V 
HEAD -BOBBING DURING FOOD-BEGGING. 
The usual preliminary of copulation is mutual Food-begging. 
The typical, complete, Food-begging behavior of the male is as 
follows. He begins begging with his neck retracted and his head 
quite low. Gradually, however, he begins to bob his head up and 
down. With each succeeding bob, his head usually goes a little 
higher. Finally he mounts the female. 
Last year we came to the conclusion that the increasing height 
of the males’ head, at the climax of each upward bob, was an 
intention movement of mounting. It certainly usually precedes 
mounting. Support for this hypothesis is given by the following 
example. "A male runs after a female, who is running up and down 
the territory. He Food-begs constantly, in a very low posture. 
Whenever he catches up with her he begins Head-bobbing.” 
There may, however, be another explanation of the male’s 
Head-bobbing during begging. What is usually considered typical 
Food-begging behavior, as exhibited by juvenal gulls of both sexes 
and usually be adult females, is probably a mixture of two 
different behavior patterns: the submissive posture and ’’pure” 
Food-begging. The submissive posture is characterized by the low 
carriage of the head, "hunched-up” on the shoulders. It is often 
seen, at least among young gulls, without Food-begging. 
Food-begging itself is characterized by Head-bobbing and the 
typical "kri" call. 
Gull chicks, below a certain age (exactly what age?), beg 
with pronounced Head-bobbing. Juvenal birds beg in the submissive 
posture. Adult females also usually beg in the submissive posture; 
but sometimes, especially at the beginning of the performance, 
they may utter the Food-begging call when in the Erect Posture, 
or they may beg with definite Head— bobbing. This latter can hardly 
be considered in any way an intention movement of mounting. 
Certain unusual examples of male Food-begging behavior may 
also throw some light on this problem. We have several times seen 
a male mount a female, after having begged in the submissive 
posture with no sign of Head-bobbing. We have seen this in the 
case of both successful and unsuccessful copulations. It is strange 
that a male would actually mount the female without showing any 
trace of the presumed intention movement of mounting. 
Is it not probable, therefore, that the gradually increasing 
Head-bobbing of the male prior to copulation is "revealed" by the 
disappearing submissive posture? (This latter posture is 
presumably the result of an activated escape drive;. 
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