proprijoreceptive . The two best examples I have of this are 
mentioned in the repoot. The business about deriving the 
cormorant's "wing flapping" display from the both-wlngs-stre tch 
hasn't much to recommend it except ingenuity. I don't think 
I believe it myself, 
°n the matter of displacement activities I have found n 
several examples of their occurrence in "low Intensity" situations. 
I remember you once asked Fae about something I had suggested 
about their occurrence in these circumstances as if it were 
not to be expected. I don't think there is much reason to 
believe there is any general rule about d. activities appearing 
only when the motivation i3 strong. The hostile ne3t quivering 
in the shag is the activity I have paid most attention to 
with this in mind and there I have no doubt that it expresses 
a lower Intensity than the shake gaping which comes near to 
being Intention movements. Preening of the mate also occurs 
when a bird is insuf f iciently motivated to mount but not 
because there is any strong conflict. 
By the way you say somewhere in your thesis that the 
thick neck of the b-fi gull is due to tension in the epaxial and 
hypaxial muscles. I wonder do you still think so and why. 
We have examined the neck anatony of several gull and it seems 
most unlikely that tension in the neck muscles is could 
produce any appreciable swelling of the neck. But we don t 
know if you conclude this from dissection or not. On the other 
hand erection of the neck feathers certainly could produce such 
an effect and from Bather's observations in the kittiwake 
is almost certainly responsible in that species. This is supported . 
by the position of the groove in the neck in such a thick- 
necked bird which seems to correspond with the apteria on 
the sides of the neck. This seems to v/ork in the kittiwake 
and herring gull where there are photos which s$ow the position 
of the groove rather well but I don't know yet about the b-h gull. 
In the choking of the b-h gull you concluded that there 
were several elemdnte which were not derived from nest building 
including raising of the ventral feathers, depressing of the 
tongue bone, and opening and shutting of the cloaca. Are the 
"ventral feathers" the same ones as those erected when ^ preparing 
to brood ? From your own picture it looks rather as if tnis 
is not so. In any case in the kittiwake and herring gull a 
close examination suggests that the main feathers which seem to 
be raised are the lateral flank feathers and that they are 
passively moved by the shift in relative position of the bird s 
body and legs as it tilts forwards. About the hyoid Esther 
thinks that this may ('almost ?)always be depressed when the 
bird utters a call. Certainly it seems to be in most of the 
photos of the herring gull in Niko's book. Of course when tne 
"bill is opened the effect won't be so strong but Plates 2a and 9 
seem rather convincing, for example. Finally do you know that 
the gull's cloaca doesn't open and close when any call is uttered j 
