6 February 57 
Zoo Dept. 
Dear Martin, 
Herewith, at last, another copy of the Grongigen 
stuff - for what good it may do you. I would be glad 
to have back the copy of the notes on the G m T conference 
after you have finished with them. There probably won t 
be many ooints of interest to you there I t-ciink, which you 
haven't heard before. The summaries of the confe '.nee talxs 
you may keep if you want to. 
Many thanks for your last letter, a very prompt 
reoly to mine. Niko sent on toe second oart 0.1 toe gull 
paper for Behaviour without showing it to anyone • here - 
indeed without our even knowing it was here - ^which ms 
rather maddening, but we shall see it soon. So^I lD a * ra ^ 
I can't send any comments on it - nice or nasty . 
In your last letter you ask me to avoid using tne 
word food-begging to desribe a certain display in tne terns 
but you don't say why and l'm not sure if understand. Is 
it because it you want a 
(or causal) name ? I am rather reluctant to change what 
p e eras to me such a convenient name unless you have a very 
strong reason, but I get the Impression from your language 
that you have. 
I was very glad to get the iniorma tion a oout 
the begging, sorry the "begging", of Gull-billed, Inca 
and Noddy Terns. , 
The Jensen paper is 1945, Dansk Orn. Foren. Tldskr. 
40:80-96. (Danish with English summary). 
I hope you will answer the question about the 
Upright Threat which you see in some terns, wnich l as, red 
in my letter of 1 Aug 56 . I nm still at a loss to know 
whether this is a real difference between your spp and 
mine or whether I am not recognising something which you 
call the upright threat. I realise tht there is ® real 
possibility of the secand alternative for even in the gulls 
I suspect that you recognise it whereas others dont. 
E.g. in winter D. Franck (Vogelwelt \95V) saw no sign of 
any uoright in B— h G s whicn he watcaed cind Gil. oert xuanley , 
who is trying to follow on your work here on the B-h G, 
has also been watching them in London and ean t see it. 
In addition Franck never saw Choking while Manley has seen 
it only once, in exactly the "right" circumstances when 
a very aggressive male was suddenly resxisted by another. 
This choking business fits nicely with you Interpretation, 
but the lack of uprights doesn't seem to fit unless they 
are completely overlooking theta. 
About the development of calls in gulls you 
will have seen Goethe s paper in the Z.f lerpsychol. on 
the Herring Gull. He seems to start from two calls and 
some of these develop into calls of the adni t.e 
