intensively. As you will have guessed there is a reason for 
her objections. She wants to derive choking from the movement 
of depositing nest material in a relatively pure state without 
the complications of superimposed broodiness or ksx sex or what 
have you. At any rate she can talk herself into believeing this 
in the kittiwake and wonders how far it may be true in the 
other species too. Incidentally we have seen this movement of 
depositing nest material in the herring gull where its form 
is much as in the kittiwake but instead of being repeated a 
number of times, only a few jerks are made at the most. This 
seems partly to be due to the kittiwake 1 s nest material 
being more sticky and partly to some intrinsic (dare I sey innate) 
difference. 
£ou will have heard that head flagging has been seen 
now in the herring and lesser black backed gulls. I don t know 
if Fae told you that the herring gulls have a well developed 
greeting ceremony: mew call, choBking, head flagging. Back to 
the herring gull indeed 1 We don t have time to watch it properly 
but • black headed gull work has put us onto lots of things 
— * 
which are at once obvious. 
A 
Does the b-h gull tend to go to Its nest or a potential 
nest site to choke 0 It looks very much like it in this greeting- 
choking in the herring gull and Esther thought that this migat 
be a sort of peason vhy the kittiwake, who of course stays on 
his nest site all the time when hi Is on his territory, should 
use choking for the song. 
Well this should raise enough bones of contention - ^ to mix 
a metaphor - to get us along for, a time. I'm sorry we can't 
talk it over as we should probably get aiaxa; your ideas more 
excECtly, and I dare say there are many provocative things in 
Esther s report you would like to know more about. A hen you 
can find time to write we'll see what we can do to satisfy your 
doubts and curiosity. 
