HP and Bent Head, which seem intimately associated 
with the E posture, seem to "be avoidance movements; are are 
presumably activated by the escape drive. It seems obvious that 
the relative intensity of the attack and escape drives, in the E 
posture, varies considerably. This is indicated by, among other 
things, the varying thickness of the neck, and the varying angles 
at which the bill is held. 
Pattern B. LONG CALL. Characteristic call, Upward, and 
Forward. 
There might be some dispute as to whether the constituent 
elements of this behavior pattern should really be grouped together 
in this fashion. For instance, the call is sometimes uttered 
unaccompanied by any marked, ritualized, posture (always indicated 
by a rudimentary U?). Moreover, it might be argued that the 
Upward should not be separated from the Forward. It is true, 
of course, that the Upward is most conspicuous when performed by 
a bird on the ground toward a flying bird. At first, therefore, 
it would seem as if the Upward were merely a particular orientation 
of the Forward. Further consideration would seem, however, to 
render this hypothesis untenable. In the first place, a marked 
F succeeds the U, even when the display is directed at a flying bird 
Secondly, the U pattern often precedes or alternates with the F 
J when swimming birds are disputing among themselves on the water, 
y (in this case the head is held horizontal rather than tilted 
obliquely). We still do not know how frequently the U is directed 
$\ ~aby one gull on the ground toward another gull on the ground; 
\^ / ^( probably rather common, but usually hurried and cursory). 
Finally, the marked difference in the call3 associated with the U 
V * and the F would seem to indicate that they are distinct, if 
closely connected. (It is still possible, nevertheless, that 
orientation plays a part in determining which of these postures 
will be adopted at any given time). 
